Paleocene-Eocene foreland basin evolution in the Himalaya of southern Tibet and Nepal: Implications for the age of initial India-Asia collision
Paleocene-Eocene foreland basin evolution in the Himalaya of southern Tibet and Nepal: Implications for the age of initial India-Asia collision
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DOI：
10.1002/2014tc003522
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发表时间：
2014-05-01
期刊：
影响因子：
4.2
通讯作者：
Ding, L.
中科院分区：
文献类型：
--
作者：
DeCelles, P. G.;Kapp, P.;Ding, L.
来自拉萨盆地南部的硅质沉积岩沉积在印度北方被动大陆边缘的岩石之上，提供了印度板块和亚洲板块大陆部分初始接触的年龄估计。本文报道了位于藏南印度-雅鲁藏布江缝合带南翼沿着的桑丹林剖面上白垩统-古新统地层的沉积学、沉积岩石学和年代学资料。这可能是最近的，因此也是最古老的，印度-亚洲碰撞的记录。这些地层是由高密度浊流（或集中密度流）和深海环境中浮游生物碎屑的悬浮沉降沉积而成。从石英砂质砂岩成分突然转变为粗砂岩成分，标志着从印度沉积物来源向亚洲沉积物来源的转变。突然的成分变化是伴随着变化的碎屑锆石U-Pb年龄的沉积物源区逆转诊断，从印度到亚洲的来源。根据碎屑锆石U-Pb年龄和剖面上部凝灰质层的锆石U-Pb年龄，将该过渡期的时间划分为60 Ma ~ 58.5 +/-0.6Ma。在一个palmitrium恢复区域古地理框架的背景下，从桑丹林部分的数据结合以前发表的数据从北方特提斯喜马拉雅山和正面的尼泊尔小喜马拉雅山和Subhimalaya表明，弯曲波迁移类似于1300公里向南跨越现在的喜马拉雅冲断带从古新世到现在。
Siliciclastic sedimentary rocks derived from the southern Lhasa terrane, sitting depositionally upon rocks of the northern Indian passive continental margin, provide an estimate of the age of initial contact between the continental parts of the Indian and Asian plates. We report sedimentological, sedimentary petrological, and geochronological data from Upper Cretaceous-Paleocene strata in the Sangdanlin section, located along the southern flank of the Indus-Yarlung suture zone in southern Tibet. This is probably the most proximal, and therefore the oldest, record of the India-Asia collision. These strata were deposited by high-density turbidity currents (or concentrated density flows) and suspension settling of pelagic biogenic debris in a deep-marine setting. An abrupt change from quartz-arenitic to feldspatholithic sandstone compositions marks the transition from Indian to Asian sediment provenance. The abrupt compositional change is accompanied by changes in U-Pb ages of detrital zircons diagnostic of a sediment provenance reversal, from Indian to Asian sources. The timing of the transition is bracketed between similar to 60Ma and 58.5 +/- 0.6Ma by detrital zircon U-Pb ages and zircon U-Pb ages from a tuffaceous bed in the upper part of the section. In the context of a palinspastically restored regional paleogeographic framework, data from the Sangdanlin section combined with previously published data from the northern Tethyan Himalaya and the frontal Nepalese Lesser Himalaya and Subhimalaya suggest that a flexural wave migrated similar to 1300km southward across what is now the Himalayan thrust belt from Paleocene time to the present.