Genetic Mechanism and Environment Implications of Siderites in the Lopingian Coal-Bearing Series, Western Guizhou of China: Constrained by Whole-Rock and In Situ Geochemistry

• DOI: 10.3389/feart.2021.779991
• Publication Date: 2021-12-01T07:34:24Z
• Authors: Tianyang Yang; Yulin Shen; Yong Qin; Yijie Zhang; Lu Lu; Jun Jin; Yong Zhao; Yulin Zhu; Yunfei Zhang
• Keywords: Trace element; Siliciclastic; Carbonatite; Ankerite

A large number of siderites have been found in the Lopingian (Late Permian) coal-bearing series western Guizhou, which occurs various microscopic morphologies and has potential insights into sedimentary diagenetic environments. An integrated set analyses, such as observation; X-ray diffraction; whole-rock major trace element, carbon, oxygen isotope; situ carried out to unravel genetic mechanism their environmental implications. According morphology, can be generally divided three types six subtypes, including gelatinous (I), microcrystal-silty siderite [II; microlite (II 1 ), powder crystal 2 )], spheroidal [III, petal-like (III radiating fibrous ) concentric 3 )]. Whole-rock geochemical results show that iron source for formation was mainly from extensive weathering Emeishan high-titanium basalts hot climate conditions. The carbon isotopic indicate origin CO type I is derived dehydroxylation organic matter. II deposited matter marine carbonate rocks, respectively. III rocks affected by different fluids during diagenesis. characteristics further point were formed synsedimentary period most strongly seawater. Redox proxies, V/Sc, V/(V+Ni), δ Ce, constrained a stable weakly reduced condition. Type could developed saltwater. Among them, early stage, whereas originated recrystallization accompanied metasomatism with calcites under weak reduction oxidation influence multistage fluids. growth reducing around conditions relatively active