Relationship between Late Pleistocene sea‐level variations, carbonate platform morphology and aragonite production (Maldives, Indian Ocean)

Abstract

A piston core from the Maldives carbonate platform was investigated for carbonate mineralogy, grain‐size distributions, calcium carbonate content and organic carbon. The sedimentary record was linked to Late Pleistocene sea‐level variations, using an age model based on oxygen isotopes obtained from planktonic foramanifera, nannofossil biostratigraphy and 14C age determinations. The correlation between the sedimentary record and Late Pleistocene sea‐level showed that variations in aragonite and mud during the past 150 000 years were clearly related to flooding and sea floor exposure of the main lagoons of the atolls of the Maldives carbonate platform. Platform flooding events were characterized by strongly increased deposition of aragonite and mud within the Inner Sea of the Maldives. Exposure events, in contrast, can be recognized by rapid decreases in the values of both proxy records. The results show that sediments on the Maldives carbonate platform contain a continuous record of Pleistocene sea‐level variations. These sediments may, therefore, contribute to a better understanding of regional and even global sea‐level changes, and yield new insights into the interplay between ocean currents and carbonate platform morphology.

The leaking bucket of a Maldives atoll: Implications for the understanding of carbonate platform drowning

“…The time of initiation of these drifts can be estimated to some degree, because the drift sediments buried the patch reefs which established earlier. In the sediments of the Inner Sea, this onset of lagoonal flushing seems to be recorded by an increase in the content of bank-derived calcareous mud and aragonite (Paul et al, 2012).…”

Current and sea-level signals in periplatform ooze (Neogene, Maldives, Indian Ocean)

“…flooding of the carbonate platforms, through the higher contents of material shed from the platform, such as fine-grained aragonite mud (Droxler and Schlager, 1985;Glaser and Droxler, 1991;Schlager et al, 1994). Highstand shedding has proven as a solid tool for the reconstruction of the sea-level history of different platforms (Droxler et al, 1983;Droxler and Schlager, 1985;Reymer et al, 1988;Droxler, 1991, 1993;Schlager et al, 1994;Rendle and Reijmer, 2002;Rendle-Bühring and Reijmer, 2005;Paul et al, 2012). Although there is growing evidence for the occurrence of bottom currents affecting periplatform areas (Isern et al, 2004;Betzler et al, 2009;Bergmann et al, 2010;Eberli et al, 2010), such currents or fluctuations of the bottom-current regime were not identified as a major agent controlling the deposition of periplatform carbonate ooze.…”

A Late Quaternary record of highstand shedding from an isolated carbonate platform (Juan de Nova, southern Indian Ocean)

“…Carbonate content in sediments adjacent to flat‐topped platforms has often been seen to increase and decrease proportionally with sea‐level change (Chabaud et al., ; Paul, Reijmer, Fürstenau, Kinkel, & Betzler, ; Reymer, Schlager, & Droxler, ), reflecting the production and export of carbonate during times when the platform top is flooded. This phenomenon (highstand shedding of carbonate platforms; Schlager, Reijmer, & Droxler, ) has been documented in both modern‐day settings (Andresen, Reijmer, & Droxler, ; Betzler, Lüdmann, Hübscher, & Fürstenau, ; Droxler, Alley, Howard, Poore, & Burckle, ; Droxler, Haddad, Mucciarone, & Cullen, ; Droxler & Jorry, ; Hine, Wilber, Bane, Neumann, & Lorenson, ; Jorry, Droxler, & Francis, ; Lantzsch, Roth, Reijmer, & Kinkel, ; Paul et al., ; Reijmer, Palmieri, & Groen, ; Rendle‐Bühring & Reijmer, ) and in the geological record (Everts, ; Reijmer, Ten Kate, Sprenger, & Schlager, ; Vecsei & Sanders, ). Past studies (Dunbar & Dickens, ; Page & Dickens, ), however, indicate that mixed systems may be more complicated than the simple highstand shedding model proposed originally by Droxler and Schlager ().…”