羌塘及南缘地区的地壳结构
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本文为地质调查项目羌塘地体地质长廊和含油气盆地构造背景综合研究(12120115026901)资助的成果。


Crustal Structure in Qiangtang and Its Southern Neighborhood
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    摘要:

    通过对INDEPTH III宽频地震资料的处理,采用最新发展的接收函数深度偏移叠加方法,获取羌塘盆地南部及与拉萨地块北侧的剖面。偏移图像勾画了羌塘地区的两盆夹一隆的基底,以及羌塘下地壳内存在的北倾构造序列。冈底斯的基底与羌塘地区有一定的延续性,而拉萨地块的上地壳则完全不同。同时通过与人工深反射地震剖面,发现主要大型的断裂构造在接收函数剖面上均可进行追踪对比,对于羌中隆起和和羌塘南北凹陷的深部成因有启示作用。同时发现班公-怒江缝合带Moho面错断并不明显,而在拉萨地块下方呈现的双Moho在色林错下方进行了合并。在南羌塘Moho面转换波强度不大,而北羌塘又重新恢复正常,推测这是拉萨地块向北的推挤造成羌塘下地壳部分地区重新分异的结果。双Moho的成因有待进一步分析,应该与拉萨地块下方大规模低速物质活动和MHT拆离断层的延伸有关。

    Abstract:

    By re-processing for the INDEPTH III broadband teleseismic data, and utilizing the recent developed depth migration of receiver function, the profile is obtained from the south of Qiantang Basin to the north of Lhasa Block. The obtained image illustrates the basement lines, e.g. one uplift clamped by two basin, as well as the northern dipping series in the lower crust Beneath Qiangtang Bains . It seems that basement of Gandes is somehow relevant to Qiantang, but is quite different to Lahsa Block. Through the comparison with deep reflection result, we found that most big discontinuities in seismic profile can also be traced along receiver function profile,which could enlighten the mechanism of the uplift in the middle and basins at north and south side. Meanwhile, the Moho break is vague beneath Bangong-Nujiang Suture, and the doubled Moho beneath Lahsa Block seems combined beneath Selin Lake. The gradient for Moho is weak at southern Qiantang, nevertheless it becomes normal at northern Qiantang. This might be deduced by the result of re-differentiation for the lower crust in Qiantang after the collision by the northern marching Lahsa Block. The origin of doubled Moho should be analysed further, which might be relevant to the activity the low velocity materials in Lasha block and the extension of MHT break-apart fault.

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钱辉,李海兵,刘栋梁,薛光琦,吴珍汉.2016.羌塘及南缘地区的地壳结构[J].地质学报,90(8):1715-1724.
huiqian, LI Haibing, LIU Dongliang, XUE Gaungqi, WU Zhenhan.2016. Crustal Structure in Qiangtang and Its Southern Neighborhood[J]. Acta Geologica Sinica,90(8):1715-1724.

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历史
  • 收稿日期:2016-03-14
  • 最后修改日期:2016-04-20
  • 录用日期:2016-04-25
  • 在线发布日期: 2016-08-23