Paleoenvironmental conditions across the Jurassic–Cretaceous boundary in central-eastern Mexico

摘要: Abstract The Padni section of central-eastern Mexico is characterized by pelagic, organic-rich carbonates and shales dated in this study calpionellid biostratigraphy to the late Tithonian-late Berriasian time interval. Microfacies, pyrite framboid size, spectrometric gamma-ray mineralogical data are herein integrated order reconstruct paleoenvironmental change during Jurassic-Cretaceous boundary. Deposits Tithonian–early laminated, facies with abundant radiolarian, tiny framboids low Th/U ratios. They linked upwelling a semi-restricted basin, high marine productivity anoxic bottom waters. early incursions Tethyan oceanic waters into proto-Gulf occurred Tithonian as attested appearance calpionellids. Short intermittent accumulations saccocomids suggest episodes sporadic connection between Tethys, proto-Atlantic Pacific ocean sea-level rise events. A full stable Tethys was established until Berriasian. This event supported presence open bioturbated population typical dysoxic conditions, higher ratios decreasing pattern total organic carbon content. In addition highlighting replenishment oxygen supply also points younger age for finalization Yucatan Block rotation end Gulf opening. Deposition studied mostly Tithonian–Berriasian arid phase reported other Atlantic regions. similarity discrete segments standard curve defined outcrop those from subsurface implies their regional continuity allowing use correlation purposes.