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Crust-mantle structure and lithospheric destruction of the oldest craton in the Indian shield
Precambrian Research ( IF 3.2 ) Pub Date : 2021-06-01 , DOI: 10.1016/j.precamres.2021.106280
A. Vasanthi , A.P. Singh , Niraj Kumar , B. Nageswara Rao , A.V. Satyakumar , M. Santosh

The Singhbhum craton is among the five Archean cratons of Peninsular India that preserves some of the oldest continental nuclei. In this work, we present a new and complete Bouguer gravity map of this craton with insights into its deep crust-mantle structure, lithospheric thickness and density variations beneath this craton. The conspicuous presence of high-order residual gravity low anomalies, together with low estimated densities, suggests voluminous presence of Singhbhum granitic batholiths that built the dominant crustal architecture. The isolated residual gravity highs correspond to the mafic and ultramafic volcanic suites like, Dhanjori, Simlipal and Dalma, while the relatively low gravity anomalies observed over the western volcanic suites like Malangtoli, Jagannathpur and Ongarbira, indicate their relatively felsic nature. The estimated lithospheric thickness of about ~ 130 km below the granitic batholithic region, and about 112 km beneath the Precambrian volcanic terranes, together with low effective elastic thickness (Te,) of only about 31 km, suggest a thin and weak lithosphere. The craton witnessed extensive lithospheric destruction with the removal of nearly 100–150 km of the cratonic root. The decratonization may be linked to subduction during the Paleo-Mesoproterozoic period, together with mantle plumes at different times, suggesting a combined mechanical, thermal and chemical erosion of the cratonic keel.



中文翻译:

印度地盾中最古老克拉通的壳幔结构和岩石圈破坏

Singhbhum 克拉通是印度半岛五个太古宙克拉通之一,保留了一些最古老的大陆核。在这项工作中,我们展示了该克拉通的新的、完整的布格重力图,深入了解了该克拉通下方的深部壳幔结构、岩石圈厚度和密度变化。高阶残余重力低异常的显着存在,连同估计的低密度,表明大量存在 Singhbhum 花岗岩基岩,它们构成了主要的地壳结构。孤立的残余重力高点对应于 Dhanjori、Simlipal 和 Dalma 等基性和超基性火山岩组,而在 Malangtoli、Jagannathpur 和 Ongarbira 等西部火山岩组上观察到的相对较低的重力异常表明它们相对长英质性质。e, ) 仅约 31 公里,表明岩石圈薄而弱。克拉通见证了广泛的岩石圈破坏,移除了近 100-150 公里的克拉通根部。去克拉通化可能与古中元古代时期的俯冲以及不同时期的地幔柱有关,这表明克拉通龙骨受到机械、热和化学侵蚀。

更新日期:2021-06-02
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