新疆准噶尔与华南湘中法门期碳同位素特征的对比研究

发布时间：2018-05-25 00:35

  本文选题：准噶尔 + 湘中　； 参考：《北京大学学报(自然科学版)》2017年05期

【摘要】：针对新疆准噶尔盆地西北缘洪古勒楞组下段是否存在弗拉-法门阶界线的问题,对比研究布龙果尔剖面该段地层以及湖南中部锡矿山剖面上泥盆统法门阶中下部碳酸盐岩的碳同位素特征,并结合已有的生物地层学证据,重新讨论洪古勒楞组下段的时代。结果表明,布龙果尔剖面洪古勒楞组下段碳同位素的变化趋势与国内外诸多典型剖面弗拉-法门期之交的δ~(13)C偏移明显不同:未见到显著正偏移;布龙果尔剖面δ~(13)C在0~1‰范围内变化,小于国际上目前已知的弗拉-法门期之交δ~(13)C正偏移的幅度(2‰~3‰)。布龙果尔剖面洪古勒楞组下段可能不存在弗拉期地层,甚至可能缺失法门阶底部(牙形石Pa.triangularis带)。法门早中期,布龙果尔剖面碳同位素曲线可与湖南锡矿山剖面同时期地层进行较好的对比,分为3个阶段:2个完整的正偏—负偏旋回以及之上的小幅正偏。主量元素特征表明,布龙果尔剖面第3-1层的下半部受陆源物质影响较大,推测可能与区域构造活动变强烈有关。
[Abstract]:In view of the question whether there is a Fla-Famen boundary in the lower part of the Hongguleleng formation in the northwest margin of the Junggar Basin, Xinjiang, The carbon isotopic characteristics of carbonate rocks in the upper Devonian Famen stage of the Xikuang section of the Broonggoer section and in the Xikuang section of the central Hunan Province are studied. Combined with the existing biostratigraphic evidence, the age of the lower part of the Hongguleleng formation is rediscussed. The results show that the change trend of carbon isotopes in the lower part of Honguleleng formation in Bronggoer profile is obviously different from the 未 ~ (13) C migration at the juncture of Fla-Famen period in many typical sections at home and abroad: there is no significant positive migration; The variation of 未 ~ (13) ~ (13) C in the Bronggoer profile is less than that of the 未 ~ (13) ~ (13) C positive migration at the point of Fla-Famen period, which is less than 2 鈥，

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