Evolving passive- and active-margin tectonics of the Paleoproterozoic Aravalli Basin, NW India
Evolving passive- and active-margin tectonics of the Paleoproterozoic Aravalli Basin, NW India
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印度西北部古元古代阿拉瓦利盆地被动和主动边缘构造的演变
DOI：
10.1130/b35027.1
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发表时间：
2018-10
期刊：
影响因子：
--
通讯作者：
Zhao Jun-Hong
中科院分区：
文献类型：
--
作者：
Wang Wei;Cawood Peter.A;P;it Manoj.K;Zhou Mei-Fu;Zhao Jun-Hong
印度西北部古元古代Aravalli超群的沉积记录提供了从被动陆缘到活动陆缘再回到被动陆缘的过程的证据，这与印度半岛前寒武纪地壳演化有关。碎屑沉积岩中的锆石U-Pb年龄数据将阿拉瓦利超群的沉积年龄限制在约1000年以内。2.4 - 1.6 Ga年龄段。条带状片麻岩杂岩的3.3 - 2.9和2.5 Ga基底花岗岩类已被确定为下Aravalli超群Delwara组的烃源岩。Delwara砂岩富Zr、贫Ti、Sc，为被动边缘沉积环境。中Aravalli Udaipur组的未成熟砂岩包含约1000年的碎屑。1.97 - 1.79 Ga岩浆弧岩（锆石ε Hf [t]值为+6.1~-7.8）和大陆基底（约1.97 - 1.79 Ga）。2.5 Ga）。中Aravalli砂岩的K2O/Na2O-SiO2、TiO2-Fe2O3、La-Th-Sc和Th-Sc-Zr/10等构造判别特征表明其为大陆弧环境，与它们的平均模态成分Q23F27L50（其中Q为石英，F为长石，L为岩屑）一致，表明其为近源和过渡弧环境。中Aravalli超群的地层较高的Bowa组接受了来自1.78至1.72 Ga与伸展有关的岩浆弧岩的额外碎屑，这些地层的特征是锆石具有亚地幔ε Hf（t）值，表明弧后环境，与构造判别图一致。上Aravalli-Debari砂岩以1.87 - 1.65 Ga碎屑岩为主。它们的高成熟度（平均：Q92F4L4）和地球化学特征与被动边缘环境一致。岩石地层关系和成分数据的整合表明，Aravalli超群的岩石档案记录的早期古元古代被动边缘台地沉积的发展，随后过渡到大陆弧，随后演变成裂谷盆地被动边缘设置。
The sedimentary record of the Paleoproterozoic Aravalli Supergroup in northwest India provides evidence for a progression from passive margin to active margin and back to passive margin that can be linked to the Precambrian crustal evolution of peninsular India. U-Pb detrital zircon age data from clastic sedimentary rocks constrain the depositional age of the Aravalli Supergroup to within the ca. 2.4–1.6 Ga age bracket. The 3.3–2.9 and 2.5 Ga basement granitoids of the Banded Gneiss Complex have been identified as the source rocks for the Delwara Formation from the Lower Aravalli Supergroup. The Delwara sandstones show enrichment of Zr and depletion of Ti and Sc, indicating a passive-margin depositional environment. Immature sandstones of the Middle Aravalli Udaipur Formation incorporate detritus from ca. 1.97–1.79 Ga magmatic arc rocks (characterized by zircon εHf[t]values varying from +6.1 to –7.8) and continental basement (ca. 2.5 Ga). Tectonic discrimination characteristics of Middle Aravalli sandstones, such as K2O/Na2O-SiO2, TiO2-Fe2O3, La-Th-Sc, and Th-Sc-Zr/10, suggest a continental arc setting, in agreement with their average modal composition of Q23F27L50(where Q is quartz, F is feldspar, and L is lithics), which indicates a proximal source and transitional arc setting. The stratigraphically higher Bowa Formation of the Middle Aravalli Supergroup received additional detritus from 1.78 to 1.72 Ga extension-related magmatic arc rocks, and these strata are characterized by zircons with subchondritic εHf(t)values, suggesting a back-arc setting, in agreement with tectonic discrimination plots. The Upper Aravalli Debari sandstones are dominated by 1.87–1.65 Ga detritus. Their high maturity (average: Q92F4L4) and geochemical features are consistent with a passive-margin setting. Integration of the lithostratigraphic relationships and compositional data suggests that the rocks of Aravalli Supergroup archive the record for the development of early Paleoproterozoic passive-margin platform sedimentation, followed by a transition to continental arc and subsequently to an evolved rift-basin–passive-margin setting.
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