| 蓟县中上元古界典型剖面锶同位素组成特征及其地层意义 |
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| 引用本文：李华芹,蔡红,秦正永,刘波.1994.蓟县中上元古界典型剖面锶同位素组成特征及其地层意义[J].地球学报,15(1,2):232-244. |
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| 中文摘要:笔者在地矿部同位素开放研究实验室资助下，对长城系、蓟县系、青白口系等各系界线及各地层组之间，进行了锶同位素组成测定，并探讨地层剖面系级之间及层内87Sr/86Sr 同位素组成可能的变化及其地层意义。为追朔地层形成时间和演化历史，乃至为全球元古宙地层划分对比提供新的依据，填被我国在锶同位素地层学研究领导域的空白。 |
| 中文关键词:蓟县剖面 锶同位素 年代效应 |
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| Strontium isotope compositions of jixian middle-upper proterozoic stratatype section and their significances |
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| Abstract:This paper briefly introduced a study method for strontium isotope stratigraphy.Also presented are the strontium isotope data on samples collected from boundaries between different formations or systems inside Jixian middle-upper Pronterozoic strataype section.Our results indicate that carbonate strata of Gaoyuzhuang,Wumishan and Tieling formation in Jixian system and Jingeryu formation in Qingbaikou system are ideal targets for studying 87Sr/86Sr-time evolution curve.If theinfluence of continental material mixing is negligible,the younger the strata ,the slightly higher the 87Sr/86Sr ratio values.For example,average 87Sr/86Sr ratio value is 0.7071 for Gaoyuzhuang formation (1600-1400±50Ma),0.7073-0.7089 for Wunishan and Tieling formations(1400-1000±50Ma),0.7086-0.7094 for Jingeryu for mation and Cambrian Fujunshan formation(800-600±50Ma),representing the original oceanic strontium isotope compositions of those periods,while Chuanlinggou,Tuanshanzi and Dahongyu formations in Great Wall system and Yangzhuang and Hongshuizhuang formations in Jixian system show exceptionally high 87Sr/86Sr isotope ratio values. One of interpretations for these anomalies is continental material addition.Most of samples collected from these strata contain more or less argillaceous components and fine sands.Consequently,their 87Sr/86Sr ratio values reflect gross compositions of mixtures of both oceanic and continentla natures. In another word,these values should not be considered as strontum isotope compositions of original oceanic water,but they may have some bearings on paleotectonic setting and deposition environments. By studying the 87Sr/86Sr-time evolution curve of Jixian middle-upper Proterozoic stratatype section,we conciuded that variations of strontium isotope compositions of carbonate stata(unmetamorphosed)may be used not only in classification and correlation of strata in different regions,but also in discussing internal relations between deposition environment and ocean-continent changes,providing a useful tool for researches on geological events and an efficient evidence for classification and correlation of global Proterozoic strata. |
| keywords:Jixian section Sr-isotope |
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