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Modern and Pleistocene large‐sized benthic foraminifers from T ahiti, F rench P olynesia, collected during IODP Expedition 310
Author(s) -
Fujita Kazuhiko,
Omori Akitoshi
Publication year - 2015
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/iar.12069
Subject(s) - geology , benthic zone , reef , pleistocene , fauna , paleontology , sedimentary depositional environment , abundance (ecology) , pyroclastic rock , oceanography , ecology , biology , volcano , structural basin
This paper reports the fauna and distribution of large‐sized benthic foraminifers ( LsBFs ; defined as benthic foraminifers >0.5 mm in size) from surface sediments collected around T ahiti, F rench P olynesia, as well as from the P leistocene deposits drilled off the T iarei area, T ahiti, during Integrated Ocean Drilling Program ( IODP ) Expedition 310. At least 6 and 22 genera of living and dead tests of LsBFs , respectively, were identified from modern surface sediments. Foraminiferal abundance in surface sediments depends mainly on the water depth and substratum type. The taxonomic composition of dead LsBF assemblages varies with depositional environments and water depths. Back‐reef lagoon assemblages are dominated by S chlumbergerina alveoliniformis , whereas fore‐reef slope and shelf assemblages are dominated by A mphistegina spp. The relative abundance of A mphistegina lessonii decreases with increasing water depth. On the shelf, A . lessonii is replaced by A mphistegina bicirculata and P lanostegina sp. Pleistocene samples consisting mainly of volcaniclastic sandstone/siltstone and skeletal grainstone contained very small numbers and low species diversity of fossil LsBFs . A mphistegina lobifera , H eterostegina depressa , and E ponides repandus were commonly found in the P leistocene samples. The taxonomic compositions showed little variation within holes. The P leistocene assemblages were compositionally similar to those found in modern fore‐reef slope environments of <30 m depth. Combined results of coral U / Th ages and paleoenvironmental interpretations from in situ corals and LsBFs indicate that the Pleistocene sequence in the Tiarei area was deposited in a fore‐reef slope environment during Marine Isotope Stage 3.