华北上石炭统太原组灰岩中的Zoop hycos痕迹组构

Zoop hycos ICHNOFABRIC IN LIMESTONES OF TAIYUAN FORMATION,NORTH CHINA

  • 摘要: 应用痕迹组构的分析方法,概要论述了华北沉积地层区上石炭统太原组灰岩中的痕迹化石产状特征和痕迹组构的主要组成特征。结合沉积学分析,首次提出了五种组构类型:类型A-Zoop hycos占绝对优势,分异度低,生物扰动强度为2级,常见于泻湖或水体较宁静的海湾环境;类型B-以ThalassinoidesZoop hycos为主,分异度和丰度都较高,生物扰动强度为3级,属正常天气浪基面和风暴浪基面间的上部沉积环境;类型C-痕迹化石丰度较高,常见有Zoop hycos、Thalassinoides、Planolites、Taenidium、PalaeophycosTeichichnus等,可分辨出4个阶梯,生物扰动强度为3~4级,形成于正常天气浪基面至风暴浪基面间的下部沉积环境;类型D-主要由Zoop hycosChondrites组成,丰度高,但分异度低,生物扰动强度为5级,产生于风暴浪基面附近或较闭塞的环境;类型E-生物扰动极强,扰动指数为26,偶而可识别出Zoop hycosChondrites,可能属局限河口湾下部或风暴浪基面之下的沉积环境。

     

    Abstract: Occurrence and constitution features of trace fossils in limestones of Taiyuan Formation, Upper Carboniferous, within sedimentary stratum areas, North China, are demonstrated with ichnofabric analysis method. Combined with sedimentation analysis, 5types of the ichnofabric are firstly suggested as follows:Type A-Zoop hycos being dominat, with low differentiation degree, BI(bioturbation index)=2, commonly occurred in lagoon or bay environmets; Type B-consisting mainly of Thalassinoides and Zoop hycos, being of high differentiation degree and abundance, BI=3, occurred in upper part between norm wether wave base and storm wave base; Type C-consisting of Zoop hycos, Thalassinoides, Planolites, Taenidium, Palaeop hycos and Teichichnus and so on, BI=3~4, occureed in lower part between norm weather wave base and storm wave base; Type D-consisting mainly of Zoop hycos and Chondrites, being of high abundence, but low differentiation degree, BI=5, formed near storm wave base or land-locked sedimentary environmetnts; Type E-being of strong bioturbation, BI=2~6, a few of Zoop hycos and Chondrites may be occasionally distinguished in some beds, commonly formed in limitary sedimentary environments such as estuary or environments below storm wave base.

     

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