Bucket structure in carbonate accumulations of the Maldive, Chagos and Laccadive archipelagos
Bucket structure in carbonate accumulations of the Maldive, Chagos and Laccadive archipelagos
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马尔代夫、查戈斯和拉克迪夫群岛碳酸盐岩堆积的桶状结构
DOI：
10.1007/s00531-013-0913-5
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发表时间：
2013
影响因子：
2.3
通讯作者：
S. Purkis
中科院分区：
文献类型：
--
作者：
W. Schlager;S. Purkis
边缘为礁的潮缘台地和边缘为深泻湖的凸起礁是热带碳酸盐工厂的特征形态;它们的几何形状与硅质岩边缘的向海倾斜的大陆架形成鲜明对比。这种结构被比作一个水桶，坚硬的礁石边缘支撑着一堆松散的沉积物。印度洋马尔代夫群岛、查戈斯群岛和拉克代夫群岛的遥感资料显示，从直径几十米的斑块礁到直径几百公里的群岛，即线性大小超过4个数量级，桶状结构的环形礁是主要的沉积样式。超过2.5个数量级，桶结构有资格作为统计分形，表现出自相似的模式和遵循幂律的尺寸分布。然而，大多数区域或遗传子集的数据遵循对数正态分布和泻湖礁的小子集呈现指数分布。马尔代夫的地震数据和钻孔表明，自渐新世以来，水桶一直是一个主要的沉积主题。对现代生物礁的生态学和水动力学研究表明，桶状结构是生物自组织的一种形式：生物礁的边缘位置比中心位置更受青睐，因为底部剪切力更高，生物礁和水之间的扩散边界层更薄。因此，珊瑚礁边缘更容易获得营养物质，也不太可能被沉积物掩埋。铲斗结构反映了这些条件。岩溶作用突出了水桶的表面起伏，特别是在第四纪晚期。
Peritidal platforms rimmed by reefs, and raised reefs rimming deep lagoons, are characteristic morphologies of the tropical carbonate factory; their geometry contrasts sharply with the seaward-sloping shelves of siliciclastic margins. The structure has been compared to a bucket—stiff reef rims holding a pile of loose sediment. Remote-sensing data from the Maldive, Chagos and Laccadive archipelagos of the Indian Ocean show that ring reefs with bucket structure are the dominant depositional pattern from patch reefs of tens of meters to archipelagos of hundreds of kilometers in diameter, that is, over more than 4 orders of magnitude in linear size. Over 2.5 orders of magnitude, the bucket structures qualify as statistical fractals, exhibiting self-similar patterns and size distributions following power laws. However, most regional or genetic subsets of the data follow lognormal distributions and small subsets of lagoon reefs exhibit exponential distributions. Seismic data and boreholes in the Maldives indicate that the bucket has been a dominant depositional motif since the Oligocene. Ecological and hydrodynamic studies on modern reefs suggest that the bucket structure is a form of biotic self-organization: the edge position in a reef is favored over the center position because bottom shear is higher and the diffusive boundary layer between reef and water thinner. Thus, the reef edge has easier access to nutrients and is less likely to be buried by sediment. The bucket structure reflects these conditions. Karst processes have accentuated the surface relief of the buckets, particularly in the late Quaternary.
影响因子：
3.2
作者：
C. Betzler;J. Fürstenau;T. Lüdmann;Christian Hübscher;S. Lindhorst;A. Paul;J. Reijmer;A. Droxler
通讯作者：
C. Betzler;J. Fürstenau;T. Lüdmann;Christian Hübscher;S. Lindhorst;A. Paul;J. Reijmer;A. Droxler