Crustal structure and rift architecture across the Krishna–Godavari basin in the central Eastern Continental Margin of India based on analysis of gravity and seismic data
Crustal structure and rift architecture across the Krishna–Godavari basin in the central Eastern Continental Margin of India based on analysis of gravity and seismic data
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DOI：
10.1016/j.marpetgeo.2012.05.005
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发表时间：
2012-11
影响因子：
4.2
通讯作者：
M. Radhakrishna;D. Twinkle;S. Nayak;R. Bastia;G. Srinivasa Rao
中科院分区：
文献类型：
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作者：
M. Radhakrishna;D. Twinkle;S. Nayak;R. Bastia;G. Srinivasa Rao
Krishna-Godavari盆地是一个裂谷型被动边缘盆地，在早白垩世印度与南极东部之间的大陆裂谷过程和随后的海底扩张过程中，沿印度中东部大陆边缘与NW-SE向的Pranhita-Godavari地块垂直发育。该盆地陆上和近海剖面的三维重力解释结合详细的地震反射和折射数据，提供了有关该盆地地壳结构和早期解体历史的重要新信息。重力地壳模型表明，东印度洋地盾边缘的地壳厚度为39-41千米，近海大洋大陆转换(OCT)时的地壳厚度为20-23千米。在围绕盆地的三个地壳区域之间，地壳的性质和边缘的形态有很大的不同：古达帕盆地、普拉尼塔-哥达瓦里地块和东加特活动带，这表明边缘的横向分段。华侨城的高密度(3.0微克/立方厘米)地壳物质带将两边的纯大陆壳和洋壳分开。莫霍面沿该带是最浅的，使上地幔明显接近地表，这表明它可能由原大洋地壳岩石组成。此外，本研究还强调了边缘深部近海地区的一个主要的基底构造高地。该构造的地球物理特征表明，它是一种地壳尺度特征，以侵入火山岩为特征，由低密度地壳组成，位于靠近华侨城的近海。根据推断的构造重建，我们认为这一构造高压可能是印度和伊兰银行解体过程中留下的大陆碎片。
The Krishna–Godavari basin is a rifted passive margin basin that developed orthogonally to the NW–SE trending Pranhita–Godavari graben along the central Eastern Continental Margin of India in response to the continental rifting process and the subsequent seafloor spreading between India and eastern Antarctica during the early Cretaceous period. The 3-D gravity interpretation of both the onshore and offshore sections of the basin integrated with detailed seismic reflection and refraction data provided significant new information about the crustal architecture and the early breakup history of the basin. The gravity-derived crustal models indicate that the crust at the eastern Indian shield margin is 39–41 km thick and thins to as much as 20–23 km at the Ocean Continent Transition (OCT) in the offshore. There is a significant variation in the nature of crust and the configuration along the margin between the three crustal domains encompassing the basin: the Cuddapah basin, Pranhita–Godavari Graben, and the Eastern Ghat Mobile Belt that indicates the lateral segmentation of the margin. A zone of high density (3.0 g/cm3) crustal material at the OCT separates the pure continental and oceanic crusts on either side. The Moho is shallowest along this zone and brought the upper mantle notably close to the surface, which indicates that it could be comprised of Proto-Oceanic Crustal rocks. Furthermore, the present study highlights a major basement structural high in the deep offshore area of the margin. The geophysical signatures over this structure suggest that it is a crustal scale feature that is characterized by intrusive volcanic rocks, comprised of low density crust, and lies close to the OCT towards offshore. Based on the inferred tectonic reconstruction, we believe that this structural high could be a continental fragment that was left behind during the process of breakup between India and the Elan Bank.