Interactions between tectonism, thermal history, and paleohydrology in the Mahakam Delta, Indonesia: Model results, petroleum consequences
- Institut Francais du Petrole, Rueil-Malmaison (France)
- Total, Paris (France)
Interactions between tectonism, thermal history, and paleohydrology are investigated in the post-mid-Miocene Mahakam delta along 70-km-long regional transects. Two-dimensional numerical thermal/organic maturity models confirm previous fluid inclusions evidence that the region has been cooled by up to 25[degrees]C in recent time. Testing various hydraulic models, the authors conclude that the cooling was caused by topography-driven circulations in the late Miocene Fresh Water Sands formation charged along a 600-m-high coastal uplift, which appeared within the Pliocene at a time of active regional tectonism. The best-fitting age of uplift is around 3 Ma. This is discussed in the regional tectonic framework. Most of the flow system has now disappeared due to erosion of the uplift during the last half Ma. The flow models explain the distribution of the meteoric waters in the basin, the present and past temperatures. Most flow occurred parallel to bedding due to the high-permeability anisotropy of deltaic facies, estimated from observed sand units interconnectivity to reach five orders of magnitude. Hydraulic models appear very sensitive to the extension of regional seals associated with flooding levels. The discharge of the meteoric waters occurred along listric normal faults that develop at the periphery of the present-day delta. Episodic focused flow along favorably oriented faults like the Handil fault perturbed local temperatures in overpressured shales. Observed temperatures and paleotemperatures do not imply that heat-flow changes need to be considered. This seems to agree with the hypothesis that the opening of the North-Makassar basin has a Paleogene age rather than the younger Oligocene-early Miocene age sometimes proposed.
- OSTI ID:
- 7018352
- Report Number(s):
- CONF-940803-; CODEN: AABUD2
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 78:7; Conference: American Association of Petroleum Geologists (AAPG) international conference and exhibition, Kuala Lumpur (Malaysia), 21-24 Aug 1994; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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