While the planet Mars is today a dry and cold wasteland dominated by aeolian processes, a large diversity of geomorphologies observed from orbit suggests that aqueous processes took place there. Most of these morphologies implies the presence of developed fluvial networks at the surface of the planet about 3.5 Ga ago. However, the precise condition...
Radionuclide transport in smectite clay barrier systems used for nuclear waste disposal is controlled by diffusion, with adsorption significantly retarding transport rates. While a relatively minor component of spent nuclear fuel, 79Se is a major driver of the safety case for spent fuel disposal due to its long half-life (3.3 × 105 yr) and its low ...
An extensive laboratory test program was conducted to analyze and compare the cation exchange processes in three different varieties of sodium bentonite (Na-B) geosynthetic clay liners (GCLs) over increased conditioning durations up to 32 days and investigate the effects of temperature, solution strength, and applied stress. The goal of this test p...
Abstract: The formation of Lau Basin records an extreme event of plate tectonics, with the associated Tonga trench exhibiting the fastest retreat in the world (16 cm/yr). Yet paleogeographic reconstructions suggest that seafloor spreading in the Lau Basin only initiated around 6 Ma. This kinematics is difficult to reconcile with our present underst...
Abstract: The upper mantle under the Afar Depression in the East African Rift displays some of the slowest seismic wave speeds observed globally. Despite the extreme nature of the geophysical anomaly, lavas that erupted along the East African Rift record modest thermal anomalies. We present measurements of major elements, H2O, S, and CO2, and Fe3+/...
The formation of abyssal serpentinites leads to deep changes of the oceanic lithosphere rheology and geochemistry, hence playing a key role on geodynamic and geochemical cycles. Here we review and discuss the geochemical diversity of serpentinites collected on abyssal floors (i.e., abyssal serpentinites) from different geodynamical settings, namely...
The numerous volcanic centres in the Main Ethiopian Rift (MER) present significant but poorly understood hazards to local populations. The MER is also an important site to gain insights into tectonic processes as it captures the transition from continental rifting (to the south) to incipient seafloor spreading (to the north). Peralkaline magmas acc...
We introduce a new isotope chronological model in which the natural mass-dependent isotopic fractionation effects of the radioactive (“parent”) and radiogenic (“daughter”) elements are systematically and rigorously considered. Using this model, we show that internally-normalized radiogenic isotopic ratios, commonly determined for daughter elements ...
In early 2022, Curiosity investigated a series of lenticular bodies interstratified within the Contigo member (mbr) of the Mirador formation (fm), part of the Mount Sharp Group (MtS_Grp) in Gale crater (Fig. 1), interpreted to represent localized changes in environment [1-3]. The lenses vary in size but are typically 0.5 to 1 metre thick and up to ...
