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氧同位素温度计已被用于古温度变化研究多年。生物化石磷酸盐中的氧同位素组成对古气候环境变化响应灵敏,牙形石在古生代到中生代的古海洋地层中广泛存在,并具有较为重要的地层学意义,是研究古温度变化的最佳样品之一。SHRIMP具备高分辨、高灵敏、高精度和微量及原位微区分析的特点,可以进行20μm范围内的原位(in-situ)同位素分析。本文介绍了作者利用SHRIMP IIe-MC建立的牙形石微区原位氧同位素分析方法,这是国内关于该方法的首次报导。本文对磷灰石标准样Durango进行了测定,连续七昼夜获得的253次测定结果,平均值为δ18 Oapatite=9.78‰±0.29‰,与该标准参考值δ18 Oapatite=9.81‰±0.25‰(Williams,未刊资料)一致。作者并以二叠系—三叠系界线上下海水温度变化研究为示范,对采自西藏文布当桑二叠系—三叠系剖面上的49个层位中的237件牙形石样品进行了914个氧同位素分析,为研究二叠系—三叠系界线上发生的生物灭绝事件前后的海水温度变化提供了可靠详实的数据。
Oxygen isotope thermometers have been used for many years in paleotemperature studies. Oxygen isotope composition of the biological fossil phosphates is sensitive to paleoclimate and environmental changes. Conodont is widespread in Paleozoic to Mesozoic paleoceanic formations and has more important stratigraphic significance. It is the best sample to study paleoclimate variation one. SHRIMP features high-resolution, high sensitivity, high precision and trace and in situ microanalysis for in-situ isotope analysis in the 20 μm range. This article describes the in situ Oxygen Isotope Analysis of the conodonts by the author using the SHRIMP IIe-MC, which is the first report of this method in China. In this paper, apatite standard Durango was measured. The results of 253 determinations obtained over seven days and nights, with an average of δ18 Oapatite = 9.78 ‰ ± 0.29 ‰, and the standard reference δ18 Oapatite = 9.81 ‰ ± 0.25 ‰ (Williams, Unpaid data). Based on the study of seawater temperature changes in the Permian-Triassic boundary, the authors analyzed 237 samples of conodont from 49 horizons collected from the Permian-Triassic Paleozoic in Tibet, China A total of 914 oxygen isotope analyzes provide reliable and detailed data to study the changes of seawater temperature before and after the biological extinction event occurred on the Permian-Triassic boundary.