Person: Arribas Mocoroa, José
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First Name
José
Last Name
Arribas Mocoroa
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Petrología y Geoquímica
Identifiers
12 results
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Now showing 1 - 10 of 12
Item Interpreting carbonate particles in modern continental sands: an example from fluvial sands (Iberian Range, Spain)(Geological Society of America. Special Paper, 2007) Arribas Mocoroa, José; Arribas Mocoroa, María EugeniaWe analyzed modern fluvial sands in the Iberian Range in order to obtain an accurate description of the different typologies of carbonate grains and to interpret their origin. Head streams of the Iberian Range mainly receive carbonate sediments as (1) fragments from ancient carbonate rocks, and (2) penecontemporaneous car bonate grains generated in the fluvial channels or in associated subenvironments. The erosion of proximal carbonate sources (Jurassic and Cretaceous in age) contributes to the generation of carbonate rock fragments. In addition, erosion of recent freshwater tufas, carbonate soils, and other recent carbonates produces an important volume of penecontemporaneous carbonate particles. Temperate to subhu mid climate and short transport conditions promote good preservation of the composition and textures of carbonate grains in modern fluvial sands. Detailed petrographic analyses on penecon temporaneous carbonates provide diagnostic clues of their origin. Four main petro graphic classes of penecontemporaneous grains have been established: (1) penecon temporaneous micritic grains, which are composed of microcrystalline calcite with a filamentous or laminated microfabric, are derived from erosion of recent freshwa ter carbonate tufas. Penecontemporaneous micritic grains with alveolar microfabric are derived from recent carbonate soils. (2) Penecontemporaneous sparitic grains, which are composed of single crystals or of mosaics with filamentous microfabric, are the result of erosion of carbonate tufas. Other penecontemporaneous sparitic grains include Microcodium and speleothems fragments. (3) Penecontemporaneous coated grains, which are composed of a nucleus plus a coating of penecontemporane ous carbonate, represent bioinduced carbonate particles (cyanoliths) that originate in streams. (4) Penecontemporaneous bioclasts, made from charophytes, ostracods, and mollusks, are rare. ldentification of these grain categories in ancient deposits has implications for coeval carbonate supplies during fluvial sedimentation.Item Significance of geochemical signatures on provenance in intracratonic rift basins: Examples from the Iberian plate(Geological Society of America Special Paper, 2007) Ochoa, M.; Arribas Mocoroa, José; Arribas Mocoroa, María Eugenia; Mas Mayoral, José RamónFollowing the Variscan orogeny, the Iberian plate was affected by an extensional tec-tonic regime from Late Permian to Late Cretaceous time. In the central part of the plate, NW-SE–trending rift basins were created. Two rifting cycles can be identified during the extensional stage: (1) a Late Permian to Hettangian cycle, and (2) a latest Jurassic to Early Cretaceous cycle. During these cycles, thick clastic continental sequences were deposited in grabens and half grabens. In both cycles, sandstone petrofacies from periods of high tectonic activity reveal a main plutoniclastic (quartzofeldspathic) character due to the erosion of coarse-grained crystalline rocks from the Hesperian Massif, during Buntsand-stein (mean Qm72F25Lt3) sedimentation and during Barremian–early Albian times (mean Qm81F18Lt1). Geochemical data show that weatheringwas more intense during the second rifting phase (mean chemical index of alteration [CIA]: 80) due to more severe climate conditions (humid) than during the arst rifting phase (mean CIA: 68) (arid climate). Ratios between major and trace elements agree with a main provenance from pas-sive-margins settings in terms of the felsic nature of the crust. However, anomalies in trace elements have been detected in some Lower Cretaceous samples, suggesting additional basic supplies from the north area of the basin. These anomalies consist of (1) low contents in Hf, Th, and U; (2) high contents in Sc, Co, and Zr; and (3) anomalous ratios in Th/Y, La/Tb, Ta/Y, and Ni/V. Basic supplies could be related to the alkaline volcanism during Norian-Hettangian and Aalenian-Bajocian times. Geochemical composition of rift deposits has been shown to be a useful and complementary tool to petrographic deduction in prov-enance, especially in intensely weathered sediments. However, diagenetic processes and hydrothermalism may affect the original detrital deposits, producing changes in geochemi-cal composition that mislead provenance and weathering deductions.Item Sedimentación lacustre (Carbonatado-salina) en las facies autuniense de la Cordillera Ibérica(Comunicaciones presentadas en el X Congreso Nacional de Sedimentología / Congreso Nacional de Sedimentología (10. 1983. Menorca), 1983) Arribas Mocoroa, José; Arribas Mocoroa, María Eugenia; Marfil, Rafaela; Peña, José Andrés de la; Obrador, A.The aim of this paper is the better understanding of the carbonate and evaporite sedimentation of the upper unit of the Autunian facies in the "Sierra de Aragoncillo". Also the diagenetic evolution of these sediments in their reactions with the interbedded ryolitic-dacitic tuffs and ashes, have reen studied. The petrographic features of these carbonates are indicative of an early process of dolomitization in a hypersaline environment. The source of magnesium could be the sorroun ding volcanic rocks close to the lacustrine basin. Other common diagenetic minerals are: Zeolites, K-feldspar, quartz and clay minerals. The authigenesis of these minerals are reported to be the result of the reaction of tuffaceous rocks with interstitial waters trapped during sedimentation in a saline-alkaline lake. Considering the above data, we can establish that the lacustrine sedimentation at the end ofthe Autunian took place in a closed basin with arid climate.Item Sandstone petrofacies in the northwestern sector of the Iberian Basin(Journal of iberian geology, 2007) Arribas Mocoroa, José; Ochoa, M.; Mas Mayoral, José Ramón; Arribas Mocoroa, María Eugenia; González Acebrón, LauraDuring the most active rifting stages in the northwestern sector of the Iberian Basin (Cameros Basin and Aragonese Branch of the Iberian Range), thick sequences of continental clastic deposits were generated. Sandstone records from Rift cycle 1 (Permo-Triassic) and Rift cycle 2 (Late Jurassic-Early Cretaceous) show similarities in composition. Based on the most recent data, this paper describes sandstone petrofacies developed during both rifting periods. Six petrofacies can be distinguished: two associated with Rift cycle 1 (PT-1 and PT-2) and four with Rift cycle 2 (JC-1 to JC-4). All six petrofacies can be classifi ed as sedimentoclastic or plutoniclastic. Sedimentoclastic petrofacies developed during early rifting stages either through the recycling of pre-rift sediments or signifi - cant palaeogeographical changes. These facies comprise a thin succession (<100 m) of clastic deposits with mature quartzose and quartzolithic sandstones containing sedimentary and metasedimentary rock fragments. Carbonate diagenesis is more common than clay mineral diagenesis. Sedimentoclastic petrofacies have been identifi ed in Rift cycle 1 (Saxonian facies, PT-1) and Rift cycle 2 (JC-1 and JC-3; Tithonian and Valanginian, respectively). In the absence of the pre-rift sedimentary cover, metasedimentoclastic petrofacies sometimes develop as a product of the erosion of the low- to medium-grade metamorphic substratum (Petrofacies JC-2, Tithonian-Berriasian). Plutoniclastic petrofacies were generated during periods of high tectonic activity and accompanied by substantial denudation and the erosion of plutonites. Forming thick stratigraphic successions (1000 to 4000 m), these feldspar-rich petrofacies show a rigid framework and clay mineral diagenesis. In Rift cycle 1, plutoniclastic petrofacies (PT-2) are associated with the Buntsandstein. This type of petrofacies also developed in Rift cycle 2 in the Cameros Basin (JC-4) from DS-5 to DS-8 (Hauterivian-Early Albian), and represents the main basin fi ll interval. Sedimentoclastic and plutoniclastic petrofacies can be grouped into three pairs of basic petrofacies. Each pair represents a ‘provenance cycle’ that records a complete clastic cycle within a rifting period. Petrofacies PT-1 and PT-2 represent the ‘provenance cycle’ during Rift-1. In the Cameros Basin, two provenance cycles may be discerned during Rift cycle 2, related both to the Tithonian-Berriasian and the Valanginian-Early Albian megasequences. Tectonics is the main factor controlling petrofacies. Other factors (e.g., maturation during transport, local supply) may modulate the compositional signatures of the petrofacies yet their main character persists and even outlines the hierarchy of the main bounding surfaces between depositional sequences in the intracontinental Iberian Rift Basin.Item Petrographic characterization of coeval carbonate grains in recent fluvial sands (Serranía de Cuenca, Spain)(Plinius (Milano), 2002) Arribas Mocoroa, María Eugenia; Tortosa, A.; Arribas Mocoroa, JoséItem Petrographic evidence of different provenance in two alluvial fan systems (Palaeogene of the northern Tajo Basin, Spain)(Special publication - Geological Society of London, 1991) Arribas Mocoroa, José; Arribas Mocoroa, María EugeniaPalaeogene detrital deposits of the northern Tajo Basin are coalescent alluvial fan systems interfingering distally with lacustrine carbonates. Non-carbonate extrabasinal clasts increase to the east while carbonate extrabasinal clasts decrease. Rock fragments increase to the west, while the feldspar/quartz ratio remains constant. Rock fragments define two sedimentary domains: the Iberian, in the east, was derived from Mesozoic rocks of the Iberian Range, and the Central System, to the west, was derived from Cretaceous cover and Palaeozoic metamorphic basement. Evolution of sandstone composition is related to erosion of the source areas and is different in the two domains. The tectonic setting is apparently "recycled orogen", providing calcareous rock fragments are included in the total lithic clasts.Item Caracterización y procedencia de las areniscas del Paleógeno del sector Norte de la cuenca del Tajo(Resúmenes de comunicaciones / XI Congreso Español de Sedimentología ; edita Lluís Cabrera ; publicación patrocinada por Generalitat de Catalunya, Comissió Interdepartamental de Recerca i Innovació Tecnológica , CIRIT, 1986) Arribas Mocoroa, María Eugenia; Arribas Mocoroa, José; Cabrera, LluísItem Caracterización y procedencia de las areniscas del Paleógeno del sector N de la Cuenca del Tajo.(Revista d'investigacions geologiques, 1986) Arribas Mocoroa, José; Arribas Mocoroa, María EugeniaLos depósitos detríticos paleógenos del sector N de la cuenca terciaria del Tajo corresponden a sistemas de abanicos aluviales progradantes asociados en sentido distal con ambientes lacustres carbonatados (ARRIBAS et al., 1983 y ARRIBAS, 1985). En el presente trabajo se caracterízan, desde un punto de vista textura I y composicional, los niveles de areniscas, correspondiendo a litoarenitas con un importante contenído en fragmentos de roca calcáreos. Asimismo, se analizan los distintos factores que han podido influir en la composición final de dichos depósitos (clima, mecanismos de transporte-sedimentación y diagénesis), siendo la naturaleza del áreafuente elfactor fundamental. Se estudia la composición de las distintasfacies (canalesy "sheets") mediante índices composicionales (F/Qy LelQ), advirtiéndose un aumento en la madurez en los depósitos de canales. Espacialmente puede observarse un incremento progresivo en el contenído de componentes extracuecales no carbonáticos hacia el E, en detrimento de los componentes extracuencales carbonáticos. Cabe destacar una importante participación de componentes intracuencales carbonáticos, asociados a los episodios lacustres-palustres intercalados. Los fragmentos de roca aumentan su contenído hacia el W La relación F/Q permanece practicam en te constante, por lo que su origen se asocia a una única área fuente. A parte del análisis detallado de la composición de losfragmentos de roca se definen dos dominios de sedimentación paleógena: 1) Dominio ibérico, al E, nutrido de los materiales mesozoicos de la Cordillera Ibérica y 2) Dominio del Sistema Central, al W, nutrído de la cobertera cretácica y de la parte superior del substrato metamóifico. Temporalmente, es posible analizar la evolución de la composición de las areniscas mediante el empleo de determinados índices (NCE/NCE + CE; D/D + C; Q/Q + M y F/F + Qm); su variación se asocia al desmantelamiento de las áreasfuentes, presentando diferentes pautas en cada uno de los dominios definidos. Por último se concluye que el entorno geotectónico corresponde a orógenos reciclados deducido de la composición de las areniscas (DICKINSON et al., 1983), si bien es necesario contabilizar los fragm en tos de roca calcárea junto con el resto defragmentos de roca.Item Factors controlling compaction in a fluvial sequence: Oligocene-early Miocene of Lorance Basin, Central Spain(17th Regional African European Meeting of Sedimentology : abstracts, March 26th-28th 1996 / IAS, International Association of Sedimentologists...[et al.], 1996) Arribas Mocoroa, José; Arribas Mocoroa, María Eugenia; Tortosa, A.Item Significance of geochemical signatures on provenance in intracratonic rift basins: Examples from the Iberian plate(Geological Society of America Special Paper, 2007) Ochoa, M.; Arribas Mocoroa, María Eugenia; Arribas Mocoroa, José; Mas Mayoral, José RamónFollowing the Variscan orogeny, the Iberian plate was affected by an extensional tectonic regime from Late Permian to Late Cretaceous time. In the central part of the plate, NW-SE–trending rift basins were created. Two rifting cycles can be identified during the extensional stage: (1) a Late Permian to Hettangian cycle, and (2) a latest Jurassic to Early Cretaceous cycle. During these cycles, thick clastic continental sequences were deposited in grabens and half grabens. In both cycles, sandstone petrofacies from periods of high tectonic activity reveal a main plutoniclastic (quartzofeldspathic) character due to the erosion of coarse-grained crystalline rocks from the Hesperian Massif, during Buntsandstein (mean Qm72F25Lt3) sedimentation and during Barremian–early Albian times (mean Qm81F18Lt1). Geochemical data show that weathering was more intense during the second rifting phase (mean chemical index of alteration [CIA]: 80) due to more severe climate conditions (humid) than during the first rifting phase (mean CIA: 68) (arid climate). Ratios between major and trace elements agree with a main provenance from passive-margins settings in terms of the felsic nature of the crust. However, anomalies in trace elements have been detected in some Lower Cretaceous samples, suggesting additional basic supplies from the north area of the basin. These anomalies consist of (1) low contents in Hf, Th, and U; (2) high contents in Sc, Co, and Zr; and (3) anomalous ratios in Th/Y, La/Tb, Ta/Y, and Ni/V. Basic supplies could be related to the alkaline volcanism during Norian-Hettangian and Aalenian-Bajocian times. Geochemical composition of rift deposits has been shown to be a useful and complementary tool to petrographic deduction in provenance, especially in intensely weathered sediments. However, diagenetic processes and hydrothermalism may affect the original detrital deposits, producing changes in geochemical composition that mislead provenance and weathering deductions.