Microbioerosion in Tahitian reefs; a record of environmental change during the last deglacial sea-level rise (IODP 310)

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doi: 10.1111/j.1502-3931.2008.00140.x
Author(s): Heindel, Katrin; Wisshak, Max; Westphal, Hildegard
Author Affiliation(s): Primary:
University of Bremen, Geosciences Department, Bremen, Germany
Other:
Erlangen University, Germany
Volume Title: Lethaia
Source: Lethaia, 42(3), p.322-340. Publisher: Wiley for the Lethaia Foundation, Oslo, Norway. ISSN: 0024-1164 CODEN: LETHAT
Note: In English. 76 refs.; illus., incl. 4 tables, sketch map
Summary: The main motivation for Integrated Ocean Drilling Program Expedition 310 to the Tahitian Archipelago was the assumption that the last deglacial sea-level rise is precisely recorded in the coral reefs of this far-field site. The Tahitian deglacial succession typically consists of coral framework subsequently encrusted by coralline algae and microbialites. The high abundance of microbialites is uncommon for shallow-water coral reefs, and the environmental conditions favouring their development are still poorly understood. Microbioerosion patterns in the three principal framework components (corals, coralline algae, microbialites) are studied with respect to relative light availability during coral growth and subsequent encrustation, in order to constrain the palaeobathymetry and the relative timing of the encrustation. Unexpectedly for a tropical, light-flooded setting, ichnotaxa typical for the deep-euphotic to dysphotic zone dominate. The key ichnotaxa for the shallow euphotic zone are scarce in the analysed sample set, and are restricted to the base of the deglacial succession, thus reflecting the deglacial sea-level rise. At the base of the deglacial reef succession, the ichnocoenoses present in the corals indicate shallower bathymetries than those in the encrusting microbialites. This is in agreement with radiocarbon data that indicate a time gap of more than 600 years between coral death and microbialite formation. At the top of the deglacial reef succession, in contrast, the microbioerosion patterns in the three framework components indicate a uniform palaeobathymetry, and radiocarbon ages imply that encrustation took place shortly after coral demise. An enigma arises from the fact that the ichnocoenoses imply photic conditions that appear very deep for zooxanthellate coral growth. During the deglacial sea-level rise increased nutrients and fluvial influx may have led to (seasonal?) eutrophication, condensing the photic zonation. This would have exerted stress on the coral ecosystem and played a significant role in initiating microbialite development.
Year of Publication: 2009
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 03 Geochronology; 24 Surficial Geology, Quaternary Geology; Absolute age; Algae; Anthozoa; Assemblages; Bioerosion; Biogenic processes; C-14; Carbon; Carbonate rocks; Cenozoic; Cnidaria; Corallinaceae; Deglaciation; East Pacific; Erosion; Expedition 310; French Polynesia; Holocene; IODP Site M0007; IODP Site M0009; IODP Site M0015; IODP Site M0016; IODP Site M0017; IODP Site M0018; IODP Site M0019; IODP Site M0023; IODP Site M0024; IODP Site M0025; Integrated Ocean Drilling Program; Invertebrata; Isotopes; Limestone; Lower Holocene; Microbialite; Microfossils; Nutrients; Oceania; Pacific Ocean; Paleobathymetry; Paleoecology; Paleoenvironment; Plantae; Pleistocene; Polynesia; Quaternary; Radioactive isotopes; Reef environment; Rhodophyta; SEM data; Sea-level changes; Sedimentary rocks; Society Islands; South Pacific; Southeast Pacific; Substrates; Tahiti; Tahiti Sea Level Expedition; Upper Pleistocene
Coordinates: S174600 S172900 W1492400 W1493600
Record ID: 2014045585
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom