The devonian-carboniferous boundary at guar sanai, kampung guar jentik, perlis: An updated map and stratigraphic section

Abstract

The Sanai Hill B outcrop, exposed at Kampung Guar Jentik, Beseri district, Perlis, exposes one of the best-preserved Devonian-Carboniferous boundary successions in Malaysia. A new geologic map for the locality is presented, which is based on better exposure of the outcrop due to active quarrying, and was constructed using a combination of aerial drone imagery, three-dimensional photogrammetry, Google Earth satellite imagery and traditional field methods. The sedimentary strata include the Silurian Mempelam Limestone, the Lower Devonian Timah Tasoh Formation, the Upper Devonian Sanai Limestone, the Lower Carboniferous Telaga Jatoh Formation and the Lower Carboniferous Chepor Member of the Kubang Pasu Formation. The Devonian-Carboniferous boundary is marked by the contact between the Sanai Limestone and the Telaga Jatoh Formation. It shows an abrupt change from carbonate to siliceous (chert) deposition, with the contact represented by a paraconformity. This unconformity can be correlated to the Devonian-Carboniferous unconformity in the Kanthan Limestone of Perak. It can also be identified in many sections throughout the Western Belt, including in southern Thailand, Langkawi, Kedah, Perak and the Selangor-Kuala Lumpur area. The unconformity can be linked to a eustatic sea level fall at the end of the Devonian. N-S trending imbricate reverse faults and repeated sections have been interpreted as evidence for collisional tectonics associated with the Late Triassic Indosinian Orogeny. E-W trending normal faults mark a Tertiary extensional phase.