MICROSTRUCTURES AND AGES OF ACTIVITY OF THE REVERSE FAULTS ALONG THE SOUTHERN MARGIN OF THE JUNGGAR BASIN
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摘要: 对准噶尔盆地南缘霍尔果斯-玛纳斯-吐谷鲁逆断裂带中的断层泥和构造岩显微构造进行了研究,并对断裂带中的石膏、石英脉和断层泥进行了ESR测年。显微构造研究表明,断裂带至少经历了3期构造变形,断层泥和石英碎粒中既发育有线状擦痕、阶步等粘滑活动显微构造,也发育有剪切滑动、定向排列等蠕滑活动变形现象。ESR测年结果显示,霍尔果斯-玛纳斯-吐谷鲁逆断裂带形成于1.5Ma前,在0.4~1.0 Ma和0.08~0.12 Ma期间进行了二次再调整。断裂活动时间与青藏高原阶段性隆升的时间一致,说明准噶尔盆地南缘霍尔果斯-玛纳斯-吐谷鲁逆断裂带的形成与青藏高原的隆升过程密切相关。Abstract: The microstructures of fault gouge and tectonite in the Huo'erguosi-Manas-Tugulu reverse fault zones along the southern margin of the Junggar basin are studied and twelve samples of gypsum,fault gouge and quartz veins were collected and dated by using the electronic spin resonance(ESR) method.The results show that the gouges underwent at least three deformation stages.Many stick-slip microstructural marks such as slickenside striations and steps appear in gouges and on quartz grains.In addition,many creep deformation marks such as shear slip and oriented arrangement of clay minerals are also found.The results show that the Huo'erguosi-Manas-Tugulu reverse fault zones formed about 1.5 Ma ago and were readjusted at 0.4-1.0 and 0.08-0.12 Ma respectively.The time of faulting is consistent with the time of uplift of the Qinghai-Tibet Plateau,suggesting that the formation of the Huo'erguosi-Manas-Tugulu reverse fault zones on the southern margin of the Junggar basin is closely related to the uplift process of the Qinghai-Tibet Plateau.
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Key words:
- Late Cenozoic /
- reverse fault /
- microstructure /
- ESR dating /
- southern margin of the Junggar basin
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