The N–S trending Neoarchaean to Palaeoproterozoic Dongargarh–Kotri belt in the Bastar Craton in central India exposes bimodal volcanics and volcaniclastics of the Nandgaon Group. In this contribution, lithofacies analysis of the Nandgaon Group has been attempted mainly based on distribution of rhyolites, basalts and pyroclastics in this ancient volcanic terrain, their field characteristics and petrography. The study area in the central part of the belt around Dongargaon–Gotatola area can be two distinct domains based on distribution and composition of volcanics and volcaniclastics. Domain-I comprises coherent and autoclastic rhyolite, and Domain-II with basic lava and pyroclastics. The rhyolites of Domain-I can be further divided into feldspar quartz phyric, quartz phyric, aphyric, and autoclastic rhyolites. Basic lava of Domain-II includes basalt and andesitic basalt. The associated volcaniclastics are mainly coarse lapilli tuff, fine lapilli tuff and ash beds. Field characteristics of coherent lavas and volcaniclastics attest to phreato-magmatically controlled plinian to sub-plinian style of eruptions. Effusive and explosive eruptive processes through multiple vents gave rise to the observed volcanic sequences. This study indicates that subaerial volcanism initially led to formation of felsic ignimbrites and ash deposits followed by effusive rhyolite lava flows. Subsequently, mafic volcanism occurred giving rise to pyroclastic flows and surges, followed by effusive mafic lava flows.

印度中部巴斯塔克拉通的 N-S 向新太古代至古元古代 Dongargarh-Kotri 带暴露了 Nandgaon 群的双峰火山岩和火山碎屑岩。在这篇文章中，主要基于流纹岩、玄武岩和火山碎屑在这个古老的火山地形中的分布、它们的现场特征和岩石学，尝试了对 Nandgaon 群的岩相分析。根据火山岩和火山碎屑岩的分布和组成，Dongargaon-Gotatola 地区周围带中部的研究区可以是两个不同的领域。Domain-I 包括相干和自碎屑流纹岩，Domain-II 包括基本熔岩和火山碎屑。Domain-I 的流纹岩可进一步分为长石石英 phyric、石英 phyric、aphyric 和自碎屑流纹岩。Domain-II 的基本熔岩包括玄武岩和安山质玄武岩。伴生火山碎屑岩主要为粗凝灰岩、细凝灰岩和灰层。连贯的熔岩和火山碎屑岩的场特征证明了潜水岩浆控制的普林阶到亚普林阶的喷发方式。通过多个喷口的喷发和爆炸性喷发过程产生了观察到的火山序列。这项研究表明，地下火山作用最初导致长英质凝灰岩和灰烬沉积物的形成，随后是喷出的流纹岩熔岩流。随后，发生了基性火山作用，产生了火山碎屑流和涌动，随后是喷出的基性熔岩流。连贯的熔岩和火山碎屑的现场特征证明了潜水岩浆控制的普林阶到亚普林阶的喷发。通过多个喷口的喷发和爆炸性喷发过程产生了观察到的火山序列。这项研究表明，地下火山作用最初导致长英质凝灰岩和灰烬沉积物的形成，随后是喷出的流纹岩熔岩流。随后，发生了基性火山作用，产生了火山碎屑流和涌动，随后是喷出的基性熔岩流。连贯的熔岩和火山碎屑岩的场特征证明了潜水岩浆控制的普林阶到亚普林阶的喷发方式。通过多个喷口的喷发和爆炸性喷发过程产生了观察到的火山序列。这项研究表明，地下火山作用最初导致长英质凝灰岩和灰烬沉积物的形成，随后是喷出的流纹岩熔岩流。随后，发生了基性火山作用，产生了火山碎屑流和涌动，随后是喷出的基性熔岩流。这项研究表明，地下火山作用最初导致长英质凝灰岩和灰烬沉积物的形成，随后是喷出的流纹岩熔岩流。随后，发生了基性火山作用，产生了火山碎屑流和涌动，随后是喷出的基性熔岩流。这项研究表明，地下火山作用最初导致长英质凝灰岩和灰烬沉积物的形成，随后是喷出的流纹岩熔岩流。随后，发生了基性火山作用，产生了火山碎屑流和涌动，随后是喷出的基性熔岩流。