Isotopic evidence for palaeotemperatures and depth stratification of Middle Cretaceous planktonic foraminifera from the Pacific Ocean
Isotopic evidence for palaeotemperatures and depth stratification of Middle Cretaceous planktonic foraminifera from the Pacific Ocean
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太平洋中白垩世浮游有孔虫古温度和深度分层的同位素证据
DOI：
10.1017/s0016756898008334
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发表时间：
1998
影响因子：
2.3
通讯作者：
J. Cartlidge
中科院分区：
文献类型：
--
作者：
G. Price;B. Sellwood;R. Corfield;L. Clarke;J. Cartlidge
本文报道了太平洋低纬度两个地点中白垩世（晚阿尔比世-赛诺曼世）浮游有孔虫和颗石基质的稳定同位素测量结果。有孔虫的蚀变程度已通过化学分析，阴极发光和扫描电子显微镜（SEM）的应用进行了评估。在深海钻探项目（DSDP）463号站点，轮虫类有孔虫的δ 18 O值在-2.29 ‰至-3.01 ‰之间，而在DSDP 305号站点，δ 18 O值在-2.74 ‰至-3.55 ‰之间。在305站，Hedbergellid有孔虫的δ 18 O在种间变化为−2.52 ‰至−3.02‰。对单个样品中的Hedbergelladelrioensis和Rotaliporaappenninicaforaminifera进行了同位素分析。delrioensis的δ 18 O值分布范围惊人地大（463站为−2.492 ‰至−3.097‰，305站为−2.454 ‰至−3.344‰），而δ 13 C值仍然局限在较窄的范围内。氧值的这种扩散可能与许多因素有关，包括微妙的成岩蚀变、与温度相关的广泛深度生境或与原生骨骼方解石生长相关的变化。的hedbergellids一贯较轻的氧和较重的碳同位素值比rotaliporid有孔虫，因此提供同位素派生的古温度与热分层的海洋相一致。在这两个网站的氧同位素数据是一致的逐渐变暖通过Albian-Cenomanian时间。然而，研究结果表明，中白垩纪赤道海洋的温度可能与今天一样高（或略高），但没有达到早期文献中所声称的高温。
Stable isotopic measurements have been made on both planktonic foraminifera and coccolithic matrix of Middle Cretaceous (Late Albian–Cenomanian) age from two Pacific low latitude sites. The degree of alteration of the foraminifera has been assessed through the application of chemical analyses, cathodoluminescence and Scanning Electron Microscopy (SEM). The rotaliporid foraminifera display an interspecies range of δ18O values from −2.29 to −3.01‰ at Deep Sea Drilling Project (DSDP) Site 463 and from −2.74 to −3.55‰ at DSDP Site 305. Hedbergellid foraminifera exhibit a δ18O interspecies variation of −2.52 to −3.02‰ at Site 305. Isotopic analysis of individual Hedbergella delrioensis and Rotalipora appenninica foraminifera from single samples shows H. delrioensis to have a surprisingly large spread of δ18O values (−2.492 to −3.097‰ from Site 463, −2.454 to −3.344‰ from Site 305), whilst δ13C values remain confined to a narrower range. Such a spread of oxygen values may be related to a number of factors, including subtle diagenetic alteration, a wide range of temperature-related depth habitats or growth related changes of primary skeletal calcite. The hedbergellids have consistently lighter oxygen and heavier carbon isotopic values than do the rotaliporid foraminifera and hence provide isotopically derived palaeotemperatures consistent with a thermally stratified ocean. At both sites the oxygen isotopic data are consistent with a gradual warming through Albian–Cenomanian time. However, the results suggest that Middle Cretaceous equatorial oceans were possibly only as warm as those of the present day (or slightly warmer), but did not reach the high temperatures claimed in older literature.
沿聚碳酸酯中重离子轨道的损伤分布 (2)
DOI：
--
发表时间：
2006
期刊：
影响因子：
--
作者：
渡邉宗一郎;山内知也;小田啓二;安田仲宏
通讯作者：
安田仲宏