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| Main Authors: | , , , , , , , , , |
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| Format: | Dataset Open Access |
| Language: | en |
| Published: |
PANGAEA
2003
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| Subjects: | |
| Online Access: | https://doi.org/10.1594/PANGAEA.786019 |
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| _version_ | 1867172222680956928 |
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| author | Machiyama, Hideaki Yamada, Tsutomu Kaneko, Naotomo Iryu, Yasufumi Odawara, Kei Asami, Ryuji Matsuda, Hiroki Mawatari, Shunsuke F Bone, Yvonne James, Noel P |
| author_facet | Machiyama, Hideaki Yamada, Tsutomu Kaneko, Naotomo Iryu, Yasufumi Odawara, Kei Asami, Ryuji Matsuda, Hiroki Mawatari, Shunsuke F Bone, Yvonne James, Noel P |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | 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 d13C and similar d18O 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. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_786019 |
| institution | PANGAEA |
| language | en |
| publishDate | 2003 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Carbonate mineralogy and stable isotope composition of cool-water bryozoans from sediments of ODP Leg 182 sites Machiyama, Hideaki Yamada, Tsutomu Kaneko, Naotomo Iryu, Yasufumi Odawara, Kei Asami, Ryuji Matsuda, Hiroki Mawatari, Shunsuke F Bone, Yvonne James, Noel P Ocean Drilling Program; ODP 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 d13C and similar d18O 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. |
| title | Carbonate mineralogy and stable isotope composition of cool-water bryozoans from sediments of ODP Leg 182 sites |
| topic | Ocean Drilling Program; ODP |
| url | https://doi.org/10.1594/PANGAEA.786019 |