Sealevel history recorded in the Pleistocene carbonate sequence in IODP Hole 310‐M0005D, off Tahiti

Abstract

Material cored during the Integrated Ocean Drilling Program (IODP) Expedition 310 'Tahiti Sea Level' revealed that the fossil reef systems around Tahiti are composed of two major stratigraphic sequences: (i) a last deglacial sequence; and (ii) an older Pleistocene sequence. The older Pleistocene carbonate sequence is composed of reef deposits associated with volcaniclastic sediments and was preserved in Hole 310-M0005D drilled off Maraa. Within an approximately 70-m-thick older Pleistocene sequence (33.22-101.93 m below seafloor; 92.85-161.56 m below present sealevel) in this hole, 11 depositional units are defined by lithological changes, sedimentological features, and paleontological characteristics and are numbered sequentially from the top of the hole downward (Subunits P1-P11). Paleowater depths inferred from nongeniculate coralline algae, combined with those determined by using corals and larger foraminifers, suggest two major sealevel rises during the deposition of the older Pleistocene sequence. Of these, the second sealevel rise is associated with an intervening sealevel drop. It is likely that the second sealevel rise corresponds to that during Termination II (TII, the penultimate deglaciation, from Marine Isotope Stages 6 to 5e). Therefore, the intervening sealevel drop can be correlated with that known as the 'sealevel reversal' during TII. Because there are limited data on the Pleistocene reef systems in the tropical South Pacific Ocean, this study provides important information about Pleistocene sealevel history, the evolution of coral reef ecosystems, and the responses of coral reefs to Quaternary climate changes.

Modern and Pleistocene large‐sized benthic foraminifers from Tahiti, French Polynesia, collected during IODP Expedition 310

“…Fossil corals from the lower part of the sequence (core M0005D‐30R) grew in shallow water, likely during MIS 11 (Iryu et al . ; Thomas et al . ).…”

Reef response to sea-level and environmental changes during the last deglaciation: Integrated Ocean Drilling Program Expedition 310, Tahiti Sea Level

“…The fossil reef systems around Tahiti are composed of two major chronological and lithological sequences (Camoin et al, 2007a(Camoin et al, , 2007b that are attributed to the last deglaciation (Des-champs et al, 2012) and to older Pleistocene time windows (Thomas et al, 2009;Iryu et al, 2010). The contact between those sequences is characterized by the occurrence of an irregular unconformity that ranges in depth from 94 to 122 mbsl on the Tiarei inner and outer ridges ( Fig.…”

Microfacies and diagenesis of older Pleistocene (pre‐last glacial maximum) reef deposits, Great Barrier Reef, Australia (IODP Expedition 325): A quantitative approach

“…Previous studies of deposits younger than MIS 11 in the Pleistocene of the Great Barrier Reef (International Consortium of Great Barrier Reef Drilling, ; Webster & Davies, ; Braithwaite et al ., ) and recently in sequences off the island of Tahiti (Iryu et al ., ) have identified biogenic packstones and grainstones with diverse biota including coralline algae, corals, Halimeda , benthic foraminifera and molluscs, similar to the deposits recorded here. Modern facies distributions (Maxwell, ; Scoffin & Tudhope, ) suggest that mixed skeletal, coral and coralgal‐dominated microfacies can be interpreted to have been deposited in a high‐(hydrodynamic) energy reef environment at the shelf margin.…”

“…Rapid coral growth in such periods promotes the formation of relatively open frameworks that are potentially available for colonization by microbes (Seard et al ., ). In partial support of this thesis, microbialites appear to be less common in pre‐LGM deposits around Tahiti (Iryu et al ., ). The scarcity of microbialites in the Holocene since ca 6 kyr bp (Camoin et al ., ; Gischler, ; Gischler et al ., ) coincides with the stalling of sea‐level rise in the western Atlantic and a fall in relative sea‐level in the South Pacific.…”