Person: Muñoz Martín, Alfonso
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First Name
Alfonso
Last Name
Muñoz Martín
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Geodinámica Interna
Identifiers
6 results
Search Results
Now showing 1 - 6 of 6
Item Inversion of moment tensor focal mechanisms for active stresses around the Microcontinent Iberia: Tectonic implications(Tectonics, 2008) Vicente Muñoz, Gerardo de; Cloetingh, Sierd; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Stich, Daniel; Vegas, Ramón; Galindo-Zaldívar, Jesus; Fernández Lozano, JavierThe Iberian microcontinent and its connected oceanic crust are affected by deformations related to the Eurasian-African plate boundary. Active stress inversions from populations of moment tensor focal mechanisms have been performed around and inside the Iberian peninsula, using a total of 213 moment tensor estimates. Main results are: 1) The tensorial solutions show better consistency and lower misfits compared to those obtained previously from first P arrival focal mechanisms. 2) Along the Eurasia- Africa western boundary, the type of active stresses progressively changes easternwards from triaxial extension to uniaxial compression along the Terceira Ridge, the Gloria Fault zone and the Gulf of Cadiz. 3) In the Betics-Alboran-Rif zone, uniaxial extension predominates with Shmax N155ºE trending. 4) In N Algeria, uniaxial compression reappears. 5) The Iberian foreland is currently under strike-slip to uniaxial extension tensorial conditions.Item El cabalgamiento cenozoico de Boinás (Cordillera Cantábrica, España)(Geogaceta, 2007) Vicente Muñoz, Gerardo de; González Nistal, S.; Muñoz Martín, Alfonso; Vegas, Ramón; Olaiz Campos, Antonio José; Fernández Lozano, Javier; Vicente, Raquel deThe opencast gold mine of Boinás, has allowed to outcrops the contact between the variscan basement and the Cenozoic sediments. It is observable that the contact is a post - Lower Oligocene thrust, with a N40ºE trend. From a macrostructural point of view, Boinás thrust spreads along more than 10 km with a constant orientation, a vertical gap that reaches 400 m, and a NW vergence. Northwestwards another Alpine thrust develops (Tineo, A l o n s o y Pulgar , 2004) with a parallel orientation an opposite vergence. Between both thrusts a tectonic pop-down appears (Narcea Pop-down). The dynamic analysis shows that this structure was activated by a paleostress tensor with an horizontal s1 trending N139ºE, with a stress regime close to uniaxial compression (R=0.06). This stress allows the geometrical interchanges between s2 and s3. The outcrop also allows to observe a secondary population of normal faults, that fits to an extensional stress tensor (R=0.01) with s3 trending N146ºE, that is coaxial with the main compressive stress tensor. We interpret both fault populations as generated by the tectonic thrust emplacement.Item Mapa de esfuerzos de Europa a partir de Mecanismos focales calculados desde el Tensor de Momento Sísmico(Geogaceta, 2006) Olaiz Campos, Antonio José; Vicente Muñoz, Gerardo de; Muñoz Martín, Alfonso; Vegas, RamónThis work shows a new stress map for Europe obtained from the inversion of earthquakes focal mechanisms calculated with the centroid tensor method (Dzieownski et al., 1982). An amount of 1608 focal mechanisms have been selected with several quality criteria from different catalogues (CMT Harvard, ETH, Med-Net, I.G.N. and I.A.G.) from 1973 to present-day. Values for the maximum horizontal stress and the shape factor of the ellipsoid (horizontal/vertical stress) have been calculated following the Reches (1983) and De Vicente (1988) slip model. The local results have been interpolated to a 1ºx1º regular grid in which the relation between tectonic horizontal stress and vertical load has been taken into account. The final map shows a good correlation with the primary tectonic forces generated in the plate boundaries and the local perturbations related with main crustal heterogeneities as suggested by Gölke and Coblentz (1996).Item Cenozoic thick-skinned deformation and topography evolution of the Spanish Central System(Global and Planetary Change, 2007) Vicente Muñoz, Gerardo de; Vegas, Ramón; Muñoz Martín, Alfonso; Silva Barroso, Pablo Gabriel; Andriessen, Paul; Cloetingh, Sierd; González Casado, José Manuel; Van Wees, Jan Diederik; Álvarez García, Juan; Carbó Gorosabel, Andrés; Olaiz Campos, Antonio JoséThe Spanish Central System is a Cenozoic pop-up with an E-W to NE-SW orientation that affects all the crust (thick-skinned tectonics). It shows antiform geometry in the upper crust with thickening in the lower crust. Together with the Iberian Chain it constitutes the most prominent mountainous structure of the Pyrenean foreland. The evolutionary patterns concerning the paleotopography of the interior of the Peninsula can be established by an analysis of the following data: gravimetric, topographical, macro and micro tectonic, sedimentological (infilling of the sedimentary basins of the relative foreland), P-T-t path from apatite fission tracks, paleoseismic and instrumental seismicity. Deformation is clearly asymmetric in the Central System as evidenced by the existence of an unique, large (crustal-scale) thrust at its southern border, while in the northern one there is a normal sequence of north verging thrusts, towards the Duero Basin, whose activity ended during the Lower Miocene. This deformation was accomplished under triaxial compression, Oligocene- Lower Miocene in age, marked by NW-SE to NNW-SSE shortening. Locally orientations of paleostresses deviate from that of the regional tensor, following a period of relative tectonic quiescence. During the Upper Miocene-Pliocene, a reactivation of constrictive stress occurred and some structures underwent rejuvenation as a consequence of the action of tectonic stresses similar to those of today (uniaxial extension to strike-slip with NW-SE shortening direction). However, the westernmost areas show continuous activity throughout the whole of the Tertiary, with no apparent pulses. At the present time there is a moderate seismic activity in the Central System related to faults that were active during the Cenozoic, with the same kinematic characteristics.Item European continuous active tectonic strain–stress map(Tectonophysics, 2009) Olaiz Campos, Antonio José; Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de; Vegas, RamónThis paper shows a new continuous strain–stress map for Europe obtained from the direct inversion of earthquake focal mechanisms calculated from the centroid tensor method. A total of 1608 focal mechanisms have been selected with several quality criteria from different catalogues (CMT Harvard, ETH, Med-Net, I.G.N. and I.A.G.) from 1973 to the present day. Values for the maximum horizontal shortening direction and brittle strain–stress regime defined by the k′ ratio (ey/ez, horizontal maximum/vertical strain) have been calculated following in Europe and Pannonian Basin the slip model of tri-axial deformation. The individual results including Dey and the shape of the active brittle strain ellipsoid have been interpolated to a final 15′ regular grid taking into account the relationship between the tectonic horizontal strain–stress value and the vertical load. Both continuous strain regime and maximum horizontal shortening (Dey) maps show a good correlation with the primary tectonic forces generated along the plate boundaries, plate kinematics and also some local perturbations related with main crustal heterogeneities and topography, as well as significant spatial variations in integrated crustal strength.Item Oblique strain partitioning and transpression on an inverted rift: The Castilian Branch of the Iberian Chain(Tectonophysics, 2009) Vicente Muñoz, Gerardo de; Vegas, Ramón; Muñoz Martín, Alfonso; Wees, Jan Dierik van; Casas Sáinz, Antonio; Sopeña, Alfonso; Sánchez-Moya, Yolanda; Arche, Alfredo; López Gómez, José; Olaiz Campos, Antonio José; Fernández Lozano, JavierThe Iberian Chain is a wide intraplate deformation zone formed by the tectonic inversion during the Pyrenean orogeny of a Permian –Mesozoic basin developed in the eastern part of the Iberian Massif. The N – S convergence between Iberia and Eurasia from the Late Cretaceous to the Lower Miocene times produced signi cant intraplate deformation. The NW –SE oriented Castilian Branch of the Iberian Chain can be considered as a “key zone ” where the proposed models for the Cenozoic tectonic evolution of the Iberian Chain can be tested. Structural style of basin inversion suggests mainly strike slip d–isplacements along previous NW –SE normal faults, developed mostly during the Mesozoic. To con rm this hypothesis, structural and basin evolution analysis, macrostructural Bouguer gravity anomaly analysis, detailed mapping and paleostress inversions have been used to prove the important role of strike slip deformation. In addition, we demonstrate that two main folding trends almost perpendicular (NE SW t–o E W an–d NW SE) w–ere simultaneously active in a wide transpressive zone. The two fold trends were generated by dierent mechanical behaviour, including buckling and bending under constrictive strain conditions. We propose that strain partitioning occurred with oblique compression and transpression during the Cenozoic.