| 滇西南牡音河组的沉积特征-环境意义及与之相关的若干地质问题 |
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| 引用本文： | 方念乔,刘本培,冯庆来.滇西南牡音河组的沉积特征-环境意义及与之相关的若干地质问题[J].地球科学,1996,5(1). |
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| 作者姓名： | 方念乔 刘本培 冯庆来 |
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| 作者单位： | 地球科学学院 |
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| 基金项目： | ＊30届国际地质大会基金项目及国家自然科学基金 |
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| 摘 要： | 地处古特提斯域的牡音河组是一套由放射虫硅质岩和凝灰岩组合而成、沉积速率极低的远洋沉积序列。它所包括的４个放射虫组合指示其形成时代为晚二叠世末至中三叠世，从而大大改变了我们以往对古特提斯演化所拟定的时间表。详细的岩相和岩石地球化学分析表明，牡音河组的中、下部与大洋岛弧的火山活动关系密切，上部则有接受更多陆源物质的趋向。这一沉积记录所反映的演化趋可能标志着古特提斯残留海的一次重大构造转折。但是，牡音河组内所有火山碎屑和陆源碎屑仅仅构成若干夹在正常远洋序列中的远源薄层，这意味着古特提斯残留海仍然具有相当规模，距离完全闭合尚远。就牡音河组与相邻一些地层单位的关系，探讨了若干造山带地层学研究中值得注意的基本问题
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| 关 键 词： | 远洋沉积，古特提斯，造山带，滇西南 |
TECTONO SEDIMENTARY FEATURES OF THE MUYINHE FORMATION AND STRATIGRAPHIC SUBJECTS CONCERNED IN SOUTHWESTERN YUNNAN |
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| Fang Nianqiao,Liu Benpei.TECTONO SEDIMENTARY FEATURES OF THE MUYINHE FORMATION AND STRATIGRAPHIC SUBJECTS CONCERNED IN SOUTHWESTERN YUNNAN[J].Earth Science-Journal of China University of Geosciences,1996,5(1). |
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| Authors: | Fang Nianqiao Liu Benpei |
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| Abstract: | Situated at the Paleoththys Province and composed mainly of radiolarian cherts and tuffs,the Muyinhe Formation is a typical pelagic sequence with extremely low sedimentation rate.Four assemblages of radiolaria found in the formation data the sequence from late Late Permian to early Middle Triassic,which greatly changes the generally estimated progress schedule for the Paleotethys' evolution.On the basis of lithofacies and petrochemistry analyses,we notice that the elder part of the Muyinhe Formation records a number of activities relative to the oceanic island arc,while its youngest part shows an affinity to terrigenous materials.The evolutionary tendance reflected by the above sedimentary record probably signifies an important tectonic turn in the history of the residual Paleotethys ocean.However,both of the pyroclastic and terrigenous detritus just constitute the thin distal beds intercalating into toe normal pelagic sequence in the Muyinhe Formation,which shows clearly the residual ocean was quite large in scale at that period and far from its thorough death.Based on the relation between the Muyinhe Formation and the other stratigraphic units in the study region,some basic subjects worthy of notice on the tectono stratigraphy of orogenic belt have been approached. |
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| Keywords: | pelagic sedimentation Paleotethys orogenic belt southwestern Yunnan |
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