Person:
Horra Del Barco, Raúl De La

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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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Start date: 2010 × Subject: 551.761 ×

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    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.
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    Palaeoenvironmental implications of aluminium phosphate-sulphate minerals in Early–Middle Triassic continental sediments, SE Iberian Range (Spain)
    (Sedimentary geology, 2013) Galán Abellán, Ana Belén; Barrenechea, José F.; Benito Moreno, María Isabel; Horra Del Barco, Raúl De La; Luque Del Villar, Francisco Javier; Alonso Azcárate, Jacinto; Arche, Alfredo; López Gómez, José; Lago San José, Marceliano
    The presence of Sr-rich aluminium-phosphate sulphate (APS) minerals in continental sedimentary rocks from the Cañizar and Eslida Formations along the eastern part of the Iberian Range (Spain) is considered as evidence of acidic and oxidising conditions during Early–Middle Triassic times. The formation of APS minerals occurred shortly after sedimentation, in early diagenetic stages, prior to the compaction of the sediments and most probably was related to the circulation of acidic meteoric waters. Such conditions might result from a sustained, damaged environment or from multiple environmental crises, but would have delayed the recovery of life after the end-Palaeozoic mass extinction. APSminerals occur as small disseminated and idiomorphic pseudo-cubic crystals (0.5 to 6 μmlong) or as massive and polycrystalline aggregates replacing fragments of fine- rainedmetamorphic rocks (mainlymetapelites). Textural data indicate that the formation of the APS minerals predated the quartz and illite cements, and that they resulted from the destabilisation of pre-existing minerals, as evidenced by the replacement of slate fragments by APSminerals and hematite and by the close association of the disseminated APS crystals and kaolinitewith altered detrital mica plates. Electronmicroprobe analyses and X-ray diffraction study of the APSminerals indicate a rather homogeneous composition in different parts of the basin, corresponding to solid solutions among woodhouseite, svanbergite, crandallite and goyazite. The sources of strontium in the APS minerals remain unclear. Phosphorous was primarily supplied by dissolution of detrital phosphates under acidic conditions, and sulphur derives from the weathering of pyrite.