CAJ | 학술논문

豫西渑池地区寒武系第三统馒头组二段主要由紫红色、褐黄色页岩夹叠层石灰岩、核形石灰岩和鲕粒灰岩组成，其下部灰岩中富含核形石，形态和纹层结构多不规则，可见弯曲、不分枝的葛万菌（Girvanella）管状体呈密集而不规则的网状缠绕于核心和暗色纹层中，在亮纹层中则少些。含核形石地层呈薄层或透镜状夹于鲕粒灰岩之间或被潮上带泥岩覆盖，形成于低能的滨岸鲕粒滩滩间或滩后洼地。从核形石的特征可以看出，后生动物的匮乏或衰退是渑池地区馒头组二段核形石产生的决定性因素，不同的水动力条件造就了核形石形态类型的多样化，持续动荡的高能条件和大量泥质（陆源物质）供应直接导致了核形石消亡。
예서민지지구한무계제삼통만두조이단주요유자홍색、갈황색혈암협첩층석회암、핵형석회암화이립회암조성，기하부회암중부함핵형석，형태화문층결구다불규칙，가견만곡、불분지적갈만균（Girvanella）관상체정밀집이불규칙적망상전요우핵심화암색문층중，재량문층중칙소사。함핵형석지층정박층혹투경상협우이립회암지간혹피조상대니암복개，형성우저능적빈안이립탄탄간혹탄후와지。종핵형석적특정가이간출，후생동물적궤핍혹쇠퇴시민지지구만두조이단핵형석산생적결정성인소，불동적수동력조건조취료핵형석형태류형적다양화，지속동탕적고능조건화대량니질（륙원물질）공응직접도치료핵형석소망。
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.