The role of currents for carbonate platform drowning

该项目的目的是验证这样一种假设，即洋流的物理影响是热带碳酸盐岩台地演化的一个主要、以前被低估甚至被忽视的控制因素，以及洋流是碳酸盐岩台地淹没的主要因素。强逆流抑制了浅水碎石和砂体在滩内的进积，从而抑制了浅水相的横向扩展。马尔代夫群岛的两个环礁受到季节性季风洋流逆转的复杂影响，将被作为一个天然实验室，为模型验证提供数据。因此，笔者建议建立一个与已建立的信风带碳酸盐岩台地发育模式相比较的沉积地层模式。这将通过侧面扫描声纳和高分辨率地震调查以及地质采样相结合的方法来实现。通过泻湖的专用横断面可以建立地层学，评估环礁内部低洼岩溶的发生和程度，并绘制河床图，作为海底水流的指示。新的数据将生成一个被淹没的碳酸盐平台的快照，从而大大扩展了我们对这一过程的认识。

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.