Magnetic properties of the detrital deposit of the Granite Cave (Bujaruelo Valley, Central Pyrenees)

En este trabajo se presentan las propiedades magnéticas analizadas en el depósito detrítico de la Cueva del Granito localizada en el valle de Bujaruelo, Zona Surpirenaica. La cueva, con un desarrollo pseudo-horizontal se abre en materiales carbonatados de edad Paleoceno-Eoceno. Dentro, aparecen diversos depósitos internos de origen químico como estalagmitas (la más antigua datada 153.6 +/- 1.2 ka, MIS6, Bartolomé et al., 2021), coladas y banderas, destacando los depósitos de la secuencia detrítica de 60 m que aparecen a lo largo de toda la cavidad. Los sedimentos están formados principalmente por arcillas, limos y arenas finamente laminados, y se diferencian tres tipos diferentes de facies, backswamps, slackwater y channel, relacionadas con los procesos de llenado y vaciado de la cavidad en respuesta a la fusión de la nieve o a precipitaciones en el pasado. Entre las estructuras sedimentarias destacan los limos finamente laminados, estratificaciones cruzadas, climbing ripples y estructuras de licuefacción, estas últimas, ligadas probablemente al aumento de carga hidrostática debido al llenado con agua de la cavidad. La concentración de los minerales ferromagnéticos varía a lo largo de la serie, disminuyendo en la parte alta. El mineral predominante parece ser magnetita (curvas termomagnéticas), aunque los valores del S-ratio indican la presencia de mineral de alta coercitividad (goetita y/o hematites). La relación de las propiedades magnéticas con el tipo de material y la información geoquímica disponible, permitirá determinar las implicaciones paleoambientales de dichos parámetros magnéticosThis work presents the magnetic properties analyzed in the detrital deposit of the Granito Cave, located in the Bujaruelo Valley, Southpyrenean Zone. The cave has a sub-horizontal development in carbonatic rocks of Paleocene-Eocene age. Inside, there are different deposits of chemical origin as stalagmites (the oldest is dated as 153.6 +/- 1.2 ky, MIS6, Bartolomé et al., 2021), flows and flags and a detrital sequence of 60m along the whole cavity. The sediments are mainly composed by clays, silts and sands and are finely laminated. Three main facies are observed, backswamps, slackwater and channel, related to the processes of cut and fill in response to the snow melt or precipitations. Among the sedimentary structures there are horizontal laminations, cross-bedding laminations, climbing ripples, and liquefaction structures, the last ones probably linked to the increase in the hydrostatic charge. The concentration of the ferromagnetic minerals varies along the sedimentary sequence, diminishing towards the top. The main carrier seems to be magnetite (results of the thermomagnetic curves), but the values of the S-ratio indicate the presence of a high coercivity mineral too (goethite and/ or hematite). The relationship of the magnetic properties with the geochemical information will help determine the paleoenvironmental implications of those magnetic parameter

Magnetoestratigrafía del Eoceno inferior y medio en el frente Surpirenaico (Sierras Exteriores): implicaciones cronoestratigráficas y cinemáticas

Esta tesis describe un trabajo centrado en la aplicaciones de técnicas paleomagnéticas con el fin de abordar diferentes problemáticas y enfoques estructurales en la parte central y oriental de las Sierras Exteriores de la Cuenca surpirenaica (del Pirineo Alto aragonés). Se presenta la adquisición un conjunto robusto y denso de nuevos datos magnetoestratigráficos a lo largo de casi 2 Km de serie en facies marino someras, principalmente de las Formaciones Boltaña y Guara con la finalidad de aportar una nueva cronología en la cuenca para el Cuisiense y Luteciense. Se presentan un conjunto significativo de datos bioestratigráficos para recalibrar de las biozonas de macroforaminíferos bentónicos involucradas. También se presenta un apartado de estudio de desarrollo metodológico de modelos numéricos y un caso de estudio que aborda en problema de solapamiento de componentes paleomagnéticas. Fuente de error que afecta los valores y estabilidad de los datos paleomagnéticos y que gracias a este estudio puede ser cuantificable y abordable. Finalmente, un estudio de generación de datos robustos y de calidad para el control de cinemática de la estructura del anticlinal de Balzes y alrededores del entorno de Arguis permite develar el origen mixto de la curvatura del pliegue y acotar etapas de plegamiento y rotación para las zonas de estudio. Estos aspectos en conjunto aquí desarrollados, aportan gran cantidad de datos de muy buena calidad y representan una aportación innovadora y significativa para el Eoceno inferior y medio de la Cuenca surpirenaica occidental

The chronology and rotational kinematics in the South-Eastern Jaca Basin (Southern Pyrenees): Las Bellostas section

Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The significant difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Pico del Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust

The chronology and rotational kinematics in the South-Eastern Jaca Basin (Southern Pyrenees): Las Bellostas section

Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm. can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm. (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The important difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Picodel Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust

The chronology and rotational kinematics in the South-Eastern Jaca Basin (Southern Pyrenees): Las Bellostas section

Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm. can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm. (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The important difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Picodel Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust

Remagnetización alpina en la Serra del Cadí (Pirineo Oriental)

The eastern Pyrenees, particularly the Cadi Range, displays the less density and quality of paleomagnetic data of the chain. This paper revisited one of the central sections (Pobla de Lillet) where we have resampled Permian, Maastrichtian and Paleocene rocks. Best results were attained in the Permian red sandstones and in the Cretaceous limestones. In the Permian, two components with paleomagnetic meaning were identified. The high temperature component (up to 670 ° C) is similar to that defined in pioneering works, it appears to be primary and does not show significant rotations. The intermediate temperature component (up to 500 ° C), not identified in previous works, seems to be a syntectonic remagnetization with Alpine age. The characterization of rotations and the extension of this remagnetization (as an additional source of kinematics information) should be addressed in Permian rocks in future works since the paleomagnetic signal of Cenozoic rocks is of lower qualityTrabajo financiado con los Proyectos Pmag3Drest-CGL2009-14214 y DR3AM- CGL2014-55118 del MINECO y del 3DR3- PI165/09 del Gobierno de Aragón.Peer Reviewe

The chronology and rotational kinematics in the South-Eastern Jaca Basin (Southern Pyrenees) : Las Bellostas section

Acknowledgement. This paper represents our modest tribute to Pep Serra-Kiel for his inspiring work, his sharp intelligence, his working tenacity, his always fruitful discussions and his camaraderie and friendship. This work was financed by the Sobrarbe County Research fellow-UNESCO Global Geopark (ARP) and by some projects from the Spanish Science National Plan (UKRIA4D- PID2019--I00/CTA, DR3AM. CGL2014 54118-C2-2-R and MAGIBER-II. CGL2017-90632-REDT). We are also very grateful to the laboratories of the universities of Burgos (Juanjo Villalaín) and Zaragoza (Teresa Román and Sylvia Gracia), Sergio Arruej Gil for the field support and Pablo Calvin and Vicky Burriel for the Burgos logistic support. Very warm acknowledged is given to Alejandro and Pablo from "Casa Molinero" in Las Bellostas for their hospitality, friendship and human warmth during all these years. Finally, we sincerely acknowledge the thorough and constructive reviews done by Miguel Garcés, Josep Tosquella and the editor Carles Martín-Closas.Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm. can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm. (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the W-E and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The important difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Picodel Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational activity seems to follow a linear and continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) in contrast to closer structures that show two distinct rotational velocities (i.e. Boltaña). These new data still let open the debate on the rotational kinematics along the South Pyrenean basal thrust

Systematics of Lutetian larger foraminifera and magneto-biostratigraphy from the South Pyrenean Basin (Sierras Exteriores, Spain)

A systematic description of the Eocene larger foraminifera recorded in the South Pyrenean Basin (Sierras Exteriores) is presented herein. The large dataset provided in this work includes Nummulites and Alveolina species, along with a variety of other porcellaneous and hyaline taxa with lesser biostratigraphic relevance. Most of the larger foraminifera described in this work correspond to the Lutetian (SBZ13 to SBZ16 biozones) interval, but late Ypresian (SBZ11, Cuisian) and early Bartonian (SBZ17) shallow benthic zones have also been identified. A new species, Idalinaosquetaensis, is described. The systematic revision of middle to late Lutetian alveolines led to a reassessment of Alveolinafusiformis and the finding of two new precursor forms, described as Alveolina aff. fragilis and Alveolina aff. elongata. The new taxa fill in the gap existing so far in the middle to late Lutetian alveolinid biostratigraphy. Despite not being exclusive to SBZ16, these forms provide realiable biostratigraphic information in facies where Nummulites are not present. This realibility lies on the correlation of Nummulitesand Alveolina biostratigraphic markers in the same sections and their calibration to the global time scale through magnetostratigraphy. Magnetostratigraphic calibration of described taxa is provided, along with an update of the SBZ calibration to the Geological Time Scale (Gradstein et al., 2012).&nbsp

Systematics of Lutetian larger foraminifera and magneto-biostratigraphy from the South Pyrenean Basin (Sierras Exteriores, Spain)

An extense systematic description of the Eocene larger foraminiferal faunas recorded in the South Pyrenean Basin (Sierras Exteriores) is presented herein. The large dataset provided in this work includes both Nummulites and Alveolina species, along with a variety of other porcellaneous and hyaline taxa with lesser biostratigraphic relevance, are represented. The larger foraminifera described in this work correspond mainly to the Lutetian (SBZ13 to SBZ16 biozones) interval, but late Ypresian (SBZ11, Cuisian) and Bartonian (SBZ17) shallow benthic zones have also been identified. As one of the most relevant results of this systematic analysis, a new species, Idalina osquetaensis, is described. The systematic revision of middle to late Lutetian alveolines led to a reassessment of A. fusiformis and the finding of two new precursor forms, described as affinis of their corresponding species, A. aff. fragilis and A. aff. elongata. The new forms A. aff. elongata and A. aff. fragilis fill the gap in the middle to late Lutetian alveolinid biostratigraphy. Despite not being exclusive to SBZ16, these new forms provide realiable biostratigraphic information where Nummulites are not present. This realibility lies on the correlation of Nummulites and Alveolina biomarkers in the same sections and their calibration to the global time scale through magnetostratigraphy. In fact, magnetostratigraphic calibration of all described taxa is also provided, along with an update of the SBZ calibration to the current Geologic Time Scale (Gradstein et al., 2012)

The early/middle Eocene transition at the Ésera valley (South Central Pyrenees): Implications in Shallow Benthic Zones (SBZ)

An integrated study including magnetostratigraphy, larger benthic foraminifera and calcareous nannofossil biostratigraphy is presented herein. This work was performed in shallow marine siliciclastics rich in larger foraminifera, around the Ypresian/Lutetian boundary in the Ésera valley (South-Central Pyrenees). Although the calcareous nannofossil content in the studied interval is low, not allowing a precise Y/L boundary to be recognised, the taxa found are enough to support the chronostratigraphic attribution. Data obtained in the Ésera valley section has improved the knowledge of larger benthic foraminifera (Nummulites and Assilina) distribution through chron C21. SBZ 11 to SBZ 12 transition took place at the lowermost C21r, as shown in previous works. SBZ 12 assemblages extend into C21n, where the SBZ 12 to SBZ 13 boundary occurs. These data, obtained in shallow marine siliciclastic facies, with in situ fauna, results in a shift of the SBZ 12/SBZ 13 boundary to the Lower Lutetian, younger than previously believed. Accordingly, the Ypresian/Lutetian boundary occurs in SBZ 12