NEOMA

The Neogene of the Maldives

Project funded by the BMBF (BMBF 03G0667A) to Christian Betzler, Christian Hübscher, John Reijmer (Amsterdam), and Eberhard Gischler (Frankfurt)

Abstract
The geologically poorly known archipelago of the Maldives (Indian Ocean) is the world's second largest carbonate platform after the Bahamas. The platform formed during the Cenozoic in a regime of high-amplitude sea-level fluctuations and global climate cooling, as well as palaeo-oceanographic change. The aim of the project is to unravel the record of these changes in order to investigate the response of the platform to such processes. The better knowledge of these tropical carbonates will not only provide new data about the climate and palaeo-oceanographic evolution of the tropics, but also new models for the seismic stratigraphy of such bodies and sedimentological models for carbonate platform slope deposits. The project will also provide new data for the controversial discussion about the process of carbonate platform drowning and its controlling mechanisms, because on the Maldives reef atolls and drowned atolls coexist. Our research relies on seismic profiling and direct sampling of the sea floor during the cruise M 74/4 of the research vessel METEOR. A high-resolution seismic grid ("2.5 D") in the NW of the platform will trace the position of the platform rim through time. This will allow to decipher the reaction of the platform to the sea-level and palaeo-oceanographic changes. The slope of the platform will be analyzed in detail in order to trace the configuration of calciturbiditic systems, i.e. to investigate the occurrence of canyon incisions and lobe systems. Seismic profiles crossing a drowned part of the platform (Fuad Bank) and an adjacent atoll (Ari Atoll) will provide data about the internal geometries of these bodies and the topography of the pre-drowning surface. Sea-floor sampling (grab samples and shallow cores) will be performed along shallow to deep transects. This will allow to determine the carbonate sediment types in the active atoll system and on the drowned bank. Shallow coring of the platform slopes will be used to unravel the response of this tropical carbonate depositional system to Holocene sea-level and palaeo-oceanographic change. These sedimentological studies are of special interest because up to the present day no systematic studies on the modern sediments and facies of the Maldives exist. Publications Betzler, C., Hübscher, C., Lindhorst, S., Reijmer, J.J.G., Römer, M., Droxler, A.W., Fürstenau, J., Lüdmann, T., 2009. Monsoon-induced partial carbonate platform drowning (Maldives, Indian Ocean). Geology, 37: 867-870. Fürstenau, J., Lindhorst, S., Betzler, C. & Hübscher, C., 2010. Submerged reef terraces of the Maldives (Indian Ocean). Geo-Marine Letters, 30: 511-515.