Siberian Traps large igneous province: Evidence for two flood basalt pulses around the Permo-Triassic boundary and in the Middle Triassic, and contemporaneous granitic magmatism
Siberian Traps large igneous province: Evidence for two flood basalt pulses around the Permo-Triassic boundary and in the Middle Triassic, and contemporaneous granitic magmatism
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DOI：
10.1016/j.earscirev.2013.04.001
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发表时间：
2013-07-01
影响因子：
12.1
通讯作者：
Nikolaeva, Irina V.
中科院分区：
文献类型：
--
作者：
Ivanov, Alexei V.;He, Huayiu;Nikolaeva, Irina V.
西伯利亚圈闭大火成岩省面积巨大（约7 × 10(6)公里），体积巨大（约4 × 10(6)公里）。其主要岩石类型为低钛玄武岩及其侵入类玄武岩，其成分从超镁铁质到长英质不等，包括溢流岩、侵入岩和火山碎屑岩。本文给出了西伯利亚圈闭地理中心的两个熔岩单元的Ar-46/39Ar年龄（240.9 +/- 13/2.6/5.5和246.6 +/- 1.4/2.7/5.6 Ma），其中年龄相对于Bern4M计算，指定年龄为18.7 (+/- 0.096)Ma，误差以+/- x/y/z表示，其中x和y和z分别为分析误差、内部误差和外部误差)。西伯利亚圈闭东南部Angara-Taseevskaya向斜（242.8 +/- 1.3/2.6/5.0 Ma、239.1 +/- 1.1/2.5/4.9 Ma和255.8 +/- 4.7/53/6.9 Ma）的3条白云岩层和Noril’sk地区（2383 +/- 13/2.6/53 Ma）的1条煌斑岩岩脉。结合现有的地质年代学资料，我们的结果表明，大量的低钛玄武岩岩浆活动出现在不同的脉冲期间。至少有两个火山脉冲被识别出来：在二叠纪-三叠纪边界（分别类似于249 Ma或252 Ma，分别使用Ar-46/39Ar和U-Pb时间尺度）和大约10 Ma之后的中三叠世。花岗质岩浆活动在时间上与两个洪水玄武岩脉冲重叠，但持续到晚三叠世（类似于229 Ma的U-Pb时间标度）。西伯利亚圈闭省的长期岩浆活动也得到地质观测和古地磁资料的支持。根据西伯利亚圈闭起源的不同模式，讨论了新的地质年代学发现，并将其应用于中三叠世大灭绝事件。(C) 2013 Elsevier B.V.版权所有
The Siberian Traps large igneous province is of enormous size (similar to 7 x 10(6) km(2)) and volume (similar to 4 x 10(6) km(3)). It contains effusive, intrusive and volcanoclastic rocks varying in compositions from ultramafic to felsic, though low-Ti basalts and their intrusive analogs are the predominant rock types. In this paper, we provide new Ar-46/39Ar ages for two lava units of the geographic center of the Siberian Traps, the Central Putorana region (240.9 +/- 13/2.6/5.5 and 246.6 +/- 1.4/2.7/5.6 Ma, where ages are calculated relative to Bern4M with an assigned age of 18.7 (+/- 0.096) Ma and errors are stated in the form +/- x/y/z, where x and y and z are analytical, internal and external errors, respectively), three dolerite sills from the Angara-Taseevskaya syncline of the southeastern Siberian Traps (242.8 +/- 1.3/2.6/5.0 Ma, 239.1 +/- 1.1/2.5/4.9 Ma and 255.8 +/- 4.7/53/6.9 Ma) and a lamproite dyke from the Noril'sk region (2383 +/- 13/2.6/53 Ma). In combination with available geochronologic data our results suggest that voluminous low-Ti basaltic magmatism appeared during different pulses. At least two volcanic pulses are recognized: at the Permo-Triassic boundary (similar to 249 Ma or 252 Ma using the Ar-46/39Ar and U-Pb timescales, respectively) and about 10 Ma later in the Middle Triassic. Granitic magmatism overlapped in time with the two flood basalt pulses, but continued into the Late Triassic (similar to 229 Ma using the U-Pb timescale). Prolonged magmatism of the Siberian Traps province is also supported by geologic observations and paleomagnetic data. New geochronologic findings are discussed in light of the different models for the origin of the Siberian Traps and applied to a Middle Triassic mass extinction event. (C) 2013 Elsevier B.V. All rights reserved.