Juan Jose Villalaín

Universidad de Burgos | UBU · Depatment of Physics

The Aïn Beni Mathar – Guefaït (ABM-GFT) region in Eastern Morocco is the object of anarchaeological, palaeontological, geological and geochronological research project, led by an interna-tional team since 2006. The research in this former fluvio-lacustrine basin, roughly 2000 km2, hasrevealed a significant number of Pleistocene and Holocene sites....

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...

Ornamental and construction stones are an intrinsic part of certain natural and cultural heritage (Brocx and Semeniuk, 2019). Studies to characterise their features and sources or their conservation are essential in order to undertake actions for their conservation and/or the restoration of emblematic buildings (Pereira y Marker, 2015). Moreover, t...

Here we report a detailed archaeomagnetic and rock-magnetic study of a pottery kiln from Burgos (Spain) to reconstruct its burning conditions and date its last use and abandonment age. During the course of a rescue archaeological excavation carried out in 2015 in the center of Burgos city, a medieval pottery workshop was discovered. Two well-preser...

The Eastern Galicia Magnetic Anomaly is the best studied anomaly of the Central Iberian Arc. This is due to its location, on the Lugo‐Sanabria gneiss dome, and to the fact that its source rocks crop out in the Xistral Tectonic Window. Multiple studies of this anomaly have been carried out, but still, new results keep on shedding light on its unders...

The Galería Complex is a cave sediment succession at the Atapuerca paleoanthropological site (Burgos, Spain) that offers detailed environmental information about the late Middle Pleistocene, especially the period between marine oxygen isotope stages MIS10 and MIS7. Previous studies have reconstructed the chronology and detailed the environmental de...

An archaeomagnetic, rock magnetic and magnetic fabric study has been carried out on seven anthropogenic ash horizons in the Middle Paleolithic sedimentary level XXIV at the rock shelter of Crvena Stijena ('Red Rock'), Montenegro. The study has multiple goals, including the identification of iron bearing minerals formed during combustion, assessment...

An archaeomagnetic, rock magnetic and magnetic fabric study has been carried out on seven anthropogenic ash horizons in the Middle Paleolithic sedimentary level XXIV at the rock shelter of Crvena Stijena ('Red Rock'), Montenegro. The study has multiple goals, including the identification of iron bearing minerals formed during combustion, assessment...

An archaeomagnetic, rock magnetic and magnetic fabric study has been carried out on seven anthropogenic ash horizons in the Middle Paleolithic sedimentary level XXIV at the rock shelter of Crvena Stijena (‘Red Rock’), Montenegro. The study has multiple goals, including the identification of iron bearing minerals formed during combustion, assessment...

The Small Circle (SC) tools analyse the stereographic tracks (small circles) followed by the palaeomagnetic vectors during folding processes. Working with interfolding and synfolding remagnetizations, the Small Circle Intersection (SCI) method allows finding the best solution of grouping that should correspond with the remagnetization direction. On...

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...

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...

The Atlas system is an ENE-WSW intracontinental chain that extends from Morocco to Tunisia. It is the result of the Cenozoic inversion of a set of intraplate extensional basins that started its development during the Triassic and continued during the Jurassic. The Central High Atlas (CHA) is located at the Moroccan part of the Atlas System, charact...

A detailed magnetic survey combined with the study of magnetic properties and spectral analysis in the Tusculum archaeological site (Alban Hills, Italy) indicates the existence of magnetic anomalies (total field and gradient, showing amplitudes up to thousands of nT) resulting from combined geological and archaeological features. In this paper we p...

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...

Archaeomagnetic and rock-magnetic methods are of great value in the identification of archaeological fire, especially in Palaeolithic sites where evidence is usually scarce, ambiguous or poorly preserved. Although taphonomic processes can significantly modify Palaeolithic combustion structures, the extent to which such processes affect the magnetic...

The Late Pliocene is a very interesting period as climate deteriorated from a warm optimum at ca. 3.3-3.0 Ma to a progressive climate cooling. Simultaneously, the Medi-terranean area witnessed the establishment of the Med-iterranean-type seasonal precipitation rhythm (summer drought). These important climate changes produced significant vegetation...

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...

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...

Fault zones constitute areas of high permeability where fluids and minerals interactions are frequent, involving the neoformation and alteration of protolith-inherited, ferromagnetic and paramagnetic minerals. This fact entails that fault zones are in most cases characterized by a heterogeneous mineralogy which hinders their study through magnetic...

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...

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...

The Eastern Galicia Magnetic Anomaly (EGMA) is a conspicuous feature of the aeromagnetic map of Iberia, which structurally overlaps the Lugo and Sanabria domes, two spatially linked late Variscan extensional structures that delineate a segment of the Ibero-Armorican Arc. In the northern part of the Lugo Dome, the Xistral Tectonic Window exposes a d...

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...

New paleomagnetic data (43 sites) from Mesozoic sediments are contributed in this work, verifying the presence of a pervasive syntectonic Early Cretaceous remagnetization in the easternmost area of the Moroccan High Atlas. Using the small circle intersection method, we have calculated the characteristic remagnetization direction (Dec: 337.3, Inc: 3...

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...

Magnetic properties of sedimentary rocks have been commonly exploited to determine the tectonic and chemical evolution of sedimentary basins. We here propose the use of the anisotropy of the anhysteretic remanent magnetization (ARM) to infer the orientation of magnetite grains formed during remagnetization stages, and hence to obtain the tectonic r...

Magnetic fabrics are usually studied to unravel the evolution of sedimentary basins, mainly focusing the attention in paramagnetic minerals. However, since basins are sometimes affected by burial-related chemical remagnetizations, magnetic fabrics can also be carried by authigenic ferromagnetic minerals related to remagnetization processes. Consequ...

A paleomagnetic and magnetic fabric study is performed in Upper Jurassic gabbros of the Central High Atlas (Morocco). These gabbros were emplaced in the core of pre-existing structures developed during the extensional stage and linked to basement faults. These structures were reactivated as anticlines during the Cenozoic compressional inversion. Ga...

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The identification of epsilon iron oxide (ε-Fe2O3) as the low Curie temperature high coercivity stable phase (HCLST) carrying the remanence in heated archaeological samples has been achieved in samples from two archaeological sites that exhibited the clearest evidence of the presence of the HCSLT. This uncommon iron oxide has been detected by Confo...

The Small Circle (SC) methods are founded upon two main starting hypotheses: (i) the analyzed sites were remagnetized contemporarily, acquiring the same paleomagnetic direction. (ii) The deviation of the acquired paleomagnetic signal from its original direction is only due to tilting around the bedding strike and therefore the remagnetization direc...

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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...

A useful tool to calculate remagnetization directions and/or to calculate the attitude of the bedding at the remagnetization acquisition time. A difference of incremental fold test, this methods can be used in asymmetric structures

Remagnetizations are common in intraplate basins. When remagnetizations occur at an intermediate stage between different tectonic processes, they can be used for paleo-geometrical reconstructions and relative dating of different structures. This has a particular interest in geological frameworks where other geological time markers are absent. In or...

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...

A paleomagnetic study has been carried out in the boundary between the Folded Middle Atlas and the Tabular Middle Atlas, around Skoura and Tighboula synclines and Boulemane anticline. The goal of this work is to test the existence of a remagnetization affecting the sedimentary rocks in this area. For this purpose different stability tests were done...

Resumen: Se tomaron muestras de 16 lavas dacíticas y riolíticas de edad paleógena y cretácica cerca de la ciudad de Bolnisi, en el sur de la República de Georgia con dos objetivos: (i) Obtener nuevos resultados paleomagnéticos para la región del Cáucaso y (ii) aportar nuevos datos de paleointensidad correspondientes a unos periodos, el Cretácico y...

Resumen: Se estudia la anisotropía de la susceptibilidad magnética (ASM) en unidades de la cuenca de Cameros (NO Cordillera Ibérica) depositadas en las últimas etapas del rifting del Jurásico superior-Cretácico inferior (Grupos Enciso y Oliván, de edad Aptiense-Albiense), en afloramientos localizados cerca del borde NE del macizo. Los portadores ma...

Abstract: Since the last 40 years the analysis of remagnetized carbonates is under debate, by studying their magnetic properties and by using electronic microscopy (SEM/TEM). Results obtained from the first analyses allowed to infer that remagnetization is carried generally by nanometric magnetite and generated during the diagenesis, therefore it c...

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Las facies continentales de la Cuenca de Tremp contienen uno de los abundantes registros con vertebrados continentales del final del Cretácico en Europa. Esta área de los Pirineos es un lugar excepcional para estudiar la extinción de los vertebrados continentales en el límite Cretácico-Paleógeno (K-Pg) al ser uno de los pocos lugares de Europa con...

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Archaeomagnetic dating based on the full geomagnetic field vector was carried out on a limekiln excavated at Pinilla del Valle archaeological site (Madrid, Spain). The limekiln tradition in this area is largely documented by historical sources for recent centuries but the date of the studied kiln's last use was unknown. The combination of mean arch...

In this work we present the results of the application of Anisotropy of Magnetic Susceptibility (AMS) to structural analysis in a sector of the Central High Atlas (Morocco). The studied sedimentary sequences comprise marly limestones and calcareous marls, having medium to high susceptibility values in most sites. The obtained magnetic fabrics (aver...

Archaeomagnetic dating is probably one of the most known applications of magnetic methods to archaeology but there are others still underutilized and of particular interest to Palaeolithic archaeology. Here, we report a novel application of archaeomagnetism as a technique to determine temporal diachronies among combustion features from the same sur...

The steeply-dipping, dolostone-hosted caves of the Sierra de Arnero (N Spain) contain low-gradient relict canyons with up to ten mapped levels of ferromanganese stromatolites and associated wall notches over a vertical range of 85 m, the highest occurring ~ 460 m above base level. Despite a plausible speleogenetic contribution by pyrite oxidation,...

New magnetic fabric data from 48 sites in Upper Triassic red beds from the Argana, Asni and Tizi n’Tichka areas in the western High Atlas, in combination with rock magnetic analyses, SEM observations and qualitative chemical analyses, reveal that mineralization processes can affect the primary (extensional) or secondary (post-depositional) magnetic...

A paleomagnetic and rock magnetic study has been carried out on 16 dacitic and rhyolitic lavas of Cretaceous and Paleogene age to find out their suitability for absolute paleointensity determinations. Experiments were aimed to obtain information about the characteristics of the remanence recorded in the lavas, to find out the carriers of remanence...

Paleomagnetism and rock magnetism experiments were carried out on the Pliocene Apnia sequence. This sequence consists of basaltic flows with K-Ar ages between 3.70 ±0.20 and 3.09 ±0.10 Ma, and is located in the western Djavakheti Highland, one of the most important volcanic regions of the Lesser Caucasus. Previous paleomagnetic studies on different...

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Palaeomagnetic data, and specifically remagnetizations, are used to constrain the geometric reconstruction at 100 Ma of three anticlines cored by gabbroic intrusions and Triassic shales in the Central High Atlas, Morocco. Previous palaeomagnetic results have revealed that the Mesozoic sediments of this region acquired a pervasive remagnetization at...

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