Analysis of volcanic facies at the Chatree gold mine and in the Loei-Petchabun Volcanic belt, central Thailand

Abstract

Chapter 1: Introduction: Significance and Aims This thesis presents a detailed volcanological study of the Permo-Triassic rocks that host the low-sulphidation epithermal gold deposit at the Chatree mine in the Loei-Petchabun Volcanic belt, central Thailand. Rocks of similar age that lack appreciable mineralisation have also been studied in the surrounding Petchabun region and in the south of the belt (on Koh Chang Island). Using volcanic facies analysis combined with whole-rock geochemistry, this study seeks to better constrain the depositional setting, origin and style of the volcanism, and volcanic facies architecture at the Chatree epithermal deposit. The aims of this project are: 1. to describe the lithologies in and around the Chatree mine, in the Petchabun Province, and Koh Chang Island and to group them into facies using observations made from drillcore, mine exposures, field outcrops and field samples, 2. to use geochemical and petrological data together with volcanic facies analysis to determine the tectonic setting and source characteristics, 3. to constrain the depositional environment and volcanic setting of the volcanic succession at the Chatree mine and to identify the sequence of eruptive events, and 4. to determine the position of hydrothermal alteration and mineralisation within the stratigraphy that host the Chatree deposit. In doing so, the relative timing of deposition of the volcanic units with respect to mineralisation is defined. This study has significant importance to understanding the host volcanic rocks of the Chatree epithermal deposit. and elsewhere in the Loei–Petchabun Volcanic belt (LVb). To date, there has been no detailed volcanological investigation in the region.