Geochemical Diversity of Late Miocene Volcanism in Southern Baja California, Mexico: Implication of Mantle and Crustal Sources during the Opening of an Asthenospheric Window

Benoît, Mathieu; Aguillón‐Robles, Alfredo; Calmus, Thierry; Maury, René C.; Bellón, Hervé; Cotten, Joseph; Bourgois, Jacques; Michaud, François

doi:10.1086/342735

Cited by 149 publications

(83 citation statements)

References 81 publications

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“…Previously, mafi c lavas in the range ca. 11-9 Ma were reported from western Sonora (Mora- Klepeis and McDowell, 2004) and in the Bahía de Los Angeles, Jaraguay, and Santa Rosalía areas in Baja California (Benoit et al, 2002;Calmus et al, 2003;Conly et al, 2005;Pallares et al, 2007). In addition to those described in the previous section, we have recognized additional Late Miocene (ca.…”

Section: Late Miocene Volcanism Of Northern Sinaloa and Offshore Areassupporting

confidence: 70%

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et al. 2013

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Although Basin and Range-style extension affected large areas of western Mexico after the Late Eocene, most consider that extension in the Gulf of California region began as subduction waned and ended ca. 14-12.5 Ma. A general consensus also exists in considering Early and Middle Miocene volcanism of the Sierra Madre Occidental and Comondú Group as subduction related, whereas volcanism after ca. 12.5 Ma is extension related. Here we present a new regional geologic study of the eastern Gulf of California margin in the states of Nayarit and Sinaloa after the end of subduction, implying that preexisting subduction-modifi ed mantle had now become isolated from melt source regions. Our study shows that rifting across the southern-central Gulf Extensional Province began much earlier than the Late Miocene and provided a fundamental control on the style and composition of volcanism from at least 30 Ma. We envision a sustained period of lithospheric stretching and magmatism during which the pace and breadth of extension changed ca. 20-18 Ma to be narrower, and again after ca. 12.5 Ma, when the kinematics of rifting became more oblique.

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Section: Late Miocene Volcanism Of Northern Sinaloa and Offshore Areassupporting

confidence: 70%

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et al. 2013

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“…In order to account for the ETMD magmatism itself, we propose a slab break-off and the melting of the metasomatized sub-continental lithosphere (with a subduction component) in response to heat provided by the asthenospheric window ( Fig. 11c; Keskin, 2003;Benoit et al 2002). Slab break-off is favoured by slow convergence, which enhances the relative downward traction of the relatively stagnant slab, and is common in the Neo-Tethys history (Wortel & Spakman, 2000;Mahéo et al 2002).…”

Section: B3 Late Paleocene (60-55 Ma)mentioning

confidence: 99%

Zagros orogeny: a subduction-dominated process

et al. 2011

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-This paper presents a synthetic view of the geodynamic evolution of the Zagros orogen within the frame of the Arabia-Eurasia collision. The Zagros orogen and the Iranian plateau preserve a record of the long-standing convergence history between Eurasia and Arabia across the Neo-Tethys, from subduction/obduction processes to present-day collision (from ∼ 150 to 0 Ma). We herein combine the results obtained on several geodynamic issues, namely the location of the oceanic suture zone, the age of oceanic closure and collision, the magmatic and geochemical evolution of the Eurasian upper plate during convergence (as testified by the successive Sanandaj-Sirjan, Kermanshah and Urumieh-Dokhtar magmatic arcs), the P-T-t history of the few Zagros blueschists, the convergence characteristics across the Neo-Tethys (kinematic velocities, tomographic constraints, subduction zones and obduction processes), together with a survey of recent results gathered by others. We provide lithospheric-scale reconstructions of the Zagros orogen from ∼ 150 to 0 Ma across two SW-NE transects. The evolution of the Zagros orogen is also compared to those of the nearby Turkish and Himalayan orogens. In our geotectonic scenario for the Zagros convergence, we outline three main periods/regimes: (1) the Mid to Late Cretaceous (115-85 Ma) corresponds to a distinctive period of perturbation of subduction processes and interplate mechanical coupling marked by blueschist exhumation and upper-plate fragmentation, (2) the Paleocene-Eocene (60-40 Ma) witnesses slab break-off, major shifts in arc magmatism and distributed extension within the upper plate, and (3) from the Oligocene onwards (∼ 30-0 Ma), collision develops with a progressive SW migration of deformation and topographic build-up (Sanandaj-Sirjan Zone: 20-15 Ma, High Zagros: ∼ 12-8 Ma; Simply Folded Belt: 5-0 Ma) and with partial slab tear at depths (∼ 10 Ma to present). Our reconstructions underline the key role played by subduction throughout the whole convergence history. We finally stress that such a long-lasting subduction system with changing boundary conditions also makes the Zagros orogen an ideal natural laboratory for subduction processes.

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“…U-Pb dating work on zircon overgrowth rims of high-grade gneisses revealed a regional hightemperature metamorphic event ($390 Ma) in the Chinese Altai (Jiang et al, accepted for publication), which, together with the abrupt change of zircon Hf isotopic composition of the early Devonian granitoids ) and the 375 Ma MORB-type mafic dykes in the region , collectively implies a sudden increase in heat flux and geothermal gradient in the beginning of the Early Devonian. The change of geothermal gradient is commonly ascribed to subduction of spreading ridges, transform faults and young and hot oceanic plates (Drummond et al, 1996;Thorkelson, 1996;Benoit et al, 2002;Fischer, 2004). To further determine the exact regime for the abrupt increase in heat flux is beyond the scope of this work.…”

Section: Tectonic Implicationsmentioning

confidence: 99%