On the generation and degradation of emerged coral reef terrace sequences: First cosmogenic 36Cl analysis at Cape Laundi, Sumba Island (Indonesia)

Type Article
Date 2021-10
Language English
Author(s) Chauveau DenovanORCID1, Authemayou ChristineORCID1, Pedoja Kevin2, Molliex Stéphane1, Husson Laurent3, Scholz Denis4, Godard Vincent5, Pastier Anne-Morwenn6, de Gelder Gino3, Cahyarini Sri Yudawati7, Elliot Mary8, Weber Michael4, Benedetti Lucilla5, Jaud Marion1, Boissier AudreyORCID9, Agusta Vera Christanti7, Aribowo SonnyORCID3, Budd Ann F.ORCID10, Natawidjaja Danny HilmanORCID7, Aster Team
Affiliation(s) 1 : LGO, IUEM, CNRS, UMR 6538, Université de Bretagne Occidentale, Plouzané, France
2 : M2C, CNRS, UMR 6143, UnivCaen-Normandie, Caen, France
3 : ISTerre, CNRS, UMR 5275, Université de Grenoble Alpes, Grenoble, France
4 : Institut für Geowissenschaften, Johannes-Gutenberg-Universität Mainz, Mainz, Germany
5 : CEREGE, CNRS-IRD, UMR 34, Aix-Marseille Université, Aix-en-Provence, France
6 : GFZ German Research Centre for Geosciences, Earth Surface Process Modelling, Potsdam, Germany
7 : Research Center for Geotechnology, Indonesian Institute of Science, LIPI, Bandung, Indonesia
8 : LPG, CNRS, UMR 6112, Université de Nantes, Nantes, France
9 : IFREMER, Géosciences Marines, Centre de Brest, Plouzané, France
10 : Department of Earth and Environmental Sciences, University of Iowa, Iowa City, USA
Source Quaternary Science Reviews (0277-3791) (Elsevier BV), 2021-10 , Vol. 269 , P. 107144 (19p.)
DOI 10.1016/j.quascirev.2021.107144
WOS© Times Cited 5
Keyword(s) Quaternary, Coral reef terrace, Cl-36 cosmogenic isotope, Denudation rate, U-Th series, Coastal erosion, MIS 5, Southeastern asia

The emerged coral reef terrace sequence at Cape Laundi, on the north coast of Sumba Island (Indonesia), with at least 18 successive strandlines, remains poorly dated in spite of numerous previous data. The age discrepancies within these coral reef terraces (CRTs) were previously explained by their polycyclic nature, triggered by marine erosion and reoccupation of old coral colonies by new ones. This study aims at highlighting these processes, as well as the continental denudation that participates in the partial stripping of the thin superficial coral reef layer overlying the pre-existing surface, exhuming older coral colonies. For this purpose, we use a combined analysis of 36Cl cosmogenic concentrations, new 230Th/U ages, and previous dating in order to quantify denudation rates affecting the sequence and to highlight the role of marine erosion in reworking the lowest CRT surface. Our results demonstrate that 1) the lowermost CRT is composite, i.e., formed by different reefal limestone units constructed and eroded during successive highstands of the last interglacial, 2) following the last deglaciation, this CRT has been subjected again to coastal erosion and reoccupation during the Mid Holocene highstand, 3) its distal edge is affected by the current marine erosion and shows denudation rates higher by one to two orders of magnitude (from 279 ± 0.4 to 581 ± 0.4 mm ka−1) than the continental denudation values of higher CRTs (14.7 ± 8.3 mm ka−1 on average), 4) at the scale of a single CRT surface, variations in continental denudation rates are caused by epikarstification roughness, and 5) the distal edges have the highest continental denudation rate due to diffusion and regressive erosion produced by the runoff occurring along the steep downward cliff.

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Chauveau Denovan, Authemayou Christine, Pedoja Kevin, Molliex Stéphane, Husson Laurent, Scholz Denis, Godard Vincent, Pastier Anne-Morwenn, de Gelder Gino, Cahyarini Sri Yudawati, Elliot Mary, Weber Michael, Benedetti Lucilla, Jaud Marion, Boissier Audrey, Agusta Vera Christanti, Aribowo Sonny, Budd Ann F., Natawidjaja Danny Hilman, Aster Team (2021). On the generation and degradation of emerged coral reef terrace sequences: First cosmogenic 36Cl analysis at Cape Laundi, Sumba Island (Indonesia). Quaternary Science Reviews, 269, 107144 (19p.). Publisher's official version : https://doi.org/10.1016/j.quascirev.2021.107144 , Open Access version : https://archimer.ifremer.fr/doc/00718/83000/