The role of currents for carbonate platform drowning

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The goal of this project is to test the hypothesis that the physical impact of currents is a major, previously underestimated or even disregarded controlling factor of tropical carbonate platform evolution, and that currents are a major contributor to carbonate platform drowning. It is proposed that strong and reversing currents inhibit progradation of shallow-water rubble and sands in the bank interior and therefore suppresses lateral expansion of shallow water facies. Two atolls of the Maldives archipelago, subjected to a complex regime of seasonally reversing monsoon currents, will be taken as a natural laboratory to provide data for model validation. It is thus proposed to compile a sedimentological and stratigraphical model contrasting with the established models of carbonate platforms developing in the trade-wind belts. This will be achieved by a combined approach of sidescan sonar and high-resolution seismic surveys as well as geological sampling. Dedicated transects through the lagoons will allow for establishing a stratigraphy, assessing the occurrence and the degree of lowstand karstification of the atoll interior, and mapping bedforms as an indicator of bottom currents. The new data will produce a snapshot of a carbonate platform caught in the drowning act, thus considerably expanding our knowledge about this process.