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It is often difficult to decipher past salt tectonics events in orogenic domains. The southwestern Alpine foreland in France presents a long and extensive salt tectonics history in the Mesozoic, which was later inverted during the Cenozoic Alpine Orogeny. Synorogenic Cenozoic salt-related deformations are difficult to identify due to the contemporaneous shortening experienced by the foreland. This study is based on sedimentological and geochemical (Sr concentrations and 87Sr/86Sr ratios) analyses of the Oligocene non-marine succession of St-Geniez (Digne region, France). Oligocene salt influences are highlighted by (1) high Sr concentrations (>1000 ppm) in most of the series, (2) the occurrence of halophytic gastropods and (3) the deposition of two gypsum beds. The 87Sr/86Sr ratios measured in the limestones and the gypsum beds confirm a Triassic origin for the Sr, originating from the Sorine diapir located to the SW, for the first part of the series and from the Authon thrust, located to the north, for the upper part of the series. The geochemistry also suggests the occurrence of two Triassic evaporite levels: one already known and attributed to the Carnian–Norian (Late Triassic) and one attributed to the Olenekian–Anisian (Early to Mid-Triassic). These results show that the combined use of field geology and geochemistry can provide information about previously erased salt tectonics events. [ABSTRACT FROM AUTHOR]

Continental carbonate bodies are widespread in the Tabernas basin, eastern Betic Cordillera. Their relationships with the topographic evolution, climate changes and extensional regional tectonic processes recognized in the region are, however, still unclear. Travertine deposits exhibit facies of cascade and pool environments often reported as related to water–air surface processes. Calcretes show a large panel of facies, indicating control by groundwater and pedogenic processes. New U/Th dates on both travertine and calcrete reveal that they precipitated from 354 ka ± 76 to 8 ka ± 0.2. The U/Th dates obtained on calcretes are in good agreement with global climate changes and support that precipitation of recent CaCO3 is episodic and occurs mainly during warm and wet conditions. C and O stable isotope geochemistry reveals travertines are thermogenic and characterized by hydrothermal fluids enriched in CO2 that interacted with aquifers. This thermogenic origin suggests a deep source of CO2 (higher positive δ13C values) likely triggered by the presence of an anomalously hot mantle that reflects thinning of the regional lithosphere and volcanism. Further analyses of the distribution of calcrete show they are carbonate-rich fluvial terraces, whose formation is controlled by the response of the river network to regional uplift and climate. Supplementary Materials: reproducibility for δ13C and δ18O of the NSB-18 internal standard available in Supplementary Table 1 (SP1) and reproducibility for U and Th of the HU-1 standard available in Supplementary Table 2 (SP2) at https://doi.org/10.6084/m9.figshare.c.4996514 [ABSTRACT FROM AUTHOR]

The constraint of temperature evolution in coastal environments is an important factor in deciphering the Earth's global climatic history. In this study, we reconstruct the evolution of sea-surface palaeotemperatures from the oxygen stable isotope compositions in four marine molluscs families in the Paris Basin during the Palaeogene. The combination of several taxa living in different environments is used to limit uncertainties related to the influence of salinity variations on palaeotemperature estimations. One family of bivalves (oysters) and three families of gastropods (Volutidae, Cerithiidae and Turritellidae) were sampled in the French part of the Paris Basin, in Belgium and in the Isle of Wight (southern England). Maximum seawater temperatures were observed during the Early Eocene (c. 30°C), which correspond to the Early Eocene Climatic Optimum, and temperatures then decreased until the Lutetian (c. 20°C). A transient warming, identified as the Middle Eocene Climatic Optimum, occurred during the Bartonian, when temperatures reached 32°C. Temperatures decreased through the Eocene-Oligocene boundary, the coolest interval of the Palaeogene (c. 12°C). A final warming period occurred throughout the Early Oligocene, with temperatures reaching 24°C. The fossils analysed thus record the global climatic intervals of the Palaeogene. [ABSTRACT FROM AUTHOR]