TY - JOUR

T1 - Miniaturized trace fossils in microbialites from the Cambrian Series 2 Qingxudong formation in the Panshi area, eastern Guizhou, China

AU - Yu, Xiantao

AU - Xiang, Fang

AU - Su, Zhongtang

AU - Zhang, Deyan

AU - Lash, Gary G.

AU - Yang, Kunmei

AU - You, Wenzhi

N1 - Funding Information: This study was supported by the projects of the National Natural Science Foundation of China (Grant No. 41972104). The authors thank Doctor Yu Liu in the Institute of Sedimentary Geology, Chengdu University of Technology for his instructive discussions, as well as the editors and several anonymous reviewers for their constructive comments and suggestions.

PY - 2021/8/15

Y1 - 2021/8/15

N2 - Trace fossils are especially useful to elucidating metazoan evolution and species extinction events through geologic history. This paper reports results of an investigation of well exposed microbialites in the Cambrian Series 2 (upper Toyonian–lower Amgan) Qingxudong Formation (QF) of the Panshi area, eastern Guizhou Province. Light and scanning electron microscopic examination of these deposits has revealed for the first time small Planolites. Detailed analysis of these trace fossils has helped elucidate their mode of formation mechanism and their relationship with the extinction of Archaeocyathids early in the Toyonian. Our results suggest that the trace-makers had a trophic specialization strategy and selectively fed in a low-energy and Girvanella-rich environment. They were the pioneers of ecosystem recovery following extinction of reef-building Archaeocyathids and had survived the earlier oxygen-depleted environment. Sedimentary facies evolution manifested by the studied deposits and penecontemporaneous siderite indicates that the trace fossils formed in a shallow sea in which a weakly reducing, sulfur-poor sedimentary environment had been established in association with transgression. The recovery and expansion of microbial reefs and the miniaturization of trace fossils suggest that the anoxic environment severely inhibited metazoans and may have contributed significantly to the extinction of reef-building Archaeocyathids during the early Toyonian time and the slow recovery of ecosystems that followed. Our results provide impetus for further research on the extinction event and the recovery process of metazoans in the late period of Cambrian Epoch 2.

AB - Trace fossils are especially useful to elucidating metazoan evolution and species extinction events through geologic history. This paper reports results of an investigation of well exposed microbialites in the Cambrian Series 2 (upper Toyonian–lower Amgan) Qingxudong Formation (QF) of the Panshi area, eastern Guizhou Province. Light and scanning electron microscopic examination of these deposits has revealed for the first time small Planolites. Detailed analysis of these trace fossils has helped elucidate their mode of formation mechanism and their relationship with the extinction of Archaeocyathids early in the Toyonian. Our results suggest that the trace-makers had a trophic specialization strategy and selectively fed in a low-energy and Girvanella-rich environment. They were the pioneers of ecosystem recovery following extinction of reef-building Archaeocyathids and had survived the earlier oxygen-depleted environment. Sedimentary facies evolution manifested by the studied deposits and penecontemporaneous siderite indicates that the trace fossils formed in a shallow sea in which a weakly reducing, sulfur-poor sedimentary environment had been established in association with transgression. The recovery and expansion of microbial reefs and the miniaturization of trace fossils suggest that the anoxic environment severely inhibited metazoans and may have contributed significantly to the extinction of reef-building Archaeocyathids during the early Toyonian time and the slow recovery of ecosystems that followed. Our results provide impetus for further research on the extinction event and the recovery process of metazoans in the late period of Cambrian Epoch 2.

KW - Anoxia

KW - Extinction

KW - Girvanella

KW - Planolites

KW - Recovery

KW - Toyonian

UR - http://www.scopus.com/inward/record.url?scp=85107429879&partnerID=8YFLogxK

U2 - 10.1016/j.palaeo.2021.110514

DO - 10.1016/j.palaeo.2021.110514

M3 - Article

AN - SCOPUS:85107429879

VL - 576

JO - Palaeogeography, Palaeoclimatology, Palaeoecology

JF - Palaeogeography, Palaeoclimatology, Palaeoecology

SN - 0031-0182

M1 - 110514

ER -