焦作地区下二叠统太原组Zoophycos遗迹化石与沉积环境

河南省焦作地区太原组几乎每层灰岩中均含有Zoophycos,但大小、形态、丰度、分异度和充填物颜色各异.对太原组L1^L8灰岩层中Zoophycos的产状及分布特征进行了详细分析,认为Zoophycos在个体形态与大小、产状、充填物颜色、丰度上均存在的差异与沉积层岩性及沉积背景有关.在纵剖面上,从L1灰岩到L8灰岩,Zoophycos遗迹化石的颜色呈现规律变化,这与水深、岩性性质密不可分,在浅水、氧化环境中,遗迹化石充填物为红色、褐色,随着水深加大,氧气减少,颜色变为灰白、浅灰色、灰色、深灰色,当水深最大时,形成了黑色充填的Zoophycos遗迹化石(仅发育在L4中上部、L7中部和L8中上部).总体看来,焦作太原组碳酸盐岩的形成共经历了两次大规模的海侵,其最大海侵分别位于L4与L8灰岩层.

Evolution character of ichnofossil Zoophycos of Lower Permian Taiyuan formation in Jiaozuo area

Ichnofossil Zoophycos occurs in almost every layer of limestone of Taiyuan Formation exposed in Jiaozuo area,Henan province,but their size,shape,abundance,diversity and the color of fillings are all different.By analyzing the occurrence and distribution character of Ichnofossil Zoophycos in L1-L8 limestone layers of Taiyuan Formation in detail,it is concluded that the composition,occurrence,shapes and sizes of individuals,the color and element of fillings,abundance,and the vertical distribution characteristic are closely related to the lithology and sedimentary background.With the depth of sedimentary water and the degree of bottom redox changing,the color of backfilling lamina changed regularly,namely as the sedimentation bottom changed from shallow water oxidation environment to deep water reduction environment,the color of backfilling lamina changed from red,brown（shallow water,oxidation environment）,gray or light-grey,dark grey to black（deep water,reduction environment） accordingly.Among them,Zoophycos with black burrow filling is only developed in the middle-upper part of L4,the middle part of L7 and the middle-upper part of L8.On the whole,Taiyuan formation exposed in Jiaozuo area has experienced two large-scale transgression processes,the bottom and the top limestone section reached the maximal transgression at the top of L4 and the middle of L8 severally.