Age and sedimentology of microbialites after the end-Permian mass extinction in Luodian, Guizhou Province
Liu Jianbo Ezaki Yoichi Yang Shouren Wang Haifeng Adachi Natsuko
1 Key Laboratory of Orogenic Belts and Crustal Evolution (Peking University),
Ministry of Education, Beijing 100871
2 School of Earth and Space Sciences, Peking University, Beijing 100871
3 Department of Geosciences, Osaka City University, Osaka 558-8585, Japan,
4 Department of Geology, Miyagi University of Education, Miyagi 980-0845, Japan
The greatest mass extinction event of the Phanerozoic severely damaged both terrestrial and marine organisms at the end of the Permian. In the aftermath of the mass extinction, microbial sediments were extensively deposited in a normal shallow-marine environment. Based on the lithologic evidence from the strata across the Permian-Triassic boundary (PTB) at Dawen of Luodian County of southern Guizhou, an extended hiatus at the PTB has been recognized, implying a major fall in relative sea level at the end of the Permian in South China and other paleoplates. The earliest Griesbachian Hindeodus parvus commonly occurs below the base of the microbialites at the Dawen section, indicating that onset of the microbialite growth had been at the earliest Triassic along with a rise of sea level and the transgression beginning from the earliest Early Triassic had provided accommodation for its development. The skeletal packstone above the microbialites contain abundant Isarcicella staeschei and I. isarcica, implying a sea level fall occurred during this time before a rapid sea-level rise at late time of the I. isarcicai Biozone. Four categories of the thrombolites are distinguished from the lowermost Triassic succession at Dawen: the spotted, the layered, the dendritic, and the reticular structures based on the preferred direction of mesoclots. Mesoclots are interpreted as products of coccoid-dominated microbial communities. The different types of mesostructures were formed by amalgamation of mesoclots, which might have been controlled by biotic and/or physical and chemical, oceanic conditions. The age and sedimentology of the microbialites in south China provide crucial evidence for reconstruction of paleoenvironmental change after the end-Permian mass extinction bio-event as well as synergetic evolution of organisms and environment.
About author: Liu Jianbo, born in 1966, graduated from Department of Geosciences, Osaka City University in 1998 with Ph.D. Now he is engaged in paleontology, sedimentology, and paleoenvironment changes. Address: Department of Geology, Peking University, Beijing 100871; Tel.: 010-62754151; E-mail: jbliu@pku.edu.cn
Cite this article:
. Age and sedimentology of microbialites after the end-Permian mass extinction in Luodian, Guizhou Province[J]. JOURNAL OF PALAEOGEOGRAPHY, 2007, 9(5): 473-486.
. Age and sedimentology of microbialites after the end-Permian mass extinction in Luodian, Guizhou Province[J]. JOPC, 2007, 9(5): 473-486.