Heavy mineral studies of Gondwana sandstones of Eastern Arunachal Himalaya and implications for provenance

Bashab N Mahanta,Tapos Kumar Goswami ,Ranjan Kumar Sarmah ,B R Syngai

doi:10.33493/scivis.17.01.02

Bashab N Mahanta, Tapos Kumar Goswami + Show 2 more

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https://doi.org/10.33493/scivis.17.01.02

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Abstract

A thin linear belt of Permian Lower Gondwana rocks occur in the Eastern Himalayas from Arunachal Pradesh to Sikkim. The Lower Gondwana Group of rocks consists of shale, siltstone, sandstone, carbonaceous shale and coaly matter and is sandwiched between Miri Group and Siwalik Group of rocks. Heavy mineral composition of sandstones is extensively used in the provenance studies as they are the surviving remnants of the rather abundant but unstable mafic components of the source rock. The sandstones of Lower Gondwana Group bear the heavy mineral assemblage of chlorite, biotite, zircon, ilmenite, epidote, garnet, amphibole, chloritoid, brown tourmaline, magnetite, staurolite, rutile, and opaques which is indicative of a provenance of metamorphic rocks with input of igneous rocks. Provenance sensitive mineral index ratios were also calculated to see the variation in the ratio of two or more stable minerals with the same characteristics.

Highlights

Heavy mineral composition of sandstones are widely used in the provenance studies in sedimentary petrology
Heavy mineral assemblage is controlled by a number of factors such as nature of the parent rocks, vagaries of climatic conditions during weathering, relative solubility and stability of the various detrital minerals, their mineralogy, abrasion history, their density, size, sorting and past depositional changes experienced by the sediments
A linear belt of Permian Gondwana rocks occur in parts of Lesser Himalayan morphotectonic unit of Arunachal Pradesh

Summary

Introduction

Heavy mineral composition of sandstones are widely used in the provenance studies in sedimentary petrology These minor accessory minerals of sandstones are marked by a higher than average specific gravity and they are the surviving remnants of the rather abundant but unstable mafic components of the source rock.[1] Over fifty different non-opaque heavy mineral species have been recognized in sandstones, many of which have specific parageneses that enable a direct match between sediment and source lithology.[2] Heavy mineral assemblage is controlled by a number of factors such as nature of the parent rocks, vagaries of climatic conditions during weathering, relative solubility and stability of the various detrital minerals, their mineralogy, abrasion history, their density, size, sorting and past depositional changes experienced by the sediments.

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