Late Permian siliceous hot springs developed on the margin of a restricted epeiric sea : insights into strata-confined silicification in mixed siliciclastic‐carbonate successions.

Resumo
Hot springs are sources of carbonate minerals in modern settings; however, few fossil structures are recorded in successions older than the Quaternary due to their enhanced erosional potential. >4500 siliceous mounds are recognized in a well-defined level from the upper part of the Permian Teresina Formation (Parana ́ Basin, SE Brazil). Additionally, a new mound level is here reported for the first time about 15 m below the main occur- rence. Remarkable lithological, mineralogical, paleontological and geochemical features characterize the mounds of both levels, pointing to a hydrothermal origin. Therefore, these structures are here called as hot springs. These were originated subaerially, on the margins of a closing epeiric sea developed on a large intra- continental sag basin. Hydrothermal fluids were sourced from deep circulating basin waters that erupted through intraplate deep-rooted faults. Our data suggests that these hot springs were active during distinct cycles of base level variations. Strata-confined silicification was enhanced during periods of high evaporation and hydrother- mal exudation. Finally, the vertical and lateral facies associations of the Permian hot spring succession are compared with modern sites, and implications for the recognition of syn-depositional hydrothermally precipitated silica in ancient sedimentary basins are discussed.
Descrição
Palavras-chave
Hot springs, Hydrothermal fluids, Intraplate tectonics, Soft-sediment deformation structures, Epeiric sea
Citação
VAREJÃO, F. G. et al. Late Permian siliceous hot springs developed on the margin of a restricted epeiric sea: insights into strata-confined silicification in mixed siliciclastic‐carbonate successions. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 604, artigo e111213, out. 2022. Disponível em: <https://www.sciencedirect.com/science/article/pii/S0031018222003832>. Acesso em: 15 mar. 2023.