Gonzalez-Fernandez Antonio

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Gonzalez-Fernandez
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Antonio
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  • Preprint
    Variation in styles of rifting in the Gulf of California
    ( 2007-06-18) Lizarralde, Daniel ; Axen, Gary J. ; Brown, Hillary E. ; Fletcher, John M. ; Gonzalez-Fernandez, Antonio ; Harding, Alistair J. ; Holbrook, W. Steven ; Kent, Graham M. ; Paramo, Pedro ; Sutherland, Fiona ; Umhoefer, Paul J.
    The rifting of continental lithosphere is a fundamental solid-earth process that leads to the formation of rifted continental margins and ocean basins. Understanding of this process comes from observations of the geometry of rifted margins and the magmatism resulting from rifting, which inform us about the strength of the lithosphere, the state of the underlying mantle, and the transition from rifting to seafloor spreading. Here we describe results from the PESCADOR seismic experiment in the southern Gulf of California and present the first crustal-scale images across conjugate margins of multiple segments within a single rift that has reached the stage of oceanic spreading. A surprisingly large variation in rifting style and magmatism is observed between these segments, from wide rifting with minor syn-rift magmatism to narrow rifting in magmatically robust segments. These differences encompass much of the variation observed across nearly all other non-end-member continental margins. The characteristics of magmatic endmember margins are typically explained in terms of mantle temperature. Our explanations for the variation in the Gulf of California, in contrast, invoke mantle depletion to account for wide, magma-poor rifting and mantle fertility and possibly the influence of sediments to account for robust rift and post-rift magmatism in the Gulf of California. These factors may vary laterally over small distances in regions that have transitioned from convergence to extension, as is the case for the Gulf of California and many other rifts.
  • Article
    Carbon released by sill intrusion into young sediments measured through scientific drilling
    (Geological Society of America, 2023-02-09) Lizarralde, Daniel ; Teske, Andreas ; Höfig, Tobias W. ; González-Fernández, Antonio
    The intrusion of igneous sills into organic-rich sediments accompanies the emplacement of igneous provinces, continental rifting, and sedimented seafloor spreading. Heat from intruding sills in these settings alters sedimentary organic carbon, releasing methane and other gasses. Recent studies hypothesize that carbon released by this mechanism impacts global climate, particularly during large igneous province emplacements. However, the direct impacts of sill intrusion, including carbon release, remain insufficiently quantified. Here, we present results from International Ocean Discovery Program (IODP) Expedition 385 comparing drill-core and wireline measurements from correlative sedimentary strata at adjacent sites cored in Guaymas Basin, Gulf of California, one altered by a recently intruded sill and one unaffected. We estimate 3.30 Mt of carbon were released due to this sill intrusion, representing an order of magnitude less carbon than inferences from outcrops and modeling would predict. This attenuated carbon release can be attributed to shallow intrusion and the high heat capacity of young, high-porosity sediments. Shallow intrusion also impacts sub-seafloor carbon cycling by disrupting advective fluxes, and it compacts underlying sediments, increasing potential carbon release in response to subsequent intrusions.
  • Article
    Farallon slab detachment and deformation of the Magdalena Shelf, southern Baja California
    (American Geophysical Union, 2012-05-08) Brothers, Daniel S. ; Harding, Alistair J. ; Gonzalez-Fernandez, Antonio ; Holbrook, W. Steven ; Kent, Graham M. ; Driscoll, Neal W. ; Fletcher, John M. ; Lizarralde, Daniel ; Umhoefer, Paul J. ; Axen, Gary J.
    Subduction of the Farallon plate beneath northwestern Mexico stalled by ~12 Ma when the Pacific-Farallon spreading-ridge approached the subduction zone. Coupling between remnant slab and the overriding North American plate played an important role in the capture of the Baja California (BC) microplate by the Pacific Plate. Active-source seismic reflection and wide-angle seismic refraction profiles across southwestern BC (~24.5°N) are used to image the extent of remnant slab and study its impact on the overriding plate. We infer that the hot, buoyant slab detached ~40 km landward of the fossil trench. Isostatic rebound following slab detachment uplifted the margin and exposed the Magdalena Shelf to wave-base erosion. Subsequent cooling, subsidence and transtensional opening along the shelf (starting ~8 Ma) starved the fossil trench of terrigenous sediment input. Slab detachment and the resultant rebound of the margin provide a mechanism for rapid uplift and exhumation of forearc subduction complexes.