On the Origin of the Meratus Uplift, Southeast Kalimantan – Tectonic and Gravity Constraints : A Model for Exhumation of Collisional Orogen in Indonesia*

Awang Harun Satyana 1) Cipi Armandita 1) 1)Exploration Division BPMIGAS, Jakarta

 

Abstract

The Meratus Mountains is a collisional orogen/suture marking the collision of Schwaner and Paternoster continents. The collision took place in the Early-Middle Cretaceous. Presently, the mountain is a basement uplift separating the Barito from the Asem-Asem and Pasir Basins. The origin of the Meratus uplift has been debated. Many authors considered that the uplift related to compression due to collision of micro-continents to the east of Sulawesi and/or rifting of the Makassar Strait. Recent seismic data in the Makassar Strait however, oppose this idea. We propose a new mechanism of the Meratus uplift based on tectonic interpretation of gravity and magnetic studies. The Meratus Mountains is rootless. It is thin allochthonous oceanic slab, submarine volcanics and deep-sea sediments overlying thick subducted Paternoster continent. Due to its buoyancy relative to upper mantle, the Paternoster continent broke off its oceanic front and started to exhume in Late Cretaceous time. The exhumation of the Paternoster continent has uplifted the Meratus suture and effectively formed a subaerial mountain separating the adjacent basins in the Mio-Pliocene. This mechanism of continental exhumation provides a model for the origins of other collisional uplifts in Indonesia such as : eastern Sulawesi, Central Ranges of Papua and Timor.

 

* Proc. Indonesian Association of Geologist 33rd Annual Convention and Exhibition

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