Carbon isotopes of graphite: Implications on fluid history

Stable carbon isotope geochemistry provides important information for the recognition of fundamental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elaboration of models for the global carbon cycle. Carbon isotope ratios in fluid-Deposited graphite are powerful tools for unravelling the ultimate origin of carbon (organic matter, mantle, or carbonates) and help to constrain the fluid history and the mechanisms involved in graphite deposition.Graphite precipitation in fluid-deposited occurrences results from CO2- and/or CH4-bearing aqueous fluids. Fluid flow can be considered as both a closed (without replenishment of the fluid) or an open system (with renewal of the fluid by successive fluid batches). In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipitation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment (depending upon the dominant carbon phase in the fluid, CO2 or CH4, respectively). In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of d13C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation

Contrasting Mineralizing Processes in Volcanic-Hosted Graphite Deposits

The only two known graphite vein-deposits hosted by volcanic rocks (Borrowdale, United Kingdom, and Huelma, Southern Spain) show remarkable similarities and differences. The lithology, age of the magmatism and geodynamic contexts are distinct, but the mineralized bodies are controlled by fractures. Evidence of assimilation of metasedimentary rocks by the magmas and hydrothermal alteration are also common features to both occurrences. Graphite morphologies at the Borrowdale deposit vary from flakes (predominant) to spherulites and cryptocrystalline aggregates, whereas at Huelma, flaky graphite is the only morphology observed. The structural characterization of graphite indicates a high degree of ordering along both the c axis and the basal plane. Stable carbon isotope ratios of graphite point to a biogenic origin of carbon, most probably related to the assimilation of metasedimentary rocks. Bulk į13C values are quite homogeneous in both occurrences, probably related to precipitation in short time periods. Fluid inclusion data reveal that graphite precipitated from C-O-H fluids at moderate temperature (500 ºC) in Borrowdale and crystallized at high temperature from magma in Huelma, In addition, graphite mineralization occurred under contrasting fO2 conditions. All these features can be used as potential exploration tools for volcanic-hosted graphite deposits

Sedimentology, clay mineralogy and palaeosols of the Mid-Carnian Pluvial Episode in E Spain: insights into humidity and sea-level variations

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

State of the art of Triassic palynostratigraphical knowledge of the Cantabrian Mountains (N Spain)

The present-day Cantabrian Mountains (North Spain) represent the western continuation of the Pyrenean-Cantabrian Orogen, which arose from a Cenozoic collision between the Iberian and Eurasian plates. The early Alpine sedimentary record of the Cantabrian basin is represented by the latest Carboniferous-Permian and Triassic rocks, mostly of continental origin. A lack of palaeontological data has led, until recently, to erroneous interpretations of the stratigraphic position of this sedimentary record. Within the framework of the Triassic sedimentary record in northern Spain, the precise age of six samples was determined and they were grouped into four palynological assemblages according to their taxonomic composition. The study of these assemblages includes a review of all the Triassic assemblages published to date as regards the Cantabrian Mountains, thereby optimising our Triassic palynostratigraphical knowledge of this area enabling comparisons with other Triassic assemblages of Central and SW Europe

State of the art of Triassic palynostratigraphical knowledge of the Cantabrian Mountains (N Spain)

The present-day Cantabrian Mountains (North Spain) represent the western continuation of the Pyrenean-Cantabrian Orogen, which arose from a Cenozoic collision between the Iberian and Eurasian plates. The early Alpine sedimentary record of the Cantabrian basin is represented by the latest Carboniferous-Permian and Triassic rocks, mostly of continental origin. A lack of palaeontological data has led, until recently, to erroneous interpretations of the stratigraphic position of this sedimentary record. Within the framework of the Triassic sedimentary record in northern Spain, the precise age of six samples was determined and they were grouped into four palynological assemblages according to their taxonomic composition. The study of these assemblages includes a review of all the Triassic assemblages published to date as regards the Cantabrian Mountains, thereby optimising our Triassic palynostratigraphical knowledge of this area enabling comparisons with other Triassic assemblages of Central and SW Europe

The beginning of the Buntsandstein cycle (Early–Middle Triassic) in the Catalan Ranges, NE Spain: Sedimentary and palaeogeographic implications

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

Palaeoenvironmental implications of aluminium phosphate-sulphate minerals in Early–Middle Triassic continental sediments, SE Iberian Range (Spain)

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

Constraining the Permian/Triassic transition in continental environments: Stratigraphic and paleontological record from the Catalan Pyrenees (NE Iberian Peninsula)

The continental Permian–Triassic transition in southern Europe presents little paleontological evidence of the Permian mass extinction and the subsequent faunal recovery during the early stages of the Triassic. New stratigraphic, sedimentological and paleontological analyses from Middle–Upper Permian to Lower–Middle Triassic deposits of the Catalan Pyrenees (NE Iberian Peninsula) allow to better constrain the Permian–Triassic succession in the Western Tethys basins, and provide new (bio-) chronologic data. For the first time, a large vertebra attributed to a caseid synapsid from the ?Middle Permian is reported from the Iberian Peninsula—one of the few reported from western Europe. Osteological and ichnological records from the Triassic Buntsandstein facies reveal a great tetrapod ichnodiversity, dominated by small to medium archosauromorphs and lepidosauromorphs (Rhynchosauroides cf. schochardti, R. isp. 1 and 2, Prorotodactylus–Rotodactylus), an undetermined Morphotype A and to a lesser degree large archosaurians (chirotheriids), overall suggesting a late Early Triassic–early Middle Triassic age. This is in agreement with recent palynological analyses in the Buntsandstein basal beds that identify different lycopod spores and other bisaccate and taeniate pollen types of late Olenekian age (Early Triassic). The Permian caseid vertebra was found in a playa-lake setting with a low influence of fluvial water channels and related to the distal parts of alluvial fans. In contrast, the Triassic Buntsandstein facies correspond to complex alluvial fan systems, dominated by high-energy channels and crevasse splay deposits, hence a faunal and environmental turnover is observed. The Pyrenean biostratigraphical data show similarities with those of the nearby Western Tethys basins, and can be tentatively correlated with North African and European basins. The Triassic Pyrenean fossil remains might rank among the oldest continental records of the Western Tethys, providing new keys to decipher the Triassic faunal biogeography and recovery.E. Mujal and J. Fortuny received funding from the SYNTHESYS Project http://www.synthesys.info/ (DE-TAF-2560, FR-TAF-3621, FR-TAF-4808 to E. Mujal and FR-TAF-435 and FR-TAF-3353 to J. Fortuny) which is financed by European Community Research Infrastructure Action under the FP7 “Capacities” Program. E. Mujal acknowledges “Secretaria d'Universitats i de Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya” (E.M., expedient number 2013 CTP 00013, at ISE-M, Université Montpellier-2) for funding used for visiting collections. E. Mujal obtained financial support from the PIF grant of the Geology Department at UAB. A. Arche, J. Barrenechea, R. De la Horra, J.B. Diez and J. López-Gómez received support from the CGL2011-24408 and CGL2014-52699 research projects of the Spanish Ministerio de Economía y Competitividad. This paper is also a contribution to the following research projects: “Sistemas Sedimentarios y Variabilidad Climática” (642853) of the CSIC, and Basin Analysis (910429), and Palaeoclimatology and Global Change (910198) of the Universidad Complutense de Madrid. J. Fortuny acknowledges the support of the Generalitat de Catalunya postdoc grant 2014 – BP-A 00048. Fieldwork campaigns have been developed under the projects “Vertebrats del Permià i el Triàsic de Catalunya i el seu context geològic” and “Evolució dels ecosistemes amb faunes de vertebrats del Permià i el Triàsic de Catalunya” (ref. 2014/100606), based by the Institut Català de Paleontologia and carried out thanks to the financial support of the Departament de Cultura (Generalitat de Catalunya).Peer reviewe

Evaluation of pre-game hydration status, heat stress, and fluid balance during professional soccer competition in the heat

This study evaluated initial hydration status (stadium arrival urine specific gravity), fluid balance (pre- and post-game nude body weight, fluid intake, urine collection), and core temperature changes (pre-game, half-time, post-game) during a professional soccer game. We monitored 17 male players (goalies included) between stadium arrival and game end (3h), playing at 34.9°C and 35.4% relative humidity, for an average Wet Bulb Globe Temperature (WBGT) heat stress index of 31.9°C. Data are mean ± SD (range). Initial urine specific gravity (USG) was 1.018 ± 0.008 (1.003-1.036); seven players showed USG ≥ 1.020. Over the three hours, body mass (BM) loss was 2.58 ± 0.88kg (1.08-4.17kg), a dehydration of 3.38 ± 1.11%BM (1.68-5.34%BM). Sweat loss was 4448 ± 1216mL (2950-6224mL), vs. fluid intake of 1948 ± 954mL (655-4288mL). Despite methodological problems with many players, core temperatures greater than or equal to 39.0°C were registered in four players by halftime, and in nine by game’s end. Many of these players incurred significant dehydration during the game, compounded by initial hypohydration; thermoregulation may have been impaired to an extent we were unable to measure accurately. We suggest some new recommendations for soccer players training and competing in the heat to help them avoid substantial dehydration.Gatorade Sports Science Institute//Universidad de Costa Rica VI-245-A4-303UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Centro de Investigación en Ciencias del Movimiento Humano (CIMOHU