Thin-skinned tectonics and fault-propagation folds: New insight to the tectonic origin of Barito folds, south Kalimantan

Proceedings of the 22nd Annual Convention of the Indonesian Association of Geologist

Thin-skinned tectonics and fault-propagation folds: New insight to the tectonic origin of Barito folds, south Kalimantan

Awang H. Satyana*, P.D. Silitonga*

* Pertamina

 

Abstract

Barito basin, South Kalimantan is located in between Sunda Shield to the west and Meratus Range to the east. The area is foreland-backarc region typified by foredeep at the frontal zone of Meratus and platform approaching the shield. The structural style of the Barito foredeep is characterized by parallel trends of folds and thrusts that repeat in closely spaced, wave-like bands constituting the belts. The folds are bounded by high angle, westerly –hanging thrust faults. These structures become increasingly imbricate towards the Meratus Range. Conjugate pair of strike-slip faults cut older structures. The platform is marked by weak tectonic patterns, some of which with gentle folds. The study tried to apply concepts of thin-skinned (detached) tectonics and fault-propagation folds in search of the tectonic origin of Barito folds. Seismic sections were examined to define the structural characteristics of the basin. Retrodeformable sections were tested to solve the problems of structural history. The study showed that the Barito Basin had been tectonized into different structural styles of un-real basement-involved tectonics with fault-related folds in the foredeep and indistinct thin-skinned tectonics in the platform with discontinuous decollement, ramps and obscure fault-propagation folds. The hydrocarbon so far is known to be trapped in the fault-related folds and paleohighs of the northeastern end of Barito foredeep. The possibility of decollement folds to trap hydrocarbon still needs to be examined by newer-and better-quality seismic sections of the platform area.

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