Machiyama, Hideaki; Yamada, Tsutomu; Kaneko, Naotomo; Iryu, Yasufumi; Odawara, Kei; Asami, Ryuji; Matsuda, Hiroki; Mawatari, Shunsuke F.; Bone, Yvonne; James, Noel P. (2004): Carbon and oxygen isotopes of cool-water bryozoans from the Great Australian Bight and their paleoenvironmental significance. Texas A&M University, Ocean Drilling Program, College Station, TX, United States, In: Hine, Albert C., Feary, David A., Malone, Mitchell J., Andres, Miriam, Betzler, Christian, Brooks, Gregg R., Brunner, Charlotte A., Fuller, Michael, Molina Garza, Roberto S., Holbourn, Ann E., Huuse, Mads, Isern, Alexandra R., James, Noel P., Ladner, Bryan C., Li, Qianyu, Machiyama, Hideaki, Mallinson, David J., Matsuda, Hiroki, Mitterer, Richard M., Robin, Cecile, Russell, Joellen L., Shafik, Samir, Simo, J. A., Smart, Peter L., Spence, Guy H., Surlyk, Finn C., Swart, Peter K., Wortmann, Ulrich G., Proceedings of the Ocean Drilling Program; scientific results; Great Australian Bight; Cenozoic cool-water carbonates; covering Leg 182 of the cruises of the drilling vessel JOIDES Resolution; Wellington, New Zealand, to Fremantle, Australia; Sites 1126-1134, 8 October-7 December 1998, 182, georefid:2005-041673

Abstract:
The carbon and oxygen isotopic compositions of selected bryozoan skeletons from upper Pleistocene bryozoan mounds in the Great Australian Bight (Ocean Drilling Program Leg 182; Holes 1129C, 1131A, and 1132B) were determined. Cyclostome bryozoans, Idmidronea spp. and Nevianipora sp., have low to intermediate magnesian calcite skeletons (1.5-10.0 and 0.9-6.4 molar percentage [mol%] MgCO3, respectively), but a considerable number include marine cements. The cheilostome Adeonellopsis spp. are biminerallic, principally aragonite, with some high magnesian calcite (HMC) (6.6-12.1 mol% MgCO3). The HMC fraction of Adeonellopsis has lower delta (super 13) C and similar delta (super 18) O values compared with the aragonite fraction. Reexamination of modern bryozoan isotopic composition shows that skeletons of Adeonellopsis spp. and Nevianipora sp. form close to oxygen isotopic equilibrium with their ambient water. Therefore, changes in glacial-interglacial oceanographic conditions are preserved in the oxygen isotopic profiles. The bryozoan oxygen isotopic profiles are correlated well with marine isotope Stages 1-8 in Holes 1129C and 1132B and to Stages 1-4(?) in Hole 1131A. The horizons of the bryozoan mounds that yield skeletons with heavier oxygen isotopic values can be correlated with isotope Stages 2, 4(?), 6, and 8 in Hole 1129C; Stages 2 and 4(?) in Hole 1131A; and Stages 2, 4, 6, and 8 in Hole 1132B. These results provide supporting evidence for a model for bryozoan mound formation, in which the mounds were formed during intensified upwelling and increased trophic resources during glacial periods.
Coverage:
West: 127.3608 East: 128.2852 North: -33.1723 South: -33.1934
Relations:
Expedition: 182
Site: 182-1129
Site: 182-1131
Site: 182-1132
Supplemental Information:
Available only on CD-ROM in PDF format and on the Web in PDF or HTML
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.2973/odp.proc.sr.182.007.2003 (c.f. for more detailed metadata)
Data download: application/pdf
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