Modelling of Moho depths and crustal composition in the Aravalli (Rajasthan) Craton, north-west India

IF 2.3 4区地球科学

Acta Geophysica Pub Date : 2024-12-25 DOI:10.1007/s11600-024-01508-y

Raju Prathigadapa, Prantik Mandal, Satish Saha, Rahul Biswas

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Abstract

Between 2022 and 2024, a 330-km-long NE-SW trending profile of ten three-component broadband seismographs has been deployed by the CSIR-NGRI, Hyderabad, in Rajasthan (India), to estimate Moho depths and crustal Vp/Vs ratios using H–K stacking of radial P-receiver functions. The modelled Moho depths range from (34.3 ± 2.50) km at SPRA [24.87°N, 74.21°E] to (43.1 ± 2.54) km at DBKR [25.60°N, 74.96°E]. Additionally, the typical values of crustal Vp/Vs range from (1.61 ± 0.04) at DNGT [26.37°N, 75.78°E] to (1.81 ± 0.05) at SPRA. The region’s average crustal thickness is (39.8 ± 2.5) km, similar to the global average for the early and middle Archean crust. Additionally, the region’s average crustal Vp/Vs ratio is 1.73 ± 0.07, indicating a felsic to intermediate composition. The Moho depths obtained from the analysis, depth migration, H–K, and Common Conversion Point (CCP) stacking of radial PRFs show a high level of agreement. Based on the results of our modelling, we can conclude that the crust beneath the northern Alluvium part of our broadband seismic network is mostly felsic, as evidenced by modelled crustal Vp/Vs ratios ranging from 1.61 to 1.77 with a mean of (1.67 ± 0.07). This contrasts with the southern portion of the profile, which has modelled crustal Vp/Vs ratios ranging from 1.74 to 1.81 with a mean of (1.78 ± 0.03). Our modelling shows a major crustal up-warping in the NE-SW direction, with a depth of 4–9 km below the region over a length of about 200–300 km. The observed crustal undulation could be linked to the Indian plate’s buckling or folding at the crustal level, which most likely occurred as a result of the Indian-Eurasian plate collision roughly 50 million years ago.

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印度西北部Aravalli （Rajasthan）克拉通Moho深度和地壳组成的模拟

2022年至2024年间，印度拉贾斯坦邦海得拉巴的CSIR-NGRI部署了一个330公里长的NE-SW趋势剖面，由10台三分量宽带地震仪组成，利用径向p接收函数的H-K叠加来估计莫霍深度和地壳Vp/Vs比。模拟的Moho深度范围为SPRA[24.87°N， 74.21°E]的（34.3±2.50）km至DBKR[25.60°N， 74.96°E]的（43.1±2.54）km。地壳Vp/Vs的典型值为（1.61±0.04）~（1.81±0.05）。该地区地壳平均厚度为（39.8±2.5）km，与全球早、中太古宙地壳平均厚度相近。地壳Vp/Vs平均值为1.73±0.07，为长英质-中等成分。通过径向PRFs的分析、深度偏移、H-K和共转换点（CCP）叠加得到的Moho深度显示出高度的一致性。根据我们的模拟结果，我们可以得出结论，我们的宽带地震网络的北冲积层部分下的地壳主要是长英质，正如模拟地壳Vp/Vs比值在1.61至1.77之间，平均值为（1.67±0.07）所证明的那样。这与剖面的南部形成对比，该剖面模拟的地壳Vp/Vs比值范围为1.74至1.81，平均值为（1.78±0.03）。我们的模型显示，在东北-西南方向上有一个主要的地壳上翘，深度为4-9公里，长度约为200-300公里。观察到的地壳波动可能与印度板块在地壳水平上的弯曲或折叠有关，这很可能是大约5000万年前印度-欧亚板块碰撞的结果。

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来源期刊

Acta Geophysica GEOCHEMISTRY & GEOPHYSICS-

CiteScore

3.80

自引率

13.00%

发文量

251

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