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三峡地区广泛发育的上震旦统 ,及下伏的南沱组和古城组冰碛层 ,有良好的生物地层控制及全球对比意义。新秭归城附近的雾河剖面 ,自南沱组顶部到水井沱组下部出露有利于化学地层学研究的一系列碳酸盐岩沉积。对这一剖面的碳、氧、锶同位素研究发现 :1)碳、锶和氧同位素在陡山沱组顶部到灯影组底部存在明显异常 ;2 )碳同位素在寒武系 -前寒武系界线附近有负异常 ;3 )碳同位素和锶同位素在剖面上的演化具有全球对比意义 ;4)陡山沱组顶部到灯影组底部的碳、锶同位素异常 ,与可能存在末远古纪的冰期 ,即所谓的“后 Marinoan冰期”有关。
The widely developed Upper Sinian in the Three Gorges area and the underlying moraine layers of Nantuo and Gucheng formations have good biological control and global contrast. A series of carbonate sediments that are beneficial to the study of chemical stratigraphy are exposed from the top of the Nantuo Formation to the lower part of the Shuijingtuo Formation. The carbon, oxygen and strontium isotope studies of this section show that: 1) carbon, strontium and oxygen isotopes are obviously anomalous at the top of the Doushantuo Formation to the bottom of the Dengying Formation; 2) carbon isotopes are significantly different between the Cambrian-Precambrian boundary There is a negative anomaly nearby; 3) the carbon isotope and strontium isotopes in the profile have a global comparative significance; 4) carbon and strontium isotope anomaly at the bottom of the Doushantuo Formation to the bottom of the Dengying Formation, The so-called “post-Marinoan ice age”.