西昆仑及邻区岩石圈结构构造演化——塔里木南—西昆仑多学科地学断面简要报道
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摘要
通过深地震反射剖面,宽频天然深地震探测,广角折射、反射剖面,结合地表地质观察、岩石矿物和地球化学研究,以及弹性模拟计算等,对当前国际上流行的所谓高原北缘向南呈A型俯冲,南缘向北俯冲构成的青藏高原地壳加厚、隆升的“双俯冲”(two-sidedsubduction)模式提出质疑,认为高原北缘至少在西昆仑与塔里木(欧亚板块)之间不存在长距离的俯冲,在新生代以来的强劲挤压中,塔里木起到了一定的阻挡作用,在这里呈现南北向挤压应力场,因而青藏高原西北缘陆-陆碰撞造山、盆山的形成受到“南北双向挤压模式”所控制,也是造成青藏高原西北缘新生代期地壳加厚、隆升的重要动力因素
Results from deep seismic reflection profiling,broadband deep seismic sounding and wide-angle reflection-refraction profiling,combined with surface geological observations ,petrological,mineralogical and geochemical studies and elastic model calculation,question the currently prevalent "two-sided subduction model"which suggests that the crustal thickening and uplift of the Qinghai-Tibet Plateau resulted from the southward A-subduction of the northern margin of the plateau and the northward subduction of its southern margin.The authors think that no long-distance subduction took place at least between the West Kunlun and Tarim(the Eurasian plate)on the northern margin of the plateau.Tarim only played a cer-tain role in resisting the pressure from the south since the Cenozoic and there a N-S compressional stress appeared.Therefore the continent-continent collisional orogeny and formation of the basin-and-range structure were controlled by the"oppositely directed N-S compression model",and the N-S compression in opposite directions is also an important dynamic factor for the crustal thickening and uplift on the northwestern margin of the plateau in the late Cenozoic.
Results from deep seismic reflection profiling,broadband deep seismic sounding and wide-angle reflection-refraction profiling,combined with surface geological observations ,petrological,mineralogical and geochemical studies and elastic model calculation,question the currently prevalent "two-sided subduction model"which suggests that the crustal thickening and uplift of the Qinghai-Tibet Plateau resulted from the southward A-subduction of the northern margin of the plateau and the northward subduction of its southern margin.The authors think that no long-distance subduction took place at least between the West Kunlun and Tarim(the Eurasian plate)on the northern margin of the plateau.Tarim only played a cer-tain role in resisting the pressure from the south since the Cenozoic and there a N-S compressional stress appeared.Therefore the continent-continent collisional orogeny and formation of the basin-and-range structure were controlled by the"oppositely directed N-S compression model",and the N-S compression in opposite directions is also an important dynamic factor for the crustal thickening and uplift on the northwestern margin of the plateau in the late Cenozoic.
引文
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[3]邓万明.青藏高原新生代岩浆岩活动的大地构造位置[J].地质学报,1995,73(4):302～314.
[4]Lyon-CaenHandMolnarP.GravityanomaliesandthesturctureofwesternTibetandthesouthernTarimbasin[J].GeophysicalResearchletters,1984,11:1251～1254.
[5]肖序常,李廷栋,李光岑,等.喜马拉雅岩石圈构造演化[M].北京:地质出版社,1988.59～63.
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[7]肖序常,李廷栋.青藏高原的构造演化与隆升机制[M].广州:广东科技出板社,2000.171～121.
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[10]丁道桂,王道轩,刘伟新,等.西昆仑造山带及盆地[M].北京:地质出版社,1996.1～57,201～225.
[11]LaiShaocong.PetrogenesisoftheCenozoicvolcanicrocksfromthenorthernpartofQinghai-TibetPlateau[J].ChineseJ.Geochem.,1999,18(4):361～371.
[12]LuoZhaohuo,ZhangWenhuiandDengJinfu,etal.Impli-cationoftheDeep-SeatedxenolithsinCenozoicbasaltinKangxiwa,W.Kunlun,China[J].EarthScienceFrontiers,2000,7(Suppl):76～78.
[13]刘国惠,金成伟,王富宝,等.西藏变质岩及火成岩,地矿部地质专报11号[M].北京:地质出版社,1990.168～188.
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