Development of a Pliocene mixed-carbonate siliciclastic reef (Limon, Costa Rica).

Bauch, Thorsten, Reijmer, John, McNeill, Donald F. and Schäfer, Priska (2011) Development of a Pliocene mixed-carbonate siliciclastic reef (Limon, Costa Rica). Sedimentary Geology, 239 (1/2). pp. 37-47. DOI 10.1016/j.sedgeo.2011.05.001.

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Abstract

The Miocene to Pleistocene Limon Group of Costa Rica is a mixed carbonate–siliciclastic succession that formed in association with the emergence of the Central American Isthmus. Our study focuses on a lower Late Pliocene reef unit, the newly excavated Contact Cut, which is located at the contact between the siliciclastic sediments of the Rio Banano Formation and the mixed reefal and coral bearing deposits and siliciclastic sediments of the Quebrada Chocolate Formation. The siliciclastic sediments were deposited in a thick, deltaic setting sourced by erosion of the Cordillera de Talamanca. Deposits of the Limon Group preserve a sequence of progressively shallowing, near-shore sediments that were exposed by uplift during the early to middle Pleistocene. The Contact Cut outcrop shows the first reef sequence in the stratigraphic sequence and thus illustrates the reestablishment of Caribbean coral reef predominance in the Neogene. It shows extensive reef growth during
a rise in sea level and a slight progradation during the succeeding sea-level highstand. Three stages of reef
evolution are recognized based on faunal diversity. The Contact Cut reef complex is comparable to the time
equivalent reef of the Las Islas roadcut, situated west of Limon, which shows a rapid burial of the corals by
siliciclastics. Both reefs document a distinct facies diversification during the final stages of the closing of the Central American Seaway. The reefs developed in an environment stressed by siliciclastic input, which ultimately caused a decrease in coral diversity and abundance followed by a temporary demise of the reefs.
The biotic composition of the patch reefs that occurred during the sea-level rise, Las Islas and Contact Cut, did not differ from the reefs that developed during the final highstand in sea level, the reefs of the overlying Moin formation (Limon Group). Differences in the position on the shelf relative to the source of the siliciclastics might have been the cause for the different response to the rise in sea level of the transgressive reefs, with a very fast give up scenario for Las Islas reef and a catch up followed by a give up phase for Contact Cut reef.

Document Type: Article
Keywords: Paleoceanography; Panama; Pliocene; Central American Seaway; Reef development; Sea level; Mixed siliciclastic–carbonate sedimentary system
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.sedgeo.2011.05.001
ISSN: 0037-0738
Date Deposited: 04 Jan 2012 08:03
Last Modified: 19 Jul 2018 11:38
URI: http://oceanrep.geomar.de/id/eprint/13223

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