Formation and evolution of Precambrian continental crust in South China

Chinese Science Bulletin

© 2007 Science in China Press

Springer-Verlag

SP

EC

IAL

TOP

ICS

R

EV

IEW

Formation and evolution of Precambrian continental crust in South China

ZHENG YongFei† & ZHANG ShaoBing

Key Laboratory of Crust-Mantle Materials and Environments, Chinese Academy of Sciences, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China

The occurrence of zircons with U-Pb ages of ~3.8 Ga and Hf model ages of ~4.0 Ga in South China suggests the existence of the Hadean crustal remnants in South China. Furthermore, a detrital zircon with a U-Pb age as old as 4.1 Ga has been found in Tibet. This is the oldest zircon so far reported in China. These results imply that continental crust was more widespread than previously thought in the late Hadean, but its majority was efficiently reworked into Archean continental crust. On the basis of available zircon U-Pb age and Hf isotope data, it appears that the growth of continental crust in South China started since the early Archean, but a stable cratonic block through reworking did not occur until the Paleoproterozoic. Thus the operation of some form of plate tectonics may occur in China conti-nents since Eoarchean. The initial destruction of the South China craton was caused by intensive magmatic activity in association with the assembly and breakup of the supercontinent Rodinia during the Neoproterozoic. However, most of the Archean and Paleoproterozoic crustal materials in South China do not occur as surface rocks, but exist as sporadic crustal remnants. Nevertheless, the occur-rence of Neoproterozoic magmatism is still a signature to distinguish South China from North China.

GE

OLO

GY

Archean, Paleoproterozoic, continental crust, growth, reworking, South China

Understanding the formation and evolution of early crust of a continent is central to studying its tectonic structure and tracing its origin[1―3]. It is already known that Ar-chean rocks are widely present in North China and the oldest zircon U-Pb age is 3.85 Ga[4], but Archean-aged crust is very scarce in South China. For a long time this difference has been viewed as a signature in distin-guishing South China from North China. Nevertheless, more and more isotopic ages of the Archean to Paleo-proterozoic have been found in crustal rocks from South China due to the accumulation of radiometric ages, par-ticularly a series of recently published zircon U-Pb ages[5―11]. These new information not only reveals the existence of ancient crustal materials in South China, but also provides insights into the possibility that the Ar-chean crustal basement may also exist in South China[12].

South China is composed of the Yangtze Block and

Cathaysia Block, collided together along the early Neo-proterozoic Jiangnan Orogen. They are different in their Precambrian basement. Conventionally, ancient rocks in the Yangtze Block are thought to be the Kongling com-plex at Yichang in Hubei Province. They consist of 2.9―2.95 Ga TTG gneisses and migmatites, 1.9―2.0 Ga me-tasediments (which contain plenty of detrital zircons with Archean ages) as well as minor amphibolites and mafic granulites occurring as lenses[13,14]. Ancient rocks in the Cathaysia Block are 1.8―2.0 Ga that were found in southeastern Zhejiang and northwestern Fujian[15―18]. The occurrence of these ancient rocks suggests that the Archean to Paleoproterozoic crustal basement might exist in South China. Lately, a large number of Archean Received September 25, 2006; accepted September 25, 2006 doi: 10.1007/s11434-007-0015-5 †Corresponding author (email: [email protected]) Supported by the National Natural Science Foundation of China (Grant No. 40334036) and the Chinese Academy of Sciences (Grant No. KZCX2-SW-141)

www.scichina.com www.springerlink.com Chinese Science Bulletin | January 2007 | vol. 52 | no. 1 | 1-12

to Paleoproterozoic zircon U-Pb ages have been found in rocks from different areas of South China[5―11], im-plying more widespread distribution of this ancient basement in South China than previously thought. As for the study concerning the formation and evolution of Precambrian crust in China, understanding the formation and destruction of ancient cratons is becoming one of the frontiers and hot topics that attract extensive atten-tion of geoscientists in the world.

1 Growth of Archean crust in South China

Table 1 lists all available Archean U-Pb ages in South China acquired by means of microscale analyses (SIMS and LA-ICPMS). Occurrence of these Archean crustal materials in South China is shown in Figure 1.

In the Yangtze Block, the Archean ages have been identified from: (i) Archean rocks; (ii) Archean xenocrystic zircons in volcanic rocks; (iii) inherited zir-con cores in igneous or metamorphic rocks; and (iv) detrital zircons in sedimentary rocks. The Archean rocks are TTG gneiss and migmatite in the Kongling complex that occurs in the northern part of the Yangtze Block. The 2.9―2.95 Ga TTG magmatism and the ~3.2 Ga inherited zircon cores were revealed from SHRIMP and LA-ICPMS analyses[8,14]. Zircon Hf isotope analyses on the ~2.9 Ga grains and the ~3.2 Ga cores show that both of them are associated with negative εHf(t) values and Hf model ages of about 3.5 Ga. This indicates that the ear-liest crustal materials at Kongling might have been ex-tracted from the mantle at Paleoarchean[8]. The xenocrystic zircons brought by volcanics have been found in several places. Zheng et al.[11] reported a plenty of Archean zircons that are found in lamproite diatremes from Jingshan (Hubei Province), Ningxiang (Hunan Province), and Zhenyuan (Guizhou Province), with two age populations at 2.9―2.8 Ga and 2.6―2.5 Ga. This indicates that the Archean basement is widespread be-neath the Yangtze Block. These Archean zircons are as-sociated with negative εHf(t) values, suggesting crustal growth in the early Archean. Zhang et al.[24] obtained SHRIMP zircon U-Pb ages of 2.5―3.2 Ga from a tranchyandesite in the Longwangshan Formation from Maanshan, Anhui Province. The Neoproterozoic tuff in the Liantuo Formation, located to the South of Kongling, yields a discordia line with an upper intercept age of

2760±50 Ma[19]. Inherited zircon cores with Archean ages are frequently found in igneous or metamorphic rocks of the Yangtze Block. Liu et al.[29] reported inher-ited cores of 2.7―2.8 Ga for the Maomaogou sodium alkaline rocks at Huili in western Panzihua. Chen et al.[30] also found inherited zircon cores with ages around 2.5 Ga in granitic gneisses at Shaba in Mianning, Si-chuan Province. In addition, inherited cores or upper intercepts with Archean ages were obtained from meta-morphic and igneous rocks in the Dabie-Sulu orogenic belt, such as those at Huangtuling[21], Shuanghe[22,23] and Wulian[25]. As for the sedimentary rocks in the Yangtze Block, Compston et al.[28] reported ages of 2914±6 to 2955±24 Ma for zircons from bentonite in the Meishu-chun Formation close to Kunming in Yunnan Province. Liu et al.[20] reported detrital zircons of 3.32―3.51 Ga ages in sandstones from the Liantuo Formation and the Nantuo Formation in the vicinity of Yichang, Hubei Province. Zhang et al.[10] found a very old detrital zircon with a U-Pb age of 3.8 Ga with a εHf(t) value of −0.8 and model Hf ages of 3.96 to 4.00 Ga for a sandstone from the Liantuo Formation in the Yangtze Gorge at Yichang (Figure 2(a)). This demonstrates the presence of the Eoarchean crustal remnant in the Yangtze Block, with possible crustal growth as early as late Hadean.

Archean ages in the Cathaysia Block are mainly re-corded in inherited zircon cores and detrital zircons. Li et al.[17] obtained inherited cores of 2.7―2.8 Ga from a Paleoproterozoic plagioclase amphibolite at Jianning in Fujian Province. Xu et al.[5] reported zircons with ages of 2.5―2.7 Ga for the Lanhe gneiss and the Devonian sediment in the Nanling Mountains area. Yu et al.[27] reported an upper intercept age of 2.5 Ga for the Taoxi granulite in the eastern Nanling Mountains. Ding et al.[31] carried on LA-ICPMS zircon U-Pb dating for Guzhai granodiorite in the eastern Guangdong Province and found ages of around 2.7 Ga. Detrital zircons of 2.5―3.0 Ga were found from the Longchuan gneiss in north-eastern Guangdong Province[6]. Yu et al.[7] reported de-trital zircons of ~2.5 Ga, 3.0―3.2 Ga and 3.76 Ga in the Tanxi gneiss at Nanxiong in northern Guangdong Prov-ince, with both positive and negative εHf(t) values[5―7]. These indicate both growth of juvenile crust and re-working of ancient crust for gneiss protolith. Although only a very old zircon with a U-Pb age of 3.76 Ga with a εHf(t) value of −1.6 and model Hf ages of 3.95 to 4.07 Ga

2 ZHENG YongFei et al. Chinese Science Bulletin | January 2007 | vol. 52 | no. 1 | 1-12

SP

EC

IAL

TOP

ICS

Table 1 Zircon U-Pb ages of Archean by Micro-scale analysis for rocks from South China

No. Province Locality Rock type Analytical method Age (Ma) Reference 1a Hubei Kongling in Yichang trondjemitic gneiss SIMS concordia point 3051±12, 2739±18 Qiu et al.[14] SIMS concordia point 2947±5(n=14), 2903±10(n=6) Qiu et al.[14]

metapelite SIMS dicordia intercept 3275±22, 3234±12, 3133±14, 3118±46, 2950±14, 2871±14, 2745±16, 2644±16

Qiu et al.[14]

metapelite SIMS dicordia intercept 2974±49 Qiu et al.[14] migmatite SIMS dicordia intercept 2916±31 Zhang et al.[8]

migmatite LA-ICPMS dicordia intercept 2936±28 Zhang et al.[8]

migmatite LA-ICPMS dicordia intercept 2947±28 Zhang et al.[8]

migmatite LA-ICPMS concordia point3253±16, 3234±14, 3124±17, 3114±17, 3125±16, 3135±19, 3113±25

Zhang et al.[8]

gneiss LA-ICPMS dicordia intercept 2930±44 Zhang et al.[8]

trondjemitic gneiss LA-ICPMS discordia intercept 2858±25 Zhang et al.[8]

tonalitic gneiss LA-ICPMS dicordia intercept 2893±29 Zhang et al.[8]

1b Hubei Liantuo in Yichang tuff SIMS dicordia intercept 2760±50 Ma et al.[19]

sandstone LA-ICPMS cooncordia point

3235±17, 3120±18, 3508±20, 3196±18, 3369±21, 3319±18, 3267±21

Liu et al.[20]

sandstone SIMS concordia point 3802±8, 3445±10, 2942±42 Zhang et al.[10] sandstone LA-ICPMS concordia point 3306±15, 2951±18 Zhang et al.[10] 1c Nantuo in Yichang sandstone LA-ICPMS concordia point 3437±15, 3502±16, 3086±18 Liu et al.[20]

2 Hubei Jingshan lamproite LA-ICPMS concordian point

2614±8, 2708±7, 2559±8, 2751±8 Zhang et al.[10]

3 Hubei Huangtuling in Luotian granulite SIMS concordia point 2723±5, 3443±13 Wu et al.[21]

4 Anhui Shuanghe in Qianshan eclogite SIMS discordia intercept 2489±25 Chen et al.[22] biotite paragneiss SIMS discordia intercept 2458±76 Chavagnac et al.[23]

5 Anhui Longwangshan in Maanshan tranchyandesite SIMS condordia point 2485±9, 3098±1, 2421±22,

2592±10 Zhang et al.[24]

6 Shandong Shichang in Wulian Mesozoic granite LA-ICPMS dicordia intercept 3565±280 Huang et al.[25]

7 Hunan Ningxiang lamproite LA-ICPMS concordia point

2415±12, 2835±10, 2485±8, 2525±7, 2751±8, 2980±7, 2487±8, 2434±8, 2492±8, 2441±8, 2740±9

Zhang et al.[10]

8 Hunan Xieshuihe Formation in Shimen tuff SIMS concordia point 2461±30,2465±17,2459±10 Yin et al.[26]

9 Guizhou Zhenyuan lamproite LA-ICPMS concordia point 2576±9,2632±10 Zhang et al.[10]

10 Fujian Tianjingping in Jianning plagioclase amphibolite SIMS concordia point 2770±27, 2696±41, 2818±8,

2432±26 Li et al.[17]

11 Fujian Taoxi granulite LA-ICPMS discordia intercept 2523±26 Yu et al.[27]

12 Yunnan Meishucun in Kunming bentonite SIMS concordia point 2955±24, 2914±6 Compston et al.[28]

13 Sichuan Huili in Panzihua alkaline syenite SIMS-207/206 point 2692±12, 2818±14 Liu et al.[29] 14 Sichuan Shaba in Mianning granitic gneiss SIMS concordia point 2468±11 Chen et al.[30]

15 Guangdong Guzhai granodiorite LA-ICPMS discordia intercept 2708±100 Ding et al.[31]

16a Guangdong Lanhe in Nanxiong gneiss LA-ICPMS concordia point 2517±9 Xu et al.[5] Devonian sediment LA-ICPMS concordia point 2669±9 Xu et al.[5]

16b Tanxi in Nanxiong gneiss LA-ICPMS concordia point

2479±18.5,2497±17, 2558±16, 3099±15.5,3755±15, 2504±17, 2650±16.3,2498±16.9, 2487±16.7

Yu et al.[7]

17 Guangdong Longchuan gneiss LA-ICPMS discordia intercept 2577±48, 3004±630 Yu et al.[6]

RE

VIE

W

GE

OLO

GY

ZHENG YongFei et al. Chinese Science Bulletin | January 2007 | vol. 52 | no. 1 | 1-12 3

Figure 1 Sketch map of occurrence of Archean crustal remnants as identified by zircon U-Pb ages in South China (numbers in the figure are the index numbers in Table 1).

Figure 2 Hadean zircon grains in Yangtze, Cathaysia and Tibet. U-Pb ages are labeled with εHf(t) values for different grains. (a) and (c) are the CL images, and (b) is the BSE image.

was found in the Tanxi gneiss[7] (Figure 2(b)), it provides evidence for the existence of the Hadean crustal rem-nants with possible crustal growth in late Hadean in the Cathaysia Block. Thus, besides the Paleoproterozoic Badu and Mayuan Formations that occur in southwest-ern Zhejiang and northeastern Fujian, the basement of the Cathaysia Block probably contains some Archean crustal components.

As shown in Figure 1, the Archean crustal compo-

nents are distributed in most areas of the Yangtze Block and the central of the Cathaysia Block. The widespread presence of the Archean crustal remnants in South China indicates that the Archean era is an important period for the growth of continental crust in South China. Some Archean information is also obtained from the neighborhood of South China. Single-grain zircon U-Pb dating by Lan et al.[32] for gneisses in the Cavinh Com-plex, south of the Red River shear zone between Viet-


SP

EC

IAL

TOP

ICS

nam and South China, gave ages of 2.5―2.8 Ga. Duo et al.[33] found a very old detrital zircon with a U-Pb age up to 4.0 Ga from a quartz schist in the Pulan County, western Tibet (Figure 2(c)), probably providing evidence for the existence of the Hadean crustal remnants in China.

RE

VIE

W

2 Paleoproterozoic reworking of conti-nental crust in South China

GE

OLO

GY

hina.

Paleoproterozoic ages are also frequently found in South China (Table 2). Qiu et al.[14] obtained concordant SHRIMP ages of 1992±16 Ma and 1933±50 Ma from trondjemitic gneiss and metapelite in the Kongling Complex. Also at Kongling, Zhang et al.[8] obtained concordant ages of about 2.0 Ga from the analyses on the overgrowth rims of zircons in migmatite and inter-preted it as the timing of migmatization. Metamorphic ages of 1.9―2.0 Ga are recorded by the Kongling me-tasedimentary rocks. These age results suggest that the Kongling Complex experienced a tectonothermal event in the Paleoproterozoic[9]. The identification of Paleo-proterozoic metamorphic-magmatic event in the north-ern edge of South China indicates that South China may also experienced the assembly of the supercontinent Columbia, just as North China did[46]. Thus, this pro-vides an important geochronological basis for the recon-struction of the position of South China in the supercon-tinent Columbia. Some metamorphic basement rocks are outcropped out in southwestern Zhejiang Province and northwestern Fujian Province, mainly including the Badu and the Mayuan Formations[18]. They consist mainly of felsic paragneiss, pelitic schist, greenschist, amphibolite, marble, calc-silicate, and quartzite, metamorphosed from greenschist to upper amphibolite facies and locally migmatitized[15]. The rocks from the Badu Formation and associated granitoids gave U-Pb zircon ages of 1.8―2.0 Ga[15—17], which unambiguously demonstrate the existence of Paleoproterozoic rocks in South C

Similar Paleoproterozoic ages are also found in many other areas of South China, indicating the extensive ex-istence of Paleoproterozoic basement in South China. Many localities mentioned with the Archean ages also record the Paleoproterozoic information, including three lamproite diatremes in Jingshan (Hubei Province), Ningxiang (Hunan Province), and Zhenyuan (Guizhou

Province)[11], the Huangtuling granulite in the Dabie orogen[21], the Maanshan tranchyandesite in Anhui[24], the Meishucun bentonite in Yunnan[28], the Tanxi gneiss in the Nanling Mountains area[7], and the Guzhai grano-diorite in eastern Guangdong[31]. In addition, Paleopro-terozoic ages have been identified in other areas of South China. Yin et al.[26] reported four SHRIMP U-Pb zircon ages of 1.90―1.99 Ga for the Neoproterozoic tuff from the Nanhua System in Shimen, Hunan Province. SHRIMP dating conducted by Peng et al.[45] for the Lin-cang biotite granite in Yunnan Province gave an age of 1977±44 Ma. Bryant et al.[35] obtained inherited zircon cores of 1.8―2.0 Ga from the Baimajian Mesozoic granite in Dabie. Similarly, inherited cores of 1.87 Ga and upper intercept ages of 2.0 Ga were obtained for the Mesozoic Wulian granite in Shandong Province[25]. The similar Paleoproterozoic ages, particularly the ages of 1.8―1.9 Ga, are also recorded in ultrahigh-pressure metamorphic rocks in the Dabie-Sulu orogenic belt that represents the subducted and exhumed materials from the Yangtze Block. These include outcrops at Shuanghe, Wumiao, Huangzhen, and Yingshan in Dabie as well as Rongcheng, Weihai and Sanqingge in Sulu[34,36 ― 44]. Zheng et al.[40] obtained an inherited zircon of 2147±22 Ma from gneiss in Wumiao, which is associated with a εHf(t) value of 8.5±0.6 and an Hf model age of 2186±96 Ma. Dated by the SHRIMP U-Pb zircon technique, an eclogite hosted in marbles from Shuanghe yielded a discordant chord with an upper intercept age at 1816±14 Ma[37], which is consistent with a zircon Hf model age of 1822±74 Ma[40] obtained from its country rock gneiss. An eclogite hosted in marbles from Xindian contains zircons with an LA-ICPMS U-Pb age of 1806±32 Ma[37]. These Paleoproterozoic zircons are of detrital origin, and their provenance is the ancient wallrocks at the rift shoulder during the middle Neoproterozoic rifting. They were weathered into detritus and involved into the lime-stone during its sedimentation in the rift basin.

Figure 3 illustrates the occurrence of Paleoproterozoic crustal components in South China. It appears that the Paleoproterozoic crustal materials are widely exposed in different areas of the Yangtze and Cathaysia Blocks. Hf isotope analyses for some of the Paleoproterozoic zir-cons suggest that the Paleoproterozoic events in South China mainly led to the reworking of ancient crust. Zheng et al.[11] reported εHf(t) values for the Paleopro-terozoic xenocrystic zircons in the Jingshan lamproite


Table 2 Zircon U-Pb ages of Paleoproterozoic by Micro-scale analysis for rocks from South China No. Province Locality Rock type Analytical method Age(Ma) Reference 1a Hubei Kongling in Yichang trondjemitic gneiss SIMS concordia point 1992±16 Qiu et al. [14] metapelite SIMS concordia point 1933±50 Zhang et al. [8] migmatite SIMS concordia point 2013±20 Zhang et al. [8] migmatite LA-ICPMS concordia point 1980±72(n=9) Zhang et al. [8] metapelite LA-ICPMS discordia intercept 1948±46, 1979±22 Zhang et al. [9] amphibolite LA-ICPMS discordia intercept 1943±44 Zhang et al. [9]

1a Hubei Liantuo in Yichang sandstone SIMS concordia point 1928±19 Zhang et al. [10] sandstone LA-ICPMS concordia point 1954±18 Zhang et al. [10]

2 Hubei Jingshan lamproite LA-ICPMS concordia point 2033±8, 1995±8, 2008±8, 2013±8, 2000±8, 2009±9, 2008±10, 2013±8, 2015±10

Zheng et al. [11]

LA-ICPMS discordia intercept 2040±23 Zheng et al. [11] 3a Hubei Huangtuling in Luotian granulite SIMS discordia intercept 2052±100 Wu et al. [21] 3a Hubei Yingshan gneiss SIMS-207/206 point 2230±10, 2122±39 Wu et al. [34]

4a Anhui Baimajian in Yuexi Mesozoic granite SIMS 207/206 point 1805±375,1865±56, 1929±25,1844±86, 2023±41 Bryant et al. [35]

4b Anhui Shuanghe in Qianshan jade quartzite SIMS discordia intercept 1921±23 Ayers et al. [36] eclogite SIMS discordia intercept 1816±14 Wu et al. [37]

marble SIMS 207/206 point 1956±31,1773±23, 1646±29,1651±25, 1873±13 Liu et al. [38]

4c Anhui Xindian in Qianshan eclogite LA-ICPMS 207/206 point 1806±32 Wu et al. [37] 4d Anhui Wumiao in Taihu eclogite SIMS 207/206 point 1861±32 Maruyama et al. [39]

gneiss LA-ICPMS discordia intercept 2147±22 Zheng et al. [40]

5a Anhui Longwangshan in Maanshan tranchyandesite SIMS concordia point 1839±6 Zhang et al. [24]

5b Anhui Huangzhen eclogite SIMS discordia intercept 1896±34 Chen et al. [41] eclogite SIMS discordia intercept 1817±102 Li et al. [42]

6a Shandong Rongcheng eclogite SIMS discordia intercept 1838±41 Tang et al. [43] Haiyangsuo amphibolite LA-ICPMS concordia point 1719±18 (n=6) Tang et al. [43]

6b Shandong Weihai eclogite SIMS discordia intercept 1822±25 Yang et al. [44] 6c Shandong Qibaoshan in Wulian Mesozoic granite LA-ICPMS concordia point 1873±56 Huang et al. [25] Dadian in Wulian Mesozoic granite LA-ICPMS discordia intercept 1999±280 Huang et al. [25]

6d Shandong Sanqingge marble SIMS 207/206 point 1698±30, 1841±12, 1824±9, 2012±77,2007±61, 1908±10 Liu et al. [38]

7 Hunan Ningxiang lamproite LA-ICPMS concordia point 2005±8, 2200±10, 2364±8 Zheng et al. [11]

8 Hunan Shimen tuff SIMS concordia point 1971±18,1811±72, 1986±30, 1976±50 Yin et al. [26]

9 Guizhou Zhenyuan lamproite LA-ICPMS concordia point 1786±12 Zheng et al. [11]

10 Fujian Tianjingping in Jian-ning

Plagioclase amphibolite SIMS concordia point

2026±14,1745±40, 1780±40,1795±29, 1773±19,1776±25, 1845±26,1737±18,1784±28, 1757±26

Li et al. [17]

11 Yunnan Lingcang granite SIMS concordia point 1977±44 Peng et al. [45]

12 Yunnan Meishucun in Kunming bentonite SIMS concordia point 1854±20,1842±13, 2069±23 Compston et al. [28]

13 Sichuan Shaba in Mianning granulite SIMS concordia point 1990±22 Chen et al. [30] 14 Guangdong Longchuan gneiss LA-ICPMS discordia intercept 1720±21 Yu et al. [6] 15 Guangdong Guzhai granodiorite LA-ICPMS discordia intercept 1718±80 Ding et al. [31]

16 Guangdong Tanxi in Nanxiong gneiss LA-ICPMS concordia point 1717±18.9,1630±20.6, 1670±18.2 Yu et al. [7]

diatreme in Hubei Province. The εHf(t) values have a large range but all are negative. Only one zircon grain has a concordant U-Pb age of 2.0 Ga with a εHf(t) value of −10. Hf isotope analyses on metasedimentary rocks in the Kongling Complex suggest their source materials are various Archean rocks. Thus the metamorphic age of

1.97 Ga recorded a crustal reworking event in the north-ern Yangtze Block[9], probably in association with the assembly of the supercontinent Columbia[46,47]. εHf(t) values for ~1.95 Ga zircons from the Liantuo sandstone are −25 to −14, also recording crustal reworking[10]. Nevertheless, the consistent zircon U-Pb and model Hf


SP

EC

IAL

TOP

ICS

RE

VIE

W

Figure 3 Sketch map of occurrence of Paleoproterozoic crustal materials as identified by zircon U-Pb ages in South China (numbers in the figure are the index numbers in Table 2).

ages at 2.15 Ga and 1.82 Ga for the Dabie metaigneous rocks possibly suggest the sporadic occurrence of Pa-leoproterozoic juvenile crust in South China.

GE

OLO

GY

A statistical analysis was conducted on all ages listed in Tables 1 and 2. The rule is that only one weighted mean was accepted for a group of similar ages in the same area in order to avoid possible artifacts due to mul-tiple analyses on the same occurrence of rocks at one locality. As shown in Figure 4, the statistical results re-veal seven age populations from Archean to Paleopro-

Figure 4 Plot of cumulative probability with histogram of Archean and Paleoproterozoic micro-scale U-Pb ages for zircons from South China.

terozoic for the crustal materials in South China: 1.8―2.0 Ga, ~2.5 Ga, ~2.7 Ga, ~3.0 Ga, ~3.2 Ga, ~3.5 Ga and 3.75 Ga. They may correspond to different episodes of magmatic activity during different periods, but further studies are needed to determine their intensity and na-ture. Nevertheless, both metamorphic and magmatic events of 2.0 to 1.8 Ga occurred in the northern part of the Yangtze Block[9], indicating that such plate tectonic processes as subduction and collision would proceed in association with the Columbia assembly.

3 Neoproterozoic crustal growth and reworking in South China A characteristic feature to distinguish South China from North China is the widespread occurrence of Neopro-terozoic igneous rocks in South China[12], especially two episodes of large-scale magmatism at about 820 Ma and 750 Ma[48―56]. These magmatic activities were associated with the crustal growth and reworking in South China during Neoproterozoic time, probably in association with the breakup of the supercontinent Rodinia.

In a combined study of applying zircon U-Pb dating and Hf isotope analysis to protolith origin of ultrahigh- pressure eclogites and gneisses in the Dabie orogen, Zheng et al.[40] found that their protoliths are ~750 Ma


mafic and felsic igneous rocks with incorporation of some Paleoproterozoic crust. Their εHf(t) values can be subdivided into two groups, one from 12.9±0.7 to 5.9±0.9 and the other from 2.3±0.3 to −2.7±0.6, which correspond to the Neoproterozoic juvenile crust and re-worked Paleoproterozoic crust, respectively. Geochro-nological and geochemical studies of Wu et al.[54] on granodiorites in South Anhui reveal: (i) two groups of zircon U-Pb ages at 824±6 Ma and 882±16 Ma, respec-tively; (ii) “mantle-like” Nd and Hf isotope composi-tions, with positive zircon εHf(t) values; and (iii) high A/CNK ratios and high δ 18O values. On the basis of these results, Wu et al.[54] concluded that arc-continent collision between the Cathaysia and Yangtze Blocks oc-curred at about 900 Ma. Subsequent to weathering and sedimentation of this juvenile crust, S-type granodiorites of “mantle-like” features were formed by the melting of the sediments during the extensional collapse of the col-lisional orogen at about 820 Ma. In other words, crustal reworking of South China in the Neoproterozoic in-cludes the reworking of both ancient crust and juvenile crust. εHf(t) values of −9 to +15 for Neoproterozoic zir-cons in lamproite diatremes at Ningxiang in Hunan Province and at Zhenyuan in Guizhou Province also suggest both growth and reworking of the crust in South China during Neoproterozoic time[11].

The growth of continental crust in South China oc-curred not only during the arc-continent collision at about 900±20 Ma[54] but also during the rift magmatism at about 750 Ma[40]. A combined Hf-O isotope study of two episodes of granitoids in South China[56] reveals that the ~825 Ma granitoids have neutral εHf(t) values of −3.4±0.8 to −1.6±0.8 and high δ 18O values of 8.7‰―

10.4‰, whereas 760―750 Ma bimodal intrusions are characterized by positive εHf(t) values of 3.5±0.8 to 9.9±0.8 and low δ 18O values of 4.2‰―6.2‰. These results suggest significant contributions of depleted mantle to the magmatism of the later episode. While only heat was transported from the asthenospheric man-tle to the continental crust for the first episodes of mag-matism at around 825 Ma, both heat and material from the asthenospheric mantle were transported to the crust for the second episode of bimodal magmatism in asso-ciation with the Rodinia breakup at about 750 Ma.

4 Formation and evolution of Precam-brian continental crust in South China Hadean zircons with U-Pb ages of 3.8 Ga are found in

both the Yangtze and Cathaysia Blocks of South China (Figure 2 (a) and (b)) with Hf model ages as old as 4.0 Ga. Zircons with ages of 3.85 Ga were report for North China[4]. Although the amount of 3.8 Ga zircons in South China is very small, the occurrence of ~3.8 Ga zircons in both South and North China may suggest that they might share similar events of geological processes since the Hadean. Thus the operation of some form of plate tec-tonics may occur in China continents since Eoarchean. The 4.1 Ga detrital zircon in Tibet is the oldest zircon so far reported in China (Figure 2(c)). Zircons with the simi-lar U-Pb age were never found in the neighbour area (e.g., India), but only occurred in Australia[3]. This may suggest that this grain of Hadean zircon came from Australia and was transported via India to the southwestern margin of China. Thus these continents were probably linked to each other in a certain way during the Precambrian times, possibly parts of the supercontinent Rodinia. Together with the zircon Hf model ages of about 4.0 Ga in the Yangtze and Cathaysia Block[7,10], these results imply that continental crust was more widespread than previously thought in the late Hadean, but its majority was effi-ciently reworked into Archean continental crust.

Figure 5 summarizes available U-Pb ages and associated Hf model ages for Precambrian zircons in South China. Based on these results, the timing and nature of the Precambrian growth and reworking of continental crust in South China can be deduced. The oldest continent nuclea (Kongling) in South China may have started to form since early Archean. After the growth in middle and late Archean and the reworking in the Paleopro- terozoic, it became cratonized. While the assembly of a supercontinent is a process to thicken continental lithosphere, the breakup of a supercontinent is a process to thin continental lithosphere at its margin. The time when the Cathaysia and Yangtze Blocks collided together along the Jiangnan Orogen, is also the time when the lithosphere of South China was thickening. When South China was split away from Rodinia at about 750 Ma, thinning and breakup only took place along its northern margin (present-day coordinates), but extensional collapse and resultant post-collisional magmatism took place in its interior. The magmatism of this episode may probably play a role on the initial thinning of continental lithosphere in South China, but it remains unclear how large it did. Nevertheless, Phanerozoic magmatism de- veloped on this basis inherited materials from underly- ing basement to different degrees. In principle, the


SP

EC

IAL

TOP

ICS

growth of juvenile crust in South China was dominated at the early stage of continental accretion. With the evo-lution of the continental crust, more juvenile crust was added to continental margins and more ancient crust was available to be reworked. Not only growth and rework-ing of juvenile crust but also reworking of Archean and Paleoproterozoic crust took place in the Neoproterozoic.

RE

VIE

W

Figure 5 Relationship between Hf model ages and U-Pb ages for Pre-cambrian zircons in South China (data are from refs. [5―11,37,40]). The zircon Hf model ages are interpreted following the principle[40] that adopts single-stage model relative to the depleted mantle when εHf(t) values are positive, but two-stage model relative to average continental crust when εHf(t) values are negative.

Archean cratons are areas of continental crust and lithosphere that exhibit long-term stability against de-formation and metamorphism. Cratonic roots may have formed originally from ancient oceanic lithosphere ei-ther via buoyant underthrusting in shallow subduction environments or via thrust stacking of arc-lithosphere in collisional environments. Although it is known that a relative thin or rehydrated cratonic lithosphere may not provide long-term stability as the Earth is cooling over geological time, it is unclear which mechanism dictates the long-term stabilization of ancient continental litho-sphere. Recent studies of chemical geodynamics con-cerning destruction of the North China craton suggest that the large-scale thinning of cratonic lithosphere may have occurred during the Mesozoic. However, different views exist with respect to thinning mechanism. Geo-chemists studying crust prefer delamination by which the destruction of lithosphere is realized by foundering of the mafic lower crust via subduction of either the South China continent[57] or the Pacific plate[58]. On the other hand, mantle geochemists advocate erosion through which the lithosphere was thinned by removal

of the lithospheric mantle via thermal and/or chemical erosion of asthenospheric mantle due to vertical upwell-ing like mantle plume[59]. The difference between de-lamination and erosion lies in the amount and rate of removal materials each time. The erosion gradually re-moved small amounts of materials every time, whereas the delamination took place in the way of avalanche to result in large-scale removal of materials. Actual thin-ning process may occur in intermediate ways between the two mechanisms; or the delamination dominates thinning of orogenic lithospheric roots along craton margins whereas the erosion dominates thinning of lithospheric mantle in the interior of craton. If a litho-spheric mantle is hydrated, its rheology would be similar to that of asthenospheric mantle. Once it is affected by mantle convection, thermal and/or chemical erosion would take place to remove the lithospheric mantle.

The similar process to thin a cratonic lithosphere may have also occurred in South China, but it remains to answer when and how it took place. Destruction of the South China craton may be initially caused principally by the assembly and breakup of the supercontinent Rodinia during the Neoproterozoic, with further re-working by several episodes of orogenic magmatism during the Phanerozoic. Westward subduction of the Pacific plate could be accelerated by mantle superplume activity in southwest Pacific during early Cretaceous, speeding up the westward convection of asthenoshperic mantle above the subducted Pacific plate. This subse-quently caused the heat anomaly beneath the continental lithosphere of eastern China. This heat anomaly would cause partial melting when encounting the root of colli-sional thickened orogen, resulting in a series of en-riched-type magmatism to emplace into the continental crust. Moreover, dehydration of serpentine could occur at the mantle transition zone due to mineral phase trans-formation in subducted oceanic crust, resulting in hy-drated melting of subcontinental lithospheric mantle and thus its thinning. One of the two mechanisms, or a com-bination of both, may be an important way for the thin-ning of lithosphere in eastern China during the Meso-zoic.

GE

OLO

GY

5 Concluding remarks

The mechanism of continental crust growth can be viewed as continuous addition by arc-continent collision around ancient continent nuclea. The formation of initial


continent nuclea might be linked to mantle plume mag-matism, which is particularly significant at the time be-fore plate tectonics played a role. Once plate tectonics began to operate, arc-continent collision and rift mag-matism turn to be two more important ways for the horizontal accretion and vertical growth of continental crust. The growth of continental crust involves three types of reworking process: (i) crustal recycling: partial melting of juvenile crust to form granitoid rocks; (ii) intracrustal recycling: the erosion of crustal materials and subsequent deposition and diagenesis; and (iii) crust-mantle recycling: subduction of crustal materials into the mantle. Large-scale rift magmatism tends to occur along the zones that a supercontinent breakups. Back-arc rifts might be the most favorite places to ulti-mately evolve into the margins of the broken-up conti-nent. Thus studies concerning the growth and reworking of continental crust also help to understand the roles of plate tectonics and mantle plumes in the evolution of the earth.

Whether continental accretion or supercontinental formation is a product of collision orogenesis. We can classify ancient orogenic belts into arc-continent and continent-continent collision types, respectively. Conti- nental accretion is principally accomplished by the mechanism of arc-continent collision, with growth of juvenile crust by oceanic arc magmatism. Superconti- nent assembly can only results from continent-continent collision. Nevertheless, residual oceanic or continental arc and its associated arc-continent collision orogen were usually present between two collided continents. Regardless of orogen types, they are associated with different depths of subduction resulting in variable grades of metamorphic rocks. Occurrence of blueschist- and eclogite-facies metamorphic rocks is a manifestation of plate motion. Island arc magmatism is generally associated with subduction of oceanic crust, but no synsub- duction magmatism has been found in continental subduction zones. Subduction causes crustal stacking and thickening in collisional orogens, where postcollisional magmatism occurred due to crustal collapse that can be caused by gravitational instability and/or lithospheric extension. Arc-continent collision results in continental accretion, and syncollisional magmatism is just the first step of intracrustal differentiation during the transforma- tion of oceanic crust to continental crust. Postcollisional magmatism is the second step of intracrustal differentiation of geochemistry. These two steps are the critical

processes for the formation and evolution of continental crust. It is the crustal melting and differentiation in the collisional orogens that result in the elemental and isotopic compositions of continental crust as observed today. Since the syncollisional and postcollisional magmatic activities are major processes resulting in growth of igneous zircon, an integrated study of zircon U-Pb dating and Hf isotope analysis is capable of providing important constraints on the continental accretion and differentiation. It is these processes that result in the episodic reworking of Precambrain crust in arc-continent collision orogens in South China at Archean[10], Paleoproterozoic[9] and Neoproterozoic[54].

Most chemically and mineralogically evolved granitoids have commensurately evolved isotopic compositions. That is, the “crustal” or “recycled” chemical nature of the granitoids is usually equally well-reflected in their radiogenic isotope compositions. Granitoids with “mantle-like” Nd-Hf isotopic compositions are frequently associated with chemically less evolved rocks, such as gabbros and diorites, which often are volumetrically much more important than the granitic suit. The very radiogenic nature of these granitoids suggest that imme- diate source materials, and the precursor material to those sources, must have had a significant proportion of depleted mantle component. Mechanism to produce ex- tremely evolved granitic magmas with mantle-like isotopic compositions is reworking of juvenile crust along continental margins. This can occur by one of the following two processes: (i) reworking of juvenile crust materials in arc-continent collision orogen[54], and (ii) rift-driven remelting of juvenile crust materials during supercontinental breakup[40].

Zircon U-Pb dating and Hf isotope analysis have been the two most important means to quantitatively date the growth and reworking of continental crust[3―11]. It must be pointed out that zircon U-Pb ages of igneous rocks do not stand for the time of crustal growth, but for the time of crustal melting and reworking[40]. In many cases, whole-rock Nd model ages do not represent the real time of crustal growth because of mixing between ancient and juvenile materials[60]. For example, Nd model ages of igneous and sedimentary rocks in South China are mostly Proterozoic[61], whereas zircon Hf isotope study reveals the episodic crustal growth in South China during the Archean and Proterozoic[5―11,40]. The Hf model age can be used to constrain the time of crustal growth, but it must meet the preconditions that not only its εHf(t)


SP

EC

IAL

TOP

ICS

value is consistent with that of coeval depleted mantle, but also its Hf model age accords with the timing of magmatism emplacement[40]. When the zircon Hf isotopic composition of metamorphic rocks is used to de- duce the nature of protolith, protolith age rather than

metamorphic age should be used to calculate εHf(t) values[40,62]. These basic rules should be taken into ac-count when dealing with relevant Hf isotope data.

Thanks are due to Drs. Fu-Yuan Wu and Guochun Zhao for comments on the manuscript , which lead to improvement of its presentation.

RE

VIE

W

1 Albarede F. The growth of continental crust. Tectonophysics, 1998, 296: 1―14

2 Condie, K C. Episodic continental growth models: afterthoughts and extensions. Tectonophysics, 2000, 322: 153―162

3 Nutman A P, Friend C R L, Bennett V C. Review of the oldest (4400―3600 Ma) geological and mineralogical record: Glimpses of the beginning. Episodes, 2001, 24: 93―101

4 Liu D Y, Nutman A P, Compston W, et al. Remnants of 3800 Ma crust in Chinese part of Sino-Korean craton. Geology, 1992, 20: 339―342

5 Xu X S, O'Reilly S Y, Griffin W L, et al. Relict Proterozoic basement in the Nanling Mountains (SE China) and its tectonothermal over-printing. Tectonics, 2005, 24(2): doi: 10.1029/2004TC001652

6 Yu J H, Wang L J, Zhou X H, et al. Compositions and formation his-tory of the basement metamorphic rocks in northeastern Guangdong Province. J China Univ Geosci, 2006, 31(1): 38―48

7 Yu J H, O’Reilly Y S, Wang L J, et al. Finding of ancient materials in Cathaysia and implication for the formation of Precambrian crust. Chin Sci Bull, 2007, 52(1): 13―22

8 Zhang S B, Zheng Y F, Wu Y B, et al. Zircon isotope evidence for ≥3.5 Ga continental crust in the Yangtze craton of China. Precambr Res, 2006, 146: 16―34

9 Zhang S B, Zheng Y F, Wu Y B, et al. Zircon U-Pb age and Hf-O isotope evidence for Paleoproterozoic metamorphic event in South China. Precambr Res, 2006, 151: 265―288

GE

OLO

GY

10 Zhang S B, Zheng Y F, Wu Y B, et al. Zircon U-Pb age and Hf isotope evidence for 3.8 Ga crustal remnant and episodic reworking of Ar-chean crust in South China. Earth Planet Sci Lett, 2006, 252: 56―71

11 Zheng J P, Griffin W L, O’Reilly S Y, et al. Widespread Archean basement beneath the Yangtze craton. Geology, 2006, 34: 417―420

12 Zheng Y F. Neoproterozoic magmatic activity and global change. Chin Sci Bull, 2003, 48(16): 1639―1656

13 Gao S, Ling W L, Qiu Y M, et al. Contrasting geochemical and Sm-Nd isotopic compositions of Archean metasediments from the Kongling high-grade terrane of the Yangtze craton: Evidence for cratonic evolution and redistribution of REE during crustal anatomies. Geochim Cosmochim Acta, 1999, 63: 2071―2088

14 Qiu Y M, Gao S, McNaughton N J, et al. First evidence of ≥3.2Ga continental crust in the Yangtze craton of South China and its impli-cations for Archean crustal evolution and Phanerozoic tectonics. Ge-ology, 2000, 28: 11―14

15 Gan X, Li H, Sun D, et al. A Geochronological study on early Pro-terozoic granitic rocks, Southwestern Zhejiang. Acta Petrol Miner (in Chinese with English abstract), 1995, 14(1): 1―8

16 Li S, Chen Y, Ge N, et al. Isotopic ages of metavolcanic rocks and metacryst mylonite in the Badu Group in Southwestern Zhejiang Province and their implications for tectonics. Acta Petrol Sin (in Chinese with English abstract), 1996, 12(1): 79―87

17 Li X, Wang Y, Zhao Z, et al. SHRIMP U-Pb zircon geochronology for

amphibolite from the Precambrian basement in SW Zhejiang and NW Fujian Provinces. Geochimica (in Chinese with English abstract), 1998, 27(4): 327―334

18 Zhao G C, Cawood P A. Tectonothermal evolution of the Mayuan assemblage in the Cathaysia Block: implications for Neoproterozoic collision-related assembly of the South China craton. Am J Sci, 1999, 299: 309―339

19 Ma G G, Li H Q, Zhang Z C. An investigation of the age limits of the Sinian System in South China. Yichang Institute Geol Miner Resour Bull (in Chinese with English abstract), 1984, 8: 1―29

20 Liu X, Gao S, Ling W, et al. The discovery of 3.5 Ga detrital zircons in the Yangtze craton and its geological implications. Prog Nat Sci, 2005, 15(11): 1334―1337

21 Wu YB, Chen D G, Xia Q K, et al. SIMS U-Pb dating of zircons in granulite of Huangtuling from Northern Dabieshan. Acta Petrol Sin (in Chinese with English abstract), 2002, 18(3): 378―382

22 Chen D G, Deloule E, Xia Q K, et al. Metamorphic zircon from Shuanghe ultra-high pressure eclogite, Dabieshan: ion microprobe and internal micro-structure study. Acta Petrol Sin (in Chinese with English abstract), 2002, 18(3): 367―377

23 Chavagnac V, Jahn B M, Villa I M, et al. Multichronometric evidence for an in situ origin of the ultrahigh-pressure terrane of Dabieshan, China. J Geol, 2001, 109: 633―646

24 Zhang Q, Jian P, Liu DY, et al. SHRIMP dating of volcanic rocks from Ningwu area and its geological implications. Sci China Ser D-Earth Sci, 2003, 46(8): 830―837

25 Huang J, Zheng Y F, Zhao Z F, et al. Melting of subducted continent: element and isotopic evidence for a genetic relationship between Neoproterozoic and Mesozoic granitoids in the Sulu orogen. Chem Geol, 2006, 229: 227―256

26 Yin C Y, Liu D Y, Gao L Z, et al. Lower boundary age of the Nanhua System and the Gucheng glacial stage: Evidence from SHRIMP II dating. Chin Sci Bull, 2003, 48: 1657―1662

27 Yu J H, Zhou X H, O’Reilly Y S, et al. Formation history and protolith characteristics of granulite facies metamorphic rock in Central Ca-thaysia. Chin Sci Bull, 2005, 50(18): 2080―2089

28 Compston W, Williams I S, Kirschvink J L, et al. Zircon U-Pb ages for the Early Cambrian time-scale. J Geol Soc London, 1992, 149: 171―184

29 Liu H, Xia B, Zhang Y. Zircon SHRIMP dating of sodium alkaline rocks from Maomaogou area of Huili County in Panxi, SW China and its geological implications. Chin Sci Bull, 2004, 49(16): 1750―1757

30 Chen Y, Luo Z, Zhao J, et al. Petrogenesis and dating of the Kangding complex, Sichuan Province. Sci China Ser D-Earth Sci, 2005, 48(5): 622―634

31 Ding X, Zhou X, Sun T. The episodic growth of the continental crustal basement in South China: single zircon LA-ICPMS U-Pb dating of Guzhai granodiorite in Guangdong. Geol Rev (in Chinese with Eng-


lish abstract), 51(4): 382―392 32 Lan C Y, Chung S L, Lo C H, et al. First evidence for Archean con-

tinental crust in northern Vietnam and its implications for crustal and tectonic evolution in Southeast Asia. Geology, 2001, 29: 219―222

33 Duo J, Wen C, Guo J, et al. 4.1 Ga old detrital zircon in western Tibet of China. Chin Sci Bull, 2007, 52(1): 23―26

34 Wu Y B, Chen D G, Deloule E, et al. Zircon U-Pb ion probe ages of gneisses from the northern Dabie terrane and their geological implications. Geol Rev (in Chinese with English abstract), 2001, 47(3): 239―244

35 Bryant D L, Ayers J C, Gao S, et al. Geochemical, age, and isotopic constraints on the location of the Sino-Korean/Yangtze Suture and evolution of the Northern Dabie Complex, east central China. Geol Soc Amer Bul, 2004, 116: 698―717

36 Ayers J C, Dunkle S, Gao S, et al. Constraints on timing of peak and retrograde metamorphism in the Dabie Shan ultrahigh-pressure metamorphic belt, east-central China, using U-Th-Pb dating of zircon and monazite. Chem Geol, 2002, 186: 315―331

37 Wu Y B, Zheng Y F, Zhao Z F, et al. U-Pb, Hf and O isotopes evi-dence for two episodes of fluid-assisted zircon growth in marble- hosted eclogites from the Dabie Orogen. Geochim Cosmochim Acta, 2006, 70: 3743―3761

38 Liu F L, Gerdes A, Liou J G, et al. SHRIMP U-Pb zircon dating from Sulu-Dabie dolomitic marble, South China: constraints on prograde, ultrahigh-pressure and retrograde metamorphic ages. J Metamorph Geol, 2006, 24: 569―589

39 Maruyama S, Tabata H, Nutman A P, et al. SHRIMP U-Pb geochro-nology of ultrahigh-pressure metamorphic rocks of the Dabie Moun-tains, Central China. Cont Dyn, 1998, 3: 72―85

40 Zheng Y F, Zhao Z F, Wu Y B, et al. Zircon U-Pb age, Hf and O iso-tope constraints on protolith origin of ultrahigh-pressure eclogite and gneiss in the Dabie orogen. Chem Geol, 2006, 231: 135―158

41 Chen D G, Deloule E, Cheng H, et al. Preliminary study of microscale zircon oxygen isotopes for Dabie-Sulu metamorphic rocks: Ion probe in situ analyses. Chin Sci Bull, 2003, 48(16): 1670―1678

42 Li X P, Zheng Y F, Wu Y B, et al. Low-T eclogite in the Dabie terrane of China: Petrological and isotopic constraints on fluid activity and radiometric dating. Contrib Miner Petrol, 2004, 148: 443―470

43 Tang J, Zheng Y F, Wu Y B, et al. Zircon U-Pb ages and oxygen isotopes of high-grade metamorphic rocks in the eastern part of the Shandong Peninsula. Acta Petrol Sin (in Chinese with English abstract), 2004, 20(5): 1039―1062

44 Yang J S, Wooden J L, Wu C L, et al. SHRIMP U-Pb dating of coe-site-bearing zircon from the ultrahigh-pressure metamorphic rocks, Sulu terrane, East China. J Metamor Geol, 2003, 21: 551―560

45 Peng T P, Wang Y J, Fan W M, et al. SHRIMP zircon U-Pb dating on early Mesozoic felsic igneous rocks in southern Lantsang River and its tectonic implications. Sci China Ser D-Earth Sci, 2006, 46: 1032―1042

46 Zhao G C, Sun M, Wilde S A, et al. Assembly, accretion and breakup of the Paleo-Mesoproterozoic Columbia supercontinent: records in the North China Craton. Gondwana Res, 2003, 6: 417―434

47 Zhao G C, Sun M, Wilde S A, et al. A Paleo-Mesoproterozoic super-continent: assembly, growth and breakup. Earth Sci Rev, 2004, 67: 91―123

48 Zhou M F, Yan D P, Kennedy A K, et al. SHRIMP U-Pb zircon geo-chronological and geochemical evidence for Neoproterozoic arc-magmatism along the western margin of the Yangtze Block, South China. Earth Planet Sci Lett, 2002, 196: 51―67

49 Zhou M F, Kennedy A K, Sun M, et al. Neoproterozoic arc-related mafic intrusions along the northern margin of South China: Implica-tions for the accretion of Rodinia. J Geol, 2002, 110: 611―618

50 Li X H, Li Z X, Ge W, et al. Neoproterozoic granitoids in South China: crustal melting above a mantle plume at ca. 825 Ma? Precambr Res, 2003, 122: 45―83

51 Li Z X, Li X H, Kinny P D, et al. Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correla-tions with other continents: evidence for a mantle superplume that broke up Rodinia. Precambr Res, 2003, 122: 85―109

52 Zheng Y F, Wu Y B, Chen F K, et al. Zircon U-Pb and oxygen isotope evidence for a large-scale 18O depletion event in igneous rocks during the Neoproterozoic. Geochim Cosmochim Acta, 2004, 68: 4145―4165

53 Wang X L, Zhou J C, Qiu J S, et al. LA-ICP-MS U-Pb zircon geo-chronology of the Neoproterozoic igneous rocks from Northern Guangxi, South China: Implications for tectonic evolution. Precambr Res, 2006, 145: 111―130

54 Wu R X, Zheng Y F, Wu Y B, et al. Reworking of juvenile crust: element and isotope evidence from Neoproterozoic granodiorite in South China. Precambr Res, 2006, 146: 179―212

55 Zhou M F, Ma Y X, Yan D P, et al. The Yanbian Terrane (southern Sichuan Province, SW China): A Neoproterozoic arc assemblage in the western margin of the Yangtze Block. Precambr Res, 2006, 144: 19―38

56 Zheng Y F, Zhang S B, Zhao Z F, et al. Contrasting zircon Hf and O isotopes in the two episodes of Neoproterozoic granitoids in South China: implications for growth and reworking of continental crust. Lithos, 2007, doi: 10.1016/j.lithos.2006.10.003

57 Gao S, Rudnick R L, Yuan H L, et al., Recycling lower continental crust in the North China craton. Nature, 2004, 432: 892―897

58 Wu F Y, Lin J Q, Wilde S A. Nature and significance of the Early Cretaceous giant igneous event in eastern China. Earth Planet Sci Lett, 2005, 233: 103―119

59 Xu Y G. Thermo-tectonic destruction of the Achaean lithospheric keel beneath the Sino-Korean craton in China: evidence, timing and mechanism. Phys Chem Earth (A), 2001, 26: 747―757

60 Kemp A I S, Hawkesworth C J, Paterson B A, et al. Episodic growth of the Gondwana supercontinent from hafnium and oxygen isotopes in zircon. Nature, 2006, 439: 580―583

61 Chen J F, Jahn B M. Crustal evolution of southeastern China: Nd and Sr isotope evidence. Tectonophysics, 1998, 284: 101―133

62 Zheng Y F, Wu Y B, Zhao Z F, et al. Metamorphic effect on zircon Lu-Hf and U-Pb isotope systems in ultrahigh-pressure eclogite-facies meta-granite and metabasite. Earth Planet Sci Lett, 2005, 240: 378―400


Documents

Formation and evolution of Precambrian continental crust in South China