巢湖平顶山北坡剖面早三叠世碳、氧同位素地层学研究  

Carbon and Oxygen isotope stratigraphy of the Lower Triassic at Northern Pingdingshan section of Chaohu,Anhui Province,China

作　　者：左景勋[1] 童金南[1] 邱海鸥[2] 赵来时[1] 

机构地区：[1]中国地质大学地球科学学院,湖北武汉430074 [2]中国地质大学材料科学与化学工程学院,湖北武汉430074

出　　处：《地层学杂志》2004年第1期35-40,47,共7页Journal of Stratigraphy

基　　金：全国地层委员会"中国主要断代地层建阶研究"项目;国家自然科学基金项目 (No.40 0 72 0 11);国家 973项目(G2 0 0 0 0 7770 5 )资助

摘　　要：取自安徽巢湖平顶山北坡下三叠统剖面中 12 4个碳、氧同位素样品的分析结果表明 ,由 Induan阶→Olenekian阶下部→ Olenekian阶中部 ,δ1 3C平均值由 - 1.8‰减小到 - 3.9‰后又快速增大到 3.7‰ ,δ1 8O的平均值由 - 6 .9‰降低到 - 8.6‰后又回升到 - 6 .5‰。 Induan阶的中、上部δ1 3C呈缓慢上升趋势 ,Olenekian阶下部δ1 3C呈明显的“U”型谷 ,Olenekian阶中部 δ1 3C表现为显著正漂。碳、氧同位素演化特征表明 ,早三叠世 Induan期环境恶劣、生物复苏缓慢 ,Olenekian早期的地质事件导致生物再次绝灭 ,延缓了生物复苏的进程。Results of 124 carbonate samples for carbon and oxygen isotopic analysis collected in the Northern Pingdingshan Section in Chaohu, Anhui Province, show relatively low mean values in δ 13 C of -1.77‰ in Induan, followed by a large negative shift with the mean values of -3.90‰ in the earliest Olenekian, and then a distinctive positive shift with the mean values of 3.65‰ in the Middle Olenekian. Similarly, the mean values inδ18O decrease from -6.87‰ in Induan to -8.56‰ in the earliest Olenekian, and then return up to -6.52‰ in the Middle Olenekian. Consequently, a gradual increase, a sharp negative shift and a pronounced positive shift in values of δ 13 C occurred in Induan, in the earliest Olenekian and in the Middle Olenekian, respectively. The characteristics of carbon and oxygen isotopic trends imply a harsh environment that was disadvantageous to marine faunas, suggesting a very slow recovery in the Early Triassic. Further more, the repeated geological events might have been responsible for the prolonged recovery interval following the mass extinction.

关 键 词：早三叠世 碳 氧 同位素 地层学 巢湖 安徽 

分 类 号：P534.51[天文地球—古生物学与地层学] P597[天文地球—地质学]