Accepted Manuscript

Geochronology and geochemistry of late Paleozoic magmatic rocks in the Yin-

waxia area, Beishan: Implications for rift magmatism in the southern Central

Asian Orogenic Belt

Rongguo Zheng, Tairan Wu, Wen Zhang, Qingpeng Meng, Zhaoyu Zhang

PII: S1367-9120(14)00189-8

DOI: http://dx.doi.org/10.1016/j.jseaes.2014.04.022

Reference: JAES 1938

To appear in: Journal of Asian Earth Sciences

Received Date: 2 December 2013

Revised Date: 21 April 2014

Accepted Date: 23 April 2014

Please cite this article as: Zheng, R., Wu, T., Zhang, W., Meng, Q., Zhang, Z., Geochronology and geochemistry

of late Paleozoic magmatic rocks in the Yinwaxia area, Beishan: Implications for rift magmatism in the southern

Central Asian Orogenic Belt, Journal of Asian Earth Sciences (2014), doi: http://dx.doi.org/10.1016/j.jseaes.

2014.04.022

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1

Geochronology and geochemistry of late Paleozoic magmatic rocks in the Yinwaxia area,

Beishan: Implications for rift magmatism in the southern Central Asian Orogenic Belt

Rongguo Zheng a, Tairan Wu a, Wen Zhang b, Qingpeng Meng a, Zhaoyu Zhang a

a MOE Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space

Sciences, Peking University, Beijing 100871, China

b Institute of Geology, Chinese Academy of Geological Sciences,

Beijing 100037, China

Corresponding author:

Tairan Wu

MOE Key Laboratory of Orogenic Belts and Crustal Evolution

School of Earth and Space Sciences

Peking University

Beijing 100871

China

Tel. +86 10 62765534

Email: twu@pku.edu.cn

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Abstract: Mafic-ultramafic rocks are distributed widely in the Beishan rift, which is located

in the southern Beishan, central southern Central Asian Orogenic Belt. The Yinwaxia study

area is located in eastern Beishan rift, where mafic-ultramafic rocks occur along major faults.

The zircon SHRIMP U-Pb age obtained of a gabbro is 281±11 Ma, and the age of the basalt is

constrained by the youngest xenocrystal with an age of 265 Ma, which substantiate that these

mafic rocks formed in Permian. Basalts and gabbros exhibit similar geochemical

characteristics including: high SiO2, total Fe2O3 and TiO2 contents; low MgO contents and

Mg# values; and tholeiitic characteristics. Yinwaxia mafic rocks have relatively high total

rare earth element contents, enrichment in light rare earth elements, enrichments in the high

field strength elements, and obvious negative Nb-Ta-Ti anomalies. Basalts exhibit low

(87Sr/86Sr)i and high εNd(t) values, while gabbros exhibit relatively high (87Sr/86Sr)i and low

εNd(t) values. Isotopic compositions of these mafic rocks display a mixed trend between

depleted and enriched mantles. Meanwhile, differing εNd(t) values show that basalts were

intensively contaminated by juvenile crustal materials, but gabbros were contaminated by

older continental crust. We conclude that Yinwaxia mafic rocks were derived from

lithospheric mantle metasomatized by fluids and/or melts from subducted slab; parental

magmas underwent AFC processes, then emplaced along faults in a continental rift. We

collected geochemical and geochronological data in the study area, and collated

geochronological data from previous workers in the Beishan orogenic belt to develop a

geochronological frequency diagram. From these data and analyses we deduced a model of

tectonic evolution for the Beishan orogenic belt. Considering the geochemistry,

sedimentological evidence for rifting, and the geochronological frequency diagram, we

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propose that the Beishan rift had entered a post-collision stage since Early Devonian, and

then changed into a continental rift stage around late Carboniferous-early Permian.

Key words: Beishan, mafic rocks, SHRIMP, Sr-Nd isotope, continental rift, Central Asian

Orogenic Belt

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1. Introduction

The Central Asian Orogenic Belt (CAOB) is the largest area of Phanerozoic continental

accretion and crustal growth in the world (Sengör et al., 1993; Jahn et al., 2000; Kovalenko et

al., 2004; Windley et al., 2007). The CAOB extends from Kazakhstan in the west to eastern

Siberia in the east (Fig. 1), and separates the Siberian craton in the north from the Tarim and

north China (or Sino-Korean) cratons in the south (Zonenshain et al., 1990; Mossakovsky et

al., 1994; Jahn et al., 2000; Badarch et al., 2002). There is a general consensus that the CAOB

grew by successive lateral accretions of arcs, accretionary complexes and a few continental

blocks southward from Siberia and southern Mongolia during the evolution of the

Paleo-Asian Ocean (Windley et al., 2007; Kröner et al., 2008; Xiao et al., 2009, 2013;

Safonova and Santosh, 2014.). Although the timing of the final closure of the Paleo-Asian

ocean is still a matter of debate, accumulating evidence suggests a diachronous closing

process which resulted in many and diverse tectonic regimes in the late Paleozoic within this

immense accretionary orogenic belt. After the amalgamation, the CAOB was affected by

continental magmatic activities and modified by intracontinental orogenic reactivations

(Windley et al., 1990; Wartes et al., 2002; Khain et al., 2003; Kröner et al., 2007, 2010).

The late Paleozoic was an important period of tectonic transition and crustal growth of

the CAOB; the crustal growth is represented by large volumes of juvenile granitoids with

positive εNd and low initial (87Sr/86Sr)i values (Han et al., 1997; Jahn et al., 2000; Chen and

Jahn, 2004). However, this period was also characterized by emplacements of many coeval

mafic-ultramafic complexes having controversial origins (Hong et al., 2003; Han et al.,

2004; Zhou et al., 2004; Zhao et al., 2006; Windley et al., 2007; Mao et al., 2008; Pan et al.,

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2008; Pirajno et al., 2008). One group of these late Paleozoic mafic-ultramafic complexes

occurs in the the Beishan orogenic belt, located in the middle region of the southernmost

CAOB (Fig.1a). The Beishan orogenic belt has many Cu-Ni-bearing mafic-ultramafic

complexes, especially in the southern portion of the belt (Mao et al., 2008; Pirajno et al.,

2008; Zhang et al., 2008). Most of these mafic-ultramafic rocks crop out along regional

large-scale faults or sutures, such as mafic rocks in the Pobei and Liuyuan areas. Chemical

and isotopic compositions of continental mafic rocks provide the best proxy record for the

chemical and physical evolution of the deep continental lithosphere and underlying mantle

(Farmer, 2003). Mafic–ultramafic rocks can also provide valuable information for

unraveling the geological history of orogenic belts. Although many researches have

focused on mafic-ultramafic rocks in the southern Beishan as noted above, there are still

controversies regarding their tectonic implications of these rocks.

Mafic-ultramafic complexes in the southern Beishan are usually described as the

products of within-plate magmatic activity (Jiang et al., 2006; Mao et al., 2008; Pirajno et al.,

2008; Zhang et al., 2008), formed as a result of post-orogenic extension or plume related

magmatic process (Qin et al., 2011; Su et al., 2011a, 2011b, 2012b). Conversely, it has also

been suggested that these mafic-ultramafic complexes are Alaskan-type intrusions, generated

in the early Permian subduction-related environment (Xiao et al., 2004a; Mao et al., 2006; Ao

et al., 2010). Alternatively, some workers have argued that mafic complexes in the southern

Beishan were associated with a mantle plume that resulted in Permian flood basalts in the

western part of the Tarim block (Qin et al., 2011; Su et al., 2011a, 2011b, 2012b). This work

certainly will provide crucial insights into the mechanism of orogenesis and tectonic history

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of the southern Beishan.

In light of these conflicting theories, we present new geochronological, and major and

trace element data, as well as whole rock Sr-Nd isotopic compositions, for the mafic rocks in

the Yinwaxia area, in the eastern sector of southern Beishan. To provide further insight into

the mechanism of orogenesis and tectonic history of the southern Beishan orogenic belt, we

also complied the geochronological data previously reported in the literature to describe

magmatic sequences of the Beishan rift. From this large data set, we endeavored to define

tectonic settings of mafic rocks in the Yinwaxia area, discuss the formation mechanism, and

develop a reasonable tectonic evolution model.

2. Geological background

The Beishan orogenic belt, situated in the southernmost CAOB, is a conjunction

region of the CAOB and North China and Tarim cratons (Fig. 1a). It is separated from the

Tianshan orogenic belt to the west by the Ruoqiang-Xingxingxia fault, and from the

Mongolia-Xing’anling orogen to the east by the Altyn Tagh-Alxa fault. The Dunhuang

block, part of the Tarim craton (Zhang et al., 2013), is located to the south of the Beishan

orogenic belt (Zhou and Graham, 1996; Wu et al., 1998; Zhang et al., 2011a). Tectonically,

the Beishan orogenic belt is often regarded as the eastern extension of the Chinese Tian

Shan (Li, 1980; Liu and Wang, 1995; Xiao et al., 2010), and it comprises an assemblage of

blocks, magmatic arcs and ophiolitic mélanges formed by subduction-accretion processes

of the Paleo Asian Ocean. The Beishan area exhibits well-preserved Neoproterozoic to late

Paleozoic sequences with intervening ophiolitic zones, and most workers usually divided

the orogenic belt into three sub-belts (southern, middle, and northern) by Xiaohuangshan

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and Niujuanzi-Yueyashan ophiolitic belts, which are southern, middle and northern Beishan

(Zuo and He, 1990). The southern Beishan belt is composed of Precambrian strata,

Paleozoic volcanic-sedimentary formations, and magmatic intrusions. The upper Paleozoic

strata in the southern Beishan are all terrestrial (GSBGMR, 1966), in contrast to the other

two belts. The southern Beishan belt is separated from the middle Beishan belt by the

Niujuanzi-Yueyashan ophiolite zone. The middle Beishan belt is characterized by early

Paleozoic volcanic-sedimentary formations and magmatic intrusions, usually regarded as

having resulted from early Paleozoic subduction events (Zuo and He, 1990; Dai et al., 2003;

Ao et al., 2010). The middle Beishan belt is separated from the northern Beishan belt by the

Xiaohuangshan ophiolitic zone. The northern Beishan belt is relatively complex, and is

further subdivided into two zones by Hongshishan ophiolitic belt. The northern zone is

mainly composed of lower Paleozoic and magmatic intrusions, however, the southern zone

of the northern belt is characterized by Carboniferous strata and late Paleozoic granitoids.

The Beishan rift is located in the southern Beishan belt, bordering on the Dunhuang

block to the south. The Huaniushan arc is located to the north of the Beishan rift, and

bounded by the Gubaoquan-Hongliuyuan shear zone (Fig. 1b; BGMRXUAR, 1993; Xu et

al., 2009). The Beishan rift is mainly composed of Carboniferous-Permian strata and

magmatic intrusions. Fault-related uplifts and sags are well developed in the rift, and the

contact between each pair of strata from Precambrian to Permian is separated by faults (Xu

et al., 2009; Su et al., 2012b). The Beishan rift is characterized by exposures of numerous

mafic-ultramafic complexes, most of which host Ni-Cu sulfide ore deposits.

Mafic-ultramafic complexes such as Poshi, Hongshishan, Bijiashan and Liuyuan

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complexes, are mainly distributed in the western and central part of the Beishan rift, and

intrude the Proterozoic and Carboniferous strata, (Jiang et al., 2006; Qin et al., 2011; Su et

al., 2011 a, 2011b; Zhang et al., 2011a).

The Yinwaxia area, in which we collected new data, is located in the eastern part of the

Beishan rift (Fig. 1b). Strata exposed in the Yinwaxia area are mainly Paleozoic, including

upper Silurian, Devonian, Carboniferous and Permian, and the Permian strata are

distributed most widely (Fig. 2). The upper Silurian strata in the Yinwaxia area are

composed of massive volcanic rocks: basic volcanic rocks dominate the lowest sequence,

though the topmost sequence comprises bimodal volcanic rocks, including amygdaloidal

basalts and rhyolites (GSBGMR, 1966; Liu et al., 1999). These Silurian basic and acidic

volcanic rocks display interbeds, similar to rift-related rock associations. The Permian

strata distributed across the southern Beishan include the Shuangbaotang group, the Jinta

group (the lower Permian) and the Fangshankou group (the upper Permian). The

Shuangbaotang group mainly consists of clastic rocks, including sandstones, pebbly

sandstones, limestones, bioclastic limestones. The Jinta group mainly consists of basalts,

andesitic basalts, and andesites with siliceous slate and phyllite interlayers. Permian strata

in the Yinwaxia area are domanited by the Fangshankou group, which consists

predominantly of felsic volcanic and pyroclastic rocks with eruption-explosion facies,

including rhyolites, dacites, rhyolite breccia lavas, rhyodacites and homogeneous volcanic

tuff. Mafic rocks occur rarely in the Fangshankou group. Additionally, there exist terrestrial

plant fossils and other terrestrial materials in the Fangshankou group. Geochemical studies

of volcanic rocks in the Fangshankou group demonstrate that they are bimodal volcanic

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rocks, and formed in a continental rift setting (Liu et al., 1999), and features of Permian

sedimentary strata also support the existence of a Permian continental rift. Late Paleozoic

granitoids are distributed widely in the Yinwaxia area, and typical examples are biotite

granites in the southern Yinwaxia pluton and monzonitic granites in the Xijianquanzi

pluton. Previous studies prove that these late Paleozoic granitoids exhibit positive εNd(t)

and εHf(t) values, implying additions of depleted mantle (or a juvenile component) in their

evolution. These granitoids were mixed products of crustal and mantle derived magmas,

and formed in an extensional tectonic setting (Zhang et al., 2010, 2011b, 2012).

3. Field occurrence and petrography

Mafic-ultramafic rocks exposed in the Yinwaxia area include basalts, gabbros, and

ultramafic rocks (Fig. 2; GSBGMR, 1966). Basalts comprise the upper part of the Permian

strata, and the remaining mafic-ultramafic rocks were emplaced into Paleo-Proterozoic

strata.

The Yinwaxia area ultramafic rocks intruded into the Paleo-Proterozoic strata as an

apophysis, including serpentinites and pyroxenites. The mineral assemblages of the

serpentinites are mainly serpentine (75–80%), calcite (10–15%), spinel (5–10%) and

magnetite (1–5%); they display microscopic crystalloblastic texture and scales

crystalloblastic texture microscopically. Mafic rocks in the Yinwaxia area include basalts

and gabbros. Yinwaxia area gabbros also intruded into the Paleo-Proterozoic strata. They

are dark–light green, and exhibit medium-grained gabbroic texture. The main mineral

assemblages of the gabbros are clinopyroxenes and plagioclase, and they also contain

minor amphibole, chlorite, magnetite and ilmenite. Many clinopyroxenes underwent

10

intensive amphibolitizations, and plagioclases were usually altered to chlorites. Basalts are

a main component of Permian strata in the Yinwaxia area, and display massive structures.

These basalts also show porphyritic textures with phenocrysts of plagioclase and pyroxene

(0.1–0.2 mm in size) set in a groundmass of plagioclase microlites, granules of pyroxene,

and glass.

4. Analytical methods

4.1 SHRIMP zircon analyses

Separations of zircon crystals were accomplished by conventional heavy liquid and

magnetic techniques. The individual crystals were mounted in epoxy together with the

TEMORA standard zircons, and then polished to approximately half thickness. Then the

zircons were photographed in reflected and transmitted light as well as SEM

cathodoluminescence (CL) images which were all taken at Peking University to study the

internal structures in order to identify the suitable target for spot analysis.

U-Pb isotopic ratios of zircon crystals were measured using the SHRIMP II in the

Beijing SHRIMP Centre, Institute of Geology, Chinese Academy of Geological Sciences,

Beijing, China. Instrumental conditions and measurement procedures are the same as those

described by Compston et al. (1992). Spots of approximately 20μm-diameter were

analyzed. Data for each spot were collected in sets of five scans. The 206Pb/238U ratios of

the samples were corrected using reference zircon of TEMORA (206Pb/238U = 0.06683; 417

Ma). The data were corrected for common Pb on the basis of the measured 204Pb. The

decay constants and present-day 238U/235U value given by Steiger and Jager (1977) were

used. Uncertainties given for individual analyses (ratios and ages) are at 1σ level whereas

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the uncertainties in calculated weighted mean ages are reported as the 95% confidence

level. Concordia plots and weighted mean age calculations were carried out using

ISOPLOT/Ex 3.23 (Ludwig, 2003). The SHRIMP U-Pb data are reported in Table 1.

4.2 Whole-rock geochemical analyses

The major, trace and rare earth elements (REEs) were analyzed at the Laboratory of

Orogenic Belts and Crustal Evolution, Peking University. Rock samples for whole rock

analyses were crushed and then pulverized in an agate mill. Whole rock major elements

were analyzed by X-ray fluorescence (XRF) on fused glass beads, following the analytical

procedures of Li et al. (2006) and the analytical precision is within 0.1%. Trace elements

were analyzed using Inductively Coupled Plasma Mass Spectrometer (ICP-MS), following

the technique of Li (1997). About 50 mg of powder from each sample was dissolved in

high-pressure Teflon bombs using a HF+HNO3 mixture. The analytical precision for the

common trace elements was superior to 5%, while that of Nb and Ta was superior to 10%.

Analytical results are listed in Table 2.

Analyses for Sr and Nd isotopes and Sm, Nd, Rb, and Sr concentrations were

performed at the Institute of Geology, Chinese Academy of Geological Sciences (IGCAGS),

using the Solid Isotope Mass Spectrometer MAT-262 from German Finnigan Corporation.

Analytical procedures are described in detail by Yang et al. (2010). During analysis, the

NBS-987 standard yielded an average value of 87Sr/86Sr=0.710274±11 (2σ) and the JMC

standard yielded an average value of 143Nd/144Nd=0.512096±12 (2σ). Mass fractionation of

Sr and Nd isotopes were corrected by 86Sr/88Sr =0.1194 and 146Nd/144Nd = 0.7219. During

analyses, the backgrounds of Rb-Sr and Sm-Nd were 100-300 pg and 50-100 pg,

12

respectively. Analytical results are listed in Table 3.

4.3 Mineral composition analyses

Clinopyroxenes were analyzed using a JEOL JXA-8100 wavelength dispersive

electron microprobe at Peking University. The operating conditions were 15 kV

acceleration voltages with 10 nA beam current and a beam diameter of 1 μm. Analytical

results are listed in Table 4.

5. Analytical results

5.1 Geochronology

Zircons from the basalt sample (Y-14) have wide ranges of U (79-500 ppm), Th

(24-198 ppm) contents and high Th/U ratios (0.23-1.04), which are characteristics of

magmatic zircons (Belousova et al., 2002；Wu and Zheng, 2004). Two older 206Pb/238U age

(1693.7Ma and 2181.9Ma) were obtained, and the other eight analyses yield 206Pb/238U

apparent ages of 267.4~314.3Ma. In the CL images (Fig. 3), zircon grains from the basaltic

sample display high variable characteristics. Some of them are similar to those in gabbro

(i.e. 8.1), and some resemble the magmatic zircon in felsic rocks (i.e. 5.1, 6.1 and 7.1).

Different zircon morphologies indicate that most of them (if not none of them) were not

formed during basaltic magmatism, but are xenocrystals captured by basaltic magma

during its eruption. Thus, the age of the basalt should be constrained by the youngest

xenocrystal (~265 Ma, i.e. late Permian), and this is in agreement with the field occurrence.

Zircons from the gabbro sample (Y-5) are mostly euhedral and short columnar. Their

CL images (Fig. 3) show that they display light color, and parallel banded patterns,

composed of light and dark bands, which are typical characteristics of zircons from gabbros

13

(Jian et al., 2003). They have wide ranges of U (63-511 ppm), Th (43-213ppm) contents

and high Th/U ratios (0.14-0.86), which are characteristics of magmatic zircons (Belousova

et al., 2002；Wu and Zheng, 2004). Two older 206Pb/238U age (1729.7Ma and 1902.6Ma)

were obtained, and the other seven analyses yield 206Pb/238U apparent ages of

264.9-297.3Ma, with a weighted mean age of 281±11 Ma (MSWD=3.4, n=7) (Fig.3).

5.2 Whole-rock geochemistry

5.2.1 Basalts

The Yinwaxia basalt samples have high SiO2 contents ranging from 46.38 to 54.15

wt. %, and plot in the andesitic basalts and andesite fields on the Nb/Y-Zr/TiO2 diagram

(Fig. 4a). The MgO contents and magnesium number (Mg#) values are low (3.14—4.29

wt. % and 36.13—47.59, respectively), suggesting evolving magma. These samples also

have relatively low total alkali contents (Na2O+K2O=2.66—6.71 wt. %), and higher Na2O

contents (mostly K2O/Na2O=0.30—0.95). They also have relatively low Al2O3 contents

(13.03—14.74 wt. %), similar to that of tholeiitic basalts. In addition, they have relatively

high total Fe2O3 (10.40—14.11 wt. %, mostly>12 wt. %), TiO2 (2.01—2.88 wt. %) and

P2O5 (0.68—1.10 wt. %) abundances, which accord with characteristics of high Fe-Ti basic

rocks around the world (FeOt >12 wt. % and TiO2> 2 wt. %; Clague and Bunch, 1976;

Clague et al., 1981; Perfit and Fornari, 1983) around the world. In the AFM ternary

diagram (Fig. 4b), these basalts exhibit tholeiitic characteristics.

These basalts exhibit consistent rare earth elements (REEs) characteristics. They have

high total REEs contents (177.89–195.03ppm), and display enrichments in the light REEs

(LREEs) relative to middle REEs (MREEs) [(La/Sm)N=1.92–2.38] and heavy REEs

14

(HREEs) [(La/Yb)N=3.63–3.97]. There are essentially no Eu anomalies (δEu=0.93–0.99),

indicating rare affections of plagioclase fractional crystallizations. In the

Chondrite-normalized REE diagram (Fig. 5a), these basalt samples have similar LREEs

contents to that of the ocean island basalt (OIB), but higher MREEs and HREEs contents.

Overall, the Yinwaxia basalts have relatively flat REE patterns compare with OIB.

In the Primitive mantle-normalized multi-element diagram (Fig. 6a), basalt samples

display obvious depletions in the Nb-Ta-Sr-Ti-La-Ce suite. In addition, they have high field

strength element (HFSE) contents which are similar to those of OIB, but higher than those

of mafic rocks from the Tarim Large Igneous Province (TLIP), the Columbia River basalts

and average continental arc rocks (Farmer, 2003; Kelemen et al., 2004; Tian et al., 2010).

The Yinwaxia basalts also have higher HREE contents than those of the TLIP, Columbia

River, and average continental arc rocks. Relative to HFSEs, there are no obvious

enrichments in the large ion lithophile elements (LILEs, e.g., Cs, Rb, Ba, Pb, and Sr).

5.2.2 Gabbros

Compared with the basalts, Yinwaxia gabbro samples have higher SiO2 contents

(50.37–55.62 wt. %), MgO contents (5.13–6.32wt. %) and Mg# values (50.41–61.49). They

also have low total alkali (Na2O+K2O=1.94–5.73 wt. %), CaO (5.60–9.36 wt. %) and Al2O3

contents (13.63–16.06 wt. %). However, the gabbros have relatively low TFe2O3

(8.72–11.08 wt. %), TiO2 (1.32–2.16 wt. %) and P2O5 (0.21–0.36 wt. %) contents. In the

Nb/Y-Zr/TiO2 diagram (Fig. 4a), Yinwaxia gabbro samples plot in the andesite field, and

display tholeiitic characteristics (Fig. 4b) in the AFM diagram.

The Yinwaxia gabbro samples have lower total REE contents (94.69–122.76 ppm)

15

than the basalts. Similarly, they also display enrichments in the LREEs relative to MREEs

[(La/Sm)N=2.03–2.72] and HREEs [(La/Yb)N=2.99–3.75]. These gabbro samples display

slight negative Eu anomalies, δEu=0.77–0.91, indicating a slight effect of plagioclase

fractional crystallization. Compared with OIB, these gabbros have higher HREE contents,

and display flatter REE patterns in the Chondrite-normalized REE diagram (Fig. 5b).

In the Primitive mantle-normalized multi-element diagram (Fig. 6b), Yinwaxia

gabbros display depletions in Nb, Ta, Ti, La and Ce and enrichments in Cs, Rb, U, Pb and

Th. They have lower HFSE content than that of basalts, which is a similar pattern to that of

mafic rocks from the Tarim Large Igneous province (TLIP) and Columbia River basalts.

Relative to HFSEs, there are also no obvious enrichments in LILEs.

5.3 Whole-rock Sr-Nd isotopic composition

Whole-rock Rb-Sr and Sm-Nd isotopic compositions for mafic rocks in the Yinwaxia

area are listed in Table 3, and plotted in Fig. 7. Initial 87Sr/86Sr and 143Nd/144Nd ratios were

calculated using 280 Ma for gabbros, and 260 Ma for basalts. The gabbros have initial

87Sr/86Sr ratios ranging from 0.706739 to 0.707990, and εNd(t) ranging from −3.42 to −0.68.

The basalts have lower initial Sr isotopic [(87Sr/86Sr)i=0.703774–0.705322], but higher εNd(t)

values (4.69–7.28). In Fig.7, samples plot in the ocean island basalts (OIB) field, indicating

a mixing trend between depleted mantle and EM2 (enriched mantle type II).

5.4 Clinopyroxenes mineral chemistry

Major element analyses of clinopyroxenes from the YInwaxia gabbros are reported in

Table 4. Plots of Alz (percentage of tetrahedral sites occupied by Al) vs. TiO2 in augite from

gabbroic and ultramafic cumulates show that augite data arrays for arc-related cumulates

16

have a trend of substantially higher Al/Ti in clinopyroxene than that of rift-related tholeiitic

rocks (Loucks, 1990). All clinopyroxenes in gabbros from the Yinwaxia study area plot

along the rift-related trend (Fig. 8a). In the discrimination diagram (Fig. 8b), all the

analyzed clinopyroxenes fall in the compositional fields for the plume-influenced basalts

from Iceland and within oceanic plate basalts, distinct from subduction-related settings.

6. Discussion

All the rocks in this study underwent strong alteration, consistent with high loss on

ignition (LOI) values (1.60-4.92 wt. %). Therefore, the major and trace element

geochemistry described here is based on immobile elements during low-temperature

alteration and metamorphism up to the greenschist facies (Beccaluva et al., 1979; Pearce

and Norry, 1979; Shervais, 1982). Generally, those immobile elements include Al, Ca, Mg,

high field strength elements (e.g. Th, Zr, Hf, Nb, Ta, Ti,Y) and REE including Sm-Nd

isotopic system.

6.1 Fractional crystallization and crustal contamination

No systematic variation trend within the different rock types can be observed in

covariations of some selected major elements and their ratios against MgO. In contrast, the

good correlation of most of the elements with MgO suggests that common processes

controlled the compositions of the different rock types. In particular, positive correlations

between CaO, CaO/Al2O3 and MgO support the fractionation of clinopyroxene. TFe2O3

and TiO2 are generally negatively correlated with MgO in all the rocks, suggesting that

Fe-Ti oxides played an important role in their evolutions. The presence of phenocrystic

plagioclase in most samples also supports significant early crystallization of this mineral,

17

which would account for the coherent negative Sr anomalies observed (Fig. 6), although

this seems nominally inconsistent with the absence of obvious negative Eu anomaly in the

REE patterns (Fig. 5). Frey et al. (1993) and Xu et al. (2001) have interpreted this

phenomenon to result from high Eu3+/Eu2+ ratios in magmas because Eu2+ is compatible

with plagioclase, whereas Eu3+ is not. It follows that relatively little Eu may be lost during

fractional crystallization of plagioclase in a system with a high oxygen fugacity.

Element covariations suggest that clinopyroxene and plagioclase should be the

principal fractionating phases in these mafic rocks. Some fractionations of Fe-Ti oxides

also occurred.

Crustal contaminations could potentially increase SiO2, K2O, Zr, Hf, Th, Cs, Rb and

Ba abundances and La/Nb and Zr/Nb ratios, but decrease Ti/Yb and Ce/Pb ratios in mafic

magmas (Campbell and Griffiths, 1993; Barker et al., 1997; MacDonald et al., 2001). It is

possible to use ratios of highly incompatible elements in mafic rocks to determine these

ratios in their mantle source regions, given that elements having similar Kds produce

incompatible element ratios that are independent of the degree of partial melting of the

mantle source or the amount of subsequent magmatic differentiation (Hanson, 1989;

Hofmann, 1997). In addition, Nb is one of the high field strength elements (HFSEs), and

generally has low concentrations in the crust. Though La is typically enriched in the crust,

Th is commonly enriched in sediments. Therefore, the high (Th/Nb)N ratio (＞1) and low

Nb/La ratio (<1) are two reliable indicators for crustal contamination (Saunders et al., 1992;

Xia et al., 2007). (Th/Nb)N ratios of Yinwaxia mafic rocks range from 1.51 to 3.90, larger

than 1, and their Nb/La ratios range from 0.0029 to 0.084, far away less than 1. In addition,

18

Ti/Y ratios vary from 168 to 307, slightly higher than those of bulk continental crust and

Archean bulk crust (160 and 187, respectively; Taylor and McLennan, 1985). Yinwaxia

mafic rocks also exhibit low Nb/U (7.43–15.42) ratios, similar to that of continental crust

(8.45, Sun and McDonough, 1989). All these ratios indicate that Yinwaxia magmas might

have experienced some degree of crustal material contamination. Trends of crustal

contamination also appear on the basis of the correlation between εNd(t), Nb/La and Mg

number. It is concluded that Yinwaxia mafic rocks experienced some degree of crustal

assimilations.

6.2 Characteristics of magma sources

Sr and Nd isotopic ratios are usually used for discrimination of mantle sources.

Mixing between Depleted Mantle (DM) and Enriched Mantle I (EM1) or Enriched Mantle

II (EM2) will produce a negative trend and OIB-like components in a plot of (87Sr/86Sr)i

versus εNd(t) (Zinder and Hart, 1986). Sr-Nd isotopic compositions of all the Yinwaxia

rocks have typical OIB-like signatures, and clearly show a mixing trend between DM and

EM2 components in the genesis of the magmas (Fig. 7). In addition, several previous

studies have attributed the mantle heterogeneity, especially the formation of an EM2

reservoir, to subduction-related modification (e.g., Zindler and Hart, 1986; Rollinson, 1993;

Turner et al., 1997; Zhou et al., 2004; Su et al., 2012b). Because the EM2 mantle

component is considered to be a mantle contaminated by subduction-related modifications

(Weaver, 1991; Greeough at al., 2005), it appears that mantle sources of mafic rocks in the

Yinwaxia area were intensively depleted and variably enriched by subduction slab-derived

components. In fact, previous studies have proved the existence of Paleozoic subduction

19

events. Previous studies (Mao et al., 2012; Su et al., 2012a; Zheng et al., 2012) discovered

numerous Paleozoic subduction-related indicators, such as late Ordovician Nb-enriched

basalts (451 Ma) in the Liuyuan area (Mao et al., 2012). Therefore, there might be an early

Paleozoic arc (Fig. 1b; Xiao et al., 2010) and the early Paleozoic subduction process could

have variably modified mantle sources beneath the Beishan rift.

Though both basalts and gabbros were significantly contaminated by crustal

materials, they exhibit very different εNd(t) values (Fig 7), which could be ascribed to the

different crustal materials incorporated into the primitive magmas of mafic rocks (Zhang

and Zou, 2012). Contamination by old crust could quickly decrease εNd values of the mafic

rocks, while contamination by juvenile crustal materials would have a weak influence on

the εNd values (Zhang and Zou, 2012). Therefore, we suggest that Yinwaxia basalts were

intensively contaminated by juvenile crustal materials, while Yinwaxia gabbros were

contaminated by the old continental crust further, supported by the fact that gabbros intrude

into the Paleo-Proterozoic, which comprises of migmatite, metavolcanic rock, and gneiss.

Previous studies (Zhang et al., 2010, 2011b, 2012) show that post-collisional and A-type

granitoids with ages of 280–250Ma are widely exposed in this region (Fig. 1b). Sr-Nd

isotopic compositions of Yinwaxia basalts display a mixing trend of magma derived from

depleted mantle with magma forming coeval A-type granites (Fig. 7). Therefore, we

speculate that these basalts were contaminated by parental magmas of coeval A-type

granites.

We conclude that Yinwaxia mafic rocks were derived from lithospheric mantle

metasomatized by fluids and/or melts derived from subducted slab materials. Parental

20

magmas underwent clinopyroxene, plagioclase and Fe-Ti oxide fractionations. In addition,

basalts were contaminated by parental magmas of coeval A-type granites, while gabbros

were contaminated by the older continental crust, and these different contaminants led to

different Sr-Nd isotopic characteristics.

6.3 Tectonic setting

In the Primitive mantle-normalized multi-element diagram (Fig. 6), Yinwaxia mafic

rocks display obvious negative Nb-Ta-Ti anomalies, similar to those of magmatic rocks

formed in a subduction zone. Compared to compositions of average continental arc rocks, it

is clear that LILEs of the Yinwaxia mafic rocks are lower, while their HFSEs are obviously

higher (Fig. 6), indicating that their mantle sources are totally different from those of

arc-derived magmatic rocks. However, the Yinwaxia mafic rocks exhibit trace element

characteristics similar to those of continental flood basalts having crustal contamination.

Because of crustal contamination, continental flood basalts generally exhibit negative

Nb-Ta-Ti anomalies, and positive Pb-Rb-Ba-Th-U anomalies, similar to basalts derived

from subduction settings (Kelemen et al., 2004). As discussed above, Yinwaxia mafic rocks

experienced crustal assimilation, which caused negative Nb-Ta anomalies. In addition,

because oxidation-reduction and aqueous solutions of melting sources in the

subduction-related setting are different from those of other tectonic settings, we can use

some trace elements ratios and covariant relationship diagrams between related elements to

distinguish within plate basalts and subduction-related basalts (Pearce and Norry, 1973;

Shervais, 1982; Rollinson, 1993). In the tectonic setting discrimination diagrams (Fig. 9),

21

Yinwaxia mafic rocks exhibit different characteristics than basalts in the arc setting, and are

instead similar to that of basalts generated within-plate.

Granitoids are distributed widely in the southern Beishan, especially in the Yinwaxia

area, most notably including the Yinwaxia and Xijianquanzi granites. The Yinwaxia pluton

has a LA-ICP-MS U-Pb age of 281.7±2.9Ma, similar to that of the Yinwaxia mafic rocks.

The pluton mainly consists of biotite granites which belong to the middle-K, calc-alkaline

series with metaluminous-peraluminous characteristics and high SiO2 and (Na2O + K2O)

contents; samples invariably exhibit relatively small Chondrite-normalized light rare earth

element (LREE) enrichments with flat heavy rare earth elements (HREE), weak negative

Eu anomalies, with depletion of Nb, Ba, P, and Ti and enrichment of Rb, Pb, and K in their

primitive mantle-normalized trace elements patterns (Zhang et al., 2010, 2011b). Yinwaxia

pluton rocks exhibit positive εHf(t) (4.4–7.8) and εNd(t) (0–1.3), and their isotopic data

emphasizes the importance of the depleted mantle (or juvenile component) in its genesis.

The Yinwaxia granites are the mixed products of crustal and mantle derived magmas and

formed under an extensional tectonic setting in the Early Permian. The LA-ICP-MS zircon

U-Pb age of the Xijianquanzi granite is 266.1±2.2 Ma, and εHf(t) values are positive,

1.3–4.7. The Xijianquanzi granitoid mainly consists of monzonitic, alkali-rich, high

potassium granites with some “A-type like” granite characteristics, e.g., high 10000×Ga/Al

values and weakly V-shaped Chondrite-normalized REE patterns. Chemical characteristics

of the Xijianquanzi granitoids indicate that they were mixed products of crustal and mantle

derived magmas, and were formed in a rift setting in an extensional period. Studies of these

granitiods in the Yinwaxia area suggest an extensional setting, and that these granitiods

22

with positive εHf(t) or εNd(t) values formed with strong crust-mantle interactions, similar to

other voluminous CAOB granites with positive εHf(t) or εNd(t) values (Han et al., 1997; Wu

et al., 2000, 2002; Chen and Jahn, 2004; Hong et al., 2004; Jahn et al., 2004).

The Permian strata distributed extensively in the southern Beishan developed

numerous faults with NE strike orientation. As noted in section 2, volcanic rocks in the

Fangshankou group are bimodal and formed in a continental rift setting (Liu et al., 1999).

Sedimentary formations of the Permian strata also support the existence of a Permian

continental rift in the Yinwaxia area. In addition, cherts occur along the regional faults (Fig.

1b), suggesting a relatively extensive Permian continental rift.

Considering the geochemical data of the Yinwaxia mafic rocks and the coeval

granitoids, and the characteristics of the Permian sedimentary formations, we conclude that

the Yinwaxia mafic rocks were formed in a continental rift, rather than a subduction setting.

6.4 Tectonic implications

The Beishan orogenic belt is considered to be a typical and key area for understanding

the formation and tectonic evolution of the central southern Altaids (the CAOB) between

the Tianshan and Inner Mongolia (Ao et al., 2010; Xiao et al., 2010; Guo et al., 2012). The

CAOB underwent a complex Paleozoic evolution including amalgamation of many

disparate tectonic terranes, and some fundamental tectonic problems have remained

unsolved, especially for the Beishan rift (Ao et al., 2010; Liu et al., 2011; Su et al., 2011a, b,

2012b; Zhang et al., 2011). To better understand the tectonic evolution of the Beishan rift,

we made a geochronological frequency diagram (Fig. 10) using published zircon ages, and

23

from this developed a tectonic evolution model of the Beishan rift (Fig. 11). The age data in

the frequency diagram (Fig. 10) were collected from mean and concordant ages of

magmatic (mostly) and metamorphic rocks in the Beishan rift and its adjacent region. Only

zircon ages measured by more precise analytical methods were compiled for Fig. 10 (Table

5), such as LA-ICP-MS, SHRIMP and SIMS zircon U-Pb ages. Rock types included in the

Fig. 10 are ultramafic rocks, mafic-ultramafic rocks, granitoids, dacites, rhyolites and

eclogites. In constructing the plots of Fig. 10, we quote the 206Pb/238U age for zircons,

instead of their mean or concordant ages, and filters were applied to screen out results with

unacceptably large analytical errors and unacceptable discordance. Based on these age data

quoted, we developed the relative probability plot of magmatic zircons from Paleozoic

rocks of the Beishan rift (Fig. 10), and from this plot, we obtained four peak ages,

including 534Ma, 450Ma, 415Ma and 282Ma.

The peak age of 534 Ma mainly reflects ages of ophiolitic mélanges. Dating results of

cumulate gabbros in the Hongliuhe ophiolite suggest it formed 516 ± 7 Ma (Zhang and Guo,

2008). In the eastern part of the same ophiolitic belt, the Yueyashan ophiolite was formed

in the early Cambrian, with a SHRIMP U-Pb age of 533±1.7 Ma (Ao et al., 2012). This

ophiolitic belt is the oldest one in the Beishan orogenic belt, and their geochemical

characteristics of these ophiolites suggest affinities with SSZ-type ophiolites (Ao et al.,

2012; Zheng et al., 2012). From these data we conclude that the major ocean, as a branch of

the Paleoasian Ocean represented in the Beishan orogenic belt, was formed in the

Precambrian (Fig. 11a), and that some micro-continental blocks might have been

distributed in this ocean, such as the Mazongshan and Hanshan blocks. Subduction of

24

intra-oceanic lithosphere generated the Hongliuhe-Yueyashan ophiolite in the period

533–516Ma.

Subduction between the Mazongshan and Dunhuang blocks continued and generated

various magmatic and metamorphic rocks (Fig.11b) with peak ages of 450Ma (Fig. 10).

Previous studies reported that U-Pb isotope analyses of zircons from the Liuyuan

Nb-enriched basalts and dacites yielded concordant ages of 450.5±3.9 Ma and 441.8±3.1

Ma, respectively. Petrogenetic studies show that the Nb-enriched basalts resulted from

partial melting of mantle wedge peridotites, which were previously metasomatized by

adakites (Mao et al., 2012). A narrow eclogite zone was reported along the boundary

between granitic gneisses and paragneisses in the Gubaoquan-Liuyuan area (Liu et al.,

2002), and the U-Pb dating of the Gubaoquan eclogites indicates an Ordovician age of c.

465 Ma for the eclogite facies metamorphism. Petrologic studies proved that eclogites

started as oceanic crust in the Palaeoasian Ocean, which was subducted to eclogite depths

in the Ordovician (Qu et al., 2011). Occurrences of early Paleozoic eclogites, Nb-enriched

basalts and arc-related dacites prove progressive subduction in the southern Beishan area

during the early Paleozoic (Liu et al., 2011; Zhang et al., 2011; Mao et al., 2012).

In the Beishan rift, there developed a series of Silurian-Devonian post-collisional

granitoids whose ages form a peak age of 415Ma in the geochronological frequency

diagram (Fig. 10), including the Shuangfengshan A-type granite (415±3Ma, Li et al., 2009),

the Huitongshan A-type granite (397±3Ma, Li et al., 2011) and high potassium

calc-alkaline granitoids (396-436 Ma, Zhao et al., 2007) in the Liuyuan area. The

Shuangfengshan A-type granite is the oldest A-type granite in the Beishan rift yet

25

discovered (Li et al., 2009). Previous studies suggest that these granitoids were formed in a

post-collisional setting, and resulted from partial melting of continental crust owing to the

under-plating of the mantle-derived magma related to slab break-off (Zhao et al., 2007; Li

et al., 2009, 2011). In addition, a molasse sedimentary sequence was found in the upper

Devonian strata around the Dundunshan area, also indicating a post-collisional setting in

the late Devonian (He et al., 2004). Thrust-nappe structures were reported in the

Precambrian to Ordovician strata, which displayed N-S compressions, W-E strike-slips and

were formed in the Late Silurian to Early Devonian (Liu et al., 2002). Characteristics of the

granitoids and strata in the Beishan rift all confirm a large-scale collisional event in the late

stage of early Paleozoic, then Beishan rift came into post-collisional stage (Fig. 11c).

The statistical results of the geochronological analysis (Fig. 10) show that magmatic

activities were rare in the Beishan rift, and no magmatic rocks have yet been reported with

an age of 340–380Ma (Table 5). Rock types of Upper Devonian and Lower Carboniferous

units in the area also correspond to the statistical results of the geochronological analysis.

The Upper Devonian is composed of keratophyre, breccia, tuff and sandstone, in

unconformable contact with the Middle Devonian. The Upper and Middle Devonian units

are continental sediments, and constitute the molasse formation in the Beishan rift (He et

al., 2004). There are also rare magmatic rocks in the Lower Carboniferous section, which is

mainly composed of phyllite, limestone, sandstone and conglomerate and characterized by

shallow-marine to nonmarine sedimentary rocks (GSBGMR, 1966). We speculate that this

period (340–380Ma) included continued orogenesis (the late Devonian) and marine

regression (the early Carboniferous) processes, with rare magmatic activities.

26

In recent studies, Zhang et al. (2008) collected age data of 18 mafic and 21 granitic

rocks from Tarim and its marginal areas, and obtained an age span of 260–320 Ma with a

peak age of 275 Ma. In addition, Qin et al. (2011) collected zircon U-Pb age data from

basalts and mafic dykes in the Beishan rift, eastern Tianshan and Tarim basin, and obtained

a peak age of 280 Ma. In the current study, we collected zircon U-Pb ages of magmatic

rocks including mafic-ultramafic rocks, diorites, granitoids and rhyolites in the Beishan rift,

and obtained a similar peak age of 282 Ma (Fig. 10). It is obvious that an important

magmatic event took place near 280Ma in the Beishan rift, even in the NW China. Most

studies suggest that magmatic rocks of this period formed in the within-plate setting (Mao

et al., 2006, 2008; Qin et al., 2011; Su et al., 2011a, 2011b, 2012b; Zhang et al., 2011a),

though there are still controversies concerning the geodynamics models, including

plume-related magmatisms (Qin et al., 2011; Su et al., 2012b) and lithospheric

delamination (Zhang et al., 2011a). As discussed above, Yinwaxia mafic rocks exhibit

obvious geochemical differences from mafic rocks in the Tarim Large Igneous Province

(TLIP). Specifically, Yinwaxia mafic rocks have obvious negative Nb-Ta-Ti anomalies, and

have higher HFSE and HREE abundances, which indicate that they derived from partial

melting of spinel lherzolites with relatively low melting degrees, unlikely typical mafic

rocks associated with plume. In addition, Yinwaxia mafic rocks also display different Sr-Nd

isotopic compositions (Fig. 7). It is notable that distributions of mafic-ultramafic rocks in

the Beishan area are linear along faults, rather than having the planar distribution expected

of a mantle plume (Fig. 1b). For example, the Poyi, Poshi and Luodong intrusions occur

along the Baidiwa fault (Mao et al., 2008; Pirajno et al., 2008), and the Liuyuan and

27

Yinwaxia mafic rocks occur along the Hongliuyuan fault (Zhang et al., 2011a; Cai et al.,

2012). It is also totally different from magmatic activities associated with a mantle plume,

which are always planar distributions (Campbell and Griffiths, 1990; Renne and Basu,

1991; Coffin and Eldholm, 1994). According to discussions above, it is hard to attribute

formations of Yinwaxia mafic rocks to magmatic activities associated with a mantle plume.

On the basis of the geochemical characteristics of Yinwaxia mafic rocks and a regional

tectonic evolutionary model using regional geochronological data, we propose that the

Yinwaxia mafic-ultramafic rocks resulted from magmatism associated with lithospheric

delamination and asthenosphere upwelling in a continental rift setting. In this scenario, the

Mazongshan and Dunhuang blocks collided in the late stage of the early Paleozoic,

thickening the lithosphere of the Beishan area, leading to a gravitational instability, which

provides the driving force for the lithosphere delamination. Afterwards the asthenosphere

upwelled and provided heat leading to partial melting of the lithopheric mantle, which had

been metasomatized by fluids or melts derived from subducted slab. In the course of rifting

in the late Carboniferous-Permian, the partial melting continued regionally, and parental

magmas of mafic and ultramafic rocks were produced owing to decompression.

Consequently, undergoing fractional crystallization (AFC) processes, parental magmas

were emplaced along faults and formed mafic and ultramafic rocks in the Beishan rift (Fig.

11d).

7. Conclusion

The Yinwaxia mafic rocks formed in the Permian (265 Ma and 281 Ma). The overall

28

isotopic compositions of these mafic rocks imply an OIB-like mantle source, display

DM-EM2 mixed trends, and indicate derivation from lithospheric mantle metasomatized by

fluids and/or melts derived from subducted slab. Parental magmas underwent fractionations

of clinopyroxene, plagioclase and Fe-Ti oxides. Yinwaxia basalts were contaminated by

parental magmas of coeval A-type granites, while gabbros were contaminated by the older

continental crust, causing different Sr-Nd isotopic characteristics for these rock types.

Taking into account the geochemistry of the Yinwaxia mafic rocks and coeval granitoids,

and characteristics of the Permian sedimentary formations, we conclude that Yinwaxia

mafic rocks were formed in a continental rift, and derived from magmatism associated with

lithospheric delamination and asthenosphere upwelling in a continental rift setting.

Acknowledgement

This study was financially supported by the National Natural Science Foundation of

China (Grant no. 41372225). We sincerely thank Wenjiao Xiao, Keda Cai and one

anonymous reviewer for their constructive comments that greatly helped to improve the

manuscript. We also appreciate the assistances of Libing Gu, Fang Ma, Hangqiang Xie,

Jinrong Li and Qiannan Li for geochronological and geochemical analyses.

29

Reference

Ao, S.J., Xiao, W.J., Han, C.M., Mao, Q.G., Zhang, J.E., 2010. Geochronology and

geochemistry of Early Permian mafic–ultramafic complexes in the Beishan area,

Xinjiang, NW China: Implications for late Paleozoic tectonic evolution of the southern

Altaids. Gondwana Research 18, 466-478.

Ao, S.J., Xiao, W.J., Han, C.M., Li, X.H., Qu, J.F., Zhang, J.E., Guo, Q.Q.,Tian, Z.H.,

2012. Cambrian to early Silurian ophiolite and accretionaryprocesses in the Beishan

collage, NW China: implications for the architectureof the Southern Altaids. Geological

Magazine 149, 606–625,

Badarch, G., Cunningham, W.D., Windley, B.F., 2002. A new terrane subdivision for

Mongolia: implications for the Phanerozoic crustal growth of Central Asia. Journal of

Asian Earth Sciences 21, 87-110.

Baker, J.A., Menzies, M.A., Thirwall, M.F. and Macpherso, C.G., 1997. Implication and

polybaric melt hybridization. Journal of Petrology 38, 1359-1390.

Belousova, E.A., Griffin, W.L., O’Reilly, S.Y., Fisher, N.I., 2002. Igneous zircon:trace

element composition as an indicator of source rock type. Contributions to Mineralogy

and Petrology 143, 602-622.

Beccaluva, L., Macciotta, G., Piccardo, G.B., Zeda, O., 1989. Clinopyroxenecompositions

of ophiolite basalts as petrogenetic indicator. Chemical Geology 77,165-182.

BGMRXUAR (Bureau of Geology and Mineral Resources of Xinjiang Uygur Autonomous

Region), 1993. Regional Geology of Xinjiang Uygur Autonomous Region. Geological

Publishing House, Beijing. pp. 1–841 (in Chinese).

30

Cai, Z.H., Xu, Z.Q., He, B.Z. and Wang, R.R., 2012. Age and tectonic evolution of ductile

shear zones in the eastern Tianshan-Beishanorogenic belt. ActaPetrologicaSinica 28(6),

1875 -1895(in Chinese with English abstract).

Campbell, I.H., Griffiths, R.W., 1990. Implications of mantle plume structure for

theevolution of flood basalts. Earth and Planetary Science Letters 99, 79–93.

Camphell, I.H. and Grifiths, R.W., 1993. The evolution of mantle’s chemical

structure.Lithos 30, 389-399.

Chen, B., Jahn, B., 2004. Genesis of post-collisional granitoids and basement nature of the

JunggarTerrane, NW China: Nd–Sr isotope and trace element evidence. Journal of

Asian Earth Sciences 23, 691–703.

Clague, D.A., Bunch, T.E., 1976. Formation of ferrobasalt at the East Pacificmidocean

spreading centres. Journal of Geophysical Research 81,4247–4256.

Clague, D.A., Frey, F.A., Thompson, G., Rindge, S., 1981. Minor and traceelements

geochemistry of volcanic rocks dredged from the Galapagosspreading center: role of

crystal fractionation and mantle heterogeneity.Journal of Geophysical Research 86,

9469–9482.

Coffin, M.F., Eldholm, O., 1994. Large igneous provinces: crustal structure,

dimensions,and external consequences. Reviews of Geophysics 32, 1–36.

Compston, W., Williams, I.S., Kirschvink, J.L., Zhang, Z.C., Ma, G.G., 1992. Zircon age

U-Pb ages for the early Cambrian time-scale. Journal of the Geological Society London

149, 171-184.

Dai, S., Fang, X.M., Zhang, X., Wang, F.C., Ren, Y.Z., Gao, Z.K., Lei, T.Z., 2003. Island

31

arc north of the Tarim-SK plate: the geology and geochemistry of Gongpoquan Group.

Journal of Lanzhou University (Natural Sciences) 39, 80–87 (in Chinese with English

abstract).

Farmer, G., 2003. Continental basaltic rocks.Treatise on geochemistry 3, 85-121.

Frey, F.A., Garcia, M.O., Wise, W.S., Kennedy, A., Gurreit, P., Albarede, F., 1993.

Theevolution of Mauna Kea volcano, Hawaii: petrogenesis of tholeiitic and

alkalibasalts. Journal of Geophysical Research 96, 14347–14375.

Greenough, J.D., Dostal, J., Mallory-Greenough, L.M., 2005. Igneous rock association 5.

Oceanic island volcanism II: mantle processes. Geoscience Canada 32, 77–90.

GSBGMR (Gansu Bureau of Geology and Mineral Resources), 1966. Regional Geology of

the Gansu Province. Geological Publishing House, Beijing (in Chinese).

Guo, Q.Q., Xiao, W.J., Windley, B.F., Mao, Q.G., Han, C.M., Qu, J.F., Ao, S.J., Li, J.L.,

Song, D.F., Yong,Y., 2012. Provenance and tectonic settings of Permian turbidites from

the Beishan Mountains, NW China: Implications for the Late Paleozoic accretionary

tectonics of the southern Altaids. Journal of Asian Earth Sciences 49, 54-68.

Han, B.F., Wang, S.G., Jahn, B.M., Hong, D.W., Kagami, H., Sun, Y.L., 1997.

Depletedmantle magma source for the UlungurRiver A-type granites from North

Xinjiang, China: geochemistry and Nd–Sr isotopic evidence, and implication for

Phanerozoic crustal growth. Chemical Geology 138, 135–159.

Han, B.F., Ji, J.Q., Song, B., Chen, L.H., Li, Z.H., 2004. SHRIMP zircon U–Pb ages of

Kalatonke No.1 and HuanShandong Cu–Ni-bearing mafic–ultramafic complexes, North

Xinjiang, and geological implications. Chinese Science Bulletin 49,2324–2328 (in

32

Chinese with English abstract).

Hanson, G.N., 1989. An approach to trace element modeling using a simple igneous system

as an example. In Geochemistry and Mineralogy of Rare Earth Elements, Reviews in

Mineralogy 21 (eds, B.R.Lipin and G.A.McKay). Mineralogical Society of America,

Washington, DC, 79-89.

He, S.P., Zhou, H.W., Yao, W.G., Ren, B.C., Fu, L.P., 2004. Discovery and significance

ofradiolarian from Middle Devonian conglomerate in Beishan area, Gansu.

NorthwesternGeology 3, 24–28 (in Chinese with English abstract).

Hoffman, A.W., 1997. Mantle geochemistry: the message from oceanic magmatism. Nature

385, 219-229.

Hong, D.W., Wang, S.G., Xie, X.L., Zhang, J.S., Wang, T., 2003. Metallogenic province

derived from mantle sources: Nd, Sr, S and Pb isotope evidence from the Central Asian

Orogenic Belt. Gondwana Research 6, 711–728.

Hong, D.W., Zhang, J.S., Wang, T., Wang, S.G., Xie, X.L., 2004. Continental crustal growth

and the supercontinental cycle: evidence from the Central Asian Orogenic Belt. Journal

of Asian Earth Sciences 23, 799–813.

IGCAS (Institute of Geological of Chinese Academy of Geological Sciences), 2006.

1:2500000 Geological Map of the western China and adjacent regions. Geological

Publishing House, Beijing (in Chinese).

Jahn, B.M., Windley, B., Natal’in, B., Dobretsov, N., 2004. Phanerozoic continental growth

in Central Asia. Journal of Asian Earth Sciences 23, 599-603.

Jahn, B.M., Wu, F.Y., Chen, B., 2000. Granitoids of the Central Asian Orogenic Belt and

33

continental growth in the Phanerozoic. Transactions of the Royal Society of Edinburgh:

Earth Sciences 91, 181-193.

Jian, P., Liu, D., Kröner, A., Windley, B.F., Shi, Y., Zhang, F., Shi, G., Miao, L., Zhang,

W.,Zhang, Q., Zhang, L., Ren, J., 2008. Time scale of an early to mid-Paleozoic

orogeniccycle of the long-lived Central Asian Orogenic Belt, Inner Mongolia of China:

implicationsfor continental growth. Lithos 101, 233–259.

Jian, P., Liu, D., Kröner, A., Windley, B.F., Shi, Y., Zhang, W., Zhang, F., Miao, L., Zhang,

L.,Tomurhuu, D., 2010. Evolution of a Permian intraoceanic arc–trench system in

theSolonker suture zone, Central Asian Orogenic Belt, China and Mongolia. Lithos

118,169–190.

Jian, P., Liu, D.Y., Zhang, Q., Zhang, F.Q., Shi, Y.R., Shi, G.H., Zhang, L.Q., Tao, H., 2003.

SHRIMP dating of ophiolite and leucocratic rocks within ophiolite. Earth Sciences

Frontiers (China University of Geosciences, Beijing) 10, 436-456 (in Chinese with

English abstract).

Jiang, C.Y., Cheng, S.L., Ye, S.F., Xia, M.Z., Jiang, H.B., Dai, Y.C., 2006.

Lithogeochemistry and petrogenesis of Zhongposhanbei mafic rock body, at Beishan

region, Xinjiang. ActaPetrologicaSinica 22, 115–126 (in Chinese with English

abstract).

Jiang, H.Y., He, Z.Y., Zong, K.Q., Zhang, Z.M., Zhao, Z.D., 2013. Zircon U-Pb dating

and Hf isotopic studies on the Beishan complex in the southern Beishan orogenic belt.

Acta Petrologica Sinica 29, 3949-3967 (in Chinese with English abstract).

34

Kelemen, P.B., Hanghoj, K., Greene, A.R., 2004. One view of the geochemistry of

subduction-related magmatic arcs, with emphasis on primitive andesite and lower crust

// Rudnick R L. The crust: treatise on geochemisty. Oxford: Elsevier, 593-659.

Khain, E.V., Bibikova, E.V., Salnikova, E.B., Kröner, A., Gibsher, A.S., Didenko, A.N.,

Degtyarev, K.E., Fedotova, A.A., 2003. The Paleo-AsianOcean in the Neoproterozoic

and early Paleozoic: new geochronology data and paleotectonic reconstructions.

Precambrian Research 122, 329–358.

Kovalenko, V.I., Yarmolyuk, V.V., Kovach, V.P., Kotov, A.B., Kozakov, I.K., Salnikova,

E.B., Larin, A.M., 2004. Isotope provinces, mechanisms of generation and sources of

the continental crust in the Central Asian mobile belt: geological and isotopic evidence.

Journal of Asian Earth Sciences 23, 605-627.

Kröner, A., Hegner, E., Lehmann, B., Heinhorst, J., Wingate, M.T.D., Liu, D.Y., Ermelov, P.,

2008. Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan:

SHRIMP zircon ages and whole-rock Nd isotopic systematics. Journal of Asian Earth

Sciences 32, 118-130.

Kröner, A., Lehmann, J., Schulmann, K., Demoux, A., Lexa, O., Tomurhuu, D., Stipska, P.,

Liu, D.,Wingate, M.T.D., 2010. Lithostratigraphic and geochronological constraints on

the evolution of the Central Asian Orogenic Belt in SW Mongolia: early Paleozoic

rifting followed by late Paleozoic accretion. American Journal of Science 310,

523–574.

Kröner, A., Windley, B.F., Badarch, G., Tomurtogoo, O., Hegner, E., Jahn, B.M., Gruschka,

S., Khain, E.V., Demoux, A., Wingate, M.T.D., 2007. Accretionary growth and crust

35

formation in the Central Asian Orogenic Belt and comparison with the Arabian–Nubian

shield. Geological Society of America Memoirs 200, 181-209.

Li, C.Y., 1980. Outlines of the Chinese Plate Tectonics: Journal of the ChineseAcademy of

Geological Sciences 2, 11-22.

Li, S., Wang, T., Hong, D.W., Ouyang, Z.X., 2009.Indentification of the early Devonian

Shuangfengshan A-type granites in Liuyuan areas of the Beishan, NW China, and its

implications for tectonic evolution.ActaPetrologica et Mineralogica, 28, 407-422 (in

Chinese with English abstract).

Li, S., Wang, T., Tong, Y., Hong, D.W., Ouyang, Z.X., 2011. Zircon U-Pb age, origin and

its tectonic significances of Huitongshan Devonian K-feldspar granites from

Beishanorogen, NW China. ActaPetrologicaSinica 27, 3055-3070 (in Chinese with

English abstract).

Li, S., Wilde, S.A., Wang, T., 2013. Early Permian post-collisional high-K granitoids from

Liuyuan area in southern Beishan orogen, NW China: Petrogenesis and tectonic

implications. Lithos 179, 99-119.

Li, X.H., 1997. Geochemistry of the Longshengophiolite from the southern margin of

Yangtze Craton, SEChina. Journal of Geochemistry 31, 323-337.

Li, X.H., Li, Z.X., Wingate, M.T.D., Chung, S.L., Liu, Y., Lin, G.C., Li, W.X., 2006.

Geochemistry of the 755Ma Mundine Well dyke swarm, northwestern Australia: part of

a Neoproterozoic mantle superplume beneath Rodinia? Precambrian Research 146,

1-15.

Liu, M.Q., Dang, Y.Y., Gong, Q.S., 2002. Yinwaxia polycyclic rift zone in Beishan area in

36

Gansu province.ActaGeologicaGansu 8, 15-22 (in Chinese with English abstract).

Liu, M.Q., Gong, Q.S., Liang, M.H., 1999. The feature of Pingtoushan thrust-nappe

structure in Beishan, Gansu. Northwest Geology 35, 22-27 (in Chinese with English

abstract).

Liu, X. Y., and Wang, Q., 1995. Tectonics and evolution of the Beishanorogenic belt, West

China: Geological Research, 10, 151-165.

Liu, X.C., Chen, B., Jahn, B.M., Wu, G., Liu, Y., 2011. Early Paleozoic (ca. 465 Ma)

eclogites from Beishan (NW China) and their bearing on the tectonic evolution of the

southern Central Asian Orogenic Belt. Journal of Asian Earth Sciences 42, 715–731.

Liu, X.C., Wu, G.G., Chen, B.L., Shu, B., 2002. Metamorphic history of eclogites from

Beishan, Gansu Province. Acta Geoscientia Sinica 23, 25–29 (in Chinese with English

abstract).

Loucks, R.R., 1990. Discrimination from opholitic and nonopholitic ultramafic–mafic

allochthons in orogenic belts by the Al/Ti ratios in clinopyroxene. Geology 18,

346–349.

Ludwig, K.R., 2003. User's Manual for Isoplot 3.00. A Geochronological Toolkit for

Microsoft Excel. BerkeleyGeochronologyCenter, Berkeley, California. Special

Publication No. 4a, 70.

Mao, J. W., Pirajno, F., Zhang, Z. H., Chai, F. M., Yang, J. M., Wu, H., Chen, S. P., Cheng,

S. L., and Zhang,C. Q., 2006. Late Variscan Post-collisional Cu-Ni sulfide deposits in

east Tianshan and Altay in China:principal characteristics and possible relationship with

mantle plume: Acta Geologica Sinica 80, 925-942.

37

Mao, J.W., Pirajno, F., Zuo, H.Z., Chai, F.M., Wu, H., Chen, S.P., Cheng, L.S., Yang, J.M.,

Zhang, C.Q., 2008. A review of the Cu–Ni sulphide deposits in the Chinese Tianshan

and Altay orogens (Xinjiang Autonmous Region, NW China): principal characteristics

and ore-forming processes. Journal of Asian Earth Sciences 32, 184–203.

Mao, Q.G., Xiao, W.J., Han, C.M., Sun, M., Yuan, C., Yan, Z., Li, J.L., Yong, Y., Zhang,

J.E., 2006. Zircon U–Pb age and geochemistry of the Baishiquan mafic–ultramafic

complex in the Eastern Tianshan, Xinjiang: constraints on the closure of the

Paleo-Asian ocean. ActaPetrologicaSinica 22, 153–162 (in Chinese with English

abstract).

Mao, Q.G., Xiao, W.J., Fang, T.H., Wang, J.B., Han, C,M., Sun, M. and Yuan, C., 2012.

Late Ordovicianto early Devonian adakites and Nb-enriched basalts intheLiuyuan area,

Beishan, NW China: implicationsfor early Paleozoic slab-melting and crustal growth

inthe southern Altaids. GondwanaResarch, 22, 534-553.

Miyashiro, A., 1974.Volcanic rock series in island arcs and active continental

margins.American Journal of Science 274, 321-355.

MacDonald, R., Roger, N.W. and Fitton, J.G., 2001. Plume lithosphere interations in the

generation of the basalts of the Kenys rift, East Africa. Journal of Petrology

42,877-900.

Mossakovsky, A.A., Ruzhentsev, S.V., Samygin, S.G., Kheraskova, T.N., 1994. Central

Asian fold belt: geodynamic evolution and history of formation. Geotectonics 6, 3-33.

Pan, J.H., Guo, Z.J., Liu, C., Zhao, Z.H., 2008. Geochronology, geochemistry and tectonic

implications of Permian basalts in Hongliuhe area on the border between Xinjiang and

38

Gansu. Acta Petrologica Sinica 24, 793-802 (in Chinese with English abstract).

Pearce, J.A., Norry M.J., 1979. Petrogenetic implications of Ti, Zr, Y, and Nb variations in

volcanic rocks. Contributions to Mineralogy and Petrology 69, 33-47.

Pearce, J.A., 1982. Trace element characteristics of lavas from destructive plateboundaries.

In: Thorpe, R.S. (Ed.), Andesites: Orogenic Andesites and Related Rocks. John Wiley,

Chichester, pp. 525–547.

Perfit, M.R., Fornari, D.J., 1983. Geochemical studies of abyssal lavasrecovered by DSRV

Alvin from Eastern Galapagos Rift, Inca Transform and Ecuador rift. 2. Phase

chemistry and crystallization history. Journal of Geophysical Research 88,

10530–10550.

Pirajno, F., Mao, J.W., Zhang, Z.C., Zhang, Z.H., Chai, F.M., 2008. The association of

mafic–ultramafic intrusions and A-type magmatism in the Tian Shan and Altay orogens,

NW China: implications for geodynamic evolution and potential for the discovery of

new ore deposits. Journal of Asian Earth Sciences 32, 165-183.

Qin, K.Z., Su, B.X., Sakyi, P.A., Tang, D.M., Li, X.H., Sun, H., Xiao, Q.H., Liu, P.P., 2011.

SIMS Zircon U–Pb geochronology and Sr–Nd isotopes of Ni–Cu bearing

mafic–ultramafic intrusions in Eastern Tianshan and Beishan in correlation with flood

basalts in TarimBasin (NW China): constraints on a ca. 280 Ma mantle plume.

American Journal of Science 311, 237-260.

Qu, J.F., Xiao, W.J., Windley, B.F., Han, C.M., Mao, Q.G.,Ao, S.J., Zhang, J.E., 2011.

Metamorphic evolution and P–T trajectory of eclogites from the Chinese Beishan:

implications for the Paleozoic tectonic evolution of the southern Altaids. Journal of

39

Metamorphic Geology 29,803-820.

Renne P.R. and Basu A.R., 1991. Rapid eruption of the Siberia traps flood basalts at the

Permo-Triassic boundary. Science 253, 176-179.

Rollinson, H R., 1993. Using geochemical data: evaluation, presentation, interpretation.

New York: Longman Scientific & Technical, 171-214.

Safonova, I.Y., Santosh, M., 2014. Accretionary complexes in the Asia-Pacific region:

Tracing archives of Ocean Plate Stratigraphy and tracking mantle plumes. Gondwana

Research 25, 126-158.

Saunders, A.D., Storey, M., Kent, R.W. and Norry, M.J., 1992. Consequences of

plume-lithosphere interaction. In: Storey B.C. Alabaster T. and Pankhurst R.J. (eds.).

Magmatism and the Causes of Continental Break-Up. Geological Special Public,

London 68, 41-60.

Sengör, A.M.C., Natal'in, B.A., Burtman, V.S., 1993. Evolution of the Altaid tectonic

collage and Palaeozoic crustal growth in Eurasia. Nature 364, 299-307.

Shervais, J W., 1982.Ti-V plots and the petrogenesis of modern and ophiolitic lavas. Earth

and Planetary Science Letters 59, 101–118.

Shinjo, R., Chekol, T., Meshesha, D., Itaya, T., Tatsumi, Y., 2011. Geochemistry and

geochronology of the mafic lavas from the southeastern Ethiopian rift (the East African

Rift System): assessment of models on magma sources, plume–lithosphere interaction

and plume evolution. Contributions to Mineralogy and Petrology 162, 209-230.

Steiger, R.H., Jäger E., 1977. Subcommission on geochronology: Convention on the use of

decay constants in geo- and cosmochronology. Earth and Planetary Science Letters 36,

40

359-362.

Su, B.X., Qin, K.Z., Sakyi, P.A., Malaviarachchi, S.P.K., Liu, P.P., Tang, D.M., Xiao, Q.H.,

Sun, H., Ma, Y.G., Mao, Q., 2012a. Occurrence of an Alaskan-type complex in the

Middle Tianshan Massif, Central Asian Orogenic Belt: inferences from petrological

and mineralogical studies. International Geology Review 54, 249-269.

Su, B.X., Qin, K.Z., Sakyi, P.A., Liu, P.P., Tang, D.M., Malaviarachchi, S.P.K., Xiao, Q.H.,

Sun, H., Dai, Y.C., Hu, Y., 2011a. Geochemistry and geochronology of acidic rocks

in the Beishan region, NW China: petrogenesis and tectonic implications. Journal of

Asian Earth Sciences 41, 31-43.

Su, B.X., Qin, K.Z., Sakyi, P.A., Li, X.H., Yang, Y.H., Sun, H., Tang, D.M., Liu, P.P., Xiao,

Q.H., Malaviarachchi, S.P.K., 2011b. U–Pb ages and Hf–O isotopes of zircons from

Late Paleozoic mafic–ultramafic units in southern Central Asian Orogenic Belt:

tectonic implications and evidence for an Early-Permian mantle plume. Gondwana

Research 20, 516-531.

Su, B.X., Qin, K.Z., Sun, H., Tang, D.M., Sakyi, P.A., Chu,Z.Y., Liu,P.P., Xiao,Q.H., 2012b.

Subduction-induced mantle heterogeneity beneath Eastern Tianshan and Beishan:

Insights from Nd–Sr–Hf–O isotopic mapping of Late Paleozoic mafic–ultramafic

complexes. Lithos 134-135, 41–51.

Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic

basalts:implications for mantle composition and processes. Geological Society

LondonSpecial Publications 42 (1), 313–345.

Taylor, S.R. and Mclenna, S.M., 1985. The Continental Crust: Its Composition and

41

Evolution. Oxford:Blackwell, 1-312.

Tian, W., Campbell, I. H., Allen, C. M., Guan, P., Pan, W. Q., Chen, M. M., Yu, H. J., and

Zhu, W. P., 2010.The Tarimpicrite-basalt-rhyolite suite, a Permian flood basalt from

northwest China with contrastingrhyolites produced by fractional crystallization and

anatexis: Contributions to Mineralogy and Petrology160,407–425.

Wartes, M.A., Carroll, A.R., Greene, T.J., 2002. Permian sedimentary record of the

Turpan-Hami basin and adjacent regions, northwest China: constraints on post

amalgamation tectonic evolution. Geological Society of America Bulletin 114,

131-152.

Weaver, B.L., 1991. The origin of ocean island basalt end-member compositions: trace

element and isotopic constraints. Earth and Planetary Science Letters 104, 381-397.

Windley, B.F., Allen, M.B., Zhang, C., Zhao, Z.Y., Wang, G.R., 1990. Paleozoic accretion

and Cenozoic redeformation of the ChineseTienShanRange, central Asia. Geology 18,

128-131.

Windley, B.F., Alexeiev, D., Xiao, W.J., Kröner, A., Badarch, G., 2007. Tectonic models for

accretion of the Central Asian Orogenic Belt. Journal of the Geological Society of

London 164, 31-47.

Wu, F.Y., Jahn, B.M., Wilde, S.A., Sun, D.Y., 2000. Phanerozoic crustal growth: U–Pb and

Sr–Nd isotopic evidence from the granites in northeastern China. Tectonophysics 328,

89-113.

Wu, F.Y., Sun, D.Y., Li, H.M., Jahn, B.M., Wilde, S., 2002. A-type granites in northeastern

China: ageand geochemical constraints on their petrogenesis. Chemical Geology 187,

42

143-173.

Wu, T.R., He, G.Q., Zhang, C., 1998. On Paleozoic tectonics in the Alxa region, Inner

Mongolia, China. ActaGeologicaSinica 72, 256–263.

Wu,Y.B., Zheng, Y.F., 2004. Genesis of zircon and its constraints on interpretation ofU–Pb

age. Chinese Science Bulletin 49, 1589–1604 (in Chinese).

Xia, L.Q., Xia, Z.C., Xu, X.Y., Li, X.M. and Ma, Z.P., 2007. The discrimination between

continental basalt and island arc basalt based on geochemical method. ActaPetrologica

et Mineralogica 26, 77-89 (in Chinese with English abstract).

Xiao, Y.F., Wang, D.Y., Deng, J.H., Sun, Y., Wu, D.C., 2004a. Volcanism during activity

period of Beishancraton rift in Xinjiang, China. Journal of ChengduUniversity of

Technology 31, 331–337.

Xiao, W.J., Zhang, L.C., Qin, K.Z., Sun, S., Li, J.L., 2004b. Paleozoic accretionary and

collisional tectonics of the eastern Tianshan (China): implications for the continental

growth of Central Asia. American Journal of Science 304, 370–395.

Xiao, W.J., Windley, B.F., Huang, B.C., Han, C.M., Yuan, C., Chen, H.L., Sun, M., Sun, S.,

Li, J.L., 2009. End-Permian to mid-Triassic termination of the accretionary processes of

the southern Altaids: implications for the geodynamic evolution, Phanerozoic

continental growth, and metallogeny of Central Asia. International Journal of Earth

Sciences 98, 1189-1217.

Xiao, W.J., Mao, Q.G., Windley, B.F., Qu, J.F., Zhang, J.E., Ao, S.J., Guo, Q.Q., Cleven,

N.R., Lin, S.F., Shan, Y.H., Li, J.L., 2010. Paleozoic multiple

accretionaryandcollisional processes of the Beishanorogenic collage. American

43

Journal of Science 310, 1553–1594.

Xiao, W.J., Windley, B.F., Allen, M.B., Han, C.M., 2013. Paleozoic multiple accretionary

and collisional tectonics of the Chinese Tianshan orogenic collage. Gondwana

Research 23, 1316-1341.

Xu, X.Y., He, S.P., Wang, H.L., Chen, J.L., 2009. Geological Background Map of

Mineralization in Eastern Tianshan–Beishan Area (in Chinese).

Xu, Y.G., Chung, S.L., Jahn, B.M., Wu, G.Y., 2001. Petrologic and geochemical

constraintson the petrogenesis of Permian-Triassic Emeishan flood basalts in

southwesternChina. Lithos 58, 145–168.

Yang, Y.H., Zhang, H.F., Chu, Z.Y., Xie, L.W., Wu, F.Y., 2010. Combined

chemicalseparation of Lu, Hf, Rb, Sr, Sm and Nd from a single rock digest and precise

andaccurate isotope determinations of Lu–Hf, Rb–Sr and Sm–Nd isotope

systemsusing multi-collector ICP-MS and TIMS. International Journal of

Massspectrometry 290, 120–126.

Zhang, C.L., Li, X.H., Li, Z.X., Ye, H.M., Li, C.N., 2008. A Permian layered intrusive

complex in the Western Tarim Block, northwestern China: product of a ca. 275-Ma

mantle plume? Journal of Geology 116, 269–287.

Zhang, C.L., Zou, H., 2012. Comparison between the Permian mafic dykes in Tarim and

the western part of Central Asian Orogenic Belt (CAOB), NW China: Implications for

two mantle domains of the Permian Tarim Large Igneous Province,

http://dx.doi.org/10.1016/j.lithos.2012.11.010.

Zhang, J.X., Yu, S.Y., Gong, J.H., Li, H.K., Hou, K.J., 2013. The latest

44

Neoarchean-Paleoproterozoic evolution of the Dunhuang block, eastern Tarim craton,

northwestern China: evidence from zircon U-Pb dating and Hf isotopic analyses.

Precambrian Research 226, 21–42.

Zhang, W., Feng, J.C., Zheng, R.G., Wu, T.R., Luo, H.L., He, Y.K., Jing, X., 2011b.

LA-ICP MS zircon U–Pb ages of the granites from the south of Yin’aoxia and their

tectonic significances. Acta Petrologica Sinica 27, 1649-1661 (in Chinese with English

abstract).

Zhang, W., Wu, T.R., He, Y.K., Feng, J.C., Zheng, R.G., 2010. LA-ICP-MS zircon U–Pb

ages of Xijianquanzi alkali-rich potassium-high granites in Beishan, Gansu Province,

and their tectonic significances. Acta Petrologica Et Mineralogica 29, 719-731 (in

Chinese with English abstract).

Zhang, Y.Y., Guo, Z.J., 2008. Accurate constraint on formation and emplacement age of

Hongliuheophiolite, boundary region between Xinjiang and Gansu provinces and its

tectonic implications. Acta Petrologica Sinica 24, 803-809 (in Chinese with English

abstract).

Zhang, Y.Y., Dostal, J., Zhao, Z.H., Liu, C., Guo, Z.J., 2011a. Geochronology,

geochemistry and petrogenesis of mafic and ultramafic rocks from Southern Beishan

area, NW China: Implications for crust–mantle interaction. Gondwana Research 20,

816-830.

Zhao, Z.H., Guo, Z.J., Han, B.F., Wang, Y., 2006. The geochemical characteristics and

tectonic–magmatic implications of the latest-Paleozoic volcanic rocks fromSantanghu

basin, eastern Xinjiang, northwest China. Acta Petrologica Sinica 22, 199-214 (in

45

Chinese with English abstract).

Zhao, Z.H., Guo, Z.J., Wang, Y., 2007. Geochronology, geochemical characteristics and

tectonic implications of the granitoids from Liuyuan area, Beishan, Gansu province,

northwest China. Acta Petrologica Sinica 23, 1847–1860 (in Chinese with English

abstract).

Zheng, R.G., Wu T.R., Zhang W., Xu C. and Meng Q.P., 2012. Early Devonian

Tectono-Magmatic Events in the Middle Beishan, Gansu Province: Evidence from

Chronology and Geochemistry of Gongpoquan Granite.

ActaScientiarumNaturaliumUniversitatisPekinensis48, 603-616 (in Chinese with

English abstract).

Zhou, D., Graham, S., 1996. Extrusion of the AltynTagh wedge: a kinematic model for the

AltynTagh Fault and palin spastic reconstruction of northern China. Geology 24,

427-430.

Zhou, M.F., Lesher, C.M., Yang, Z.X., Li, J.W., Sun, M., 2004. Geochemistry and

petrogenesis of 270 Ma Ni-Cu-(PGE) sulfide-bearing mafic intrusions in the Hangshan

district, Eastern Xinjiang, Northwest China: implications for the tectonic evolution of

the Central Asian orogenic belt. Chemical Geology 209, 233-257.

Zindler, A., Hart, S.R., 1986. Chemical geodynamics. Annual Review of Earth and

Planetary Sciences 14, 493-571.

Zonenshain, L.P., Kuzmin, M.I., Natapov, L.M., 1990. Geology of the USSR: A

Plate-Tectonic Synthesis. American Geophysical Union, Washington D. C. 242 p.

Zuo, G.C., Zhang, S.L., He, G.Q., Zhang, Y., 1991. Plate tectonics during the early

46

Paleozoic in Beishan near Sino-Mongolian border region, China. Tectonophysics 188,

385–392.

47

List of Figures

Fig. 1 (a) Geological sketch map of the Central Asian Orogenic Belt (modified after Şengör

et al., 1993; Jahn et al., 2000). (b) The geological map of the Beishan rift and its

adjacent region (modified after Wang et al., 2007; age data are from Zhao et al., 2007;

Li et al., 2009, 2011, 2013; Su et al., 2011 and references therein; Zhang et al., 2011a;

Mao et al., 2012; Jiang et al., 2013).

Fig. 2 The geological map of the Yinwaxia area (modified after GSBGMR, 1966).

Fig.3 Cathodoluminescence (CL) images and SHRIMP dating results of zircons from the

basalt and the gabbro in the Yinwaxia area.

Fig. 4 (a) The Zr/TiO2 versus Nb/Y chemical classification diagram for mafic rocks from

the Yinwaxia (after Winchester and Floyd, 1977); (b) AFM diagram (A=Na2O+K2O,

F=FeO, M=MgO) for mafic rocks from the Yinwaxia area. The boundary line between

tholeiitic and calc-alkaline rock types is from Miyashiro (1974).

Fig. 5 The Chondrite-normalized REE pattern of basalts (a) and gabbros (b) from the

Yinwaxia area (normalized data and N-MORB values are from Sun and McDonough,

1989). Mafic rocks in the Tarim large igneous province are basalts from boreholes at

depths between 5,166 and 6,333 m in the northern Tarim uplift (Tian et al., 2010).

48

Fig.6 The N-MORB-normalized trace elements spiderdiagram of basalts (a) and gabbros(b)

from the Yinwaxia area (normalized data and E-MORB values are from Sun and

McDonough, 1989).Mafic rocks in the Tarim large igneous province are basalts from

boreholes at depths between 5,166 and 6,333 m in the northern Tarim uplift (Tian et

al., 2010). Data of basalts in the East African Rift, average continental arc and OIB are

collected from Shinjo et al. (2011), Kelemen et al. (2004) and Sun and McDonough

(1989).

Fig. 7 εNd(t) vs. (87Sr/86Sr)i diagram for mafic rocks from the Yinwaxia area (Zindler and

Hart,1986). Data for mafic rocks in the western part of Beishan rift are from Su et al.,

(2012). Data for mafic rocks in the Liuyuan area are from Zhang et al. (2011a). Data

for granites in the Yinwaxia area are from Zhang et al. (2011b) and Feng et al. (2012).

DMM, depleted mantle-derived melt; EM1, enriched mantle1; EM2, enriched mantle2;

εNd(280Ma)=10.96 and (87Sr/86Sr)i=0.7022 are values of DMM.

Fig. 8 (a) Plots of Alz (percentage of tetrahedral sites occupied by Al) vs. TiO2 in

clinopyroxenes from gabbros of the Yinwaxia area (after Loucks, 1990).

(b) The TiO2-Na2O-SiO2/100 diagram, using compositions of clinopyroxenes for

discriminating different tectonic settings (after Beccaluva et al., 1989). Abbreviations,

E-MORB: enriched mid-ocean ridge basalt; N-MORB: normal mid-ocean ridge basalt;

WOPB: within oceanic plate basalts; ICB: Iceland basalts; SSZ: supra-subduction

49

zone basalts.

Fig. 9 Tectonic setting discrimination diagrams for Yinwaxia mafic rocks. (a) Zr/Y-Zr

diagram (after Pearce and Norry, 1979); (b) Ti–Zr diagram (after Pearce, 1982).

Fig. 10 Relative probability plots of zircon 206Pb/238U ages from magmatic and

metamorphic rocks in the Beishan rift and its adjacent area.

Fig. 11 The tectonic evolution model for the Beishan rift. See text for detailed discussions.

List of tables

Table 1 SHRIMP U-Pb data of the basalt (Y-14) and the gabbro (Y-5) in the Yinwaxia area.

Notes: Errors are 1-sigma; Pbc and Pb* indicate the common and radiogenic lead,

respectively. Common Pb corrected using measured 204Pb.

Table 2 Major and trace elements compositions of basalts and gabbros in the Yinwaxia

area.

Table 3 Whole rock isotopic compositions of basalts and gabbros in the Yinwaxia area.

Table 4 Major element analyses of clinopyroxenes from gabbros of the Yinwaxia area.

Table 5 Compiled ages of magmatic and metamorphic rocks in the Beishan rift and its

adjacent area.

50

Table 1

Notes: Common Pb corrected using the measured 204Pb. Pb* indicate the radiogenic lead, Pbc indicate the common lead.

Spots U

(ppm)

Th

(ppm) Th/U

206Pb*

(ppm)

206Pbc

(%)

207Pb* 206Pb*

±%

207Pb* 235U

±%

206Pb* 238U

±%

Age(Ma) 206Pb 238U

1σ 207Pb 206Pb

1σ

The gabbro sample ( Y-5) 1.1 216 174 0.84 8.9 1.25 0.0557 9.9 0.36 10.2 0.0472 2.5 297.3 7.3 441 220

2.1 63 52 0.86 2.6 5.69 0.0576 49.7 0.35 50.0 0.0445 6.0 280.9 16.4 516 1091

3.1 303 42 0.14 11.5 1.57 0.0471 8.8 0.28 9.1 0.0437 2.1 275.8 5.7 54 210

4.1 263 55 0.22 77.9 0.24 0.1139 1.7 5.39 2.6 0.3433 2.0 1902.6 32.2 1862 30

5.1 398 213 0.55 14.4 0.56 0.0530 6.1 0.31 6.5 0.0420 2.0 264.9 5.3 328 139

6.1 511 196 0.40 19.8 1.54 0.0542 5.2 0.33 5.8 0.0445 2.6 280.5 7.0 380 118

7.1 133 58 0.45 5.2 1.02 0.0470 3.7 0.29 4.3 0.0454 2.2 286.2 6.1 50 87

8.1 117 64 0.56 4.7 0.79 0.0470 7.5 0.30 7.8 0.0468 2.2 295.0 6.4 49 179

9.1 162 81 0.52 43.0 0.06 0.1032 0.8 4.38 2.2 0.3078 2.0 1729.7 30.5 1683 15

The basalt sample ( Y-14)

1.1 79 24 0.31 27.6 0.67 .1437 2.1 7.98 3.0 .4028 2.2 2181.9 41.3 2273 36

2.1 201 183 0.94 7.2 2.44 .0510 16.0 0.29 16.2 .0406 2.4 256.7 6.0 242 369

3.1 500 112 0.23 21.6 0.66 .0516 2.9 0.36 3.5 .0500 1.9 314.3 5.8 268 66

4.1 233 139 0.62 9.3 1.37 .0487 9.5 0.31 9.7 .0456 2.1 287.3 5.9 136 222

5.1 241 152 0.65 8.9 1.88 .0479 6.9 0.28 7.2 .0423 2.1 267.4 5.5 92 163

6.1 133 58 0.45 5.2 1.02 .0470 3.7 0.29 4.3 .0454 2.2 286.2 6.1 50 87

7.1 117 64 0.56 4.7 0.79 .0470 7.5 0.30 7.8 .0468 2.2 295.0 6.4 49 179

8.1 197 198 1.04 7.8 1.81 .0466 24.1 0.29 24.2 .0454 2.5 286.2 7.1 27 577

9.1 200 117 0.60 8.2 4.55 .0318 32.9 0.20 33.0 .0454 2.5 286.1 6.9 -983 972

10.1 142 63 0.46 36.6 0.00 .1133 1.2 4.69 2.4 .3005 2.1 1693.7 31.1 1852 22

51

Table 2

No. Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 Y-7 Y-8 Y-9

Rocks Gabbro Gabbro Gabbro Gabbro Gabbro Gabbro Gabbro Basalt Basalt

SiO2 55.62 52.81 52.96 53.33 51.70 53.27 50.37 53.29 54.15 TiO2 1.59 1.38 2.06 2.16 1.36 1.32 1.335 2.56 2.56 Al2O3 15.48 16.06 15.31 15.25 15.27 15.27 13.63 14.74 14.53

TFe2O3 9.54 9.28 11.04 11.08 9.20 8.96 8.72 12.89 11.98 MnO 0.16 0.15 0.20 0.16 0.15 0.12 0.164 0.24 0.22 MgO 5.46 6.22 5.36 5.13 6.26 6.16 6.32 3.72 3.14 CaO 5.60 9.36 6.70 6.45 8.96 7.49 8.46 6.35 6.59Na2O 2.79 1.00 1.80 1.87 2.33 2.22 4.97 1.64 1.51 K2O 0.52 0.93 0.88 0.90 0.91 1.19 0.76 1.35 1.69 P2O5 0.27 0.21 0.34 0.36 0.23 0.23 0.237 0.78 0.80LOI 2.83 2.47 3.21 3.20 3.52 3.64 4.92 2.29 2.72Total 99.85 99.88 99.88 99.89 99.88 99.87 99.89 99.86 99.89 Mg# 55.75 59.59 51.66 50.49 59.99 60.21 61.49 38.81 36.59

Sc 31.0 30.9 36.3 34.0 33.8 26.5 36.1 26.3 25.8 V 183 165 230 225 178 152 220 174 177 Co 33.8 35.8 30.6 31.4 35.3 32.8 34.2 21.8 18.1 Ga 17.9 17.2 18.0 18.7 17.4 17.1 19.0 22.9 21.4 Li 13.9 14.5 15.7 16.5 14.5 14.7 10.7 8.05 7.37Be 1.29 1.03 1.05 1.33 1.03 1.32 1.129 1.66 1.41 Cs 0.38 0.41 0.58 0.68 0.90 0.73 0.8182 0.89 0.80 Rb 3.71 72.3 15.6 13.8 11.6 43.4 20.7 14.7 17.5 Sr 232 341 197 187 406 347 588 220 331 Ba 222 107 164 118 102 125 175 226 254 Th 3.54 2.55 2.49 3.00 2.65 3.97 2.48 2.77 2.52 U 1.30 0.825 0.741 0.934 0.813 1.15 0.855 1.07 1.13Ta 0.593 0.462 0.581 0.591 0.434 0.573 0.417 0.923 0.864 Nb 8.84 7.02 8.77 9.30 7.19 8.55 7.38 14.6 13.5 Hf 6.34 4.84 5.48 6.31 5.02 6.39 6.74 8.53 7.96 Zr 299 228 262 299 229 303 248 406 377 Y 40.1 33.1 40.8 42.0 34.3 37.4 40.9 63.3 61.7 Pb 11.8 11.7 15.9 4.86 7.77 9.55 10.7 7.84 6.46 La 15.5 12.4 12.2 15.8 12.5 15.3 14.4 24.7 23.5 Ce 39.5 31.5 33.4 40.5 32.3 38.4 37.2 61.2 58.8Pr 5.09 4.02 4.52 5.25 4.16 4.86 5.10 8.23 7.97 Nd 23.5 18.6 22.1 24.6 19.5 22.1 22.9 39.8 38.9 Sm 5.96 4.80 5.99 6.37 5.08 5.61 5.85 10.2 10.1Eu 1.74 1.52 1.95 1.89 1.62 1.51 1.79 3.47 3.37 Gd 7.04 5.62 7.11 7.43 6.02 6.49 6.84 11.9 11.7 Tb 1.16 0.943 1.18 1.24 1.01 1.08 1.14 1.92 1.89 Dy 7.42 5.99 7.51 7.79 6.39 6.99 7.21 12.0 11.7

52

Table 2 continued

No. Y-10 Y-11 Y-12 Y-13 Y-14 Y-15 Y-16 Y-17

Rocks Basalt Basalt Basalt Basalt Basalt Basalt Basalt Basalt

SiO2 51.46 51.73 53.90 52.82 51.77 53.18 53.33 47.38 TiO2 2.77 2.69 2.57 2.88 1.99 2.10 2.05 2.62 Al2O3 14.00 14.16 14.66 14.65 14.55 13.74 13.03 13.73

TFe2O3 13.61 13.72 12.94 13.23 11.00 11.61 10.40 14.11 MnO 0.24 0.28 0.25 0.23 0.21 0.21 0.21 0.20 MgO 4.03 4.08 3.33 3.55 3.90 3.93 4.29 3.99 CaO 6.56 6.43 5.84 5.26 6.43 6.10 6.84 6.59 Na2O 2.50 1.59 1.61 2.05 4.40 4.45 3.81 4.14 K2O 1.04 1.07 1.54 1.72 1.30 2.26 1.96 1.36 P2O5 0.82 0.86 0.80 0.88 0.75 0.69 0.68 1.10 LOI 2.87 3.28 2.43 2.41 3.59 1.60 3.30 4.69 Total 99.89 99.88 99.87 99.68 99.90 99.89 99.9. 99.91 Mg# 39.44 39.53 36.13 37.13 43.84 42.70 47.59 38.39

Sc 27.5 26.0 26.2 27.4 28.0 28.6 27.7 35.1 V 209 176 170 179 174 197 188 336 Co 24.5 23.4 19.3 22.9 18.0 20.8 17.8 37.5 Ga 21.2 21.2 22.7 22.8 24.7 25.5 23.6 23.1 Li 8.89 9.64 8.72 10.1 9.11 5.27 6.64 22.2 Be 1.56 1.41 1.54 1.45 1.40 1.64 1.46 1.07 Cs 0.462 0.361 1.00 0.794 1.31 0.711 0.911 3.43 Rb 11.0 10.8 16.8 16.9 13.0 21.7 23.1 31.4 Sr 239 290 220 299 317 332 266 346 Ba 150 131 265 250 442 379 247 179 Th 2.32 2.47 2.82 2.63 2.82 2.99 2.70 1.56 U 0.872 0.903 0.921 1.13 1.31 1.17 0.878 0.561Ta 0.813 0.851 0.872 0.864 0.749 0.813 0.427 0.554 Nb 12.8 13.6 14.2 13.9 13.8 14.2 10.9 8.64 Hf 7.44 7.59 8.71 8.24 10.4 11.2 10.0 7.27 Zr 353 363 418 388 388 421 377 238 Y 59.8 59.9 64.6 63.9 70.9 72.1 66.1 55.7 Pb 6.18 8.29 11.3 11.2 10.7 9.45 10.7 16.9 La 22.0 22.6 24.5 24.5 25.0 25.9 24.5 19.1

Ho 1.52 1.23 1.54 1.59 1.31 1.43 1.47 2.43 2.37Er 4.50 3.65 4.45 4.64 3.87 4.26 4.30 7.02 6.83 Tm 0.642 0.513 0.622 0.662 0.551 0.622 0.612 0.994 0.953 Yb 4.25 3.41 4.08 4.34 3.64 4.08 3.97 6.51 6.19 Lu 0.621 0.494 0.591 0.632 0.533 0.592 0.584 0.972 0.914

∑REE 118.45 94.69 107.25 122.76 98.49 113.33 113.33 191.35 185.19

（La/Nb）N 3.65 3.64 2.99 3.64 3.43 3.75 3.62 3.79 3.79

δEu 0.82 0.89 0.91 0.84 0.86 0.77 0.87 0.97 0.95

53

Ce 55.8 56.8 61.9 62.1 65.6 65.9 61.7 50.2 Pr 7.63 7.72 8.32 8.39 9.06 9.01 8.35 7.18 Nd 37.6 37.6 40.2 41.0 45.4 43.9 41.3 37.1 Sm 9.84 9.76 10.3 10.7 11.4 11.2 10.5 9.91 Eu 3.25 3.25 3.45 3.58 3.69 3.74 3.59 3.45 Gd 11.6 11.5 12.1 12.4 12.9 12.9 12.0 11.4 Tb 1.86 1.85 1.96 1.99 2.12 2.13 1.95 1.79 Dy 11.6 11.5 12.2 12.3 13.0 13.1 12.1 10.7 Ho 2.32 2.32 2.48 2.49 2.61 2.65 2.44 2.09 Er 6.61 6.69 7.25 7.14 7.56 7.69 7.05 5.78 Tm 0.924 0.933 1.02 0.992 1.05 1.09 0.992 0.774 Yb 5.99 6.09 6.67 6.47 6.90 7.06 6.47 4.81 Lu 0.872 0.891 0.983 0.952 1.03 1.05 0.961 0.692

∑REE 177.89 179.50 193.33 195.03 207.43 207.24 193.86 164.90

（La/Nb）N 3.67 3.71 3.67 3.78 3.63 3.67 3.79 3.97

δEu 0.93 0.94 0.95 0.95 0.93 0.95 0.98 0.99 Note: Major elements are analyzed using XRF (in wt %), trace elements using ICP-MS (in ppm)

54

Table 3

Sample No.

Rb [ppm]

Sr [ppm]

87Rb/86Sr 87Sr/86Sr Error (2σ)

(87Sr/86Sr)i Sm [ppm]

Nd [ppm]

147Sm/144Nd 143Nd/144Nd Error (2σ)

(143Nd/144Nd)i εNd(t)

Y-8 13.4 204.3 0.1895 0.704475 0.000012 0.703774 10.4 39.6 0.1598 0.512938 0.000011 0.512644 7.09

Y-9 17.2 265.6 0.1874 0.706015 0.000013 0.705322 10.5 39.2 0.1617 0.512945 0.000010 0.512648 7.16

Y-10 9.75 189.8 0.1487 0.704405 0.000015 0.703854 9.20 34.7 0.1608 0.512950 0.000012 0.512654 7.28

Y-11 10.4 198.4 0.1516 0.704556 0.000014 0.703996 9.52 35.9 0.1605 0.512949 0.000011 0.512654 7.27

Y-12 16.4 196.5 0.2422 0.704718 0.000013 0.703822 10.3 38.8 0.1605 0.512817 0.000013 0.512521 4.69

Y-6 41.4 345.8 0.3612 0.709434 0.000011 0.707990 5.61 22.10 0.1359 0.512351 0.000015 0.512101 -3.41

Y-7 20.5 568.0 0.1018 0.707188 0.000015 0.706781 5.71 22.4 0.1276 0.512410 0.000014 0.512175 -1.97

Y-5 11.4 407.3 0.0824 0.708110 0.000015 0.707781 5.18 19.71 0.1405 0.512500 0.000010 0.512241 -0.68

Y-2 71.3 336.1 0.6137 0.709193 0.000012 0.706739 4.60 18.53 0.1283 0.512463 0.000011 0.512227 -0.96

Y-1 3.51 231.2 0.0462 0.707304 0.000011 0.707119 5.76 23.13 0.1385 0.512497 0.000012 0.512242 -0.66

55

Table 4

Continued

Sample 4.3 5.1 5.2 6.1 6.2 6.3 7.1 7.2

SiO2 52.03 52.15 52.24 52.41 51.63 51.07 50.92 51.67

TiO2 0.85 0.71 0.72 0.73 0.84 1.05 0.85 0.81

Al2O3 2.23 2.45 2.14 2.04 2.01 2.04 2.2 2.51

Cr2O3 0.21 0.41 0.26 0.44 0.01 0 0.05 0.57

Fe2O3 1.53 1.19 0.05 0.94 2.43 1.11 2.69 2.6

FeO 5.44 5.1 6.44 5.46 5.54 7.72 5.27 3.98

Sample 1.1 2.1 2.2 3.1 3.2 4.1 4.2 9.2

SiO2 51.13 51.58 52.16 50.83 50.9 51.17 51.37 51.39

TiO2 0.93 0.88 0.87 0.79 0.8 0.94 0.99 0.86

Al2O3 3.15 2.28 2.42 3.17 2.3 1.93 2.17 2.46

Cr2O3 0.62 0.03 0.12 0.76 0.45 0.02 0 0.27

Fe2O3 2.31 1.66 1.87 2.05 2.57 2.05 1.78 2.42

FeO 4.5 5.85 5.46 4.35 4.22 6.42 6.3 4.45

MnO 0.13 0.23 0.21 0.19 0.2 0.24 0.23 0.14

MgO 16.25 15.93 16.38 16.33 16.17 15.55 15.8 15.72

CaO 20.67 20.73 20.84 20.35 20.81 20.26 20.21 21.7

Na2O 0.41 0.31 0.33 0.37 0.35 0.36 0.36 0.39

K2O 0 0 0.02 0.02 0.02 0.01 0.02 0

Totals 100.1 99.48 100.68 99.21 98.79 98.94 99.23 99.8

Cations normalized to 6 oxygens

Si 1.88 1.913 1.909 1.883 1.897 1.915 1.913 1.899

Ti 0.026 0.025 0.024 0.022 0.022 0.026 0.028 0.024

Al 0.137 0.1 0.104 0.138 0.101 0.085 0.095 0.107

Cr 0.018 0.001 0.003 0.022 0.013 0.001 0 0.008

Fe3+ 0.064 0.046 0.051 0.057 0.072 0.058 0.05 0.067

Fe2+ 0.138 0.181 0.167 0.135 0.131 0.201 0.196 0.138

Mn 0.004 0.007 0.007 0.006 0.006 0.008 0.007 0.004

Mg 0.89 0.881 0.893 0.901 0.898 0.867 0.877 0.866

Ca 0.814 0.824 0.817 0.808 0.831 0.813 0.807 0.859

Na 0.029 0.022 0.023 0.027 0.025 0.026 0.026 0.028

K 0 0 0.001 0.001 0.001 0 0.001 0

Sum 4 4 4 4 4 4 4 4

Wo 42.69 42.63 42.35 42.48 42.99 41.91 41.79 44.52

En 46.7 45.58 46.32 47.43 46.48 44.75 45.46 44.87

Fs 10.61 11.79 11.33 10.09 10.53 13.34 12.75 10.61

56

MnO 0.21 0.17 0.14 0.18 0.25 0.25 0.15 0.17

MgO 16.49 16.4 16.23 16.67 15.96 15.11 15.77 16.42

CaO 20.55 20.92 20.53 20.57 20.53 19.82 20.72 20.97

Na2O 0.34 0.36 0.28 0.35 0.42 0.37 0.34 0.48

K2O 0.01 0.01 0 0 0 0 0 0

Totals 99.89 99.87 99.04 99.78 99.62 98.54 98.96 100.18

Cations normalized to 6 oxygens

Si 1.916 1.918 1.939 1.929 1.914 1.923 1.902 1.896

Ti 0.024 0.02 0.02 0.02 0.023 0.03 0.024 0.022

Al 0.097 0.106 0.094 0.089 0.088 0.091 0.097 0.109

Cr 0.006 0.012 0.008 0.013 0 0 0.001 0.017

Fe3+ 0.042 0.033 0.001 0.026 0.068 0.031 0.075 0.072

Fe2+ 0.168 0.157 0.2 0.168 0.172 0.243 0.165 0.122

Mn 0.007 0.005 0.004 0.006 0.008 0.008 0.005 0.005

Mg 0.905 0.899 0.898 0.914 0.882 0.848 0.878 0.898

Ca 0.811 0.824 0.816 0.811 0.815 0.8 0.829 0.825

Na 0.024 0.026 0.02 0.025 0.03 0.027 0.025 0.034

K 0 0 0 0 0 0 0 0

Sum 4 4 4 4 4 4 4 4

Wo 42.1 43.08 42.62 42.25 42.1 41.6 42.58 43.02

En 47 47 46.88 47.64 45.54 44.12 45.09 46.87

Fs 10.9 9.92 10.51 10.11 12.37 14.28 12.33 10.12 Continued

Sample 7.3 8.1 8.2 9.1

SiO2 51.46 50.85 51.32 51.73

TiO2 0.74 0.96 0.96 0.91

Al2O3 2.3 3.17 2.34 2.2

Cr2O3 0.56 0.46 0.03 0.07

Fe2O3 2.32 1.41 2.22 1.36

FeO 3.96 5.03 5.6 6.13

MnO 0.21 0.14 0.22 0.18

MgO 16.9 15.94 15.67 15.95

CaO 20.48 20.43 20.82 20.57

Na2O 0.36 0.4 0.39 0.34

K2O 0 0.02 0 0

Totals 99.29 98.81 99.56 99.45

Cations normalized to 6 oxygens

Si 1.902 1.892 1.905 1.919

Ti 0.021 0.027 0.027 0.025

57

Al 0.1 0.139 0.102 0.096

Cr 0.016 0.014 0.001 0.002

Fe3+ 0.065 0.04 0.062 0.038

Fe2+ 0.122 0.156 0.174 0.19

Mn 0.007 0.004 0.007 0.006

Mg 0.931 0.884 0.867 0.882

Ca 0.811 0.814 0.828 0.818

Na 0.026 0.029 0.028 0.024

K 0 0.001 0 0

Sum 4 4 4 4

Wo 42.04 42.99 42.88 42.41

En 48.27 46.67 44.91 45.76

Fs 9.69 10.34 12.21 11.83

58

Table 5

Location Rock type Age (Ma) Analytical method Data source

Xuanwoling Gabbro 260.7±2.0 SIMS Su et al., 2010a

Poshi Olivine gabbro 275.5±1.2 SIMS Ao, 2010

Poshi Olivine gabbro 284±2.2 SIMS Qin et al., 2011

Poyi Alkaline granite vein 251.4±1.4 SIMS Su et al., 2010b

Poyi Gabbro 271±6.2 SIMS Ao, 2010

Luodong Gabbro 284.0±2.3 SIMS Su et al., 2010b

Luodong Gabbro 283.8±1.1 LA-ICP-MS Ao, 2010

Hongshishan Olivine gabbro 281.8±2.6 LA-ICP-MS Ao et al., 2010

Hongshishan Troctolite 286.4±2.8 SIMS Su et al., 2010c

Hongshishan Diorite 279.7±4.8 SIMS Qin et al., 2011

Hongshishan Dacite 279.1±2.9 SIMS Qin et al., 2011

Hongshishan Ryholite 321.7±3.4 SIMS Su et al., 2011

Bijiashan Gabbro 279.2±2.3 SIMS Qin et al., 2011

Liuyuan Nb-enriched basalts 451.6±4.4 SIMS Mao et al., 2012

Liuyuan Dacites 442.23±3.1 SIMS Mao et al., 2012

Liuyuan Diorite 272.7±4.4 SHRIMP Zhang et al., 2011

Liuyuan Diorite 291.4±4.9 SHRIMP Zhang et al., 2011

Liuyuan Ultramafic rocks 250.4±9.0 SHRIMP Zhang et al., 2011

Liuyuan Granodiorite 423±8 SHRIMP Zhao et al., 2007

Liuyuan Monzonitic granite 396±15 SHRIMP Zhao et al., 2007

Liuyuan K-feldspar granite 436±9 SHRIMP Zhao et al., 2007

Shuangfengshan A-type granite 415±3 LA-ICP-MS Li et al., 2009

Huitongshan A-type granite 397±3 LA-ICP-MS Li et al., 2011

Gubaoquan Eclogite 465±10 LA-ICP-MS Liu et al., 2011

Hongliuhe ophiolite Cumulate gabbro 516.2±7.1 SHRIMP Zhang and Guo, 2008

Hongliuhe ophiolite Biotite granite 404.8±5.2 SHRIMP Zhang and Guo, 2008

Qiaowan Granodiorite 303.7±2.4 LA-ICP-MS Feng et al., 2012

59

Yinwaxia Biotite granite 281. 7 ± 2. 9 LA-ICP-MS Zhang et al., 2011

Xijianquanzi Monzonitic granite 266.1±2.2 LA-ICP-MS Zhang et al., 2010

Yueyashan ophiolite Plagiogranite 533±1.7 SIMS Ao et al., 2011

Yueyashan ophiolite Plagiogranite 536±7 SHRIMP Hou et al., 2012

60

61

62

63

64

65

66

67

68

69

70

71

Highlights

� Yinwaxia mafic rocks were formed in Permian (265 Ma and 281 Ma).

� They derived from lithospheric mantle metasomatized by fluids and/or melts.

� Yinwaxia mafic rocks formed in a continental rift.