Atoll lagoons as archives of environmental change: tsunami deposits, reef and island development, and sea level in the Maldives, Indian Ocean
Final Report Abstract
For the first time, the Holocene development of an atoll in the Maldives, one of the major carbonate platform regions in the world, was detailed. Pleistocene atolls were prone to karst dissolution and soil development during the last glaciation and developed saucer-shaped morphologies. During the subsequent sea-level rise, swamps formed in atoll interiors, leaving behind peat deposits. With continued rise of the sea and marginal reef growth, carbonate deposition commenced in atoll interiors. Starting in the late Holocene, sand apron progradation has significantly added to the infilling process of the lagoon, i.e., the filling of accomodation space. Apart from background sedimentation, event sedimentation tied to tsunamis may be detected in lagoonal successions of the Maldives. Confusion with storm deposits may be largely excluded as the Maldives located adjacent to the equator are virtually a storm-free region. Even though atolll lagoons evidently have a high potential as environmental recorders, the tsunami archive in atoll lagoons is presumably far from complete. The abundance of faroes, annular reefs so common to marginal reefs and lagoons in the Maldives, is largely a consequence of the changing wind and current regime in the NW Indian Ocean. By means of lateral sand/sediment transport, reefs develop sand spits that are subsequently colonized by corals. Eventually, sand spits merge and amalgamate to form faroes. The early lagoon flooding phase and the development of faroes, i.e., the formation of subbasins in atolls lagoons, may also be detected by the occurrence and biodiversity of benthic foraminifera. These organisms are major sediment producers and reach a species richness of >270 taxa in the central Maldives. Benthic foraminifera also exhibit trends of diversification and dominance as predicted by the intermediate disturbance model.
Publications
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(2012): Changes in assemblage and diversity structure of shallow-water benthic foraminifera during the Holocene in the Maldives, Indian Ocean. Geologische Vereinigung, Jahrestagung Hamburg
Storz, D. & Gischler, E.
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(2012): Holocene sedimentary events in an atoll lagoon, Maldives, Indian Ocean. Geologische Vereinigung, Jahrestagung Hamburg
Klostermann, L., Storz, D. & Gischler, E
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(2013): Sedimentary record of three late Holocene tsunami-events in a mid ocean lagoon, Maldives, Indian Ocean. Geologische Vereinigung, Jahrestagung Tübingen
Klostermann, L., Gischler, E., Storz, D.
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(2013): Sizes, shapes, and patterns of coral reefs in the Maldives, Indian, Ocean: the influence of wind, storms, and precipitation. Geologische Vereinigung, Jahrestagung Tübingen
Gischler, E. Storz, D., Schmitt, D.
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(2013): The influence of time and environmental change on diversity and assemblages of benthic foraminifera during the Holocene in an atoll of the Maldives, Indian Ocean. Geologische Vereinigung, Jahrestagung Tübingen
Storz, D., Gischler, E., Parker, J.H., Klostermann, L.
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(2014): Sizes, shapes, and patterns of coral reefs in the Maldives, Indian Ocean: the influence of wind, storms, and precipitation on a major tropical carbonate platform. Carbonates and Evaporites, 29: 73-87
Gischler, Eberhard; Storz, David & Schmitt, Dominik
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(2014): Changes in diversity and assemblage structure of foraminifera through the Holocene in an atoll from the Maldives, Indian Ocean. Marine Micropaleontology, 106: 40-54
Storz, David; Gischler, Eberhard; Parker, Justin & Klostermann, Lars
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(2014): Holocene sedimentary evolution of a mid-ocean atoll lagoon, Maldives, Indian Ocean. International Journal of Earth Sciences, 2015, Volume 104, Issue 1, pp 289–307
Klostermann, Lars & Gischler, Eberhard
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(2014): Sedimentary record of late Holocene tsunami events in a mid-ocean atoll lagoon, Maldives, Indian Ocean: potential for deposition by tsunamis. Marine Geology, 348: 37-43
Klostermann, Lars; Gischler, Eberhard; Storz, David & Hudson, J. Harold
