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- Title
Protracted formation of nodular cherts in marine platform: new insights from the Middle Permian Chihsian carbonate successions, South China.
- Authors
Liu, Chao; Ma, Jiao; Zhang, Lin; Wang, Chenglong; Liu, Jiao
- Abstract
Widespread distribution of chert nodules in the Chihsian Formation, South China, provides insightful clues for Middle Permian paleoceanography, while the occurrence of these cherts is enigmatic. In this study, micro-area and in situ geochemical analyses were conducted on cherts and carbonates from the eastern Pingdingshan outcrop, aiming to decipher the origin and forming of chert nodules. Silicon isotope (δ30Si) and petrologic results showed that nodular cherts were formed at syn-depositional stage and had allochthonous origin. Isotopic signatures (δ30Si, δ18O, and 87Sr/86Sr), trace (Fe, Mn, Cu, Co, Ni, etc.) and rare-earth elements indicated that chert cores originated from deep-marine organisms influenced by volcanic activities. By contrast, chert rinds were formed from dissolved silica transported by deep-marine hydrothermal fluids (mixture of seawater and submarine magmatic fluids). The assemblage of spots and veins occurring in chert nodules were formed due to hierarchical precipitation of saddle dolomites and fine-sized quartz. Silica has been transported by hydrothermal fluids from deep marine to platform. Consequently, a protracted forming pattern was proposed to clarify quartz origins, evolution of transporting fluids, and occurrence of chert cores and rinds. This study provides a new perspective with regard to chert origin and formation in marine carbonate successions.
- Publication
Carbonates & Evaporites, 2022, Vol 37, Issue 1, p1
- ISSN
0891-2556
- Publication type
Article
- DOI
10.1007/s13146-022-00757-6