Person: Horra Del Barco, Raúl De La
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First Name
Raúl De La
Last Name
Horra Del Barco
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Estratigrafía
Identifiers
12 results
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Item 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 MaríaThe 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.Item The Anisian continental-marine transition in Sardinia (Italy): state of the art, new palynological data and regional chronostratigraphic correlation(Journal of iberian geology, 2022) Stori, L.; Diez, J. B.; Juncal Rosales, Manuel Antonio; Horra Del Barco, Raúl De La; Borruel Abadía, Violeta; Martín Chivelet, Javier; Fernández Barrenechea, José María; López Gómez, José; Ronchi, AusonioThe scarce evidence of paleontological records between the upper Permian and the Anisian (Middle Triassic) of Western Europe could reflect (1) large stratigraphic gaps in the continental successions and/or (2) the persistence of disturbed conditions after the Permian–Triassic Boundary extinction event and the succession of ecological crises that occurred during the Early Triassic. In this context, the study of palynological associations, integrated with the stratigraphical and sedimentological data, plays a key role in dating and correlating the successions of the Western European domain and improves our understanding of environmental and paleoclimatic conditions. In some cases, pre-Anisian paleontological evidence is lacking, as in Sardinia (Italy), where a long gap encompasses the middle Permian (pars) to late Lower Triassic successions. Although fragmented and disseminated, the continental Lower-Middle Triassic sedimentary successions (Buntsandstein) of Sardinia have proved crucial to our understanding of the evolution of the southern edge of the Paleo-Europe and the different timings of the Tethys transgression (Muschelkalk facies) in some of these areas. Various paleogeographic reconstructions were attempted in previous works, without providing any consensus on the precise position of Sardinia and its surrounding seaways in the Western Tethys domain during this time interval. At present, the configuration and distribution of the subsiding and emerging landmasses and the temporal development of the transgressions of the Western Tethys during the Middle Triassic remain unclear. This work focuses on the stratigraphical, sedimentological and palynological aspects of three Middle Triassic continental-marine sedimentary successions in Sardinia, with particular attention to the analysis of the palynological associations sampled there, and it also provides a detailed review of all previous palynological publications on the Sardinian Anisian. The studied successions are: Su Passu Malu section (Campumari, SW Sardinia), Arcu is Fronestas section and Escalaplano section (Escalaplano, Central Sardinia). These sections were also correlated to other significant sections in the SW (Scivu Is Arenas) and NW (Nurra) parts of the island.Item Transition between Variscan and Alpine cycles in the Pyrenean-Cantabrian Mountains (N Spain): Geodynamic evolution of near-equator European Permian basins(Global and Planetary Change, 2021) Lloret, Joan; López Gómez, José; Heredia, N.; Martín González, Fidel; Horra Del Barco, Raúl De La; Borruel Abadía, Violeta; Ronchi, Ausonio; Fernández Barrenechea, José María; García-Sansegundo, Joaquín; Galé, Carlos; Ubide, Teresa; Gretter, Nicola; Diez, José B.; Juncal Rosales, Manuel Antonio; Lago, MarcelianoIn the northern Iberian Peninsula, the Pyrenean-Cantabrian orogenic belt extends E-W for ca. 1000 km between the Atlantic Ocean and Mediterranean Sea. This orogen developed from the collision between Iberia and Eurasia, mainly in Cenozoic times. Lower-middle Permian sediments crop out in small, elongated basins traditionally considered independent from each other due to misinterpretations on incomplete lithostratigraphic data and scarce radiometric ages. Here, we integrate detailed stratigraphic, sedimentary, tectonic, paleosol and magmatic data from well-dated lithostratigraphic units. Our data reveal a similar geodynamic evolution across the Pyrenean-Cantabrian Ranges at the end of the Variscan cycle. Lower-middle Permian basins started their development under an extensional regime related to the end of the Variscan Belt collapse, which stars in late Carboniferous times in the Variscan hinterland. This orogenic collapse transitioned to Pangea breakup at the middle Permian times in the study region. Sedimentation occurred as three main tectono-sedimentary extensional phases. A first phase (Asselian-Sakmarian), which may have even started at the end of the Carboniferous (Gzhelian) in some sections, is mainly represented by alluvial sedimentation associated with calc-alkaline magmatism. A second stage (late Artinskian–early Kungurian), represented by alluvial, lacustrine and palustrine sediments with intercalations of calc-alkaline volcanic beds, shows a clear upward aridification trend probably related to the late Paleozoic icehouse-greenhouse transition. The third and final stage (Wordian-Capitanian) comprised of alluvial deposits with intercalations of alkaline and mafic beds, rarely deposited in the Cantabrian Mountains, and underwent significant pre- and Early Mesozoic erosion in some segments of the Pyrenees. This third stage can be related to a transition towards the Pangea Supercontinent breakup, not generalized until the Early/Middle Triassic at this latitude because the extensional process stopped about 10 Myr (Pyrenees) to 30 Myr (Cantabrian Mountains). When compared to other well-dated basins near the paleoequator, the tectono-sedimentary and climate evolution of lower-middle Permian basins in Western and Central Europe shows common features. Specifically, we identify coeval periods with magmatic activity, extensional tectonics, high subsidence rates and thick sedimentary record, as well as prolonged periods without sedimentation. This comparison also identifies some evolutionary differences between Permian basins that could be related to distinct locations in the hinterland or foreland of the Variscan orogen. Our data provide a better understanding of the major crustal re-equilibration and reorganization that took place near the equator in Western-Central Europe during the post-Variscan period.Item Gradual changes in the Olenekian-Anisian continental record and biotic implications in the Central-Eastern Pyrenean basin, NE Spain(Global and Planetary Change, 2020) Lloret, Joan; Horra Del Barco, Raúl De La; Gretter, Nicola; Borruel Abadía, Violeta; Fernández Barrenechea, José María; Ronchi, Ausonio; Diez, José B.; Arche, Alfredo; López Gómez, José TrinidadThis work focuses on the Olenekian-Anisian (Early-Middle Triassic) continental record of the Central-Eastern Pyrenean basin (NE Spain), a near-equator (10°-14°N) basin located in the western peri-Tethys margin, inside the Variscan fold-belt. Due to the mass mortality of the end-Permian and the subsequent Smithian-Spathian Boundary (SSB) crisis, the Early Triassic and its transition to the Middle Triassic was a time period with intermittent stages of environmental instability that affected fauna and flora intensely. Compared to other crisis, a remarkable feature is the longer time required to achive life recovery during this time-interval and the fact that continental environments have been less globally studied than their marine counterparts. Furthermore, in SW Europe there is almost no sedimentary continental record from the beginning of the Triassic. This multidisciplinary study, embracing sedimentology, mineralogy, palaeontology, palaeopedology and palaeogeography, of 10 complete and well dated Early-Middle Triassic field sections has allowed (1) the location and characterization of the oldest Mesozoic sedimentary record in the basin, which is of late Smithian age and overlies the late-middle Permian continental rocks and of (2) the Smithian-Spathian transition (SST), (3) the timing of life recovery during the late Spathian-Anisian, (4) the characterization of the first incursion of the Tethys sea into the basin, and (5) the comparison of the evolution of this basin with other basins of the same age in SW Europe. The SST coincides with hyper-arid climate conditions, evolving to semi-arid in the late Spathian and semi-arid to semi-humid in Anisian times. Poorly sorted breccias and conglomerate alluvial sheets with aeolian reworking dominate the SST, as a result of these environmental changes and tectonicsA broader comparison, based on stratigraphic studies by other authors, indicates less aridity in the basin studied compared to other SW Europe basins in the same period, maybe due to its greater proximity to the equator. Sedimentary characteristics changed during the late Spathian, when sandy braided fluvial systems developed and the first dispersed plants, pollen assemblages and paleosols appeared. Well-developed floodplains and associated paleosols and plants developed during the early Anisian, when more humid conditions prevailed. The occurrence of aluminium phosphate-sulphate (APS) minerals might be considered as evidence of environmental acidification during the Olenekian with an amelioration during the early Anisian, as described in neighboring basins, although in the Pyrenean basin this acidification was probably less intensive. The first incursion of the Tethys sea reached the Central-Eastern Pyrenean basin during the Anisian-Ladinian transition, about 3 My later than in neighbouring Southwestern Europe basins. General comparison with other Early-Middle Triassic continental records of Western Europe basins indicates contrasting trends of climate and sedimentary evolution, probably related to the still prevailing great paleorelief of the Variscan foldbelt, where part of the study basin could constitute an elevated area during some time-intervals, possibly related to the so-called Ebro High.Item Impact of Permian mass extinctions on continental invertebrate infauna(Terra Nova, 2021) Buatois, Luis A.; Borruel Abadía, Violeta; Horra Del Barco, Raúl De La; Galán Abellán, Ana Belén; Fernández Barrenechea, José María; Arche, AlfredoThe Capitanian (late middle Permian) and end‐Permian mass extinctions were particularly severe from a palaeoecological perspective. Previous studies of their expressions on land underscored their impacts on plants and vertebrates, but the effects on the continental invertebrate infauna remain poorly understood. A multiproxy analysis from the Iberian Basin (Central Spain) reveals a dramatic decrease in bioturbation intensity on land by the end of the Capitanian. This pattern cannot be explained by facies effects because our analysis is based on similar types of deposits through the succession and over an extensive area. The bioturbation crisis coincided with an increase in weathering intensity and acidic conditions, and a collapse in plant communities spanning the late Permian–Early Triassic in the Iberian Basin. Reduced bioturbation may have contributed to decrease in mechanical reworking of the sediment and soil, affected geochemical recycling, increased sediment acidification and impacted on ecosystem structure. Identification of this infaunal crisis on land underscores the ecological severity of mass extinctions and emphasises the significance of feedback loops in riparian ecosystems.Item Geochemical markers of paleoenvironments, weathering, and provenance in Permian–Triassic terrestrial sediments(Journal of Sedimentary Research, 2020) Galán Abellán, Ana Belén; Fernández Barrenechea, José María; Horra Del Barco, Raúl De La; Alonso Azcárate, Jacinto; Luque del Villar, Francisco Javier; Borruel Abadía, Violeta; López Gómez, JoséThis study compares several geochemical factors (major and minor rare earth elements, Ti/Al ratios, and chemical index of alteration, CIA, values) in the Early Triassic Cañizar Formation (Fm) (Buntsandtein facies) of E Iberia with those of adjacent Middle Permian and Middle Triassic units (Alcotas and Eslida fms, respectively). According to significant differences detected, it seems that most geochemical perturbation occurred during the Early Triassic. Variations in Ti/Al ratios suggest changes in source areas between the studied units and even within the Cañizar Fm. These provenance changes correlate with successive tectonic pulses during the opening and development of the Iberian Basin, as they can be linked to major sedimentary surfaces and unconformities, as well as major sedimentological variations. Ti enrichment in the lower and middle part of the Cañizar Fm, together with high Sr and P concentrations, may be indicative of environmental alterations related to acid meteoric waters. Moreover, this acid alteration took place under arid conditions as reflected by CIA values, indicating that during the deposition of the Cañizar Fm, variable but predominantly physical weathering prevailed in contrast to the chemical weathering that took place when the Alcotas and Eslida formations were deposited. Our data along with the known fossil record of the study area indicate that during the Middle–Late Permian and Early Triassic, conditions in this tectonically active area changed from humid to arid-acid, hampering biotic recovery. Then, during late Early–Middle Triassic times, the return of more humid and less acid environments promoted biotic development. Geochemical markers emerged as useful tools complementary to sedimentological, paleontological, and tectonic data for unveiling paleoenvironmental events, especially in a setting of significant regional change.Item Palynostratigraphy of the Middle Triassic (Anisian) Eslida Formation, SE Iberian Ranges, Spain(Palynology, 2017) Fernández Barrenechea, José María; Juncal, Manuel; Horra Del Barco, Raúl De La; Borruel Abadía, Violeta; Arche, Alfredo; López-Gómez, José; Diez, José BThe 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 consists of sandstone bodies intercalated with thick, red siltstone beds. Where this unit is presented, it lies always conformably layers 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 has been sometimes 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 concordance with its stratigraphic position, as both the underlying and overlying units are also Anisian in age. In this work, we date the Eslida Formation on the basis of a palynological assemblage, obtained from a locality near the city of Teruel (SE Iberian Ranges), that includes: Alisporites grauvogeli, Alisporites oppii, Calamospora tener, Concentricisporites neversii, Cyclotriletes oligogranifer, Hexasaccites muelleri, Illinites kosankei, Lunatisporites noviaulensis, Punctatisporites fungosus and Voltziaceaesporites heteromorpha. This palynological association suggests an Anisian age, more precisely a period of time close to the Bithynian-Pelsonian transition. 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 paleogeographical considerations on the rapid subsidence represented by the sedimentary record of this unit in the new N.NE-S.SE Middle Triassic rift developed in eastern Iberia.Item Quantifying aluminium phosphate–sulphate minerals as markers of acidic conditions during the Permian–Triassic transition in the Iberian Ranges, E Spain(Chemical geology, 2016) Borruel Abadía, Violeta; Fernández Barrenechea, José María; Galán Abellán, Ana Belén; Alonso Azcárate, Jacinto; Horra Del Barco, Raúl De La; Luque del Villar, Francisco Javier; López Gómez, JoséIn this paper, a method based on element mapping of randomly selected areas of thin sections on electron microprobe is proposed to quantify the relative contents of strontium-rich hydrated aluminium phosphate-sulphate (APS) minerals in siliciclastic continental sedimentary rocks. The main problems for these minerals to be quantified are related to their small size, low concentrations, and optical properties. By comparing the element maps obtained for the rocks in the study area of the Iberian Ranges (E Spain) with the results of whole rock analysis and with factors indicating the presence of life (bioturbation, palaeosols, and macro-plant remains), it has been possible to correlate relatively high levels of APS minerals in the first sedimentary record (Cañizar Formation) after the Permian–Triassic boundary, with the lack of living organisms. The APS are related to early diagenetic phases precipitated at low pH conditions and are therefore markers of formation in an acidic environment. Our findings suggest a long period of sustained acidic conditions followed by an environmental change linked with the recovery of life and with lower APS mineral contents. This change is detected at the top of the Cañizar Formation, at the end of the Sphatian. The method proposed could be used as a tool to address the environmental changes that took place during the Permian–Triassic transition in continental environmentsItem New lithostratigraphy for the Cantabrian Mountains: A common tectono-stratigraphic evolution for the onset of the Alpine cycle in the W Pyrenean realm, N Spain(Earth-Science Reviews, 2019) López Gómez, José; Martín González, Fidel; Heredia, N.; Horra Del Barco, Raúl De La; Barrenechea, José F.; Cadenas, Patricia; Juncal, Manuel; Diez, José B.; David Pedreira, David; Borruel Abadía, Violeta; García-Sansegundo, Joaquín; Farias, Pedro; Galé, Carlos; Lago, Marceliano; Ubide, Teresa; Fernández-Viej, Gabriela; Georges Gand, GeorgesThe Pyrenean-Cantabrian Orogen arose through the collision of the Iberian and Eurasian plates, mostly in Cenozoic times. This orogen comprises two main mountain ranges, the Pyrenees to the east, and the Cantabrian Mountains to the west. To date, the early Alpine tectono-sedimentary phases preserved in the Cantabrian Mountains, of Permian and Triassic age, have been considered independently from the same phases in neighbouring basins of SW Europe, and even from the eastern part of the same orogeny (the Pyrenean orogeny). In consequence, the beginning of the Alpine cycle in the Cantabrian Mountains has been interpreted within a specific geodynamic context, far from the general evolutionary phases of the western Peri-Tethys basins. Through detailed field work, including geological mapping, sedimentology, lithostratigraphy and petrology of volcanic rocks, and new palaeontological data, here we define several new lithostratigraphical formations and five new tectono-sedimentary cycles (TS I-V) for the initial phases of evolution of the Mesozoic Basque-Cantabrian Basin, interrupted by periods of tectonic stability. To complete this information, we include data from an onshore borehole (Villabona Mine) and two offshore boreholes constrained by 2D reflection seismic profiles acquired in the North Iberian continental platform. The main tectono-sedimentary cycles, related to the deposition of five major identified lithostratigraphic units, can be described as follows: TS I (late Gzelian-early Asselian), relating to the late Variscan deformation and preserved in a single outcrop in all the Cantabrian Mountains (San Tirso Formation). This formation is constituted by medium-distal alluvial fan deposits in which humid intervals predominate, forming some thin coal beds. TS II (Asselian-Sakmarian), a post-Variscan extensional phase with associated calc-alkaline magmatism, represented by profuse volcanic and volcanosedimentary intercalations in the early Permian sedimentary basins (Acebal Formation) and small plutons in surrounding areas. TS III (Kungurian), or reactivation of the post-Variscan extension leading to alluvial and lacustrine carbonate sedimentation in arid climate conditions, which do not change during the rest of the Permian and Triassic periods (Sotres Formation). A generalized karstification in the basin represents the end of Permian deposition, followed by an interruption in sedimentation longer than 30 Myr. The Permian tectono-sedimentary cycles (TS II and TS III) are contemporary with Variscan belt collapse and the basins are controlled by extensional reactivation of NE-SW and E-W Variscan structures, and NW-SE late Variscan structures. TS IV (late Anisian–middle Carnian), renewed sedimentation in more extensive basins, precursors of the great Mesozoic Basque-Cantabrian Basin. This cycle is represented by fluvial deposits (Cicera Formation, or Buntsandstein facies), which are interrupted by the first Mesozoic marine ingression (Rueda Formation, or Muschelkalk facies). TS V (Norian-Rhaetian), or shallow marine carbonate deposits (Transición Formation) related to increasingly compartmentalized sub-basins, controlled by normal faults. This final TS is broadly connected with different basins of the western Peri-Tethys domain. The identification of units TS I-V in the Cantabrian Mountains along with the volcanic character of TS II, all indicate the development of a common post-Variscan to early Alpine tectono-sedimentary evolution for the whole Pyrenean-Cantabrian realm.Item Climate changes during the Early–Middle Triassic transition in the E. Iberian plate and their palaeogeographic significance in the western Tethys continental domain(Palaeogeography, Palaeoclimatology, Palaeoecology Volume 440, 15 December 2015, Pages 671-689, 2015) Borruel Abadía, Violeta; López Gómez, José; Horra Del Barco, Raúl De La; Galán Abellán, Belén; Barrenechea, José F.; Arche, Alfredo; Ronchi, Ausonio; Grette, Nicola; Marzo Carpio, MarianoUntil recently the climate of the Early–Middle Triassic at low latitudes was broadly considered as generally temperate-warm with no major climate oscillations. This work examines the climate of this period through a detailed study of the sedimentary, plant, soil and mineral records of continental rocks (Buntsandstein facies) in eastern Iberian basins. Our findings indicate temporal climate variations for these near equator (10°–14°N) regions and unveil the significance of such variations in the southern Laurasian domain. The climate of Iberia's Early Triassic was mainly dominated by alternating brief (< 0.4 ma) arid and semi-arid climate periods, with two main arid periods documented at the end of the Smithian and middle Spathian. However, an initial short subhumid to semi-arid period was also observed in the late Spathian. Remarkably, this latter period appears just after an unconformity related to the tectonically induced Hardegsen Event in western Europe. It is also of interest that this short subhumid climate period is concurrent with the beginning of faunal and floral recovery in the basins examined. The Early Triassic ended again with a short very arid period. Although the beginning of the Anisian (Aegean) was represented by alternating arid and semi-arid to subhumid intervals, during the Bithynian and Pelsonian clearly wetter climates are recorded by the succession consisting of alternating semi-arid to semi-humid intervals. This general tendency was interrupted by three short but marked intervals, two humid intervals in the late Bithynian, and one arid period near the Bithynian/Pelsonian boundary.