Using Global Cycle Charts in Tectonically Active Basins, Neogene of the Southeast Asia Region, and Comparison with the Passive Margin Standard
J. Frederick Sarg1 and John W. Snedden2
1 Wm. M. Cobb & Assoc., Inc, Dallas, TX
2 ExxonMobil Upstream Research Company, Houston, TX
The Kutei (Indonesia), Sarawak (Malaysia), and Gulf of Papua (Papua New Guinea) basins are three areas where tectonics have greatly impacted the formation of stratigraphic sequences. Sequence stratigraphy is a widely used approach to stratigraphic correlation in passive margin settings. Detailed study in the Kutei and Sarawak basins of Borneo, and in the Gulf of Papua provide the opportunity to assess the viability of the approach in areas with relatively complex, multi-phased tectonics, and to compare the chronostratigraphy of these basins with an age-equivalent well documented passive margin setting in the Bahamian Atlantic Region. All of these Southeast Asian basins have different histories of structural deformation. Three sequence boundaries are most prominently developed in each of these areas and serve to illustrate the linkage between these diverse tectonic settings, and the viability of using the Global Cycle Charts to help delineate a more regional geologic understanding and assess the hydrocarbon source and maturation history of these hydrocarbon-bearing provinces. These three surfaces, Messinian-2 (base Pliocene), Serravallian-4/Tortonian 1 (basal Late Miocene), and Langhian-2/Serravallian 1 (early Middle Miocene), are indicated as major unconformities on newly revised worldwide stratigraphic sequence charts. The Lan2/Ser1 sequence boundary records uplift in Sarawak, the initiation of significant sediment influx in Kutei, and intiation of rapid subsidence and reef platform drowning in the Gulf of Papua. The Ser4/Tor1 boundary is followed by rapid subsidence in Sarawak, and uplift, erosion, and karst development in Kutei and the Gulf of Papua. The Messinian-2 surface is a time of uplift in Sarawak and the New Guinea highlands, rapid subsidence and slope instability in Kutei, and initiation of the Fly River delta into the Gulf of Papua.