中国西北帕米尔东北缘的活动断裂研究(英文)
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摘要
在卫星遥感图像的详细地质解译分析基础上,结合野外地质与地貌观察,对帕米尔东北缘山前与印度-亚欧大陆碰撞相关的活动断层进行了分析.研究结果指出,NW-NWW走向的断层主要表现为南倾逆冲断层,并伴随有强烈的右旋走滑分量.流经活动断层带的水系显示出右旋累积位错:小水系的水平位错量为4.0～20.0 m,大河流的水平位错量达8～12 km.沿断层带的上新世至早更新世地层也显示出一致的水平位错,位错量为8～12 km.这些证据表明,帕米尔东南山前的NW—NWW走向的断层很可能开始于上新世末期至早更新世早期(2.2～Ma).研究结果首次厘定了帕米尔东北缘山前与向北逆冲州伴随的右旋走滑速率在第四纪期间达4.0～6.8 mm/a.根据与现代地震活动相关的活断层分析,推测帕米尔东北缘山前7级以上地震重复周期为1 000 a左右.
Based on the detailed geologic mapping and analyses of satellite imagery combining with the field geologic and geomorphic observations, active faults due to India-Eurasia collision have been documented in the northeastern front of the Pamir. Our analyses indicate that NW-NWW striking faults are mainly expressed by the south-dipping thrusting with extensive right-lateral strike-slip component. Drainage systems across the active faults show the cumulative right-lateral displacement and horizontal offset varying from 4.0 m to 20.4 m for small streams. The displaced largest stream and Tertiary to lower Pleistocene sequences show identical horizontal displacement of 8-12 km along the fault zone. Our results firstly constrain that northward overthrusting accommodates a right-lateral partitioning with a long-term slip rate of 4.0-6.8 mm/yr in the northeastern front of the Pamir during Quaternary. From the analysis of active faults associated with current seismic events, we inferred that recurrence interval of large seismic events (Ms >7) is ca. 1 kyr.
Based on the detailed geologic mapping and analyses of satellite imagery combining with the field geologic and geomorphic observations, active faults due to India-Eurasia collision have been documented in the northeastern front of the Pamir. Our analyses indicate that NW-NWW striking faults are mainly expressed by the south-dipping thrusting with extensive right-lateral strike-slip component. Drainage systems across the active faults show the cumulative right-lateral displacement and horizontal offset varying from 4.0 m to 20.4 m for small streams. The displaced largest stream and Tertiary to lower Pleistocene sequences show identical horizontal displacement of 8-12 km along the fault zone. Our results firstly constrain that northward overthrusting accommodates a right-lateral partitioning with a long-term slip rate of 4.0-6.8 mm/yr in the northeastern front of the Pamir during Quaternary. From the analysis of active faults associated with current seismic events, we inferred that recurrence interval of large seismic events (Ms >7) is ca. 1 kyr.
引文
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[12] Chen J, Burbank D W, Scharer K M, et al. Magnetochronology of theupper Cenozoic strata in the southwestern Chinese Tian Shan: rates ofPleistocene folding and thrusting[J]. Earth and Planetary ScienceLetters, 2002,195:113-130．
[13] Fu B, Lin A, Kano K, et al. A flexible method to creating satellitestereoscopic imagery and its application for studying the Quaternaryfolding and faulting structures [J]. International Journal of RemoteSensing, 2001 submitted.
[14] Feng X, Luan C, Li J, et al. Study on paleoearthquakes in theKazkearte fault[J]. Inland Earthquakes, 1987,1:231-239．
[15] Sobel E R, Dumitru T A. Thrusting and exhumation around themargins of the western Tarim basin during the India-Asia collision[J].Journal of Geophysical Research, 1997,102:5043-5063．
[16] Lin A, Fu B, Kano K, et al. Late Quaternary right-lateral displacementalong the active faults in the Yanqi basin, southeastern Tian Shan,northwest China[J]. Tectonophysics, 2002, (in press).
[17] Arrowsmith J R, Strecker M R. Seismotectonic range-frontsegmentation and mountain-belt growth in the Pamir-Alai region, Kyrgyzstan (India-Eurasia collision zone) [J]. Geological Society ofAmerican Bulletin, 1999． 111:1665-1683．
[18] Molnar P, Brown E T. Burchfiel B C, et al. Quaternary climatic changeand the formation of river terraces across growing anticlines on thenorth flank of the Tien Shan, China[J]. The Journal of Geology, 1994,102:583-602．
[19] Brunel M, Arnaud N, Tapponnier P, et al. Kongur Shan normal fault:Type example of mountain building assisted by extensional(Karakoram fault, eastern Pamir) [J]. Geology, 1994, 22:707-710．
[20] Burchfiel B C, Brown E T. Deng Q, et al. Crustal shortening on themargins of the Tien Shan, Xinjiang, China[J]. International GeologyReviews. 1999, 41:665-700．
[21] Zheng H., Powell C, An Z, et al. Pliocene uplift of the northern TibetanPlateau[J]. Geology, 2000, 28:715-718．
[22] Tapponnier P, Peltzer G, Le Dain, et al. Propagating extrusion tectonicsin Asia: new insights from simple experiments with plasticine[J].Geology, 1982,10:611-616．
[23] Tapponnier P, Xu Z, Roger F, et al. Oblique stepwise rise and growth ofthe Tibet Plateau[J]. Science, 2
[2] Burtman V S, Molnar P. Geological and geophysical evidence for deep subduction of continental crust beneath the Pamir[A]. Geological Society of America Special Paper[C], 1993, 281:1-76．
[3] Fang G W, Ni J F, Wallace T C. Active tectonics of the Pamirs and Karakorum[J]. Journal of Geophysical Research, 1994,99:7131-7160．
[4] Sheng Z, Wang M, Li Y, et al. Crustal deformation along the AltynTagh fault system, western China, from GPS[J]. Journal ofGeophysical Research, 2001, 106:30607-30621．
[5] Feng X. The paleoearthquakes in Xinjiang region, China[M]. Urumqi:Xinjiang Science, Technology and Hygiene Press, 1997, 260．
[6] Jia D, Lu H, Cai D, et al. Structural Features of the northern Tarimbasin: implications for regional tectonics and petroleum traps [J].American Association of Petroleum Geologists Bulletin, 1998,82:147-159．
[7] Burtman V S, Skobelev S F, Molnar P. Late Cenozoic slip on theTalas-Ferghana fault, the Tien Shan, Central Asia[J]. GeologicalSociety of America Bulletin, 1996,108:1004-1021．
[8] Abdrakhmatov K Ye, Alddazhanov S A, Hager B, et al. Relativelyrecent construction of the Tien Shan inferred from GPS measurementsof present-day crustal deformation rales[J]. Nature, 1996,384:450-453．
[9] Wang Q M, Nishidai T, Coward M P. The Tarim Basin, NW China:formation and aspects of petroleum geology[J]. Journal of PetroleumGeology. 1992, 15:5-34．
[10] Bureau of Geology and Mineral Resources of Xinjiang UygurAutomomous Region (BGMXJ). Regional Geology of Xinjiang UygurAutomomous Region[M]. Beijing, Geological Publishing House,1993,841．
[11] Chen H, Lin X L, Guan K N, et al. Early Pleistocene deposits and itlower boundary (Q/N) in Tian Shan Mts., Xinjiang Region[J].Quaternary Science, 1994, 1: 38-47．
[12] Chen J, Burbank D W, Scharer K M, et al. Magnetochronology of theupper Cenozoic strata in the southwestern Chinese Tian Shan: rates ofPleistocene folding and thrusting[J]. Earth and Planetary ScienceLetters, 2002,195:113-130．
[13] Fu B, Lin A, Kano K, et al. A flexible method to creating satellitestereoscopic imagery and its application for studying the Quaternaryfolding and faulting structures [J]. International Journal of RemoteSensing, 2001 submitted.
[14] Feng X, Luan C, Li J, et al. Study on paleoearthquakes in theKazkearte fault[J]. Inland Earthquakes, 1987,1:231-239．
[15] Sobel E R, Dumitru T A. Thrusting and exhumation around themargins of the western Tarim basin during the India-Asia collision[J].Journal of Geophysical Research, 1997,102:5043-5063．
[16] Lin A, Fu B, Kano K, et al. Late Quaternary right-lateral displacementalong the active faults in the Yanqi basin, southeastern Tian Shan,northwest China[J]. Tectonophysics, 2002, (in press).
[17] Arrowsmith J R, Strecker M R. Seismotectonic range-frontsegmentation and mountain-belt growth in the Pamir-Alai region, Kyrgyzstan (India-Eurasia collision zone) [J]. Geological Society ofAmerican Bulletin, 1999． 111:1665-1683．
[18] Molnar P, Brown E T. Burchfiel B C, et al. Quaternary climatic changeand the formation of river terraces across growing anticlines on thenorth flank of the Tien Shan, China[J]. The Journal of Geology, 1994,102:583-602．
[19] Brunel M, Arnaud N, Tapponnier P, et al. Kongur Shan normal fault:Type example of mountain building assisted by extensional(Karakoram fault, eastern Pamir) [J]. Geology, 1994, 22:707-710．
[20] Burchfiel B C, Brown E T. Deng Q, et al. Crustal shortening on themargins of the Tien Shan, Xinjiang, China[J]. International GeologyReviews. 1999, 41:665-700．
[21] Zheng H., Powell C, An Z, et al. Pliocene uplift of the northern TibetanPlateau[J]. Geology, 2000, 28:715-718．
[22] Tapponnier P, Peltzer G, Le Dain, et al. Propagating extrusion tectonicsin Asia: new insights from simple experiments with plasticine[J].Geology, 1982,10:611-616．
[23] Tapponnier P, Xu Z, Roger F, et al. Oblique stepwise rise and growth ofthe Tibet Plateau[J]. Science, 2
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