Temporal Distribution of Diagnostic Biofabrics in the Lower and Middle Ordovician in North China: Clues to the Geobiology of the Great Ordovician Biodiversification Event

Abstract

Abstract:The temporal distribution of the diagnostic biofabrics in the Lower and Middle Ordovician in North China distinctly illustrates that the sedimentary systems on the paleoplate have been changed markedly as consequences of the Great Ordovician Biodiversification Event (GOBE). The pre‐GOBE sedimentary systems deposited in Tremadoc display widespread microbialite and flat‐pebble conglomerates, and a less extent of bioturbation. Through the transitional period of early Floian, the sedimentary systems in the rest of the Early and Mid‐ Ordovician change to GOBE type and are characterized by intensive bioturbation and vanishing flat‐pebble conglomerates and subtidal microbial sediments. The irreversible changes in sedimentary systems in North China are linked to the GOBE, which conduced the increase in infaunal tiering, the expansion of infaunal ecospace, and the appearance of new burrowers related to the development of the Paleozoic Evolutionary Fauna during the Ordovician biodiversification. Thus, changes in sedimentary systems during the pivotal period of the GOBE were consequences of a steep diversification of benthic faunas rather than the GOBE's environmental background.