Thalassinoides Ichnofabrics of Lower Cambrian Longwangmiao Formation(Stage 4,Toyonian)on the Yangtze Platform,South China:Improving Paleoenvironmental Interpretations  

作　　者：TANG Ruifeng ZHANG Jizhi DU Yao WEN Siying ZHONG Bo JIANG Huachuan 

机构地区：[1]Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China [2]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China [3]Exploration Division of PetroChina Southwest Oil&Gasfield Company,Chengdu 610041,China [4]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China [5]School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第1期243-255,共13页地质学报（英文版）

基　　金：financially supported by the National Key Science and Technology Planning Project(2016ZX05007–004 and 2017ZX05001001–002)。

摘　　要：An analysis of Thalassinoides ichnofabrics in the Cambrian Stage 4 Longwangmiao Formation from six sections near Chonqing in the Middle and Upper Yangtze Block of South China was conducted to promote the understanding of the paleoenvironment of this period.Thalassinoides ichnofabrics are divided into three types according to their morphology,bioturbation index,abundance and related parameters:banded,mottled and grid.The completeness of the ichnofabrics gradually increases from banded to grid,the scale of the burrows expands,and the structure transitions from twodimensional to three-dimensional.Malacostracans,phyllocarids and enteropneusts are the most likely burrowers.The findings reveal that frequent changes in paleoenvironmental conditions are the dominant factors for generating the various Thalassinoides ichnofabrics.The changes in depositional rate,substrate properties and nutrient levels affect the behavior and building patterns of the burrowers,thus leading to the diversity of Thalassinoides ichnofabrics.In the lower Longwangmiao Formation beds,many incomplete Thalassinoides burrow systems were built in the substrates with terrigenous detrital minerals,revealing significant environmental pressure on the burrowers.Later,the Thalassinoides burrows went into complete three-dimensional boxworks.At the end of the stage,bioturbation almost disappeared,which indicates that burrowers were finding it difficult to survive in the harsh environment.

关 键 词：ICHNOLOGY invertebrate paleontology Thalassinoides carbonate platform PALEOENVIRONMENT Toyonian 

分 类 号：Q915.2[天文地球—古生物学与地层学] P534.41[生物学—古生物学]