Palaeomagnetism of Permian and Triassic red beds of NW Spain and implications for the tectonic evolution of the Asturian-Cantabrian Arc

Parés, J. M.; Voo, Rob Van der; Stamatakos, John

doi:10.1111/j.1365-246x.1996.tb04711.x

Cited by 18 publications

(5 citation statements)

References 21 publications

(10 reference statements)

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“…Note, however, that the results from Iberia are on the rocks that are dated as Late Permian‐‐Lower Triassic, and the 241–256 Ma ages (∼250 Ma on average) are ascribed to them in the Global Palaeomagnetic Database (GPMDB). Thus the steeper‐than‐predicted inclinations from the Western Pyrenees (Schott & Peres 1988) and the Tudanca locality (Pares et al 1996) may stem from the studied rocks being younger than the data that were used to determine the TDP. This assumption agrees with mixed polarity of these two results, whereas the only purely reverse, albeit rather imprecise, datum from the Capos de la Ermita area (Turner et al 1989) fits the TDP predictions.…”

Section: Discussionmentioning

confidence: 96%

Late Permian palaeomagnetism of Northern Eurasia: data evaluation and a single-plate test of the geocentric axial dipole model

Bazhenov¹,

Shatsillo

2010

Geophysical Journal International

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S U M M A R YHow the first-order structure of the magnetic field changed through geological time is one of the most long-living and hotly debated questions in geomagnetism. For the last 5 Ma, the geomagnetic field is found to be essentially dipolar with about 5 per cent quadrupole term and, possibly, still smaller octupole term. Proving this became possible after accumulation of a large set of globally distributed reliable palaeomagnetic data and their analysis in the coordinates tied to the rotation axis. For older times, the data are less reliable, scarce and unevenly distributed, while tectonic motions destroyed the global coordinates. In this paper, a method to determine the geomagnetic field structure for a single plate is discussed. It is suggested that the coordinate system for analysis can be derived from great circles, each being drawn through a sampling point and the corresponding palaeomagnetic pole (SP-circle). Such circles are to intersect at a true (i.e. pure dipole) pole that is largely purified from the contributions of non-dipole zonal terms and inclination shallowing. The scrutiny of late Permian (270-250 Ma) palaeomagnetic poles from Northern Eurasia revealed two distinct groups: one includes several poles from a limited area in South France (SF), and the other consists of tightly clustered nine poles from locations spread over a large part of Eurasia. Tentatively, the former group can be explained by either rotation of SF with respect to main Eurasia, or less likely, remagnetization in Early Triassic time; irrespectively, these poles cannot be used for calculation of the true dipole pole nor for computation of the apparent polar wander path of Eurasia. The poles from the main part of Eurasia were used to find the position of the true dipole pole of this plate and for analysis of the field. The minimum of residual dispersion of the observed data is found for the quadrupole and octupole terms of less than 10 per cent when each term is varied separately. When both terms are varied together, the best fit is observed for the quadrupole and octupole terms of −4 and 12 per cent, respectively. Our analysis shows that the position of the true dipole pole is robust, while the estimates of non-dipole terms are not. We argue that these estimates should be regarded as the upper limits on the non-dipole contributions to the Late Permian geomagnetic field; at the same time, we are pretty sure that octupole term of 20 per cent or more are not permitted by the data.

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Section: Discussionmentioning

confidence: 96%

Late Permian palaeomagnetism of Northern Eurasia: data evaluation and a single-plate test of the geocentric axial dipole model

Bazhenov¹,

Shatsillo

2010

Geophysical Journal International

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“…Similar rotation values have been obtained in the overlying Triassic red beds (Izquierdo-Llavall et al . 2012 a ) with regards to the Permian-Triassic reference for this sector of the Pyrenees (Dec., Inc. = 345, 14; α95 = 5.8°, k = 138.3; from data by Parés, van der Voo & Stamatakos, 1996; Schott & Perés, 1987 and Osete et al . 1997, compiled in Osete & Palencia, 2006).…”

Section: Discussionmentioning

confidence: 96%

Palaeomagnetism and magnetic fabrics of the Late Palaeozoic volcanism in the Castejón-Laspaúles basin (Central Pyrenees). Implications for palaeoflow directions and basin configuration

et al. 2013

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-The Castejón-Laspaúles basin is one of the South Pyrenean basins of Late Variscan age that were strongly inverted during the Alpine compression (Late Cretaceous-Tertiary). It is mainly composed by Stephanian pyroclastic and volcanic deposits that reach a maximum thickness of ß 500 m, and are overlain by Permian and Triassic sedimentary units. A palaeomagnetic and magnetic fabrics (AMS) study was carried out in the Stephanian units, where the general absence of flow markers at the outcrop scale and the Alpine inversional structure prevent the straightforward reconstruction of the original volcanic and basinal configuration. Magnetic fabric data are not overprinted by Alpine internal deformation and can be interpreted in terms of primary volcanic and pyroclastic fabrics. The obtained directions coincide in the different sampled units, suggesting a constant source area during the development of the basin, and show the dominance of N-S-trending K 1 axes that are interpreted to be parallel to flow directions. Palaeomagnetic data indicate the presence of a pre-folding palaeomagnetic component that is rotated clockwise by an average of +37°(±32°) with regards to the Stephanian reference. This rotation probably took place during Alpine thrusting since it is also registered by the overlying Triassic deposits. The whole dataset is interpreted in terms of basin development under sinistral transtension with two main fault sets: deep-rooted E-W-striking faults, probably responsible for magmatic emissions, and shallow-rooted, listric faults of N-S orientation.

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“…This is in contrast to other tectonic models for secondary folding [e.g., Aller and Gallastegui , 1995; Alonso et al , 1996], which argue that much of the reactivation and superposed folding in this part of the Cantabrian Arc was due to significant Alpine north‐south shortening. Although it is clear that Alpine shortening is responsible for substantial uplift of the Cantabrian Arc range, as well as reactivation along the northern and southern margins of the range, significant Alpine induced rotation within the Cantabrian Arc is unlikely, based on the presence of unrotated Late Permian‐Triassic magnetizations found throughout the Cantabrian Arc region [e.g., Weil et al , 2001; Parés et al , 1996].…”

Section: Discussionmentioning

confidence: 99%

Kinematics of orocline tightening in the core of an arc: Paleomagnetic analysis of the Ponga Unit, Cantabrian Arc, northern Spain

Weil

2006

Tectonics

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Paleomagnetic and structural analyses of the Western European Variscan Belt (WEVB) suggest that the most viable kinematic model for Variscan deformation in northern Iberia is oroclinal bending of an originally linear belt in a two‐stage tectonic history. This history represents two regional compression phases (E‐W in the Late Carboniferous and N‐S in the Permian, both in present‐day coordinates), which resulted in the refolding (about steeply plunging axes) of initially north‐south trending thrusts and folds in the hinge zone, and oroclinal tightening due to vertical axis rotation of the belt's limbs. However, the orocline model has yet to be critically tested in the WEVB's core. This study reports new paleomagnetic, rock magnetic, and structural data from the inner core of the WEVB in order to test opposing kinematic models for the well‐documented fault and fold interference structures formed by late stage Variscan deformation and to better understand the overall development of the WEVB arc. Map‐scale structural features within the WEVB core have a highly sinuous geometry characterized by transverse and thrust‐parallel fold systems formed by fault bend folding over footwall ramps. The intersections of these two fold systems produce steeply plunging interference folds, which are best exposed in the Ponga thrust unit. A total of 67 paleomagnetic sites were collected in the Barcaliente Formation of the Ponga Unit, with emphasis placed on detailed spatial coverage of individual structural domains. A multicomponent paleomagnetic remanence was measured, which is interpreted to be composed of two components; a low unblocking temperature recent viscous magnetization and a high unblocking temperature ancient magnetization that was acquired in the latest Stephanian to Early Permian after initial D1 thrusting and folding bur prior to major secondary rotation. Rock magnetic experiments show that the characteristic remanence magnetization is carried by secondary authigenic pseudosingle‐domain magnetite. These paleomagnetic results are used to determine the kinematics and geometry of postmagnetization deformation by restoring in situ magnetic vectors back to a defined reference direction. On the basis of the restored Ponga Unit geometry, the steeply plunging interference folds found in the WEVB core are best described by a combination of secondary buckling of frontal‐ramp‐parallel hanging wall anticlines and modification of D1 lateral/oblique ramps as frontal ramps during late stage north‐south shortening. This combination of structural modification of the inner core of the WEVB was necessary to accommodate oroclinal bending during the final amalgamation of Pangea in the late Paleozoic.

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Palaeomagnetism of Permian and Triassic red beds of NW Spain and implications for the tectonic evolution of the Asturian-Cantabrian Arc

Cited by 18 publications

References 21 publications

Late Permian palaeomagnetism of Northern Eurasia: data evaluation and a single-plate test of the geocentric axial dipole model

Late Permian palaeomagnetism of Northern Eurasia: data evaluation and a single-plate test of the geocentric axial dipole model

Palaeomagnetism and magnetic fabrics of the Late Palaeozoic volcanism in the Castejón-Laspaúles basin (Central Pyrenees). Implications for palaeoflow directions and basin configuration

Kinematics of orocline tightening in the core of an arc: Paleomagnetic analysis of the Ponga Unit, Cantabrian Arc, northern Spain

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