The western Indian volcanic rifted margin, and its large-scale tectonic feature called the Panvel flexure, formed at 62.5 Ma during the late stages of Deccan Traps flood volcanism. We present a geological account of late-stage (≤ 62.5 Ma) Deccan volcanism and plutonism in the relatively poorly studied Thane–Vasai region in the Panvel flexure zone. The study area shows west-dipping basaltic sequences up to hundreds of meters thick, overlain by pyroclastic deposits of various types. The volcanic units are intruded by gabbro plutons, and all these units are in turn intruded by dykes of varied compositions (including tholeiitic basalt, lamprophyre, and granophyre). There are also early tholeiitic dykes, some of which may be feeders to the basaltic sequence. We focus on the gabbro intrusions and provide extensive petrographic and mineral chemical data on them. The gabbros are tholeiitic, and of considerable interest in commonly containing interstitial silicic melts (granophyre or silicic glass). One of the intrusions, the Chena pluton, shows clear outcrop transitions from gabbro, and gabbro with interstitial granophyre, to transitional gabbro-granophyre, and then to a distinct upper zone of granophyre and microgranite. Granophyre is common in mafic intrusions in continental flood basalt provinces of the world (e.g., the Palisades Sill and the Skaergaard Intrusion), where its genesis is ascribed to mechanisms such as fractional crystallisation, liquid immiscibility, or crustal melting, typically based on geochemical data. The Chena gabbro outcrops are valuable in providing direct evidence for a fractional crystallisation origin of the granophyres (and silicic glasses) found in the Thane–Vasai gabbro intrusions, with which the mineral chemical compositions are also consistent.

西印度火山裂谷边缘及其被称为潘维尔挠曲的大规模构造特征，形成于德干圈闭洪水火山活动晚期的 62.5 Ma。我们对 Panvel 弯曲带中研究相对较少的 Thane-Vasai 地区的晚期（≤ 62.5 Ma）德干火山作用和深成作用进行了地质解释。研究区显示西倾玄武岩层序厚达数百米，上面覆盖着各种类型的火山碎屑沉积物。火山单元被辉长岩侵入，所有这些单元又被不同成分的岩墙侵入（包括拉斑玄武岩、斑岩和花斑岩）。还有早期拉斑岩脉，其中一些可能是玄武岩层序的馈线。我们专注于辉长岩侵入体，并提供有关它们的大量岩相和矿物化学数据。辉长岩是拉斑岩，对通常含有间隙硅熔体（花岗石或硅玻璃）非常感兴趣。其中一个侵入体，Chena 岩体，显示出清晰的露头从辉长岩和带有间隙花岗岩的辉长岩过渡到过渡辉长岩-花岗岩，然后到明显的花岗岩和微花岗岩上部区域。粒状岩在世界大陆洪水玄武岩省的镁铁质侵入体中很常见（例如，Palisade Sill 和 Skaergaard 侵入体），其成因归因于诸如分步结晶、液体不混溶或地壳熔化等机制，通常基于地球化学数据. Chena 辉长岩的露头为在 Thane-Vasai 辉长岩侵入体中发现的花斑岩（和硅质玻璃）的分级结晶起源提供直接证据是有价值的，矿物化学成分也与其一致。