Controlling Factors of a Miocene Carbonate Platform: Implications for Platform Architecture and off-Platform Reservoirs (Luconia Province, Malaysia)
Valentina Zampetti, 2010. "Controlling Factors of a Miocene Carbonate Platform: Implications for Platform Architecture and off-Platform Reservoirs (Luconia Province, Malaysia)", Cenozoic Carbonate Systems of Australasia, William A. Morgan, Annette D. George, Paul M. (Mitch) Harris, Julie A. Kupecz, J. F. (Rick) Sarg
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A multidisciplinary approach was used to better reconstruct the architecture of a Miocene carbonate platform in the Luconia Province to provide a better understanding of the complexity of South-East Asian Cenozoic carbonate systems and their controlling factors. Platform growth began in the Late Oligocene to Early Miocene by coalescence of isolated patch reefs, and includes phases of progradation, backstepping and occasional collapse of platform flanks terminated by gradual submergence (drowning). Geometry was controlled not only by the balance between the rate of accommodation space and carbonate production, but also extrinsic factors such faulting and ocean currents that strongly influenced platform architecture. A 2-D regional study of the carbonate platforms in the Luconia province indicates that asymmetry of the platform margins is largely related to ocean currents rather than wind-shear over the platform top.
The structural relief created by block tilting has determined the location of the initial carbonate buildup. However, the platform was strongly affected by active strike-slip deformation during sedimentation that controls its shape and size. Syndepositional faulting has been interpreted to be responsible for the slope failure affecting the platform margins. Platform material is deposited as slide masses in the adjacent basin floor. Such deposits are likely to pass into debris-flow and turbidites deposits, i.e. breccias and carbonate sands, and can extend many kilometers across the basin floor. Because slumping did not affect only the studied platform but also the adjacent buildups, debris tongues are likely to interfinger. Faults are also interpreted to have acted as conduits for deep-seated fluids responsible for hydrothermal dissolution. The diagenetic history of the studied platform shows that much secondary porosity was created by dissolution during deep burial conditions, a process that may not be limited to the carbonate platforms but could also affect the slopes and intervening basins. Consequently, the carbonate slump, debris-flow and turbiditic deposits on the lower slopes and basin floors may well contain significant secondary porosity. These porous bodies may onlap other platform slopes, terminate there and become enveloped in clay-rich hemipelagic sediment. In addition, porous layers may establish fluid conduits between neighboring platforms if slides and turbidites from different platforms interfinger on the basin floor.
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The Cenozoic carbonate systems of Australasia are the product of a diverse assortment of depositional and post-depositional processes, reflecting the interplay of eustasy, tectonics (both plate and local scale), climate, and evolutionary trends that influenced their initiation and development. These systems, which comprise both land-attached and isolated platforms, were initiated in a wide variety of tectonic settings (including rift, pas-sive margin, and arc-related) and under warm and cool-water conditions where, locally, siliciclastic input af-fected their development. The lithofacies, biofacies, growth morphology, diagenesis, and hydrocarbon reser-voir potential of these systems are products of these varying influences. The studies reported in this volume range from syntheses of tectonic and depositional factors influencing carbonate deposition and controls on reservoir formation and petroleum system development, to local studies from the South China Sea, Indonesia, Kalimantan, Malaysia, the Marion Plateau, the Philippines, Western Australia, and New Caledonia that incor-porate outcrop and subsurface data, including 3-D seismic imaging of carbonate platforms and facies, to un-derstand the interplay of factors affecting the development of these systems under widely differing circum-stances. This volume will be of importance to geoscientists interested in the variability of Cenozoic carbonate systems and the factors that controlled their formation, and to those wanting to understand the range of po-tential hydrocarbon reservoirs discovered in these carbonates and the events that led to favorable reservoir and trap development.