Interaction between the Central Asian Orogenic Belt (CAOB) and the Siberian craton as recorded by detrital zircon suites from Transbaikalia
Interaction between the Central Asian Orogenic Belt (CAOB) and the Siberian craton as recorded by detrital zircon suites from Transbaikalia
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DOI：
10.1016/j.precamres.2015.05.015
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发表时间：
2015-09
影响因子：
3.8
通讯作者：
V. Powerman;A. Shatsillo;Nikolai Chumakov;I. Kapitonov;J. Hourigan
中科院分区：
文献类型：
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作者：
V. Powerman;A. Shatsillo;Nikolai Chumakov;I. Kapitonov;J. Hourigan
本研究的目的是确定亚洲两个主要地壳省（西伯利亚克拉通和中亚造山带）相互作用的初始年龄和时间跨度。利用西伯利亚克拉通新元古代被动边缘地层中碎屑锆石单颗粒U-Pb年龄确定了区域外源区的首次出现。本文分析了西伯利亚贝加尔-帕托姆边缘新元古代的12块碎屑岩和一个不整合沉积在加积CAOB地壳之上的火山岩Padrinsky群样品。总共分析了1152粒，703粒用于种源解释。西伯利亚边缘地层较低的地层产生了太古代-古元古代碎屑锆石年龄，其与西伯利亚前寒武纪克拉通相似，并且可能源自西伯利亚前寒武纪克拉通。此外，还发现了少量区域外的中元古代颗粒，物源转换发生在剖面的上部，并以区域外锆石的流入为标志。最年轻的锆石（610马）限制沉积年龄和提供证据的时间CAOB和西伯利亚之间的初始相互作用在这一地区。新元古代锆石也占主导地位的CAOB上覆沉积单元，表明继续收敛。在加积的CAOB岩上沉积的同时代火山岩单元具有相似的U-Pb碎屑锆石年龄分布，加强了造山带两侧的物源联系。对局部构造的分析表明，加积的开始可能早于新元古代锆石的首次出现：在区域不整合的发展过程中，635 Ma（？）Dzhemkukan组的“雪球地球”冰碛岩。在新元古代的Dzhemkukan组中没有锆石可能是由于没有发展一个非常厚的地壳。我们的数据与收集到的其他新元古代沉积盆地的西伯利亚克拉通南部，包括Cisbaikalia和Bodaibo复向斜的数据是一致的。
This study was carried out to determine the initial age and time-span of interaction of two major crustal provinces of Asia: the Siberian craton and the Central Asian Orogenic Belt (CAOB). Single grain U–Pb ages of detrital zircon suites from the Neoproterozoic passive margin strata of the Siberian craton were used to determine the first appearance of extraregional source regions. Twelve Neoproterozoic clastic rocks from the Baikal-Patom margin of Siberia and one sample from the volcaniclastic Padrinsky Group that was deposited unconformably above accreted CAOB crust were analyzed. In total, 1152 grains were analyzed, 703 were used for provenance interpretation. Stratigraphically lower strata from the Siberian margin yield Archean – Paleoproterozoic detrital zircon ages, which are similar to, and probably derived from the Siberian Precambrian craton. A few extra-regional Mesoproterozoic grains are also present.The provenance shift happens in the upper portion of the section and is marked by the influx of extra-regional zircons. The youngest included zircons (610 Ma) constrain the age of deposition and provide evidence for the timing of initial interaction between CAOB and Siberia in this region. Neoproterozoic zircons also dominate the overlying sedimentary units of the CAOB, suggesting continuing convergence. Coeval volcaniclastic unit deposited across the accreted CAOB terrane has a similar U–Pb detrital zircon age distribution, strengthening the provenance links between the two sides of the orogen.Analysis of the local tectonics suggests that the beginning of accretion might have started even before the first appearance of Neoproterozoic zircon: during the development of a regional unconformity, capped by 635 Ma (?) “Snowball Earth” tillites of Dzhemkukan Formation. The absence of Neoproterozoic zircons in Dzhemkukan Formation is probably explained by the absence of development of an extremely thickened crust.Our data are in good agreement with data collected from other Neoproterozoic sedimentary basins of southern Siberian craton, including Cisbaikalia and Bodaibo Synclinorium.