Belén Oliva-Urcia

University of Zaragoza | UNIZAR · Earth Sciencies

Paleomagnetic data from the Internal Sierras unravel the kinematic relationship between basement (Guarga, Gavarnie, Bielsa) and cover thrusts (Larra-Monte Perdido). The new data come from an area of 100 km along strike and 5-15 km across strike of the southwestern Pyrenees. The area covers a variety of structural positions that range from cover to...

Here we present a detailed study of the magnetic fabrics and subfabrics of remagnetized Upper Cretaceous limolites that crop out in the Internal Sierras (west central Pyrenees) affected by a penetrative pressure-solution cleavage. The bulk magnetic fabrics of these rocks (RT-AMS) show variable orientations that do not conform to what is typically r...

New paleomagnetic analyses of Triassic, Cretaceous and Eocene strata in the south-central Pyrenees show evidence for a widespread remagnetization, located along the southern border of the Axial Zone, the Internal Sierras, and the northern part of the Jaca-Pamplona basin. This remagnetization, always reversed in polarity, was acquired after an exten...

During the Jurassic, Iberia and western North Africa underwent extensional tectonics conditioned by their position with respect to the African, Eurasian and North American plates and related to the Central and North Atlantic opening and westward expansion of the Tethys. In Iberia, the Jurassic is characterized by the presence of wide shallow marine...

The Devonian is a period of climatic and biodiversity changes and known "black shales" events that are linked with hypoxia/anoxia, eustatic fluctuations, faunal variations and geochemical anomalies. Magnetic susceptibility measurements are used as a complementary tool for correlation and more recently, as a tool for paleogeographic reconstructions...

Los incendios suponen una de las mayores causas de destruc- ción del Patrimonio Natural y Cultural. El aumento brusco de tem- peratura durante un incendio provoca la reducción de la resistencia mecánica de las rocas. El presente trabajo evalúa los efectos mecá- nicos generados por las altas temperaturas en una granodiorita re- lacionada con el yaci...

In this introductory chapter we summarize the geological evolution of the atlasic domain, making reference to many (not all) of the significant previous works carried out in the area. The geological setting of the Moroccan Central High Atlas is characterized by a complex Mesozoic-Cenozoic evolution that included (i) an extensional to transtensional...

From the application of the magnetic techniques (Anisotropy of Magnetic Susceptibility and paleomagnetism) it can be seen that to determine the age (and origin) of structures in the Moroccan Central High Atlas is not straightforward from geometrical features only and that similar structures can have different origins, or that the two limbs of a par...

From a 3-D reconstruction based on serial cross-sections, structural observations, and potential field geophysical data we characterize the major structural frame of the Moroccan Central High Atlas. Its overall structure shows two fold-and-thrust systems (each one showing particular features) at the northern and southern borders of the chain, resul...

The anisotropy of magnetic susceptibility provides valuable information on the imprint of the different tectonic processes occurred in the Central High Atlas (CHA), complementing the structural analysis and paleomagnetic information. Different types of magnetic ellipsoids, related with extensional, diapiric or intrusive processes occurred during th...

Wildfires are one of the main threats of natural areas and often fires can affect protected or heritage areas and properties, in which the preservation requirements demand the use of non-destructive techniques (NDTs). The magnetic susceptibility is an NDT that provides information on the mineralogical composition of the materials but has never been...

The Pyrenees constitutes an exceptional example of an Alpine orogenic belt characterized by basement thrust sheets involving Paleozoic rocks and Mesozoic and Cenozoic cover units detached on the Triassic evaporites, the main décollement level. This work is located in the Central Pyrenees, where gravity data help to better constrain the internal arc...

The analysis of the Anisotropy of Magnetic Susceptibility (AMS) constitutes a fast and non-destructive technique that has gained the acceptance of structural geologists because it provides valuable information related to the orientation and intensity of the strain ellipsoid of deformed rocks. Part of its strength results from the possibility of (i)...

A new gravity survey (1164 gravity stations and 180 samples for density analysis) combined with two new geological cross sections has been carried out in a sector of the Central Pyrenees in order to improve the characterization of basement and cover architecture. From North to South, the study area comprises the southern half of the Axial Zone and...

The aim of this work is the application of the anisotropy of magnetic susceptibility (AMS) to the study of volcanic materials from the Late Carboniferous-Permian Cadí basin (southern Pyrenees) in order to (i) explore the limits of this technique in ancient volcanic materials that have undergone strong chemical alteration and a complex tectonic evol...

Las relaciones geométricas y cinemáticas entre las unidades de basamento de los Pirineos Suroccidentales, específicamente entre la terminación de la Zona Axial y el afloramiento de los Macizos Vascos, son desconocidas y potencialmente muy complejas (Oliva-Urcia, 2018). La gravimetría se ha aplicado con éxito en otras regiones pirenaicas para resolv...

A short video (8 min) allows, on the one hand, to spread information and on the other hand to determine its educational purpose of the Pyrenean geology. The script is based on a dialogue between the Posets Mountain and a geologist who is sampling for studying its deformation. Concepts about geological time and paleogeographic reconstructions (Scote...

Magnetic fabric analyses are a fast and non-destructive method used to determine the fabric in rocks, since the first studies of magnetic fabric, a parallelism between the magnetic fabric and the rock fabric was observed. The mineral distribution in rocks is modified by stress. Magnetic fabric analyses in relation with deformation in folded rocks c...

The interfolding remagnetizations are those acquired between two deformational stages, and they are common in inverted sedimentary basins. They can be used as a tool to restore the structure at the remagnetization time (Villalaín et al., 2016). This technique is used in the Central High Atlas (Morocco) in the frame of the CGL2016-77560-C2-P researc...

To deal with magnetic modelling, remanent magnetization as well as susceptibility of the rocks that generate an induced magnetic field by the interaction with the Earth Magnetic field has to be addressed. In presence of primary and/or secondary fields, it is essential to consider the total magnetization as the sum of induced and remanent components...

Studying the magnetic fabric in volcanic edifices, particularly lava flows from recent eruptions, allows us to understand the orientation distribution of the minerals related to the flow direction and properly characterize older and/or eroded flows. In this work, the magnetic fabric from recent (Quaternary) lava flows (slightly inclined in seven si...

The characterization of the basement architecture of the Pyrenean Axial Zone, backbone of the chain, is crucial to understand its geodynamic evolution and the interplay between tectonism and magmatism. In this work, a new gravity-constrained cross section was built along the Central Pyrenees, between two of the largest Pyrenean Late Variscan granit...

Mountain glaciers have generally experienced an accelerated retreat over the last 3 decades as a rapid response to current global warming. However, the response to previous warm periods in the Holocene is not well-described for glaciers of the southern Europe mountain ranges, such as the Pyrenees. The situation during the Medieval Climate Anomaly (...

We introduce a field trip to the southwestern termination of the Pyrenean sole thrust: the Santo Domingo anticline. The field trip is articulated in three main stops with panoramic views. We pursue to emphasize some outstanding characteristics of this structure: (A) the large-scale progressive (laterally angular) unconformity that crops out in its...

Mountain glaciers have generally experienced an accelerated retreat over the last three decades as a rapid response to current global warming. However, the response to previous warm periods in the Holocene is not well-described for glaciers of the of southern Europe mountain ranges, such as the Pyrenees. The situation during the Medieval Climate An...

The propagation of the deformation front in foreland systems is typically accompanied by the incorporation of parts of the basin into wedge‐top piggy‐back basins, this process is likely producing considerable changes to sedimentation rates (SR). Here we investigate the spatial‐temporal evolution of SR for the Tremp‐Jaca Basin in the Southern Pyrene...

Geophysical surveying (both gravity and magnetic) is of great help in 3D modeling of granitic bodies at depth. As in any potential-field geophysics study, petrophysical data (density [r], magnetic susceptibility [k] and remanence) are of key importance to reduce the uncertainty during the modeling of rock volumes. Several works have already demonst...

Shear zones, or their counterparts in near-surface conditions, the brittle fault zones, constitute crustal-scale, narrow, planar domains where deformation is strongly localized. The variation with depth of deformation conditions (P-T), rheology and strain rates entails a wide range of fault rock types, characterized by different petrofabrics and cl...

The Jurassic carbonates of the Central High Atlas (CHA) are affected by a widespread and homogeneous chemical remagnetization. This is an interfolding remagnetization (dated in ca. 100 Ma by comparison with the GAPWP of the African plate) that separates two deformational events; the first one is related to the basinal period in the Atlas (Triassic...

The Atlas system, an ENE-WSW intracontinental chain in the NW of Africa, grew because of the inversion of Mesozoic extensional basins during the Cenozoic convergence between the African and European plates. The Central High Atlas (CHA) is located in the mid-western sector of the chain and is characterized by (i) the presence of an Upper Triassic dé...

New residual magnetic map is presented to help decipher the magnetic imprints in the Central High Atlas (CHA) fold-and-thrust belt. The total intensity map shows a main direction mimicking the N070 trend which features the Atlas range. Detailed structural and paleomagnetic studies performed in the selected area demonstrate that similar shortening f...

The aim of this work is to apply the anisotropy of magnetic susceptibility (AMS) to determine the primary and tectonic fabrics of lava flows and volcanoclastic materials in one of the Pyrenean Stephano-Permian basins. The Pyrenean Range is a double vergence orogen located at the northern end of the Iberian Peninsula. During Carboniferous-Early Perm...

Multiple constraints, including poorly known parameters, determine along-strike changes of frontal thrust structures in fold-and-thrust belts. Along the 400 km long, continuous Central Moroccan Atlas belt, structural style shows significant changes, preserving similar figures of shortening. This implies the absence of large-scale vertical-axes rota...

During the Paleogene and Neogene the NE Iberian plate underwent significant paleogeographic changes driven by the Iberian and European plate collision and the resulting formation of the Pyrenean orogen and its corresponding foreland basin. Shortening resulted in the advance of the orogenic wedge, emplacement of allocthonous units, and progressive b...

Resumen: En este trabajo se aplica el análisis de la anisotropía de la susceptibilidad magnética (ASM) con la finalidad de ayudar a descifrar la evolución mesozoica y cenozoica de un sector del Alto Atlas Central. El Atlas es la cadena intraplaca más importante del norte de África, resultado de una compleja evolución durante el Mesozoico y Cenozoic...

Resumen: Las cuencas sedimentarias invertidas con un importante apilamiento de sedimentos presentan frecuentemente remagnetizaciones muy intensas y ubicuas que, en la mayoría de los casos, sustituyen la magnetización primaria en áreas muy extensas. El Atlas es una cadena intracontinental generada por la inversión de cuencas extensionales mesozoicas...

Contractional deformation in the transition between the Iberian and Catalan Coastal Ranges (Linking Zone) generated both thin-skinned structures detached in low-strength Triassic units, and basement involved structures. To evaluate their extent and relative contribution to the overall structure, we carried out a study combining structural geology a...

During the Triassic, Iberia and western North Africa displayed a unique situation in relation with the Central and North Atlantic opening and westward expansion of the Tethys. Unravelling the stretching direction in Triassic deposits of the studied area can help in our understanding of this scenario. The tectonic setting is characterized by localiz...

Dating the sedimentary infill of the northern margin of the Ebro foreland basin informs about the orogen-basin evolution. A magnetostratigraphic section of ~5 km-thick combines new magnetostratigraphic results from the syntectonic alluvial Uncastillo Fm (Upper Oligocene-Lower Miocene, 1 km-thick, the Fuencalderas section) with previous (3.3 km-thic...

AMS and structural analysis are here applied to study the deformed zone associated with a large-scale, active normal fault in the central Betic Cordillera (Spain), namely the Baza fault system, to determine: i) the kinematics of structures and their relation with fault zone architecture and segmentation degree, ii) the correlation between deformati...

In the frame of the GEOPIRI3D Project (financed by the Spanish Ministry of Science, Innovation and University), two new gravity-constrained cross sections have been made. The goal of this study is to analyze the Axial Zone of the central part of the Pyrenees to better constrain the geometry of the basement host rocks and genesis of the Late Varisca...

Twenty chain-scale cross-sections (between 50 and 100 km long) in the Central High Atlas (between Demnate and Rich, Morocco) considering potential field data and constrained by means of paleomagnetism (paleodips for cross-section reconstruction) and AMS (anisotropy of magnetic susceptibility as an indicator of internal deformation) reveal the inter...

In this work we present the preliminary paleomagnetic results in the framework of an ambitious research project that is being carried out in the Central High Atlas (CHA). The Atlas is an intracontinental chain generated by the inversion of extensional Mesozoic basins due to the convergence between Africa and Europe during the Cenozoic. The deposits...

During the Triassic, Iberia and nearby areas of the North-African systems constituted the transition zone between the North Atlantic Ocean opening and the westernmost Tethyan realm. Unravelling the stretching direction (i.e. primary magnetic lineation) during this period can help to understand the tectonic setting of the studied area. In this work,...

In this work the analysis of the anisotropy of magnetic susceptibility (AMS) has been applied to decipher the Mesozoic and Cenozoic evolution of the Central High Atlas. The Atlas is the most important intraplate mountain range in North Africa, resulting from a complex evolution during the Mesozoic and the Cenozoic. Its evolution during the Mesozoic...

The Atlas system is an intracontinental inverted basin located in North Africa. After being subjected to the extensional stage in the Mesozoic, the basin was inverted during the Cenozoic due to the convergence between Africa and Europe. The Central High Atlas is located in the Moroccan Atlas and it is characterized by thick sequences of Jurassic ca...

Paleomagnetism is a technique very useful in structural geology providing that the rocks keep a stable record of the paleoearth magnetic field information. Paleomagnetism has been used in deciphering the evolution and geometry of orogens and extensional basins. The evolution of an orogen has many points of view, but the use of paleomagnetism allows...

Magnetic properties of rocks can be useful for determining paleoenvironmental changes. A dramatic climate change that occurred in the Paleocene-Eocene Thermal Maximum (PETM) modified the environment and, hence, the magnetic properties recorded in the sediments. New paleomagnetic data from marine records of the PETM in the Southern Pyrenean zone dis...

Of the several factors involved in the development of magnetic fabrics in fault zones at shallow crustal levels, lithology and deformation intensity have probably the most important conse- quences for the reconstruction of their kinematic history. The basement-involved Cenozoic thrusts in the Demanda Massif (N Spain) provide the opportunity for tes...

This work aims to characterize the Gavarnie thrust, one of the large-scale thrusts that defie the Alpine structure of the west-central sector of the Pyrenees. A detailed comparison of structural analysis and magnetic fabrics is carried out for the Paleozoic phyllonites of the Gavarnie thrust, in order to decipher strain distribution and transport d...

Deception island is one of the three most relevant Quaternary volcanic edifices in the northern Antarctic Peninsula region. The growth of the island is controlled by a main eruptive centre which configured a complete volcanostratigraphic sequence (Pre-, Syn- and Post-caldera stages). The final stages (historic eruptions) produced small cinder cones...

The structure of the Pyrenean Axial Zone laterally transitions from an imbricate thrust system to an antiformal stack displaying downward facing structures in its frontal part (the Nogueras zone). We carried out a paleomagnetic study through this structural transition to better constrain thrust kinematics and better define the factors controlling t...

Positive tectonic inversion of sedimentary basins has been recognized as one of the primary mechanisms of mountain building and intraplate deformation. Reconstructing the tectonic history of basins is relatively easy for the inversion stage but becomes more difficult for the basinal stage, especially when strong deformation involving cleavage devel...

The Quaternary volcanism in the Bransfield Basin, northern Antarctic Peninsula region is related to the extension of the back-arc basin and the former Phoenix Plate subduction and roll-back under the South Shetlands Block, combined with the eastward motion of the Scotia Plate along the South Scotia Ridge. The main and more active volcanic edifices...

The study of the magnetic fabric (AMS) is a quick and effective technique that allows to determine the rock fabric and, in a extensional context, the extension direction at local scale. In this work we present the results of structural analysis and AMS recorded in the Baza Fault, with the aim of characterizing the kinematics of the structure. Five...

Magnetic fabric allows to unravel the petrofabric of sedimentary rocks and to assess their deformational history. The use of this technique, in addition to classical structural field observations in the limbs of seven asymmetric folds in the Pyrenees, helps to determine the differences of internal deformation as well as the folding kinematics. Thre...

Sedimentological, geochemical and magnetic data in a ~ 7-m sequence from Marboré Lake (2612 m asl, central Pyrenees) provide information about environmental variability since the last glacier retreat (14.6 cal ka BP) in high-altitude Pyrenean environments. The sediment sequence is composed of millimeter- to centimeter-thick rhythmites made of finer...

The Pyrenean Chain has drawn an extensive attention which has produced a plethora of research papers and doctoral theses about the structure-sedimentation relationships, and in recent years, geophysical and geochemical techniques have allowed quantifying the processes active during the convergence of Iberian-Eurasian plates from late Santonian to M...

This paper presents the environmental, climate and vegetation changes reconstructed for the last 14.6 kyr cal BP from the Marbor? Lake sedimentary sequence, the highest altitude record (2612 m a.s.l.) in the Pyrenees studied up to date. We investigate the sensitivity of this high altitude site to vegetational and climate dynamics and altitudinal sh...

In this paper we report on a compilation of more than 2,200 sites (more than 10,000 individual measurements) where anisotropy of magnetic susceptibility (AMS) was studied in granite from the Variscan Pyrenees. The standardization and homogenization of this information has allowed us to produce three maps that synthesize all the information related...

This work deals with the application of the anisotropy of magnetic susceptibility (AMS), structural analysis and microstructural analysis to the study of shear zones. Mylonitized fault rocks have been sampled in the Gavarnie Trust, one of the main structures of the Pyrenean Axial Zone, which was structured as a south-verging antiformal stack during...

Major discontinuities in the Earth’s crust are expressed by faults that often cut across its whole thickness favoring, for example, the emplacement of magmas of mantelic origin. These long-lived faults are common in intra-plate environments and show multi-episodic activity that spans for hundred of million years and constitute first-order controls...

Thrusting at shallow depths often precludes analysis by means of structural indicators effective in other geological contexts (e.g., mylonites, sheath folds, shear bands). In this paper, a combination of techniques (including structural analysis, magnetic methods, as anisotropy of magnetic susceptibility and paleomagnetism, and paleothermometry) is...

The occurrence of a generalized remagnetization at 100 Ma makes the Cameros basin, a 8 km-thick Cretaceous extensional trough inverted during the Cenozoic, a perfect natural frame to apply paleomagnetic vectors to geometrical reconstructions. The widespread remagnetization that occurred between the extensional and the compressional episodes, linked...

We introduce a method and software to process demagnetization data for a rapid and integrative estimation of characteristic remanent magnetization (ChRM) components. The virtual directions (VIDI) of a paleomagnetic site are “all” possible directions that can be calculated from a given demagnetization routine of “n” steps (being m the number of spec...

Magnetic fabric studies in sedimentary rocks were firstly focused on strongly deformed tectonic contexts, such as fold-and-thrust belts. As measurement techniques were improved by the introduction of high-resolution equipments (e.g. KLY3-S and more recent Kappabridge susceptometers from AGICO Inc., Czech Republic), more complex tectonic contexts co...

This work describes several structures located in the northern limb of the Ait Attab syncline, Central High Atlas, Morocco. The studied structures consist of E-W trending folds affecting the marine terms of the Bajocian, constituted by an alternate sucession of marls and limestones and an angular unconformity of Bathonian sandy limestones above the...