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Early Late Cretaceous uplift of Provence gave rise to the Durance Isthmus. In the present study, U–Pb dating on calcite of compressional structures related to Pyrenean foreland compressional deformation in Provence shows that N‐S shortening occurred coeval with emersion of the Durance Isthmus, through the development of combined top‐to‐the‐North to NW thrusts between 97 and 90 Ma. This large‐scale event, recorded from the Pyrenees to the Middle‐East regions is interpreted as a far‐field internal plate precursor of the Africa‐Europe plates reorganization. Furthermore, the change in tectonic style and amount of shortening between Provence and Pyrenees was accommodated by sinistral reactivation of the NE–SW Cevennes and Nimes faults, acting as transform boundaries in this incipient collisional context. [ABSTRACT FROM AUTHOR]

In the context of increasing evidence of plate interface coupling variability in subduction zones, there is a need to extend the short time window given by instrumental data and to gather data over multiple time and spatial scales. We hence investigated the long‐term topography on Barbuda island, located in the northern part of the Lesser Antilles, west of the Caribbean subduction zone. Following pioneering work using a set of marine terraces on the eastern side of the island, we performed the first U‐Th dating on 10 corals in growth position from the lowest terrace, for which the highest relative sea‐level (RSL) indicator is found at 9 ± 1 m above the mean sea level. We find that this terrace corresponds to the Last Interglacial (LIG) (ages between 122.8 ± 0.3 ka and 128.1 ± 0.3 ka) and we estimate a paleo RSL of 7 ± 2 m above the current mean sea level. The present elevation of the LIG shoreline on Barbuda might imply tectonics as an additional mechanism to eustatic sea level, mantle dynamic topography and glacial isostatic adjustment. East‐west morphological asymmetry of Barbuda and difference in LIG shoreline elevation between Barbuda and Antigua suggest a regional tectonic process. As with the proposed westward tilting from the forearc to the volcanic arc of the Guadeloupe archipelago, vertical deformation on Barbuda could be related to plate‐scale subduction processes. Long‐term uplift of Barbuda might be related to the accumulation of residual coseismic deformation not fully recovered by interseismic subsidence and the corresponding seismogenic segment would extend below the Moho. Key Points: Highest Last Interglacial sea level indicator on Barbuda island is found at 9 ± 1 m above present mean sea levelWe present the first U‐Th ages from corals found in growth position within the Last Interglacial marine terrace on BarbudaBarbuda may record subduction‐related uplift superimposed on effects of various non‐tectonic processes [ABSTRACT FROM AUTHOR]

The use of silicon (Si) isotopes has led to major advances in our understanding of Si cycling in modern and past environments. This inter‐laboratory comparison exercise provides the community with the first set of soil and plant reference materials with an analytically challenging matrix containing organic material that is known to induce isotopic bias, for use as secondary reference materials in Si isotope measurement. Seven laboratories analysed four soil reference materials (GBW‐07401, GBW‐07404, GBW‐07407, TILL‐1) and one plant reference material (ERM‐CD281). Participating laboratories employed a range of chemical preparation methods and analytical setups but all analyses were performed by MC‐ICP‐MS. Irrespective of the chemical preparation method or analytical conditions, the results show excellent agreement among laboratories within 2s for at least three replicates. Data were combined together to calculate δ29Si and δ30Si mean values (relative to NBS 28) and their expanded uncertainties (U, coverage factor k = 2). The δ30Si values are as follow: GBW‐07401: −0.27 ± 0.06‰, GBW‐07404: −0.76 ± 0.12‰, GBW‐07407: −1.82 ± 0.17‰, TILL‐1: −0.16 ± 0.06‰ and ERM‐CD281: −0.28 ± 0.11‰. Also, a compilation of published data provides an up‐to‐date mean δ30Si for BHVO‐2 of −0.28 ± 0.08‰. [ABSTRACT FROM AUTHOR]

Germanium (Ge) exists at trace levels in the Earth's crust and is a powerful geochemical tracer of the silicon (Si) cycle. This study proposes a simple and reliable method for determining Ge contents in environmental samples using ICP‐MS. As Si and Ge have very similar chemical properties, we investigated the applicability of the chemical preparation procedure developed for Si isotopes for the determination of Ge in environmental samples. Advantages of this procedure are as follows: (a) efficient removal of the matrix and main interferences affecting Ge determinations by ICP‐MS, (b) a low limit of detection (6 ng l−1), (c) relative repeatability of approximately 3% obtained on 74Ge and (d) robustness and accuracy based on agreement within errors with the published Ge values for rock reference materials (BHVO‐2, AGV‐2 and BCR‐2). This procedure allowed revision of the Ge values of three soil reference materials (1.67 ± 0.09 μg g−1, 2.41 ± 0.18 μg g−1, 1.89 ± 0.10 μg g−1 for GBW 07401, GBW 07404 and GBW 07407, respectively) and proposal of a value for the plant reference material ERM‐CD281 (70 ± 3 μg g−1). This method provides a convenient procedure for determining Ge mass fractions in environmental samples and opens the possibility of coupling two tracers of the Si biogeochemical cycle with a single measurement procedure. [ABSTRACT FROM AUTHOR]

Abstract: The North West European Shelf break acts as a barrier to the transport and exchange between the open ocean and the shelf seas. The strong spatial variability of these exchange processes is hard to fully explore using observations, and simulations generally are too coarse to simulate the fine‐scale processes over the whole region. In this context, under the FASTNEt program, a new NEMO configuration of the North West European Shelf and Atlantic Margin at 1/60° (∼1.8 km) has been developed, with the objective to better understand and quantify the seasonal and interannual variability of shelf break processes. The capability of this configuration to reproduce the seasonal cycle in SST, the barotropic tide, and fine‐resolution temperature profiles is assessed against a basin‐scale (1/12°, ∼9 km) configuration and a standard regional configuration (7 km resolution). The seasonal cycle is well reproduced in all configurations though the fine‐resolution allows the simulation of smaller scale processes. Time series of temperature at various locations on the shelf show the presence of internal waves with a strong spatiotemporal variability. Spectral analysis of the internal waves reveals peaks at the diurnal, semidiurnal, inertial, and quarter‐diurnal bands, which are only realistically reproduced in the new configuration. Tidally induced pycnocline variability is diagnosed in the model and shown to vary with the spring neap cycle with mean displacement amplitudes in excess of 2 m for 30% of the stratified domain. With sufficiently fine resolution, internal tides are shown to be generated at numerous bathymetric features resulting in a complex pycnocline displacement superposition pattern. [ABSTRACT FROM AUTHOR]

Timing is a key data for understanding the origin of faulting. The Balcones fault system (BFS) extends ~600 km along the northern margin of the Gulf of Mexico oil basin and controls springs that supply the major cities in Texas, but its origin is unclear. We provide its first direct timing by applying U–Pb geochronology on seven calcite‐mineralized fault surfaces. We have found that this extensional fault system formed during the Palaeocene‐middle Eocene time (from 61.3 ± 2.7 to 45.4 ± 2.1 Ma), which is much earlier than previous estimates. We show that the formation of the BFS coincides with the largest clastic influx in the northern Gulf of Mexico basin that resulted from Laramide uplift and erosion. This timing and the location of the BFS along the Ouachita suture, support our interpretation of this fault system formed as the result of lithospheric flexure related to Paleogene sedimentary loading. [ABSTRACT FROM AUTHOR]

Syn‐rift extensional faults play a significant role during the early stage of rifting. Constraining the age of faulting, and how and when deformation shifts from the proximal to the distal margin areas, is crucial for the reconstruction of the rifting process. Previous assessments of the structural and temporal evolution of rift‐related faults of the Adria proximal margin have primarily relied on indirect biostratigraphic evidence. Additionally, the majority of rift‐related faults underwent tectonic inversion during the Alpine orogeny. In this study, in‐situ U‐Pb geochronology was applied on syn‐kinematic calcites to unravel the activity of the Amora Fault, a remarkable example of a Jurassic growth fault unaffected by the Alpine orogeny. The obtained ages, spanning from Hettangian to Callovian, extend the AF activity beyond the previously established Early Jurassic time. This chrono‐structural model has significant implications on the role of major extensional faults in focusing deformation throughout the rift system's evolution. [ABSTRACT FROM AUTHOR]