U-Pb carbonate dating reveals long-lived activity of proximal margin extensional faults during the Alpine Tethys rifting. 

M. Rocca, S. Zanchetta, M. Gasparrini, X. Mangenot, F. Berra, P. Deschamps, A. Guihou, and A. Zanchi

This open-access article unveils the significant role of syn-rift extensional faults during the early stages of rifting. Using in-situ LA-ICPMS U-Pb geochronology on syn-kinematic calcites, the research reveals the extended activity of the Amora Fault from Hettangian to Callovian periods. This discovery provides a new chrono-structural model that highlights the importance of major extensional faults in the deformation processes throughout the evolution of rift systems.

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Diagenetic history of calcite fractures in Vaca Muerta shales (Argentina) inferred from paired Δ47 and fluid inclusion geothermometry.

X Mangenot, S Larmier, JP Girard, V Dyja-Person, and JM Eiler.

Fracture diagenesis in low-permeability hydrocarbon-bearing rocks like Vaca Muerta shales significantly impacts petroleum production. Traditional analyses often fall short in characterizing these natural fractures. Our research aims to fill this gap.🔬 Utilizing secondary ion mass spectrometry (SIMS), carbonate clumped isotope geothermometry, and fluid inclusion analysis, we precisely reconstructed the fluid geochemistry, temperature, and pressure during fracture formation. Our findings reveal that fractures formed at consistent temperatures within individual sites but varied significantly at the basin scale, correlated with thermal maturity from the oil to dry gas window. 🌡
This study highlights how combining multiple paleothermometry techniques can provide a comprehensive understanding of fracture diagenesis in old sedimentary rocks, enhancing our ability to predict natural fracture behavior in subsurface engineering operations.

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Constraining the Timing and Evolution of Hydrocarbon Migration in the Bight Basin, Marine and Petroleum Geology

Julien Bourdet, Richard H. Kempton, Vanessa Dyja-Person, Jacques Pironon, Se Gong, and Andrew S. Ross

This study sheds light on the complex processes and factors influencing hydrocarbon migration in the Bight Basin, Australia. Through advanced geochemical analyses and geological modeling, we identified key periods and mechanisms guiding the formation and movement of hydrocarbons. Our research utilized cutting-edge technologies for precise analysis, discovered new data on hydrocarbon migration timelines, and provided an in-depth understanding of the specific geological conditions of the Bight Basin. By better understanding these processes, we can help optimize exploration strategies and minimize environmental risks. Micron-sized fluid inclusions within quartz grains from Late Cretaceous sandstones in four wells in the Great Australian Bight reveal multiple palaeo-hydrocarbon migrations. Using advanced microscopic, spectroscopic, and thermometric techniques, we analyzed petroleum fluid inclusions, estimating fluid types, palaeo-pressures, and palaeo-temperatures (PT) of hydrocarbon entrapment. Our study dated petroleum migration in the Ceduna Sub-basin, showing earliest oil entrapment at 58°C as light oil around the end of the Cretaceous (circa 75 Ma).

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