| 天山北麓活动背斜区河流阶地与古地震事件 |
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| 引用本文： | 杨晓平,李安,黄伟亮,张玲.天山北麓活动背斜区河流阶地与古地震事件[J].地震地质,2011(4):739-751. |
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| 作者姓名： | 杨晓平 李安 黄伟亮 张玲 |
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| 作者单位： | 中国地震局地质研究所国家地震活动断层研究中心 |
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| 基金项目： | 地震行业科研专项(200808013);国家自然科学基金(40572126)共同资助 |
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| 摘 要： | 利用航空遥感照片和Google earth卫星影像,对天山北麓独山子活动背斜区奎屯河两侧的河流地貌进行解释,结合野外调查发现,奎屯河流经独山子背斜段发育7级基座阶地,阶地基座为上新统独山子组泥岩,其上部为2.5 ～ 15m厚的砂砾石层和砂质黏土.在开挖或剥离的各级阶地堆积物剖面中采集细粒堆积物样品,实验室中采用细粒石英...
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| 关 键 词： | 河流阶地 古地震 同震隆升 活动褶皱 天山 |
PALEOEARTHQUAKE EVENTS AND FORMATION OF RIVER TERRACES IN ACTIVE ANTICLINE REGION,NORTHERN PIEDMONT OF TIANSHAN MOUNTAINS,CHINA |
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| G Xiao-pingLI,G Wei-liangZHANG,ing.PALEOEARTHQUAKE EVENTS AND FORMATION OF RIVER TERRACES IN ACTIVE ANTICLINE REGION,NORTHERN PIEDMONT OF TIANSHAN MOUNTAINS,CHINA[J].Seismology and Geology,2011(4):739-751. |
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| Authors: | G Xiao-pingLI G Wei-liangZHANG ing |
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| Institution: | LI AnHUANG Wei-liangZHANG Ling(National Center for Active Fault Studies,Institute of Geology,China Earthquake Administration,Beijing100029,China) |
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| Abstract: | Using the aerial remote sensing photos and Google earth satellite images,we find seven terraces at the both sides along the Kuytun River in Dushanzi active anticline area,northern piedmont of Tianshan.Based on the field investigation,we find that all these terraces are pedestal terraces.The rock of pedestal is Pliocene mud rock,and on the top of each terrace pedestal are the stratums of sandy gravel or sandy clay with 2.5～15m in thickness.We collected samples from deposits of all terraces for OSL(optically stimulated luminescence)geological dating using the SMAR(single-multiple-aliquot-regeneration)method on fine grains.We also performed dating using the \{14C\} method to the samples from the deposit of terrace T1 of the Kuytun River.The results show that the ages of all these deposits are the later phase of the Late Pleistocene.The accumulation time of the upper stratum for T1,T2,T3,T5,T6and T7 terraces is about 1.7ka,14.98ka,20.7～27.3ka,29.3～39.2ka,47～56ka and 103～118ka,respectively.Combining with late Quaternary climate change,we believe that the formation age for T1～T7 terraces of Kuytun River are 1.7ka,14ka,20ka,25ka,30ka,50ka and 100kaBP.Paleoearthquake data reveal that eight paleoearthquake events occurred on the Dushanzi-Anjihai reverse fault since about 25kaBP,respectively at 2ka,3.4ka,4.3ka,5.8ka,7.5ka,12.8ka,18ka and 24kaBP.Comparing the ages of paleoearthquakes and terraces,we find that the ages of the latest,the sixth,the seventh and the eighth paleoearthquake are roughly corresponding to the formation times of T1,T2,T3and T4 terraces,respectively.The other four paleoearthquake events occurred during the period after the formation of T2and before the formation of T1.In this time,no terraces developed along the Kuytun River,but the Kuytun River incised rapidly for 40m.We believe that the paleoearthquake events resulted in the fast uplift of Dushanzi active anticline on the hanging wall of Dushanzi-Anjihai Fault and the increase of riverbed slope and river incision ability,which led to the formation of river terraces or deep canyons.The terrace sequence in active anticline region may reflect the paleoearthquake sequence associated with fault or blind fault. |
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| Keywords: | river terrace paleoearthquake coseismic uplift active fault Tianshan |
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