The Deccan Continental Flood Basalt of the Indian Peninsula is characterized by extensive basaltic eruptions ornamented with three spectacular distinct dyke swarms: the Pune – Nasik, Narmada – Tapi, and Western Coastal dyke swarms. Our study area is the Pune – Nasik dyke swarm, which has ∼465 mappable dykes. These dykes exhibit different orientations with a predominant trend of N101° and vary in length from less than 1 km to ∼64 km. These dykes are massively jointed and occasionally contain vesicles filled with secondary minerals like quartz and calcite. The host rock is weathered basalt of various older Deccan flows. In this study, we have calculated magmatic overpressures and magma chamber depths using the aspect ratios (length/thickness) of the dykes. The average estimated source depth is ∼13 km, based on an average Young's modulus for the host rock basalt (Eavg, 7.5 GPa). Additionally, we compared the inferred magma source depths of the Pune – Nasik, and Narmada-Tapi dyke swarms which include the Nandurbar – Dhule, and Pachmarhi dykes of the Deccan Flood Basalt Province. Our findings indicate that the magma chamber source depth is greater in the Pune – Nasik dyke swarm compared with other dyke swarms. The variation in strike distribution of the Pune-Nasik dyke swarm may be attributed to several factors, including a larger magma chamber, local stress fields generated by shallow magma chamber, or the superimposition of tectonic stress fields (N-S and E-W extension) during the emplacement of dykes. This contrasts with the commonly held belief that the dykes are solely connected to a central edifice of the Reunion hotspot.

中文翻译：

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浦那的构造岩浆演变 – Nasik Deccan Dykes：来自结构和维度尺度的见解


印度半岛的德干大陆泛洪玄武岩的特点是广泛的玄武岩喷发，并点缀着三个壮观的独特岩脉群：浦那 - 纳西克、纳尔默达 - 塔皮和西部沿海岩脉群。我们的研究区域是 Pune – Nasik 堤坝群，它有 ∼465 个可映射的堤坝。这些堤坝表现出不同的方向，主要趋势为 N101°，长度从不到 1 公里到 ∼64 公里不等。这些岩脉是巨大的节理，偶尔包含充满石英和方解石等次生矿物的囊泡。主岩是各种较老的德干流的风化玄武岩。在这项研究中，我们使用岩脉的纵横比（长度/厚度）计算了岩浆超压和岩浆室深度。根据主岩玄武岩的平均杨氏模量（平均，7.5 GPa），估计的平均源深度为 ∼13 公里。此外，我们比较了浦那 – Nasik 和 Narmada-Tapi 岩脉群的推断岩浆源深度，其中包括德干洪水玄武岩省的 Nandurbar – Dhule 和 Pachmarhi 岩脉。我们的研究结果表明，与其他岩脉群相比，Pune – Nasik 岩脉群的岩浆室源深度更大。Pune-Nasik 岩脉群走向分布的变化可能归因于几个因素，包括更大的岩浆室、浅层岩浆室产生的局部应力场或岩脉放置过程中构造应力场的叠加（南北和东西延伸）。这与人们普遍持有的堤坝仅与留尼汪岛热点的中心建筑相连的观点形成鲜明对比。