高校地质学报Issue(4)：634-641,8.
豫西渑池地区寒武系第三统馒头组二段的核形石
The Oncoids from the Second Member of Mantou Formation (the Third Series, Cambrian), Mianchi Area, Western Henan Province
摘要
Abstract
The Second Member of Mantou Formation (the Third Series, Cambrian) crops out in Mianchi Area of western Henan and is characterized by purple and isabelline mudstones interbedded with stromatolite, oncoidal and oolitic limestones. Abundant oncoids occur in the lower part of the Member. They exhibit variations of shapes, irregular cortex structures and clearly winding Girvanella filamentous structures. These filaments are mainly found in the core and dark-colored laminae, and are less found in light-colored laminae. They display as flexuous, unsegmented and unbranched tubular objects and constitute a dense and dark network. The settings containing oncoids occur as thin-bedded or lenses between oolitic limestones or are underlain by upper supratidal mudstones. They are preserved in low-energy coastal oolitic inter-shoal or back-shoal facies. The genetic analysis on oncoids shows that:barren of metazoan plays a determining role for the occurence of oncoids in the Second Member of Mantou Formation, Mianchi area;the diversified shapes of oncoids are associated to different water energy;the high-energy condition of sustained agitation and influx of terrigenous clays are the direct controlling factors for the ultimate demise of oncoids.关键词
渑池/核形石/控制因素/馒头组二段/寒武系第三统Key words
Mianchi/oncoids/controlling factors/the Second Member of Mantou Formation/the Third Series of Cambrian分类
天文与地球科学引用本文复制引用
齐永安,代明月,常玉光,王敏,李妲..豫西渑池地区寒武系第三统馒头组二段的核形石[J].高校地质学报,2013,(4):634-641,8.基金项目
国家自然科学基金项目（41072003）；河南省基础与前沿项目（112300413213）和高校博士点基金博导类联合课题（20114116110001）联合资助 （）
