| 运用碳稳定同位素进行底栖生物组合环境古盐度的比较研究 |
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| 引用本文： | 阴家润 Fues.,FT.运用碳稳定同位素进行底栖生物组合环境古盐度的比较研究[J].现代地质,1994,8(4):380-392. |
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| 作者姓名： | 阴家润 Fues. FT |
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| 作者单位： | Yin Jiarun F. T. Fursich Winfried Werner(Institut fur Palaontologie der Universitat Wurzburg，Germany) (China University of Geosciences，Beijing，100083) (Bayer，Staatsammlung fur Palaontologie add historische Geologie，Munchen，Germany) |
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| 摘 要： | 从葡萄牙卢西塔尼亚盆地侏罗纪生物底栖组合的化石中选取了５４件样品用作碳稳定同位素成分测试，分析其古盐度。按这种方法所恢复的古盐度数据和按底栖组合分析所得到的古盐度能够较好地吻合，由此可作下列结论：（１）尽管化石壳体的原始稳定同位素值可能会受到成岩作用、生物效应、温度差异等因素的影响，但碳稳定同位素值与氧同位素值相比，其重结晶作用产生的成岩影响很小，生物效应却是非常明显地表现于双壳类壳顶区和壳缘的碳同位素值的差异。（２）碳同位素的古盐度表明，葡萄牙卢酉塔尼亚盆地在侏罗纪时曾是一半咸水海湾，其水体含盐度低于２４‰。，所以生物组合中以机会种和半咸水地方性种占优势。（３）机会种分布于中盐至高半咸水的盐区域，而大部分地方性半咸水种局限于中盐度域．（４）卢西塔尼亚盆地晚侏罗世的牡蛎类生存于真盐和高半成水域，定量的盐度研究可能提供牡蛎类自中生代以来对盐度的适应演化。（５）卢西塔尼亚盆地晚侏罗世双壳类虽然属于半咸水属种，但仍然具有厚壳体大的特征。
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| 关 键 词： | 侏罗纪，葡萄牙卢西塔尼亚盆地，碳稳定同位素成分，古盐度 |
COMPARATIVE STUDY ON SALINITY ANALYSIS BETWEEN STABLE CARBON ISOTOPES AND THE BENTHIC ASSOCIATIONS |
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| Yin Jiarun F. T. Fursich,Winfried Werner.COMPARATIVE STUDY ON SALINITY ANALYSIS BETWEEN STABLE CARBON ISOTOPES AND THE BENTHIC ASSOCIATIONS[J].Geoscience——Journal of Graduate School,China University of Geosciences,1994,8(4):380-392. |
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| Authors: | Yin Jiarun F T Fursich Winfried Werner |
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| Abstract: | samples of Jurassic shells, which are a portion of the collection used to the benthicassociations of Lusitanian basin, Portugal, are subjected to analysis of stable carbon isotopic composition for reconstructing palaeosalinity. The salinity values agree well with theenvironmental interpretation based on the benthic associations.Stable carbon isotopic composition of shells can be used for quantitative paleosalinityanalysis, which can offer details for reconstructing environments. Various affections suchas diagenesis, biogenic effects, temperature effect may greatly change the original stableisotopic compositions of samples. However, it is believed that in comparison with their 81BOvalues, 813C values of the samples studied here only subjected to a slight affection of recrystallization. But the biogenic effects indicated by the difference of δ03C values between umbonal and marginal portions, are significant.The palaeosalinity analysis indicates that the Lusitanian basin was ever a stronglybrackish bay or lagoon, marked by mesohaline and lower brackyhaline regimes during theLate Jurassic, as the salinity values of most samples are lower than 24‰. Thus the ancientenvironment was fairly occupied by opportunity species and brackish endemic species.The opportunity species ranged mostly from mesohaline to upper brackyhaline, noneof them in euhaline. The most brackish endemic species lived in mesohaline environment.Thus, it is indicated that abnormal environmental press (brackish water) was essential forproducing opportunity species. However, the brackish endemic species emerged mainly inmesohaline water.The Upper Jurassic Oysteriids of the Lusitanian basin are inferred to have lived in euhaline and upper brackyhaline water. Thus the quantitative salinity data can provide a wayto analyze the adaptive ability to salinity in Oysteriid since Mesozoic.Some of Jurassic bivalves of the Lusitanian basin are characterized by large size andthick shell, even though most of them were brackish water species.Special thanks to the AvH Foundation of Germany,which offered the financial support(DM 1800) for analysis fee during Yin Jiarun's tenure of an Alexander von Humboldt Fellowship, which is greatly acknowledged. |
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| Keywords: | Jurassic Lusitanian basin (Portugal) carbon isotopic composition Paleosalinity |
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