Titel: Cementation rates of detrital platform carbonates and sequence stratigraphic implications
Thomas Mann1, Hildegard Westphal2
1Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Hannover, Germany; 2Leibniz-Zentrum für Marine Tropenforschung (ZMT), Bremen, Germany
Veranstaltung: ECSM 2021
Different views exist on the prevalent processes that control transport and deposition of detrital platform carbonates in a sequence stratigraphic framework. While some models indicate that meteoric cementation during sea-level lowstands retards sediment transport into deeper basins, others imply marine cementation during highstands as dominant process affecting the architecture of carbonate depositional sequences. These opposing views are based on observations from the Bahamian archipelago, an isolated carbonate platform with a significantly higher carbonate saturations state than any other carbonate factory worldwide. Accordingly, it is unlikely that the Bahamas Platform provide a universally applicable, modern analogue for tropical carbonate environments. Here we show that in the Indonesian Archipelago, intragranular marine carbonate cementation of detrital platform deposits occurs at higher rates than intergranular meteoric cementation. Our observations are based on microfacies analyses and radiometric dating of Holocene segments from the calcifying green alga Halimeda. The analyzed specimens show occurrences of highly diverse, early-diagenetic cements that all formed in the marine realm. Additionally, the unlithified nature of segments older than 6 ka BP imply that the formation of intergranular cements, that would inhibit sediment transport, is a significantly slower process on carbonat platforms than what has hitherto been assumed from the Bahamas. Accordingly, results from this study indicate that high rates of sediment production during sea-level highstands determine sequence stratigraphic depositional patterns, rather than platform diagenetic processes alone.
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