Authigenic carbonate formation and its impact on the biomarker inventory at hydrocarbon seeps – A case study from the Holocene Black Sea and the Plio-Pleistocene Northern Apennines (Italy)

摘要: Carbonates are widespread at methane and petroleum seeps often precipitated as consequence of an alkalinity increase due to the anaerobic oxidation (AOM) or, less reported, higher hydrocarbons. These carbonates taphonomic windows into Earth's history, because they excellently protect in situ formed microbial signatures (e.g. lipid biomarkers) from diagenetic destruction. A complication for paleoreconstructions, however, is that seep also encapsulate variable amounts allochthonous organic matter, sometimes even completely obscuring authigenic signatures. Seep Holocene Black Sea, Pleistocene Enza River Pliocene San Lorenzo (both Northern Apennines, Italy) provide hints better understand (i) importance processes other than AOM formation (ii) controls autochthonous contribution biomarkers matter carbonates. Biomarker distributions different parts a Sea carbonate clearly demonstrate high entrapped if intrasedimentary, particularly supply relatively low external input high. High contributions were found biomarker inventory ancient Italian Apennines (Enza Lorenzo) pointing their precipitation within sediment. Specific complex conditions indicated our data location. Carbonate facies compositions, with abundant sulfate reducing bacteria, suggest reduction using alkaline, eventually sulfate- hydrocarbon-enriched fluids triggered growth these Our this process has be more considered interpreting settings, where rely on rising deep reservoirs.