Seagrass-related carbonate ramp development at the front of a fan delta (Burdigalian, New Caledonia): Insights into mixed carbonate-siliciclastic environments

Type Article
Date 2020-11
Language English
Author(s) Tournadour Elsa1, 2, Fournier F.3, Etienne S.1, 2, Collot Julien2, Maurizot P.2, Patriat MartinORCID4, Sevin B.2, Morgans H.E.G.5, Martin-Garin B.3, Braga J.C.6
Affiliation(s) 1 : Adecal Technopole, 1 bis Rue Berthelot, Doniambo, B.P. 2384-98 846, Nouméa, New Caledonia
2 : Service Géologique de Nouvelle-Calédonie, DIMENC, B.P. 465, 98845, Nouméa, New Caledonia
3 : Aix Marseille Univ, CNRS, IRD, INRAE, Coll France, CEREGE, Case 67, 3, 13331, Marseille Cedex 03, France
4 : IFREMER, Unité Géosciences Marines, 29280, Plouzané, France
5 : GNS Sciences, PO Box 30368, Lower Hutt, 5040, New Zealand
6 : Universidad de Granada, Departamento de Estratigrafía y Paleontología, Avenida de La Fuente Nueva, 18071, Granada, Spain
Source Marine And Petroleum Geology (0264-8172) (Elsevier BV), 2020-11 , Vol. 121 , P. 104581 (26p.)
DOI 10.1016/j.marpetgeo.2020.104581
WOS© Times Cited 8
Keyword(s) Miocene, Seagrass, Tropical carbonates, Terrigenous inputs, Alluvial fan, Facies association, New Caledonia

Past shallow-water carbonate environments of the main island of New Caledonia (NC) have been subject to high terrigenous influx derived from the erosion of ultramafic obducted nappes and are therefore a relevant case study for characterizing neritic carbonate production in mixed carbonate-siliciclastic systems under a tropical climate. More particularly, we focused on Burdigalian carbonate sedimentary records cropping out on the western coast of NC, in the Népoui area. Based on a comprehensive sedimentological study of cores and outcrops, we established a new depositional model of an alluvial fan to carbonate ramp transition. Shallow-water (euphotic) carbonate production was dominated by seagrass-related biota and corals derived from small-sized bioconstructions. Extensional tectonics and associated normal faulting, driven by post-obduction isostatic rebound, favored carbonate ramp aggradation and preservation. The carbonate ramp was incised by conglomerate-filled terminal distributary channels, which indicate that terrigenous inputs remained significant during marine transgression and did not inhibit the development of seagrass and scleractinian carbonate factories. Phytal substrates induced by seagrass and/or macro-algae seafloor colonization strongly controlled the nature of carbonate production and promoted the accumulation of foraminiferal-coralline algal sediments. Seagrass development at the front of the fan delta is interpreted to have controlled the preservation of a diverse and significant carbonate production by reducing water turbidity and by limiting the risk of suffocation for filter-feeding biota in such a high terrigenous influx setting.

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Tournadour Elsa, Fournier F., Etienne S., Collot Julien, Maurizot P., Patriat Martin, Sevin B., Morgans H.E.G., Martin-Garin B., Braga J.C. (2020). Seagrass-related carbonate ramp development at the front of a fan delta (Burdigalian, New Caledonia): Insights into mixed carbonate-siliciclastic environments. Marine And Petroleum Geology, 121, 104581 (26p.). Publisher's official version : , Open Access version :