龙门山北东段山前涪江第四纪冲洪积扇地貌演化及其构造响应

发布时间：2018-04-01 19:31

本文选题：龙门山　切入点：冲积扇　出处：《沉积学报》2017年01期

【摘要】：青藏高原东缘龙门山北东段山前涪江冲积扇在武都盆地内的覆盖面积约为25 km2,区域构造上为江油断层、香水—让水断层等组成的江油断裂带右旋走滑构造域。通过宇宙核素成因埋藏年龄测试技术精确地测定发源于龙门山北东段主要河流—涪江自第四纪以来发育的三期冲积扇形成年代,即早更新世冲积扇(1.84 Ma)、中更新世冲积扇(0.54 Ma)和全新世冲积扇。由于龙门山北东段—江油断裂的右旋走滑兼逆冲运动,导致涪江早更新世冲积扇扇头右旋错动约3.2 km,之后形成新的冲积扇(中更新世积扇)。随着江油断裂继续的继续活动,中更新世冲积扇扇头又被右旋错动了约0.8 km,之后形成全新世的冲积扇。涪江形成以来总共右旋错动距离约为4 km。同时,早、中更新世冲积扇褶皱隆升了约50 m,早更新世冲积扇总共褶皱隆升了约100 m。这在一定程度上反映了龙门山构造带北东段第四纪以来沉积对构造演化的响应过程。
[Abstract]:The Foreland Fujiang alluvial fan on the eastern margin of Longmen Mountain on the eastern margin of the Qinghai-Tibet Plateau covers about 25km2 in the Wudu basin, and the regional structure is a Jiangyou fault. Perfume-dextral strike-slip tectonic domain of Jiangyou fault zone composed of water faults etc. The origin of Fujiang, a major river in the eastern part of Longmen Mountain, developed since the Quaternary by means of the cosmic radionuclide burial age test technique. The age of the formation of the third stage of the alluvial fan, That is, the early Pleistocene alluvial fan is 1.84 Ma, the middle Pleistocene alluvial fan is 0.54 Ma. and the Holocene alluvial fan. Due to the right-lateral strike-slip and thrusting movement of the East Longmenshan fault, This resulted in the right-lateral dislocation of the head of the alluvial fan in the early Pleistocene of Fujiang River, and the formation of a new alluvial fan (the Middle Pleistocene fan). The middle Pleistocene alluvial fan head was about 0.8 km of right lateral dislocation, and then formed Holocene alluvial fan. The total right-lateral dislocation distance since Fujiang formation is about 4 km. The middle Pleistocene alluvial fan fold uplifted about 50 mand the early Pleistocene alluvial fan uplifted about 100 m.This reflects to some extent the process of sedimentary response to the tectonic evolution in the eastern segment of the northern part of the Longmenshan tectonic belt since the Quaternary.
【作者单位】：曲阜师范大学地理与旅游学院;
【基金】：国家自然科学基金项目(41072164)~~
【分类号】：P542

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