Isolated carbonate platforms are abundant and widespread in Cenozoic strata and in the present-day oceans of Southeast Asia. The purposes of this article are (1) to describe the basic oceanographic setting of present-day Southeast Asia oceans; (2) to synthesize, compare, and contrast observations of the character of extant platforms in the context of fundamental oceanographic controls; and (3) to leverage these insights to develop a more complete understanding of older isolated platforms, especially the Miocene systems of Central Luconia. The data, presented to mimic an offshore-to-nearshore transect, illustrate Holocene platforms with a spectrum of sizes, depositional relief, facies abundances, and water depths. Although the first-order patterns of relief, size, and orientation are controlled by the geologic setting and Pleistocene history, the results demonstrate the influences of physical processes (waves, tides, currents), siliciclastic sediment, and chemical oceanography (nutrients, salinity, temperature) on the sedimentologic and geomorphic character of these platforms. Careful and critical application of these concepts to Central Luconia reservoirs in isolated carbonate platforms provides actualistic examples and process-response analogs. Although these perspectives offer understanding into controls on horizontal and vertical reservoir heterogeneities, they also emphasize that any one modern system can only be a partial analog for an ancient reservoir in an isolated carbonate platform.

Carbonate reservoirs are often comprised of a heterogeneous pore system within a matrix of variably distributed minerals including anhydrite, dolomite, and calcite. When describing carbonate thin sections, it is routine to assign relative abundance levels to each of these components, which are qualitative to semiquantitative (e.g., point counting) and vary greatly depending on the petrographer. Over the past few decades image analysis has gained wide use among petrographers; however, thin-section characterization using this technique has been primarily limited to quantifying the pore space due to the difficulty associated with optical recognition beyond the blue-dyed epoxy associated with the pores. Here, we present a new method of computerized object-based image analysis (Quantitative Digital Petrography: QDP) that relies on a predefined rule set to enable rapid, automated thin-section quantification with limited interaction of a petrographer. We have developed a novel work flow that automatically isolates the sample on a high resolution (i.e., <1 μm/pixel) scanned thin section, segments the image, and assigns those segments to predefined categories; e.g., pores, cement, and grains. With this technique, statistically relevant numbers of thin sections can be rapidly batch processed and quality controlled, thereby allowing quantitative data from conventional core analysis, special core analysis, and reservoir surveillance to be integrated with the petrographic data for a more dynamic description of the carbonate rock. Our technique can also incorporate multiple layers, such as cross-polarization, backscatter electron imaging, and elemental maps, which allow additional information to be easily integrated with results from QDP. The QDP approach is a significant improvement over previous digital image analysis methods because it (1) does not require binarization, (2) eliminates the subjectivity in assessing abundance levels, (3) requires less interaction with a petrographer, and (4) provides a much fuller dataset that can be incorporated across an entire well or field to better address common challenges associated with carbonate reservoir characterization, such as understanding pore type and cement abundance, pore connectivity, grain distribution, and reservoir flow characteristics.

Abstract Quaternary glacio-eustasy has traditionally been determined in part by the examination of fossil coral reefs on carbonate islands and coasts uplifted by tectonics. These studies do not properly account for dissolutional denudation, which is cumulative, making higher and therefore older terraces exist at elevations far below their assumed depositional elevation. Karst pedestals (karrentische) on Guam reveal the extent of the denudation ( c. 50 mm ka −1 ) and demonstrate that theoretical denudation models can be accurately applied to eogenetic carbonates in tropical settings. Aeolian calcarenite islands such as the Bahamas have been used as tectonically stable sea-level calibrations for other islands, which may not be correct. Flank margin caves, forming in the distal margin of the freshwater lens within a carbonate island, are excellent sea-level indicators. Analysis of flank margin cave elevations indicates that the Bahamas have had past sea-level highstands >6 m, perhaps up to 15 m or more, for which no fossil coral data exist. Denudational removal of these older corals has biased the record to younger events and only flank margin caves remain as viable terrestrial signatures of these older sea-level highstands.