Northern Lhasa thrust belt of central Tibet: Evidence of Cretaceous–early Cenozoic shortening within a passive roof thrust system?
Northern Lhasa thrust belt of central Tibet: Evidence of Cretaceous–early Cenozoic shortening within a passive roof thrust system?
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DOI：
10.1130/2014.2507(03
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发表时间：
2014-08
期刊：
影响因子：
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通讯作者：
John E. Volkmer;P. Kapp;B. Horton;G. Gehrels;J. Minervini;L. Ding
中科院分区：
文献类型：
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作者：
John E. Volkmer;P. Kapp;B. Horton;G. Gehrels;J. Minervini;L. Ding
晚侏罗世-早白垩世，大洋岩石圈沿着班公湖缝合带被消耗，西藏拉萨和羌塘板块发生碰撞。该大陆碰撞导致了向南的北方拉萨冲断带的发展，该冲断带在西藏中部沿沿着走向暴露约1200 km。我们在位于拉萨市西北约250 km的北方拉萨市的杜巴地区进行了地质填图、地层学和地质热年代学研究。在杜巴地区，花岗岩侵位到中地壳之间的139和121马，随后被挖出，并与白垩纪地层之间的105和90马的下盘解释被动顶板逆冲系统。我们认为，这种构造样式主导了拉萨北方冲断带的构造-新生代早期演化，并为拉萨冲断带尽管上地壳缩短>50%，但基底岩石出露稀少提供了解释。此外，我们强调碰撞相关的北方拉萨和特提斯喜马拉雅冲断带之间的相似之处，这两个都是由缝合线和下板岩石圈的下冲。
The Lhasa and Qiangtang terranes of Tibet collided following Late Jurassic– Early Cretaceous consumption of oceanic lithosphere along the intervening Bangong suture zone. This continental collision led to the development of the south-directed, northern Lhasa thrust belt that is exposed ~1200 km along strike in central Tibet. We conducted geologic mapping and stratigraphic and geothermochronologic studies in the Duba region of the northern Lhasa terrane, located ~250 km northwest of the city of Lhasa. In the Duba region, granites were emplaced into the mid-crust between 139 and 121 Ma and subsequently exhumed and juxtaposed against Cretaceous strata between 105 and 90 Ma in the footwall of an interpreted passive roof thrust system. We suggest that this structural style dominates the Cretaceous–early Cenozoic evolution of the northern Lhasa thrust belt and provides an explanation for the scarcity of basement rock exposures in the Lhasa terrane despite >50% upper crustal shortening. Furthermore, we highlight similarities between the collision-related northern Lhasa and Tethyan Himalayan thrust belts, both of which are bound by sutures and associated with underthrusting of lower plate lithosphere.