242 research outputs found
Strike-slip faults in the Southern border of the Vera basin (Almería, Betic Cordilleras)
The Southern border of the Vera basin is affected by a dextral fault (Cortijo Grande fault) trending N70E. This is crossed by other faults trending NNE-SSW, and particulary at the Eastern end where it is severely bent by the Palomares fault.
The movements of the Cortijo Grande fault started at the latest during the Serravallian with compression trending from N80W to N60W wich steadily turned to N20W during the Messinian-Pliocene. Fault displacements affect Quaternary deposits in many occasions. Neogene sediments clearly show deformations contemporary to the deposit.El borde sur de la depresión de Vera está afectado por una falla dextrorsa (falla de Cortijo Grande) de dirección N70E. Esta ha sido cortada por otras fallas de dirección NNE-SSW, en especial en su terminación oriental donde está fuertemente flexionada por la falla de Palomares.
Los movimientos de la falla de Cortijo Grande se han producido al menos desde el Serravalliense con compresiones según la dirección N80W a N60W que progresivamente rotaron a N20W en el Messiniense - Plioceno. Los desplazamientos de las fallas llegan a afectar en muchos casos a sedimentos cuaternarios. Los del Neógeno muestran claramente estas deformaciones coetáneas con el depósito
Evolution of Iberia during the Cenozoic with special emphasis on the formation of the Betic Cordillera and its relation with the western Mediterranean
The extensional process affecting Iberia during the Triassic and Jurassic times change from the end of the Cretaceous and,
throughout the Palaeocene, the displacement between the African and European plates was clearly convergent and part of the future
Internal Zone of the Betic Cordillera was affected. To the west, the Atlantic continued to open as a passive margin and, to the north, no significant deformation occurred. During the Eocene, the entire Iberian plate was subjected to compression. which caused major deformations in the Pyrenees and also in the Alpujarride and Nevado-Filabride, Internal Betic, complexes. In the Oligocene continued this situation, but in addition, the new extensional process ocurring in the western Mediterranean area, together with the constant eastward drift of Iberia due to Atlantic opening, compressed the eastern sector of Iberia, giving rise to the structuring of the Iberian Cordillera. The Neogene was the time when the Betic Cordillera reached its fundamental features with the westward displacement of the Betic-Rif Internal Zone, expelled by the progressive opening of the Algerian Basin, opening prolonged till the Alboran Sea.
From the late Miocene onwards, all Iberia was affected by a N-S to NNW-SSE compression, combined in many points by a near perpendicular extension. Specially in eastern and southern Iberia a radial extension superposed these compression and extension
Estructura del borde oriental de la Sierra de Gádor (zona Alpujárride, Cordilleras Béticas)
En el borde oriental de la unidad de Gador existen numerosas escamas. La unidad de Felix es una de éstas. Correlaciones con unidades occidentales permiten la división en esta región de las unidades alpujárrides en dos grupos: Contraviesa y Lújar
Una propuesta de clasificación de las cuencas neógenas béticas
There are numerous neogene basins in the Betic Cordillera (Southern Spain), with a thick sedimentary infill constituted by Miocene, Pliocene and/or Pleistocene materials, in which important stratigraphical differences can be detected. During the Neogene the Betic Cordillera adquired its present configuration and the formation, evolution and total or partial destruction of the Neogene sedimentary basins were highly controlled by the geodynamic situations and the position of the basins in it. We proposed a classification dividing the Betic Neogene Basins in two groups, according to the two main different geodynamic situations existing in the Betic Cordillera in this interval of time. The first group corresponds to the basins formed during the Early and Middle Miocene, coetaneously with the westward drift of the Internal Zones. It is impossible to establish a complete classification of the basins formed during this time, because in many cases only small outcrops remain. The basins formed in the Internal Zones may be considered as back-arc and intrachain basins. In the External Zones, former South Iberian Margin appeared the foreland basin (the North Betic Strait) with an active sector (foredeep), located in front of the new formed reliefs, that received huge olistostromic masses. This foredeep evolved differently in its eastern and western sectors. The second group of basins is constituted by those formed from the Tortonian onward, when the westward drift of the Internal Zones stopped. With the exception of the already existing foreland basin, the basins formed from the Tortonian onwards, are intramontane basins, which can be subdivided according to the different movements of the fault sets that controlled their evolution. The foreland basin (Guadalquivir Basin), located between the Betic Chain and the emerged Iberian Massif, acquired a structure similar to that of the present basin and its extension was also similar to that of the present Neogene outcrops
El Torcal de Antequera, un ejemplo de estructura formada por un importante sistema transcurrente dextrorso
The Torcal de Antequera is situated in the Penibetic (part of the Betic External Zone) very near of the contact with the Internal Zone. It has an E-W fusiform shape and corresponds to a monocline structure, surrounded and uplifted by large scale dextral strike-slip faults. Its interior includes a large number of map-scale fractures, most of which can be explained by a mega dextral shear system. The minor structures measured, linked to the faults, are also consistent with this shear system and with its progressive evolution. The deduced predominant direction of s1 is NW-SE, congruent with the oblique displacements occurred between the Internal Zone and the Penibetic in this area; the Torcal area is one of the megastructures formed by it.El Torcal de Antequera está situado en el Penibético (parte de la Zona Externa Bética) cercano a la Zona Interna. Tiene una forma ahusada en la dirección E-O y corresponde a una estructura monoclinal, rodeada y levantada por grandes fallas de desgarre dextrorsas. En su interior existen innumerables fallas, la mayoría de las cuales pueden explicarse dentro de un sistema de desgarre dextrorso a gran escala. Las estructuras menores medidas, ligadas a las fallas, son consistentes con este sistema de cizalla y con su progresiva evolución. La dirección predominante de s1 deducida es NO-SE. En esta área, el sistema de cizalla está ligado a los desplazamientos de la Zona Interna en relación con el Penibético; el área del Torcal corresponde a una de las megaestructuras formadas en él
Estructura de los mármoles alpujárrides situados entre Calahonda y Castell de Ferro (Cordillera Bética, provincia de Granada)
Formaciones del Paleozoico superior al Triásico depositadas discordantes sobre las peridotitas de Ronda: Evidencia de su emplazamiento cortical durante el Herciniano
The age of the emplacement of the Ronda Peridotites has been widely debated during recent decades, and ages ranging from the Palaeozoic to the early Miocene have been proposed, although most of the current interpretations suggest an Oligocene-Miocene age. In this article, we describe two meta-sedimentary formations (the lower one formed by detrital sediments and the upper one by marbles) that were unconformably deposited over the Ronda peridotites and now record low-grade metamorphism. The detrital formation contains layers of acidic rocks with an age of 269±9 Ma and the overlying marbles are assumed to be Triassic. The existence of these unconformable formations over the peridotites is crucial for the dating of the exhumation of the latter. The presence of peridotite clasts in the detrital formation indicates that peridotites were exposed during the Permian and other data suggest that peridotites were exhumed during the late Carboniferous. During the Alpine cycle, the peridotites operated as an element situated at the bottom of the tectonically higher Alpujarride/Sebtide unit (the Jubrique unit) and forming part of it, then being incorporated to the Alpine thrusts of this unit.La edad del emplazamiento de las peridotitas de Ronda ha sido discutida ampliamente en las últimas décadas, con hipótesis que van desde el Paleozoico al Mioceno inferior, aunque la mayoría de las interpretaciones actuales sugiere una edad oligo-miocena. En este artículo, describimos la existencia de dos formaciones meta-sedimentarias (la inferior formada originalmente por sedimentos detríticos y la superior por carbonatos) que se depositaron en discordancia sobre las peridotitas de Ronda y ahora registran un grado bajo de metamorfismo. La formación detrítica contiene capas de rocas ácidas con una edad de 269±9 Ma y los mármoles situados encima se atribuyen al Trías. La existencia de esas dos formaciones es crucial para la datación de la exhumación de las peridotitas. La presencia de clastos de peridotitas en la formación detrítica indica que aquellas estuvieron expuestas durante el Pérmico, otros datos sugieren que las peridotitas fueron exhumadas durante el Carbonífero superior. Durante el ciclo alpino, las peridotitas actuaron como un elemento ya antes situado en la base de la unidad Alpujárride/ Sébtide superior (unidad de Jubrique), formando parte de ésta
Late Palaeozoic to Triassic formations unconformably deposited over the Ronda peridotites (Betic Cordilleras): Evidence for their Variscan time of crustal emplacement
Estructura del Complejo Alpujárride y observaciones hidrogeológicas al NO de Sierra Tejeda (provincias de Granada y Málaga, Zona Interna Bética)
In the NW of Sierra Tejeda (Spain) it is possible differentiate only two Alpujarride tectonic units, i.e. the Almijara and, in an upper position, the Robledal unit, simplifying previous divisions. Hydrogeological data support this interpretation since a hydraulic connection exists between the two areas occupied by marbles (Sierra Tejeda and Rodaderos sectors). Both areas has been previously considered as belonging to two different tectonic units not directly connected. In the Robledal unit, gneisses in the lower part of the lithologic sequence correlate with other units of the Guájares-Jubrique/Los Reales group (upper group of Alpujarride units). Extensional deformations are superposed over these tectonic units, but, according to field observations, they have not the enormous importance attributed to them in previous models, as they do not differentiate new tectonic units, at least in this area. New E-W faults are drawn along the northern edge of Sierra Tejeda, contributing to the westward drift of the Betic Internal Zone.Al NO de Sierra Tejeda solo se pueden diferenciar dos unidades tectónicas alpujárrides, la de Almijara y, sobre ella, la de Robledal, simplificando divisiones previas.
Datos hidrogeológicos avalan esta interpretación ya que apuntan a la posible conexión hidráulica entre dos áreas ocupadas por mármoles (sectores de Tejeda y Rodaderos) que previamente han sido consideradas como unidades tectónicas diferentes lo que lo hace improbable. En la unidad Robledal la presencia de gneises en la parte inferior de la secuencia litológica permite su correlación con otras unidades del grupo Guájares-Jubrique/ Los Reales (grupo superior de unidades del Complejo Alpujárride). Deformaciones extensionales se superponen al cabalgamiento de unidades, pero a las que no damos la enorme importancia atribuida en previos modelos, pues no permiten, al menos en esta área, la diferenciación de nuevas unidades tectónicas. Se muestran, además, nuevas fallas E-O situadas al N de Sierra Tejeda, que facilitaron el desplazamiento hacia el oeste de la Zona Interna Bética
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