Journal of Earth Science, Vol. 21, Special Issue, p. 257–259, June 2010 ISSN 1674-487X Printed in China

Grain Size Variation of Quaternary Sediments Related to Paleoclimate Change in Tarim Basin,

Northwest China

Song Shuhong (宋淑红)

School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;

Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences,

Shijiazhuang 050061, China

Bi Zhiwei* (毕志伟)

Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences,

Shijiazhuang 050061, China

Yang Jing (杨靖)

School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China

Yang Zhenjing (杨振京)

Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences,

Shijiazhuang 050061, China

INTRODUCTION

Quaternary sediments contain the records related

to the changes in paleoclimate and paleoenvironment.

Grain size of the sediments is taken as the good indi-

cator of the sedimentary environmental conditions re-

lated to the climate change (Xiao et al., 1995;

McLaren and Bowles, 1985; Glasiter and Nelson,

1975). We report here the data of KT2 core samples to

show the change of Quaternary paleoclimate in Tarim

basin in Northwest China. BH KT2 core is located at

the hinterland of Tarim basin (Fig. 1) and covers the

whole Quaternary strata. The grain size was measured

This study was supported by the Youth Science Funds of Chi-

nese Academy of Geological Sciences (Nos. SK200808,

SK200603).

*Corresponding author: ssh5288@163.com

© China University of Geosciences and Springer-Verlag Berlin

Heidelberg 2010

Manuscript received December 22, 2009.

Manuscript accepted February 10, 2010.

by Mastersizer-2000 Laser Grain Size Analyzer in the

Laboratory of Institute of Hydrogeology and Envi-

ronmental Geology, Chinese Academy of Geological

Sciences.

Figure 1. The plot showing the regional tectonics in

Tarim basin and the location of KT2 core.

The KT2 core was 885.99 m long, and 206 sam-

ples were taken. 11 layers were identified on the basis

of the color, textures, grain size, the thickness of clay

and sand sediments (Fig. 2). The paleomagnetic and

Song Shuhong, Bi Zhiwei, Yang Jing and Yang Zhenjing

258

OSL dating indicated that the M/G boundary is lo-

cated at 634.30 m, and the B/M boundary at 130.25 m.

The boundary (130 kaBP) between the Late and the

Middle Pleistocene is at 30.79 m (Xu et al., 2003), and

the boundary (10 kaBP) between Late Pleistocene and

Holocene at the top of the borehole.

RESULTS AND DISCUSSION

The sedimentary environment is relatively stable

due to the slight changes in the grain size, generally

with the diameter between 2.5φ–6.2φ (Lerman and

Lakes, 1978). Three intervals can be identified based

on variations of the grain size, including the mean

values, the frequency and the probability cumulation

of the grain size (Fig. 2), along with the lithology,

sporopollen records and some other information (Cao,

2003).

Figure 2. Lithology and grain size distribution of KT2 core.

The depth interval from 650 m downward, cor-

responding to samples Nos. 144 to 206, is Late Plio-

cene. The sediments mainly consist of silty fine sand,

followed by fine sand and silt, with unimodal grain

size frequency curves. The samples below 855 m at

depth are mainly featured by coarse sand, generally

with the diameter of the grains between 2.5φ–3.4φ,

indicating a sedimentary environment of fluvial facies

with strong hydrodynamic condition. The samples

above 855 m at depth are mainly composed of fine

sand with much clay, positive skew distribution, gen-

erally with the diameter between 4.1φ–6.2φ. This in-

Grain Size Variation of Quaternary Sediments Related to Paleoclimate Change in Tarim Basin, Northwest China

259

fers a sedimentary environment of depression facies

with weak hydrodynamic condition.

The interval at 650–130 m deep, corresponding

to samples Nos. 19 to 143, is Early Pleistocene.

Coarse sand and fine sand appear to occur alternately.

The frequency curve of the grain size is unimodal but

the proportion of bimodal and multi-peak increases

greatly, reflecting a basic sedimentary environment of

fluvial facies associated with the alternative presence

of alluvion and diluvial sediments. Above the depth of

180 m, aeolian deposits occurred, and the grain di-

ameters are between 2.2φ–3.8φ. The unimodal distri-

bution and well-sorted grains demonstrate the occur-

rence of the desert.

The interval above 130 m at depth, corresponding

to samples Nos. 1 to 18, is Middle–Late Pleistocene.

The sediments mainly consist of silty fine sand and

fine sand, showing mostly the unimodal distribution

with the diameter of the grains between 2.8φ–3.9φ.

This indicates a change in sedimentary environment

from fluviatile facies slowly to eolian facies. The de-

sert was formed and expanded at a large scale.

CONCLUSIONS

The fluvial-lacustrine sediments dominated in

Early Pleistocene in Tarim basin, followed by the oc-

currence of the aeolian deposits. The lacustrine sedi-

ments were found in the early period of the Middle

Pleistocene while the aeolian sediments became

stronger, and dominated in the late period of the Mid-

dle Pleistocene. Since the Late Pleistocene, the desert

was formed and expanded widely throughout the

Holocene.

REFERENCES CITED

Cao, B. X., 2003. Geomorphology and Quaternary Geology.

China University of Geosciences Press, Wuhan (in Chi-

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Glasiter, R. P., Nelson, H. W., 1975. Grain Size Distributions

and Aid in Facies Identification. Bull. Can. Pertro., 22(3):

203–240

Lerman, A., Lakes, C., 1978. Geology, Physics. Springer, Ber-

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McLaren, P., Bowles, D., 1985. The Effects of Sediment

Transport on Grain Size Distribution. Journal of Sedimen-

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Xiao, J. L., Proter, S. C., An, Z. S., et al., 1995. Grain Size of

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