Petrography And Field Study Of Andesitic Ignimbrite In Temangan, Kelantan

Nur Shafiqah Shahman,Norazif Anuar,Elvaene James,Arham Muchtar Achmad Bahar,Muhammad Irfan Hadhi

doi:10.7186/bgsm72202118

Abstract

The volcanic rocks in Temangan, Kelantan consist of felsic to intermediate volcanic rocks, that is mainly of pyroclastic with rhyolitic, dacitic, and andesitic tuff. A geological review has been carried out in Kampung Bukit Besi, Temangan, in Kelantan, Malaysia, which is composed of schist, shale, andesite, and ignimbrite. In Temangan, andesite and ignimbrite show an intimate relationship, as the ignimbrite exists as the fragments and andesite as the matrix. The methodology used in this study are petrography and X-ray Diffraction (XRD) analyses, to determine the mineralogical composition of andesitic ignimbrite. Andesite shows aphenitic and porphyritic textures and consist of pyroxene, plagioclase, alkali feldspar, quartz, biotite and iron oxides. A range of plagioclase textures indicate imperfect equilibrium condition from andesite, reflecting plagioclase dissolution and regrowth. The structural analysis suggest that thrust fault occurred in the study area. Andesite and ignimbrite of the two stages are suggested to have derived from the andesite magma eruption which produced pyroclastic flow eruptions in small amount in most caldera volcanoes at high temperature gradient.

Highlights

In Peninsular Malaysia, andesite distribution is widespread from north Kelantan, through Pahang to Kluang in Johor in the south (Hutchison & Tan, 2009)
A geological review has been carried out in Kampung Bukit Besi, Temangan, in Kelantan, Malaysia, which is composed of schist, shale, andesite, and ignimbrite
The methodology used in this study are petrography and X-ray Diffraction (XRD) analyses, to determine the mineralogical composition of andesitic ignimbrite

Summary

INTRODUCTION

In Peninsular Malaysia, andesite distribution is widespread from north Kelantan, through Pahang to Kluang in Johor in the south (Hutchison & Tan, 2009). PETROGRAPHIC ANALYSIS The andesite shows porphyritic and hypocrystalline textures, and is composed of clinopyroxene, orthopyroxene, hornblende, plagioclase, and quartz phenocrysts Schist occurs at the north-west due to the thrust fault and is the oldest unit followed by shale and andesite of late Triassic to Permian, while the youngest is the ignimbrite of Late Permian that is an intrusion, as a dyke porphyry (Aw, 1967) (Figure 2). The Temangan area was deformed by minor folds drag, and the folds were a result of the deformation of the rock which produced dextral faults and joints trending north-west and south-west

DISCUSSION

Findings

CONCLUSION