Person: Mas Mayoral, José Ramón
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First Name
José Ramón
Last Name
Mas Mayoral
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Area
Estratigrafía
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Item Sandstone petrography of continental depositional sequences of an intraplate rift basin: western Cameros Basin (North Spain)(Journal of sedimentary research, 2009) Arribas Mocoroa, José; Alonso Millán, Ángela; Mas Mayoral, José Ramón; Tortosa, A.; Rodas González, Magdalena; Fernández Barrenechea, José María; Alonso Azcárate, Jacinto; Artigas, RosanaThe Cameros Basin in Central Spain is an intraplate rift basin that developed from Late Jurassic to Middle Albian time along NW–SE trending troughs. The sedimentary basin fill was deposited predominantly in continental environments and comprises several depositional sequences. These sequences consist of fluvial sandstones that commonly pass upward into lacustrine deposits at the top, producing considerable repetition of facies. This study focused on the western sector of the basin, where a total of seven depositional sequences (DS- 1 to DS-7) have been identified. The composition of sandstones permits the characterization of each sequence in terms of both clastic constituents and provenance. In addition, four main petrofacies are identified. Petrofacies A is quartzosedimentolithic (mean of Qm85F2Lt13) and records erosion of marine Jurassic pre-rift cover during deposition of fluvial deposits of DS-1 (Brezales Formation). Petrofacies B is quartzofeldspathic (mean of Qm81F14Lt5) with P/F > 1 at the base. This petrofacies was derived from the erosion of low- to medium-grade metamorphic terranes of the West Asturian–Leonese Zone of the Hesperian Massif during deposition of DS-2 (Jaramillo Formation) and DS-3 (Salcedal Formation). Quartzose sandstones characterize the top of DS-3 (mean of Qm92F4Lt4). Petrofacies C is quartzarenitic (mean of Qm95F3Lt2) with P/F > 1 and was produced by recycling of sedimentary cover (Triassic arkoses and carbonate rocks) in the SW part of the basin (DS-4, Pen˜ - acoba Formation). Finally, depositional sequences 5, 6, and 7 (Pinilla de los Moros–Hortigüela, Pantano, and Abejar–Castrillo de la Reina formations, respectively) contain petrofacies D. This petrofacies is quartzofeldspathic with P/F near zero and a very low concentration of metamorphic rock fragments (from Qm85F11Lt4 in Pantano Formation to Qm73F26Lt1 in Castrillo de la Reina Formation). Petrofacies D was generated by erosion of coarse crystalline plutonics located in the Central Iberian Zone of the Hesperian Massif. In addition to sandstone petrography, these provenance interpretations are supported by clay mineralogy of interbedded shales. Thus, shales related to petrofacies A and C have a variegated composition (illite, kaolinite, and randomly interlayered illite–smectite mixed-layer clays); the presence of chlorite characterizes interbedded shales from petrofacies B; and Illite and kaolinite are the dominant clays associated with petrofacies D. These petrofacies are consistent with the depositional sequences and their hierarchy. An early megacycle, consisting of petrofacies A and B (DS-1 to DS-3) was deposited during the initial stage of rifting, when troughs developed in the West Asturian–Leonese Zone. A second stage of rifting resulted in propagation of trough-bounding faults to the SW, involving the Central Iberian Zone as a source terrane and producing a second megacycle consisting of petrofacies C and D (DS-4, DS-5, DS-6, and DS-7). Sandstone composition has proven to be a powerful tool in basin analysis and related tectonic inferences on intraplate rift basins because of the close correlation that exists between depositional sequences and petrofacies.Item Cyclicity recorded in the provenance sandstones in the sedimentary infill of the Cameros basin (N. Spain)(Boletín geológico y minero, 2013) González Acebrón, Laura; Arribas Mocoroa, José; Omodeo-Salé, S.; Arribas Mocoroa, María Eugenia; Le Pera, E.; Mas Mayoral, José Ramón; López-Elorza, M.; Fernández-Díaz, P.R.The intraplate Cameros rift basin in the north of Spain was formed came into being between the Tithonian and the Early Albian and contains 9 000 m of mostly continental sediments. This basin is a good example of cyclicity of different depositional sequences (DSs) in sedimentary environments, which show clear repetition in their sandstone composition (petrofacies) and diagenetic patterns. The DSs are arranged in two megasequences (MSs) separated by a tectonic unconformity. A similar vertical sandstone compositional evolution, subdivided into two stages that repeat cyclically, has been recognised in both MSs: the first comprises quartzo-sedimentolithic petrofacies and the second is made up of several quartzo-feldspathic petrofacies. This was caused by a progression from the recycling of the pre-rift sedimentary cover to the erosion of the mainly plutonic and metamorphic crystalline basement. These changes in the erosion of the different source areas were conditioned by the tectonics of the basin. Furthermore, the original sandstone framework composition conditioned the diagenetic pattern of the two stages: quartzo-sedimentolithic sandstones containing large amounts of very pervasive carbonate cement that reduce their original porosity considerably, and quartzo-feldspathic petrofacies with a rigid framework that maintained the original pores during burial diagenesis. This compositional and diagenetic pattern is probably applicable to other non-volcanic rifted basins, depending upon the original amount of carbonate rock fragments present.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.Item Iron-coated particles from condensed Aalenian-Bajocian deposits: evolutionary model (Iberian Basin, Spain)(Journal of sedimentary research, 2012) García Frank, Alejandra; Ureta Gil, María Soledad; Mas Mayoral, José RamónCondensed intervals provide a framework to study evolution of iron-coated particles. This study examines the ironrich particles contained in the condensed carbonate deposits spanning from uppermost Toarcian to lower Bajocian in the northwestern Iberian Range (northern Spain), to unravel the controls on geochemical changes in the basin by determining variation in mineralogy and REY (rare earth elements and yttrium) as potential predictors of provenance. The articles are composed mostly of the ferrous phyllosilicate berthierine, and by Fe-oxyhydroxide goethite. Depositionally, iron-rich particles occur at specific horizons, and display changes in character, from iron cortoids (Stage 1) in lowest Aalenian sediments, passing to small-sized iron ooids (Stage 2) in early Aalenian strata and to more complex iron-grain aggregates and larger iron ooid–oncoid mixed particles (Stage 3) in the middle–upper Aalenian succession. In the lower Bajocian sediments that represent the most condensed interval, diagenetic processes strongly affected previously iron-coated particles. The genesis of the diverse suite of iron-rich particles is explained by petrographic and mineralogic studies revealing oscillation in redox conditions. Berthierine genesis is linked with suboxic conditions below the water–sediment interface. Subsequent periods of low rates of sediment accumulation allowed the exhumation of particles, and exposing them to oxic conditions that favored goethite formation. Definitive burial led to the development of isopachous circumgranular berthierinic cement rims and dissolution and replacement. Studies of REY and comparison with iron-rich samples of diverse provenance suggest a conceptual model for geochemical evolution of these deposits. The lack of both contemporaneous soil deposits and evidence of subaerial exposure in this arid paleoclimatic setting rule out weathering processes as the main source of iron. Instead, geochemical indexes (Y/Nb and Y/La ratios) suggest that coeval Iberian volcanism was the most plausible iron source. The sedimentological, mineralogical, and chemical attributes of these iron deposits provides proxies to interpret redox and geochemical fluctuations and integrate all the data in an evolutionary model. Variations in REY patterns offer a framework for correlation at both local and subregional scales. Likewise, as this study provides new geochemical data for the Aalenian period, including the Fuentelsaz GSSP worldwide reference section, it enhances knowledge of the evolution of the westernmost Tethyan basins and the significance of widely distributed oolitic ironstones. The data collectively reveal how the REY signature of condensed sediments can be used to obtain detailed information on the geochemical and paleoceanographic conditions of depositional basins.Item Micro-Sized Dolomite Inclusions in Ferroan Calcite Cements Developed During Burial Diagenesis of Kimmeridgian Reefs, Northern Iberian Basin, Spain.(Journal of sedimentary research, 2006) Benito Moreno, María Isabel; Lohmann, Kyger C.; Mas Mayoral, José RamónBurial diagenesis of the Upper Jurassic Torrecilla Reef Complex is recorded by a complex paragenetic sequence initiated with emplacement of ferroan calcite cements and followed by the precipitation of ferroan saddle dolomite. Ferroan calcite cements contain micro-sized dolomite inclusions (MDIs). Elemental and isotopic compositions of MDIs are virtually indistinguishable from those of ferroan saddle dolomite cements. In contrast to other scenarios for the formation of microdolomite inclusions that invoke either a magnesian calcite precursor or incomplete dedolomitization, the paragenetic relations of MDIs to their host ferroan calcite and their geochemical composition implies formation by fine-scale burial replacement of ferroan calcite by fluids associated with the emplacement of ferroan saddle dolomite. Petrographic observations and mass-balance considerations suggest that it is unlikely that Fe and Mg incorporated into ferroan dolomite could have been derived from the cannibalization of the reefal host rock. Rather, dolomitizing fluids were likely associated with the hydrothermal, low-grade metamorphic event that affected the Cameros Basin during the middle to Late Cretaceous. Interaction of these fluids with preexisting burial cements produced MDIs in the ferroan calcites.Item Early Syn-Rift Evolution In the West Cameros Basin (Upper Jurassic, NW Iberian Range), Spain and Pedogenetic Calcretes In Early Syn-Rift Alluvial Systems (Upper Jurassic, West Cameros Basin), Northern Spain—Reply(Journal of Sedimentary Research, 2017) Arribas Mocoroa, María Eugenia; Mas Mayoral, José Ramón; Sacristán Horcajada, SaraFirst, we would like to highlight our appreciation of Dr. Platt's and Dr. Wright's comments and the opportunity they give us to discuss some aspects of our papers (Sacristan-Horcajada et al. 2015, 2016) improving the final state of our work.Knowledge about sedimentology of alluvial systems has had an important development in recent years, with new proposals for models in rift basins where tectonics play a predominant role (Nichols and Fisher 2007; Hartley et al. 2010; Weismann et al. 2010; Fielding et al. 2012). The differential behavior of the extensional structures during the earliest syn-rift stage (Tithonian) in the West Cameros Basin played a key role in the architecture of the various alluvial systems (Sacristan-Horcajada et al. 2015) as well as the distribution of various calcrete sequences (Sacristan-Hocajada et al. 2016). We discuss the points raised Drs. Platt and Wright in the same order they established.Item Evolución diagenética de los carbonatos arrecifales de la Formación Torrecilla en Cameros y de los carbonatos continentales suprayacentes (Kimmeridgiense inferior-Titónico) en el Sector de Soria. Cuenca de Cameros, N. España(Journal of iberian geology, 2002) Benito Moreno, María Isabel; Mas Mayoral, José RamónEl último episodio de sedimentación marina del Jurásico en el área de Soria se produjo durante el Kimmeridgiense inferior con el depósito de la Fm. Torrecilla en Cameros, formada por areniscas y calizas arrecifales y oolíticas que se depositaron en una rampa carbonática somera. Fue durante el depósito de esta unidad cuando tuvieron lugar los procesos diagenéticos sinsedimentarios de micritización y precipitación de micrita peloidal y de calcita fibrosa. En el Kimmeridgiense superior la unidad arrecifal quedó expuesta y fue afectada por las aguas meteóricas que favorecieron la disolución y neomorfismo del aragonito y de la HMC, produciéndose asimismo la precipitación de un cemento de calcita meteórica y la edafización y desarrollo de una costra hematítica en el techo de la unidad. A partir del Titónico y durante el Cretácico inferior se desarrolló el episodio de rifting que dio lugar a la formación de la Cuenca de Cameros. En este sector la sedimentación de la cuenca, esencialmente continental, comenzó en el Titónico con el depósito de la Afm. Ágreda. Los carbonatos de la base de esta unidad poseen unas características geoquímicas (elementales e isotópicas) muy similares a las de los cementos meteóricos precipitados en la unidad arrecifal, lo que sugiere la existencia de condiciones ambientales muy similares durante la precipitación de ambos. Con el progresivo enterramiento de ambas unidades se produjo la precipitación de un cemento de calcita ferrosa en fracturas y en la porosidad remanente. Posteriormente precipitó un cemento de anquerita barroca que pudo estar relacionado con el metamorfismo hidrotermal que afectó a los depósitos de la cuenca en el sector nororiental durante el Cretácico medio-superior. Finalmente precipitó una generación de calcita no ferrosa y rica en Mg, precipitación que pudo ocurrir durante el Cretácico terminal. Las últimas etapas diagenéticas preservadas se produjeron como consecuencia del levantamiento tectónico de esta región durante la compresión alpina y la exhumación de la unidad arrecifal durante la cual tuvo lugar el remplazamiento de la anquerita y de la calcita ferrosa por un mosaico de calcita no ferrosa rica en inclusiones de óxidos/hidróxidos de Fe. [ABSTRACT] The last marine Jurassic unit deposited in the Soria area corresponds to the Torrecilla en Cameros Fm. (Early Kimmeridgian). This unit, composed of sandstones and reefal and oolitic limestones, was deposited in a shallow carbonate ramp. The synsedimentary diagenetic processes of micritization and precipitation of peloidal micrite and fibrous calcite occurred during the episode of sedimentation. In the Late Kimmeridgian the reefal unit was subaerial exposed and was affected by the meteoric waters which led to the dissolution and neomorphism of aragonite and HMC and the precipitation of a generation of meteoric calcite. The top of the unit was also edaphized and a ferruginous crust was developed. The episode of rifting, that led to the formation of the Cameros Basin, occurred from the Tithonian and during the Early Cretaceous. In this sector, the sedimentation of the basin, mainly continental, started with the deposition of the Ágreda Alloformation. Carbonates deposited of the base of this continental unit have elemental and isotopic features very similar to those of the meteoric cements precipitated in the reefal unit. This suggests that the environmental conditions were very similar during precipitation of meteoric carbonates in both units. With the progressive burial, precipitation of a ferroan calcite cement occurred in fractures and remaining porosity in both units. Later, a generation of saddle ankerite precipitated, perhaps in relation to the hydrothermal metamorphism that affected the northeastern sector of the basin during the Middle-Late Cretaceous. Lastly, the precipitation of a generation of nonferroan and Mg-rich calcite cement occurred, possibly during the Latest Cretaceous. The last preserved diagenetic stages were related to the tectonic uplift of the region during the alpine compression, and the exhumation of the reefal unit during which ankerite and ferroan calcite were replaced by nonferroan, inclusion rich calcite.Item Criteria for recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic, fluid inclusion, and isotopic analysis of the Tera Group, Northern Spain(International journal of earth sciences, 2011) González Acebrón, Laura; Goldstein, Robert H.; Mas Mayoral, José Ramón; Arribas Mocoroa, JoséStratigraphic relations, detailed petrography, microthermometry of fluid inclusions, and fine-scale isotopic analysis of diagenetic phases indicate a complex thermal history in Tithonian fluvial sandstones and lacustrine limestones of the Tera Group (North Spain). Two different thermal events have been recognized and characterized, which are likely associated with hydrothermal events that affected the Cameros Basin during the mid- Cretaceous and the Eocene. Multiple stages of quartz cementation were identified using scanning electron microscope cathodoluminescence on sandstones and fracture fills. Primary fluid inclusions reveal homogenization temperatures (Th) from 195 to 350 C in the quartz cements of extensional fracture fillings. The high variability of Th data in each particular fluid inclusion assemblage is related to natural reequilibration of the fluid inclusions, probably due to Cretaceous hydrothermal metamorphism. Some secondary fluid inclusion assemblages show very consistent data (Th = 281–305 C) and are considered not to have reequilibrated. They are likely related to an Eocene hydrothermal event or to a retrograde stage of the Cretaceous hydrothermalism. This approach shows how multiple thermal events can be discriminated. A very steep thermal gradient of 97–214 C/km can be deduced from d18O values of ferroan calcites (d18O -14.2/-11.8% V-PDB) that postdate quartz cements in fracture fillings. Furthermore, illite crystallinity data (anchizone–epizone boundary) are out of equilibrium with high fluid inclusion Th. These observations are consistent with heat-flux related to shortlived events of hydrothermal alteration focused by permeability contrasts, rather than to regional heat-flux associated with dynamo-thermal metamorphism. These results illustrate how thermal data from fracture systems can yield thermal histories markedly different from hostrock values, a finding indicative of hydrothermal fluid flow.Item Reply to comment on González-Acebrón, L., Mas, R., Arribas, J., Gutiérrez-Mas, J.M., Pérez-Garrido, C. “Very coarse-grained beaches as a response to generalized sea level drops in a complex active tectonic setting: Pleistocene marine terraces at the Cadiz coast, SW Spain”(Marine Geology, 2019) González Acebrón, Laura; Mas Mayoral, José Ramón; Arribas Mocoroa, José; Gutiérrez-Mas, José Manuel; Pérez Garrido, CarlosA series of Pleistocene marine terraces comprised of conglomerate and coarse-grained sandstone aligned NNW-SSE along the Cadiz coast have been recognized and interpreted as formed in very coarse-grained beaches in our work (González-Acebrón et al., 2016). They unconformable overlie either Pliocene units or older Pleistocene deposits. In these terraces, five sedimentary sequences were described and dated by Sr isotopic analysis of well-preserved oysters. This dating provided an Early Pleistocene age (1.3 Ma) for the oldest marine terrace, which corresponds to Sequence 1. Aguirre (2018) does not agree with the dating of the first sequence. Instead, in Aguirre (1995) and Aguirre et al. (1995) these deposits are considered as laterally equivalent to lacustrine deposits located more than 50 km far away (Mesas de Asta, Jerez Basin), and their age (Late Pliocene-lowermost Early Pleistocene) extrapolated to Sequence 1. This is an impossible correlation given the fact that the studied deposits (Sequences 1 to 5) are marine terraces without lateral continuity inland. Finally, Aguirre's (2018) sedimentological interpretation of the deposits of Sequence 1 as part of a “wave- and tide-dominated delta” breaks down when one considers that this delta would be a mixture of non-coeval deposits (the continental deposits of Mesas de Asta together with Sequence 1 deposits).Item Causes of variation in crystal morphology in metamorphogenic pyrite deposits of the Cameros Basin (N Spain)(Geological Journal, 2001) Alonso Azcárate, Jacinto; Rodas González, Magdalena; Fernández Díaz, María Lourdes; Bottrell, S.H.; Mas Mayoral, José Ramón; López De Andrés, María SolThe low-grade metasediments of lthe Cameros Basin, northem Spain, host a number of deposits of spectacular quality pyrite mineralization. These formed during regional metamorphism and the pyrite crystals exhibit a wide range of morphologies. On the basis of pyrite crystal habit, the deposits can be classified into two groups: Group 1 comprises deposits with cubic, elongated or platy crystals; Group 11 comprises deposits charactenzed by pyntohedra and cubo-pyritohedra with striated faces, along with blocky crystals and he-grained aggregates. Group 1 deposits are formed in sequences dorninated by meandriform fluviatile sediments, while Group 11 is hosted by deltaic plain and lacustrine metasediments. Temperature differences between deposits and As content are possible causes of the different ynte morphologies in the deposits, but no significant variation exists between the two groups for either factor. Comparison with experimentally grown pyrite crystals suggests that Group 1 deposits have morphologies indicative of lower degrees of pyrite supersaturation than pyrite crystals in Group 11 deposits. The sedimentary facies hosting Group 11 deposits provides a greater availability of sedimentary sulphur (pyrite and sulphates). Moreover, reactions involving sulphate during metamorphism may have modified fluid chernistry, which would also act to produce higher degrees of pynte saturation in fluids derived from the sulphate-rich deltaic plain and lacustrine metasediments osting the Group 11 deposits. This hypothesis is confirmed by sulphur isotope data on the pyrites, which show a larger component of 34S-Enriched sulphate-derived sulphur in these deposits.