The geology and stratigraphic framework of the Kuching Zone Sarawak: Current understanding and unresolved issues

Abstract

The geological record of the Kuching Zone extends back in time to more than 300 million years ago. The rock units in the area records a complex history of sedimentation, magmatism and tectonism in the Mesozoic and Cenozoic times. Pre-Upper Carboniferous metamorphic rocks are the oldest rock. Exposure of the younger metamorphic rocks of Late Mesozoic have been assigned to various formations with uncertain protoliths and origin, and have been interpreted to be related to Cretaceous-Cenozoic accretionary setting. Some of the significant events that have occurred include the deposition of clastic sediment with volcanic flow and pyroclastic during Carboniferous to Triassic, and deposition during Jurassic-Cretaceous was siliciclastic-typed sediment. Cretaceous granitoid intruded this sequence before deposition of paralic siliciclastic sediment of Cretaceous to Miocene age. Although the geology of this zone is relatively well studied, many of the interpretations are still debatable due to the complex geology and insufficient biostratigraphic data and dating of the igneous and metamorphic bodies. Several major unresolved issues still remain unanswered. This paper highlights the current understanding and unresolved issues of rock units in Kuching Zone, proposes an updated stratigraphic framework which incorporating igneous and tectonic events, and an updated geological map integrating information from previous published reports and new field investigations.