Submarine Basaltic Magmatism in the Subbetic Basin (Southern Spain): Insights into Melt-Weakening Processes during Mesozoic Continental Rifting

Abstract Mantle-derived volcanic rocks from the Subbetic hyperextended basin in SE Spain provide new insights into composition and mechanical behavior of mantle during continental rifting. The present study describes a sequential restored cross-section along with geochemical characteristics basaltic interbedded within Mesozoic succession basin. Sedimentary stacking patterns minibasins above mobilized salt reflect relationships coeval volcanism. We recognize two type localities on basis facies, presence shallow intrusive bodies, age associated sedimentary formations. first corresponds to subaqueous pillow-lava flows subvolcanic sills dikes Lower Jurassic marly limestones Middle oolitic limestones. basalts enriched MORB compositions moderate La/Sm low Sm/Yb ratios. Interestingly, significant group this magmatism departs typical MORB-OIB array, showing deep Nb-Ta negative anomalies high Th/Nb second comprises lava flows, also including pillow-shaped interlayered hyaloclastite deposits Upper Cretaceous clays, radiolarites, is characterized by highly compositions. Furthermore, values positive correlation between LREE/HREE Zr point involvement (Grt-present) sources origin melts. interpret Lower-Middle calc-alkaline signal as due partial melting recycled crustal upper mantle, i.e., remnants pre-Mesozoic subducted slabs. These are similar those described Triassic widespread throughout External Zone Betic Cordillera. syn-rift indicate that deformation lithospheric was initiated early Accordingly, we suggest Early melts promoted failure thus contributing inception lithospheric-scale shear zones, which, turn, controlled evolution magma-poor margin. Subsequently, rift gave way activation deeper melt an increase alkaline signature at time.