Strontium-isotope stratigraphy: methodology, standard values (SRM987, EN-1, E&A), a new Neogene curve of 87Sr/86Sr against time, its implications for astrochronology ([I]ODP Sites 1146, 1264, U1337, and U1338), and its application to ODP Site 758 (Indian summer monsoon) and IODP Site 1120 (a new age-model)

查看详情 浏览次数:1
中文题名锶同位素地层学:方法论、标准值(SRM987、EN-1、E&A),一条新的新近纪时期87Sr/86Sr随时间变化的曲线及其对天体年代学的启示(IODP 站点1146、1264、U1337 和 U1338),以及其在ODP 758 站点(印度夏季季风)和 IODP 1120 站点(新年龄模型)中的应用
作者J.M. McArthur1CA1;I.L. Millar2;A.J. Drury1,3,4;D. Wagner2
作者单位1Department of Earth Sciences, UCL, Gower Street, London WC1E 6BT, UK;2National Environmental Isotope Facility, British Geological Survey, Keyworth, Nottingham NG12 5GG, UK;3School of Geography, Geology and the Environment, University of Leicester, Leicester LE1 7RH, UK;4Current Address
刊名Palaeogeography, Palaeoclimatology, Palaeoecology
2025
669
摘要
For the standards SRM(NIST) 987, EN-1, and E&A, we present compilations of 87Sr/86Sr from the literature, and 125 new measurements of 87Sr/86Sr, to arrive at recommend values of 0.710 248, 0.709 172, and 0.708 021 respectively, for normalising 87Sr/86Sr data for use in Sr-isotope stratigraphy. Using these standards, interlaboratory comparison of 87Sr/86Sr data is, nevertheless, impaired by residual bias of up to 0.000 072 that is not removed by normalisation of 87Sr/86Sr data to accepted values for standards. We also provide a new reference curve of 87Sr/86Sr against time for the period 11 to 20 Ma that is based on high-precision (± 0.000 003, 2 s.e.) analysis of 87Sr/86Sr in microfossil calcite from the ODP Sites 1146 and 1264, and IODP Sites U1337 and U1338. Ages for Site U1338 are calibrated by bio-magnetostratigraphy, whilst the others are calibrated by astrochronology, within which anomalies of up to 1.0 myrs are noted. With literature data, we extend the curve to 0 and 32 Ma. We show that the previous 87Sr/86Sr reference curve for the interval 0 – 7 Ma, that of Farrell et al. (1995) for Site 758 in the southern Bay of Bengal, is compromised by riverine influences from the Ganges/Brahmaputra rivers: differences between that curve and our new curve are interpreted to be a proxy for the intensity of the Indian summer monsoon. Finally, for Site 1120, a new age-model is presented, based on 87Sr/86Sr, in order to test the biostratigraphic age-model for the site, which is found to be good. This work shows that integrated approaches to improving the chronological framework of Cenozoic successions should include Sr-isotope stratigraphy.

@ 2023 版权所有 中国地质图书馆 (中国地质调查局地学文献中心)

京ICP备 05064591号 京公网安备11010802017129号

建议浏览器: 火狐、谷歌、微软 Edge、不支持 IE