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Middle Miocene to Pliocene sedimentation on the NW Borneo margin has been interpreted as the product of one relatively large deltaic system, the Champion Delta. However, several lines of evidence indicate that the Champion system was not a simple, large delta; its drainage basin was too small, fluvial outcrops indicate multiple, relatively small rivers and outcrop studies indicate the same facies associations as the diverse, modern depositional systems. The number and location of rivers reaching the shoreline changed as rapidly subsiding footwall synclines, episodically active inversion anticlines and growth faults created an evolving structurally-generated topography that not only controlled drainage pathways, but also segregated Champion strata into thick, wave-dominant and tide-dominant successions. Although the principal rivers within the Champion system, the Limbang, Padas and Trusan Rivers, transport significant loads of coarse sediment, the intermittent proximal ponding of sand in local basins, as is currently occurring in Brunei Bay, resulted in a variable delivery of sand to the shelf edge. The number and distribution of shelf edge canyons also changed with time. Consequently, the spatial and temporal distribution of deepwater sand accumulations sourced from the Champion system are not solely related to relative sea level fluctuations; such accumulations should be smaller and more scattered than those sourced from a large shelf edge delta. Because the catchments of the Champion system’s principal rivers represent different provenances, the system’s deepwater sands may carry the signal of specific rivers. For example, mineralogical contrasts between in the main reservoir sands of the deepwater Gumusut and Kikeh fields suggest that the relative contributions of the principal rivers shifted with time with the Trusan and Limbang Rivers dominating sand supply for the youngest reservoirs at Gumusut. 相似文献
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Late Permian foraminifers were found from six localities belonging to the Doi Chiang Dao Limestone, which is considered as having a Paleo-Tethyan seamount-capping carbonates origin, distributed in the Inthanon Zone of Northern Thailand. Among them, three age-diagnostic assemblages are recognized. They are represented by the occurrences of Codonofusiella kwangsiana, Palaeofusulina cf. minima, and P. prisca, and are referable to the Wuchiapingian, early Changhsingian, and late Changhsingian, respectively. In particular, the discovery of an assemblage characterized by advanced Palaeofusulina (P. prisca) is significant because it clearly indicates that the deposition of the Doi Chiang Dao Limestone had continued until the very end of the Permian. These three Late Permian assemblages can be compared with those recently reported from the Shifodong Formation of Pa-leo-Tethyan mid-oceanic carbonates in the Changning-Menglian Belt of West Yunnan, Southwest China. 相似文献
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