Person:
Horra Del Barco, Raúl De La

First Name

Raúl De La

Last Name

Horra Del Barco

URI

https://hdl.handle.net/20.500.14352/75215

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Estratigrafía

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Now showing 1 - 10 of 26

Permian-Triassic continental rocks of the SE Iberian Ranges: Architecture, tectonics and geochemical characteristics in the context of a rift basin
(2011) López Gómez, Julián; Arche, A.; Horra Del Barco, Raúl De La; Galán-Abellán, B.; Fernández Barrenechea, José María
Paleoecological and paleoenvironmental changes during the continental Middle–Late Permian transition at the SE Iberian Ranges, Spain
(Global and planetary change, 2012) Horra Del Barco, Raúl De La; Galán Abellán, Ana Belén; López Gómez, José; Sheldon, N.D.; Fernández Barrenechea, José María; Luque del Villar, Francisco Javier; Arche, Alfredo; Benito Moreno, María Isabel
The Middle and Late Permian are characterized by a pair of mass-extinction events that are recorded in both marine and continental environments. Here, we present the first continental western peri-Tethyan record of an extinction event located in the Middle–Late interval. In the SE Iberian Ranges, Central Spain, the transition between the Lower and Middle subunits of the Middle Permian Alcotas Formation indicates a significant paleoclimatic change from arid and semiarid conditions towards more humid conditions. Coincident with the onset of humid conditions there were changes in the sedimentology, mineralogy, and geochemistry that indicate significant environmental changes including a shift in weathering intensity and a change of fluvial style from braided to meandering systems. Near the top of the Middle Subunit, a local biotic crisis is recorded by palynomorph assemblages. Following this crisis, there is a total absence of coal beds, plant remains, and microflora that defines a barren zone in the uppermost part of the Alcotas Formation which is recorded throughout the basin. The barren zone is accompanied by a shift back to braided stream systems, but not by a return to carbonate-bearing paleosols indicative of arid or semi-arid conditions. This combination of features is consistent with other Middle–Late continental basins related with mass extinctions, so the barren zone is interpreted as the extinction interval. The regional character of the extinction interval and its proximity with the Middle–Late Permian transition could be related with the global mid-Capitanian biotic turnover described in this period of time in other marine basins. However, the common difficulties of dating with precision non-marine rocks make this relationship difficult to probe in the Iberian Basin and in other Middle– Late Permian basins. Further work, including high resolution carbon-isotope analyses and complete studies of the magnetostratigraphy, should be desirable in order to obtain a better age constraint and to produce reliable comparisons with marine sections.
Palynostratigraphy of the Middle Triassic (Anisian) Eslida Formation, SE Iberian Ranges, Spain
(Palynology, 2018) Juncal Rosales, Manuel Antonio; Diez, José B.; Horra Del Barco, Raúl De La; Galán Abellán, Ana Belén; Borruel Abadía, Violeta; Fernández Barrenechea, José María
The Triassic record in the SE Iberian Ranges starts with two tecto-sedimentary units of continental origin in Buntsandstein facies: and Cañizar and Eslida Formations. The Eslida Formation always lies conformably on top of the Cañizar Formation and it grades upwards into overlying coastal mud flats, traditionally assigned to the Röt facies. In the past, accurate dating of the Eslida Formation was problematic because of its continental character, absence of datable fossil remains, and lithological similarities with Middle–Upper Permian rocks. Macroflora and fossilised vertebrate footprints in the Eslida Formation indicate an Anisian age (Middle Triassic). In this work, we date the Eslida Formation on the basis of a palynological assemblage. The precise dating of the Eslida Formation is essential in order to establish stratigraphical correlations with other units in the Iberian Ranges and to obtain palaeogeographical considerations on the rapid subsidence represented by the sedimentary record of this unit in the new NNE–SSE Middle Triassic rift developed in eastern Iberia.
Sedimentary evolution of the continental Early–Middle Triassic Cañizar Formation (Central Spain): Implications for life recovery after the Permian–Triassic crisis
(Sedimentary Geology, 2012) López Gómez, José; Galán Abellán, Ana Belén; Horra Del Barco, Raúl De La; Fernández Barrenechea, José María; Arche, Alfredo; Bourquin, Sylvie; Marzo Carpio, Mariano; Durand, Marc
The Permian–Triassic transition (P–T) was marked by important geochemical perturbations and the largest known life crisis. Consequences of this event, as oxygen-depleted conditions and the unusual behavior of the carbon cycle, were prolonged during the Early Triassic interval delaying the recovery of life in both terrestrial and marine ecosystems. Studies on Lower Triassic sediments of continental origin, as in the case of Western Europe, are especially problematic due to the scarcity of fossils and absence of precise dating. The Cañizar Fm. is an Early–Middle Triassic unit of continental origin of the SE Iberian Ranges, E Spain. A detailed sedimentary study of this unit allows a shedding of light on some unresolved problems of the continental deposits of this age. The top of this unit is dated as early Anisian by means of a pollen association, while the age of its base is here estimated as late Smithian or Smithian–Spathian transition. Different facies associations and architectural elements have been defined in this unit. In the western and central parts of the basin, this unit shows sedimentary characteristics of fluvial deposits with locally intercalated aeolian sediments, while in the eastern part there is an alternation of both aeolian and fluvial deposits. Sedimentary structures also indicate changes in the climate conditions, mainly from arid to semiarid. Two marked arid periods when well-preserved aeolian sediments developed during early–middle Spathian and Spathian–Anisian transition. They alternated with two semiarid but more humid periods during the late Spathian and early Anisian. These conditions basically correspond with the general arid and very arid conditions described for central–western European plate during the same period of time. The Ateca–Montalbán High, in the northern border of the study basin, must have represented an important topographic barrier in the western Tethys separating aeolian dominated areas to the N and NE from fluvial dominated areas to the south. The Cañizar Fm. has been subdivided into six members (A–F) separated by seven (1–7) major bounding surfaces (MBS). These surfaces are well recognized laterally over hundred of km and they represent 104–105 My. MBS-5 is considered to be of late Spathian age and it is a clear indication of tectonic activity, represented by a mild unconformity. This event represents a change in the sedimentary characteristics (reactivation) of the unit and from here to the top of the unit are found the first signals of biotic recovery, represented by tetrapod footprints, plants, roots and bioturbation. All of these characteristics and the estimated age represented by the MBS-5 event permit this surface to be related to the coeval Hardegsen unconformity of Central–Western Europe. These first signals of biotic recovery can thus be related to an increased oxygen supply due to the new created paleogeographical corridors in the context of this tectonic activity. These biotic signals occurred 5 My after the Permian–Triassic limit crisis; a similar delay as occurred in other coeval and neighboring basins.
Sources of Sr and S in Aluminum-Phosphate–Sulfate Minerals in Early–Middle Triassic Sandstones (Iberian Ranges, Spain) and Paleoenvironmental Implications for the West Tethys
(Journal of sedimentary research, 2013) Galán Abellán, Ana Belén; Alonso Azcárate, Jacinto; Newton, Robert J.; Bottrell, Simon H.; Fernández Barrenechea, José María; Benito Moreno, María Isabel; Horra Del Barco, Raúl De La; López Gómez, José; Luque del Villar, Francisco Javier
Aluminum-phosphate–sulfate (APS) minerals, formed during early diagenesis in relation to acid meteoric waters, are the main host of Sr and S in the Early–Middle Triassic continental sandstones of the Iberian Ranges (east of the Iberian Peninsula). The sources of these elements and the effects of paleoenvironmetal changes on these sources and on the formation of APS minerals during Early–Middle Triassic times, were established on the basis of Sr and S isotopic analyses. The S and Sr data (d34S V-CDT = +11 to +14% and 87Sr/86Sr = 0.7099–0.7247, respectively) can be interpreted as resulting from mixing of different sources. Strontium was sourced from the dissolution of pre-existing minerals like K-feldspar and clay minerals inherited from the source areas, causing high radiogenic values. However, the isotopic signal must also be influenced by other sources, such as marine or volcanic aerosol that decreased the total 87Sr/86Sr ratios. Marine and volcanic aerosols were also sources of sulfur, but the d34S was lowered by dissolution of pre-existing sulfides, mainly pyrite. Pyrite dissolution and volcanic aerosols would also trigger the acid conditions required for the precipitation of APS minerals. APS minerals in the study area are found mainly in the Cañizar Formation (Olenekian?–Aegian), which has the lowest 87Sr/86Sr ratios. The lower abundance of APS minerals in the Eslida Formation (Aegian–Pelsonian) may indicate change in the acidity of pore water towards more alkaline conditions, while the increased 87Sr/86Sr ratios imply decreased Sr input from volcanic activity and/or marine aerosol inputs during Anisian times. Therefore, the decrease in abundance of APS minerals from the Early to Middle Triassic and the variations in the sources of Sr and S are indicative of changes in paleoenvironmental conditions during the beginning of the Triassic Period. These changes from acid to more alkaline conditions are also coincident with the first appearance of carbonate paleosols, trace fossils, and plant fossils in the upper part of the Cañizar Formation (and more in the overlying Eslida Formation) and mark the beginning of biotic recovery in this area. The presence of APS minerals in other European basins of the Western Tethys (such as the German Basin, the Paris Basin and the southeastern France and Sardinia basins) could thus also indicate that unfavorable environmental conditions caused delay in biotic recovery in those areas. In general, the presence of APS minerals may be used as an indicator of arid, acidic conditions unfavorable to biotic colonization.
Shallow burial dolomitisation of Middle–Upper Permian paleosols in an extensional tectonic context (SE Iberian Basin, Spain): Controls on temperature of precipitation and source of fluids
(Sedimentary Geology, 2011) Benito Moreno, María Isabel; Horra Del Barco, Raúl De La; López Gómez, José; Fernández Barrenechea, José María; Luque del Villar, Francisco Javier; Arche, Alfredo
This work is focused on carbonate paleosols developed in three stratigraphic sections (Landete, Talayuelas and Henarejos) of theMiddle–Late Permian Alcotas Formation in the SE Iberian Basin. The Alcotas Formation, of alluvial origin, was deposited in semi-connected half-grabens developed during the early stages of the Permian–Triassic rifting stage that affected the Iberian Basin. The studied sections were located in two of these half-grabens, the Henarejos section being much closer to the basin boundary fault than the other two sections. The mineralogy and texture of the carbonate precursor of paleosols in the three studied sections are not preserved because original carbonate is replaced by coarse crystals of dolomite and/or magnesite. Dolomite crystals are typically euhedral, displaying rhombohedral shapes and reddish luminescence, although in the Henarejos section dolomite displays non-planar boundaries and frequently saddle habit. Micas are deformed and adapted to dolomite crystals, which, in turn, are affected by stylolites, suggesting that dolomite precipitated before mechanical and chemical compaction. Carbon and oxygen isotopic compositions of dolomite fromthe three sections showdifferent values (δ13CVPDB mean values=−6.7‰,−5.5‰ and −7.5‰; δ18OVPDB mean values=−4.0‰; –5.6‰and−8.2‰, at Landete, Talayuelas and Henarejos sections, respectively). The 87Sr/86Sr ratios are similar in the three sections yielding values between 0.71391 and 0.72213. The petrographic and geochemical features of dolomite in the three studied sections suggest precipitation fromsimilar fluids and during shallow burial diagenesis. Assuming that theminimum temperature for dolomite precipitation in the Henarejos sectionwas 60 °C (as suggested by the presence of non-planar saddle habit), and that the dolomitizing fluid had similar δ18O values at the three localities, then dolomite in the Talayuelas and Landete sections precipitated at temperatures around 16 and 25 °C cooler, respectively. In addition, the δ18OVSMOW values of the water from which dolomite precipitated would have ranged between −0.3 and −2.9‰. Dolomite is partially or totally replaced by non- to dark dull luminescent magnesite in the Landete and Talayuelas sections. Magnesite crystals are affected by stylolites, indicating that it precipitated before chemical compaction. The δ13C mean values are −6.5 and −6.0‰ and the δ18OVPDB mean values are −6.7 and −7.8‰, in the Landete and Talayuelas sections, respectively. The 87Sr/86Sr ratios of magnesite are similar in both sections yielding values between 0.71258 and 0.72508. This suggests that they probably precipitated from similar fluids during progressive burial and at higher temperatures than dolomites at the same sections. Assuming thatmagnesite precipitated froma fluid with similar δ18O values in both sections, then it had to precipitate at a temperature around 8 °C higher in Talayuelas than in the Landete section. Dolomitisation and magnesite precipitation probably occurred via reflux of saline to hypersaline brines from the overlying Mid-Late Triassic Muschelkalk and/or Keuper facies. The temperatures inferred for dolomite precipitation, however, are too high for shallow burial if a normal geothermal gradient is applied. Thus, it can be inferred that salinefluidswere heated as theyflowed through the syn-sedimentary extensional faults that controlledMiddle Permian to Middle Triassic sedimentation; consequently fluidswould have been at higher temperatures near the Henarejos area, which was closer to the basin boundary fault than at the Talayuelas and Landete areas, whichwere situated further away. This contention is in agreement with recent studies which demonstrate that an important thermal event took place during Late Triassic–Early Jurassic times in the Iberian Peninsula.
Sedimentology, clay mineralogy and palaeosols of the Mid-Carnian Pluvial Episode in E Spain: insights into humidity and sea-level variations
(Journal of the Geological Society, 2018) Barrenechea, José F.; López Gómez, José; Horra Del Barco, Raúl De La
This study examines rainfall variations of the Mid-Carnian Pluvial Episode (CPE) based on the continental fluvial sedimentology, palaeosol and clay mineralogy records of the Stable Meseta (E Spain). In the formation examined, Manuel Fm or K2 Fm, the CPE is represented by three regressive-transgressive sequences (R-T), or subunits K2.1, K2.2 and K2.3, from base to top. Each subunit broadly consists of a genetic stratigraphic sequence bearing well-developed highstand, lowstand and transgressive system tracts (HST, LST and TST). Hydromorphic features in the palaeosols suggest changes in the activity of both ground and surface waters. The clay mineral assemblage is dominated by illite, with a minor presence of kaolinite and traces of smectite in some samples. After ruling out tectonism in the study area, climate and eustatism emerge as the main allogenic controls in the sedimentary record. Differentiated sedimentary facies and architectural elements in the K2.2 subunit were likely controlled by both a more humid climate and source area, while K2.1 and K2.3 were more related to base-level changes and eustatic control. The presence of more waterlogged pedotypes and of kaolinite and traces of smectite in the clay mineral assemblage of K2.2 also indicates increased humidity. Notwithstanding, our data do not point to intense rainfall periods for the CPE in E Spain.
The beginning of the Buntsandstein cycle (Early–Middle Triassic) in the Catalan Ranges, NE Spain: Sedimentary and palaeogeographic implications
(Sedimentary geology, 2013) Galán Abellán, Ana Belén; López Gómez, José; Barrenechea, José F.; Marzo Carpio, Mariano; Horra Del Barco, Raúl De La; Arche, Alfredo
The Early–Middle Triassic siliciclastic deposits of the Catalan Ranges, NE Spain, are dominated by aeolian sediments indicating a predominance of arid climate during this time span, in sharp contrast with the coeval fluvial sediments found in the Castilian Branch of the Iberian Ranges, 300 km to the SW. The NE–SW-oriented Catalan Basin evolved during the Middle–Late Permian as the result of widespread extension in the Iberian plate. This rift basin was bounded by the Pyrenees, Ebro and Montalbán–Oropesa highs. The Permian–Early Triassic-age sediments of the Catalan Basin were deposited in three isolated subbasins (Montseny, Garraf, Prades), separated by intrabasinal highs, but linked by transversal NW–SE oriented faults. The three subbasins show evidence of diachronic evolution with different subsidence rates and differences in their sedimentary records. The Buntsandstein sedimentary cycle started in the late Early Triassic (Smithian–Spathian) in the central and southern domains (Garraf and Prades), with conglomerates of alluvial fan origin followed by fluvial and aeolian sandstones. Source area of the fluvial sediments was nearby Paleozoic highs to the north and west, in contrast with the far-away source areas of the fluvial sediments in the Iberian Ranges, to the SW. These fluvial systems were interacting with migrating aeolian dune fields located towards the S, which developed in the shadow areas behind the barriers formed by the Paleozoic highs. These highs were separating the subbasins under arid and semi-arid climate conditions. The dominating winds came from the east where the westernmost coast of the Tethys Sea was located, and periods of water run-off and fields of aeolian dunes development alternated. Some of the fluvial systems were probably evaporating as they were mixed into the interdune areas, never reaching the sea. From the end of the Smithian to the Spathian, the Catalan Basin and neighbour peri-Tethys basins of the presentday southern France, Sardinia andMinorca islands constituted a geographical archwhere arid and semi-arid conditions represented an extension of the prevailed arid and hyper-arid conditions in surrounding areas of the Variscan Belt. Harsh climatic conditions in this area prevented the life recovery in the aftermath of the Permian– Triassic extinction event until the early Anisian, when more humid climate allowed for the colonisation of the area by plants, amphibians and reptiles. The boundary between desert areas and semi-arid and/or seasonal climate domains during the Smithian–Spathian in SW Europe can be precisely established in NE Iberia, between the Catalan–Ebro region and the Castilian Branch of the Iberian Ranges, to the SW.
U-Pb Ages of Detrital Zircons from the Permo-Triassic Series of the Iberian Ranges: A Record of Variable Provenance during Rift Propagation
(The Journal of geology, 2012) Sánchez Martínez, Sonia; Horra Del Barco, Raúl De La; Arenas Martín, Ricardo; Gerdes, A.; Galán Abellán, Ana Belén; López Gómez, José; Fernández Barrenechea, José María; Arche, Alfredo
The provenance of the Permo-Triassic series of the Talayuelas anticline (Iberian Ranges) have been studied using UPb geochronology (laser ablation inductively coupled plasma mass spectrometry) of detrital zircons. These intracontinental siliciclastic series were formed by extensive sandy braided fluvial systems associated with ephemeral lake deposits and aeolian sediments, with paleocurrents suggesting constant NW-SE transport directions. Upper Permian reddish sandstones from the Upper Alcotas Formation (Lopingian) contain a dominant Variscan zircon population (290–360 Ma), which indicates source areas located in the axial zone of the Variscan belt, in the core of the Ibero- Armorican arc. However, in the Lower Triassic sandstones of the Canñizar Formation (Olenekian), the Variscan zircon population is almost completely replaced by Cadomian zircons (520–750 Ma), with important Avalonian (390–520 Ma), Mesoproterozoic (900–1750 Ma), Eburnian (1.78–2.35 Ga), and post-Eburnian and Archaean (12.4 Ga) zircon populations. This detrital zircon content now suggests source areas located more to the NW, in the Avalonian microcontinent, although a limited supply coming from the southern part of Laurentia cannot be ruled out. Finally, in the Middle Triassic (Anisian), the source areas returned to the Variscan axial zone, since the Variscan zircon population is again highly dominant during this period. The changes detected in the source areas of the Permo-Triassic series are related to the development and propagation of the Iberian rift, one of the large extensional structures that determined the generation of the sedimentary basins and finally caused the breakup of Pangea. The methodology followed in this article is very useful to understand the generation and evolution of these intracontinental basins and also the relationships between the different rift systems generated in the North Atlantic realm during the Permo- Triassic times.
First report of a Middle-Upper Permian magmatism in the SE Iberian Ranges: characterisation and comparison with coeval magmatisms in the western Tethys
(Journal of Iberian Geology, 2012) Fernández Barrenechea, José María; Benito Moreno, María Isabel; Lago San José, Marceliano; Galé, Carlos; López Gómez, José; Horra Del Barco, Raúl De La; Ubide Garralda, Teresa; Galán Abellán, Ana Belén; Arche, Alfredo; Alonso Azcárate, Jacinto; Luque del Villar, Francisco Javier; Timmerman, Martin J.
A multiple basic to intermediate sill is reported for the first time in the south-eastern Iberian Ranges. It is composed of several tabular to irregular levels intercalated within the fluvial sediments of the Alcotas Formation (Middle-Upper Permian). The sill could represent the youngest Paleozoic subvolcanic intrusion in the Iberian Ranges. The igneous rocks are classified as basaltic andesites. They show a subophitic microstructure constituted by plagioclase (An62 – An6), augite (En48Wo44Fs7 –En46Wo39Fs15), pseudomorphosed olivine, minor amounts of oxides (magnetite and ilmenite)and accessory F-apatite. According to the mineralogy and whole-rock composition, their geochemical affinity is transitional from subalkaline to alkaline. Radiometric dating of the sill is not feasible due to its significant alteration. Field criteria, however, suggest an emplacement coeval to the deposition of the Alcotas Formation (Middle-Upper Permian). This hypothesis is supported by the transitional affinity of these rocks, similar to other Middle-Upper Permian magmatisms in the western Tethys, e.g., from the Pyrenees. Taking into account their isotopic signature (εSr: -6.8 to -9.2; εNd:+1.7 to +8.3), an enriched mantle source with the involvement of a HIMU component has been identified. This interpretation is supported by the trace element contents. Some of these HIMU characteristics have been recognised in the Middle-Upper Permian magmatisms of the Central Pyrenees (Anayet Basin) and the High Atlas (Argana Basin). However, none of these source features are shared with other Middle-Upper Permian magmatisms of the western Tethys (Catalonian Coastal Ranges, Corsica-Sardinia and southern France), nor with the Lower Permian magmatism of the Iberian Ranges. These differences support the presence of a heterogeneous mantle in the western Tethys during the Permian.