Cenozoic carbonates in Borneo: case studies from northeast Kalimantan

Modern and Tertiary carbonate production is, and was, extensive and diverse in the seas surrounding Borneo, and mirrors the variety of carbonate depos itional systems seen in SE Asia. The availability of favourable conditions for carbonate sedimentation around Borneo was related to a combination of f actors, including tectonic setting, the formation of large basinal areas, d ifferential subsidence providing shallow marine areas, a tropical climate a nd a range of local factors, such as currents or limited elastic input, A d etailed sedimentological and diagenetic study was undertaken of middle Eoce ne to Plio-Pleistocene carbonates which developed in the north Kutai Basin and the Mangkalihat Peninsula, northeast Kalimantan. Carbonate sedimentatio n in this area occurred in a range of depositional environments, from mixed carbonate elastic shelves, localised and transient shoals or reefs, a vari ety of platform top settings to deep water redeposited carbonates. An under standing of carbonate depositional environments, spatial facies relationshi ps, and diagenesis is essential in order to develop models for these carbon ates which can be used as predictive tools in the subsurface. This study al so helps to evaluate tropical carbonate development in SE Asia and the evol ution of sedimentary environments in Borneo during the Cenozoic. (C) 1999 E lsevier Science Ltd. All rights reserved.