The mechanisms driving crustal deformation and uplift of orogenic plateaus are fundamental to continental tectonics. Large-scale crustal flow has been hypothesized to occur in eastern Tibet, but it remains controversial due to a lack of geologic evidence. Geochemical and isotopic data from Cenozoic igneous rocks in the eastern Tibet-Gongga-Zheduo intrusive massif, provide a way to test this model. Modeling results suggest that Cenozoic magmas originated at depths of ∼30-40 km, the depth that crustal flow has been postulated to occur at. Detailed isotopic analyses indicate that the igneous rocks are derived from partial melting of the local Songpan-Ganzi crust, arguing against a long-distance crustal flow. Episodic magmatism during the Cenozoic showing a repeated shifting of magmatic sources can be correlated with crustal uplift. The continued indentation of the Indian Block and upwelling of the asthenosphere contribute to the crustal deformation, magmatism, and uplift.
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http://dx.doi.org/10.1029/2022GL098756 | DOI Listing |
Front Microbiol
November 2024
Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States.
Underlying the thick sediment layer in ocean basins, the flow of seawater through the cracked and porous upper igneous crust supports a previously hidden and largely unexplored active subsurface microbial biome. Subseafloor crustal systems offer an enlarged surface area for microbial habitats and prolonged cell residence times, promoting the evolution of novel microbial lineages in the presence of steep physical and thermochemical gradients. The substantial metabolic potential and dispersal capabilities of microbial communities within these systems underscore their crucial role in biogeochemical cycling.
View Article and Find Full Text PDFSci Total Environ
December 2024
Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
Hydrogeological numerical models are essential for assessing radioactive waste disposal by understanding groundwater flow systems. These models typically rely on hydraulic head data, with other state variables often underutilized in model inversions. In Flanders' Neogene aquifer, where safety studies for Boom Clay are ongoing, existing models face uncertainties due to dependence on hydraulic heads alone.
View Article and Find Full Text PDFR Soc Open Sci
August 2024
Université de Strasbourg, CNRS, Institut Terre et Environnement de Strasbourg, UMR 7063, 5 rue Descartes, Strasbourg F-67084, France.
Beyond a threshold applied compressive stress, porous rocks typically undergo either dilatant or compactant inelastic deformation and the response of their physical properties to deformation mode is key to mass transport, heat transport and pressure evolution in crustal systems. Transitions in failure modes-involving switches between dilatancy and compaction-have also been observed, but to date have received little attention. Here, we perform a series of targeted mechanical deformation experiments on porous andesites, designed to elucidate complex post-failure deformation behaviour.
View Article and Find Full Text PDFNature
September 2024
Advanced Institute for Ocean Research, Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
Crustal accretion at mid-ocean ridges governs the creation and evolution of the oceanic lithosphere. Generally accepted models of passive mantle upwelling and melting predict notably decreased crustal thickness at a spreading rate of less than 20 mm year. We conducted the first, to our knowledge, high-resolution ocean-bottom seismometer (OBS) experiment at the Gakkel Ridge in the Arctic Ocean and imaged the crustal structure of the slowest-spreading ridge on the Earth.
View Article and Find Full Text PDFNat Commun
May 2024
Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Florence, 50121, Italy.
Decades of studies at divergent plate margins have revealed networks of magmatic sills at the crust-mantle boundary. However, a lack of direct observations of deep magma motion limits our understanding of magma inflow from the mantle into the lower crust and the mechanism of sill formation. Here, satellite geodesy reveals rift-scale deformation caused by magma inflow in the deep crust in the Afar rift (East Africa).
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