On the heat budget in the equatorial Pacific in the 1/4 of degree OCCAM simulation

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Reverse magnetic anomaly controlled by Permian igneous rocks in the Iberian Chain (N Spain)

Two important reverse dipolar magnetic anomalies in the Iberian Chain (Spain) are located over Permian igneous rocks. A detailed study of one of them, the Loscos magnetic anomaly, where the geological structure is well constrained, reveals that the source of the anomaly must be a reverse remanent magnetisation carried by igneous rocks, acquired during the period of the Kiaman reverse magnetic superchron. Magnetic and gravimetric detailed survey (with 50 new gravimetric measurements and 8 main magnetic profiles -six of them N–S and the rest E–Wwith a total length of 40km), together with a study of the petrophysical characteristics of igneous materials, data processing and interpretation (upward continuation, 2.5D modelling, etc.) allowed to characterize qualitatively the anomaly and its source. Two overlapping anomalies with different wavelength were identified, indicating the presence of a shallower strongly altered igneous body with heterogeneous magnetic properties, and a deeper, large igneous body, responsible for the main, long-wavelength anomaly

Coupling far and near tectonic signals in syn-orogenic sediments: The Olvena growth strata (Sierras Marginales, southern Pyrenees)

The Olvena area (Sierras Marginales, southern Pyrenees) provides an outstanding example for studying the relationships between tectonics and sedimentation related to fold-and-thrust systems having shallow décollements. Stratigraphic and sedimentological features allow infer i) the relationship between Oligocene-Miocene locallysourced alluvial fans and a far-sourced wider fluvial system, and ii) the control exerted by tectonics on the stratigraphic architecture. Initially, uplift resulting from folding and thrusting in the Sierras Marginales precluded the entrance through this area into the Ebro basin of a wide fluvial system sourced in internal zones of the Pyrenean chain (including the Axial Zone). A subsiding area was created in the southern front of the Sierras where west-flowing alluvial fans generated, having their source areas in the rejuvenated reliefs. The subsequent cessation of movement of the tectonic structures permitted these reliefs to be subdued and the overpassing of the north-coming fluvial system that progressively covered a wider area. Sequential evolution and stratigraphic architecture evidence thrust emplacement geometry and chronology, including out-of-sequence reactivation of structures and the influence of evaporite flow along the décollement. Although these syn-tectonic deposits belong to the Ebro basin succession, its megasequential evolution differs from the general sequence established for the basin fill, highlighting the importance of differentiating the influence of near-coming sedimentary systems when interpreting basin-scale sequence stratigraphy

Coupling far and near tectonic signals in syn-orogenic sediments: the Olvena growth strata (Sierras Marginales, southern Pyrenees)

The Olvena area (Sierras Marginales, southern Pyrenees) provides an outstanding example for studying the relationships between tectonics and sedimentation related to fold-and-thrust systems having shallow décollements. Stratigraphic and sedimentological features allow infer i) the relationship between Oligocene-Miocene locallysourced alluvial fans and a far-sourced wider fluvial system, and ii) the control exerted by tectonics on the stratigraphic architecture. Initially, uplift resulting from folding and thrusting in the Sierras Marginales precluded the entrance through this area into the Ebro basin of a wide fluvial system sourced in internal zones of the Pyrenean chain (including the Axial Zone). A subsiding area was created in the southern front of the Sierras where west-flowing alluvial fans generated, having their source areas in the rejuvenated reliefs. The subsequent cessation of movement of the tectonic structures permitted these reliefs to be subdued and the overpassing of the north-coming fluvial system that progressively covered a wider area. Sequential evolution and stratigraphic architecture evidence thrust emplacement geometry and chronology, including out-of-sequence reactivation of structures and the influence of evaporite flow along the décollement. Although these syn-tectonic deposits belong to the Ebro basin succession, its megasequential evolution differs from the general sequence established for the basin fill, highlighting the importance of differentiating the influence of near-coming sedimentary systems when interpreting basin-scale sequence stratigraphy

Reverse magnetic anomaly controlled by Permian Igneous rocks in the Iberian Chain (N Spain)

Two important reverse dipolar magnetic anomalies in the Iberian Chain (Spain) are located over Permian igneous rocks. A detailed study of one of them, the Loscos magnetic anomaly, where the geological structure is well constrained, reveals that the source of the anomaly must be a reverse remanent magnetisation carried by igneous rocks, acquired during the period of the Kiaman reverse magnetic superchron. Magnetic and gravimetric detailed survey (with 50 new gravimetric measurements and 8 main magnetic profiles -six of them N–S and the rest E–Wwith a total length of 40km), together with a study of the petrophysical characteristics of igneous materials, data processing and interpretation (upward continuation, 2.5D modelling, etc.) allowed to characterize qualitatively the anomaly and its source. Two overlapping anomalies with different wavelength were identified, indicating the presence of a shallower strongly altered igneous body with heterogeneous magnetic properties, and a deeper, large igneous body, responsible for the main, long-wavelength anomaly

Structural and paleomagnetic evidence for non-rotational kinematics of the South Pyrenean Frontal Thrust at the western termination of the External Sierras (southwestern central Pyrenees)

The definition of the structure and kinematics of the South-Pyrenean Frontal thrust, to the west of its westernmost outcrop in the External Sierras is the goal of this work. The methodology used is based on the construction and restoration of three balanced cross-sections. In addition to that, paleomagnetic analyses are applied to unravel possible vertical axis rotations linked to thrust kinematics. Stepwise thermal demagnetizations of 22 new sites together with previously published data from 25 sites (sampled in Bartonian-Priabonian sediments) define reliable primary directions in the region allowing for potential vertical axis rotations estimation. The comparison between the deformed and the pre-deformational states in the cross-sections agrees with the paleomagnetic data in that neither gradient of shortening, nor significant vertical axis rotations can be invoked to explain the along-strike changes of the main structures (folds and thrusts) linked to the South-Pyrenean Frontal thrust, west of the western termination of the External Sierras. Therefore, these changes are here interpreted as the result of a wedge thrust in the Paleozoic basement, whose displacements in transferred to the Mesozoic-Tertiary cover through the Upper Triassic detachment level. This non-rotational kinematics of deformation implies a change of deformational style with respect to the External Sierras, where clockwise vertical axis rotations and gradient of shortening linked to rotational kinematics are found to be controlled by the Upper Triassic detachment level

Structural and paleomagnetic evidence for non-rotational kinematics of the South Pyrenean Frontal Thrust at the western termination of the External Sierras (southwestern central Pyrenees)

The definition of the structure and kinematics of the South-Pyrenean Frontal thrust, to the west of its westernmost outcrop in the External Sierras is the goal of this work. The methodology used is based on the construction and restoration of three balanced cross-sections. In addition to that, paleomagnetic analyses are applied to unravel possible vertical axis rotations linked to thrust kinematics. Stepwise thermal demagnetizations of 22 new sites together with previously published data from 25 sites (sampled in Bartonian-Priabonian sediments) define reliable primary directions in the region allowing for potential vertical axis rotations estimation. The comparison between the deformed and the pre-deformational states in the cross-sections agrees with the paleomagnetic data in that neither gradient of shortening, nor significant vertical axis rotations can be invoked to explain the along-strike changes of the main structures (folds and thrusts) linked to the South-Pyrenean Frontal thrust, west of the western termination of the External Sierras. Therefore, these changes are here interpreted as the result of a wedge thrust in the Paleozoic basement, whose displacements in transferred to the Mesozoic-Tertiary cover through the Upper Triassic detachment level. This non-rotational kinematics of deformation implies a change of deformational style with respect to the External Sierras, where clockwise vertical axis rotations and gradient of shortening linked to rotational kinematics are found to be controlled by the Upper Triassic detachment level

Análisis de estrías en pliegues N-S del Pirineo central meridional

Este trabajo muestra el análisis de indicadores cinemáticos (estrías) tomados sobre planos de estratificación de varios pliegues N-S con inmersión N de la vertiente meridional del Pirineo Central. Para explicar la orientación no perpendicular al eje del pliegue de varias estrías encontradas se han propuesto dos modelos geométricos relacionados con pliegues cilíndricos formados por mecanismo de flexural-slip: (1) dos etapas de plegamiento e inmersión sucesivas, y (2) plegamiento e inmersión simultáneos. This work studies the use of slickenfibres measured on bedding surfaces as kinematic indicators in N-S trending, N-plunging folds located in the Southern Pyrenees. To explain oblique to fold axis slickenfibres, two geometrical models are derived from flexural-slip mechanism of cylindrical folding: (1) two sequential stages of folding and plunging, and (2) simultaneous folding and plunging