194 research outputs found

    Composition of modern stream sand derived from a mixture of sedimentary and metamorphic source rocks (Henares River, Central Spain)

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    The Henares River, central Spain, flows westward from the Iberian Range (Mesozoic sedimentary rocks) under semiarid climatic conditions. In the middle and lower reaches, the Henares River receives sediment from three tributaries (Cañamares, Bornova and Sorbe rivers) that drain the Central System (Paleozoic crystalline rocks, low-grade metamorphic rocks, and minor amounts of Mesozoic sedimentary rocks). Modern sands from the Henares River and its tributaries offer an excellent opportunity to evaluate the importance of lithology and physiography in determining detrital modes from mixed metamorphic and sedimentary source terrain. Sand modes from the Henares River and its tributaries are quartzolithic. They plot in a restricted area on a QmFLt diagram, with low contents of feldspar and variable amounts of quartz, and carbonate, metamorphic and minor siliciclastic lithic fragments. Higher feldspar abundances in the Cañamares and Bornova stream sands are related to the erosion of gneissic rocks. By contrast, sands from Sorbe River are low in feldspar, reflecting the absence of coarse metamorphic sources. Thus, proportions of bedrock lithologies in the drainage sub-basins are the main control on detrital modes of the tributaries. In addition, slope acts on the sand productivity of source rocks. Sedimentary source rocks in the upper reaches of the three tributaries have a poor productivity in the carbonate lithic fragments (Lsc), compared with the Lsc productivity of sedimentary sources located downstream, with higher relief. The percentage of bedrock types in the source area versus petrographic indices (Lm/L, Lss/L and Lsc/L) provide a useful contrast between source and sand composition in the tributaries. Thus, the high content of metamorphic lithic grains in the lithic grain population over-represents this lithology (slate plus schist) at the source terrain. Lithic grains from sedimentary clastic sources generate few recognizable grains (Lss) in the lithic grain population. Local supplies from carbonate sources may produce important increases of Lsc in short reaches of the channels. Sand compositions in the Henares River seem to be very homogeneous in a QmFLt diagram, with only minor differences caused by the supplies from the tributaries. These differences can be modeled in terms of end-member mixing processes between Henares detritus and detritus from the relevant tributary. These mixing processes are more evident when lithic grain contents (LmLvLs and LmLssLsc diagrams) are compared. Changes produced by inputs from the Cañamares, Bornova and Sorbe rivers are not permanent along the Henares course. An important homogenization of Henares sand composition takes place by the mixing of tributary deposits with previously deposited Henares River terraces. Abrasion during transport does not appear to cause significant changes in the sand composition along the Henares River

    Provenance, paleogeographic and paleotectonic interpretations of Oligocene-Lower Miocene sandstones of the western-central Mediterranean region: A review

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    The changing nature of detrital signatures in clastic wedges of the Circum-Mediterranean orogenic systems reflect the provenance relations from different source rocks of evolving geo-puzzle terranes, including ophiolite bearing, uplifted continental crust (both shallow to deep crust terranes), volcanic and sedimentary source rocks. We selected here sandstone suites directly occurring over the Mesomediterranean Micropaleoplate during the final stages of closure of the western-southern Tethyan realm. They are unconformably over the internal domains of the Circum-Mediterranean thrust belts, and include Oligocene-to-lower Miocene siliciclastic formations of the Betic Cordillera (As, Bosque, Río Pliego, El Niño, Ciudad Granada, Fuente-Espejos, Alozaina and Viñuela fms), Rif Chain (Fnideq and Sidi Abdeslam fms), and Calabrian terranes (Paludi, Pignolo and Stilo Capo d'Orlando fms). All these sandstone suites range from quartzolitic to quartzofeldspathic detrital modes reflecting close relations with their Paleozoic metasedimentary and plutonic source rocks and their related Mesozoic sedimentary covers. Marked differences have been recognized from western (Betic-Rif) to eastern (Calabria) portions in terms of detritic suites. Detrital suites of the Betic-Rif portions reflect a transition between a craton, transitional and recycled orogenic provenance type. Contrarily, detrital suites of the Calabria portions reflect their transition from transitional continental to basement uplift orogenic provenance reflecting deposition in wedge-top basins during final subduction of the MFB below the MM and the opening of the Mediterranean basin as a backarc.Support from Ministero Italiano dell'Università e della Ricerca Scientifica to S. Critelli, is acknowledged. Research Project PID2020-114381GB-I00 to M. Martín-Martín and S. Critelli, Spanish Ministry of Education and Science; Research Groups and Projects of the Generalitat Valenciana, Alicante University (CTMA-IGA) are also acknowledged

    Cenozoic detrital suites from the Internal Betic-Rif Cordilleras (S Spain and N Morocco): implications for paleogeography and paleotectonics

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    A synthesis of Cenozoic detrital suites from the Internal Betic-Rif Cordilleras is discussed in relations with major paleotectonic phases during growth of orogenic belts. The discussion has been focused on the Malaguide and Ghomaride complexes that have a Cenozoic sedimentary detritic cover. The heterogeneous petrographic composition of coarse detrital rocks, and the mineralogy and geochemistry of mudrocks indicate a multiple source area consisting in metamorphic, and recycled siliciclastic and carbonate source rocks, with a minor supply of mafic rocks during the early Miocene. The siliciclastic coarse detrital suites plot mainly in a wide area at the Qm-Lt side in a Qm-F-Lt diagram reflecting their transition between a craton, quartzose recycled, quartzose transitional orogenic, and finally lithic transitional orogenic provenance type. The Paleocene-Eocene successions seem to be affected by higher weathering effects than the Oligo-Miocene ones. Significant recycling and reworking processes should take place during the Paleocene-Eocene and the Oligo-Miocene before the final deposition. The source areas were characterized by non-steady-state weathering conditions reflecting a progressive cooling contemporaneous to the typical evolution of source areas where active tectonism allows erosion within weathering profiles developed on source rocks. A sharp increase of siliciclastic content together with the changes in sorting-recycling-weathering suggests abrupt changes in the source area starting from Oligocene. This fact allows subdividing the succession into the lower (Paleocene-Eocene) and the upper (Oligocene-Early Miocene) cycles. Lower cycle was contemporaneous to the Eo-Alpine tectonic phase, which was reflected in the Malaguide and Ghomaride domains by basement folding and deep tectonics with fault-propagation folds, accomplished by minor rising or reliefs and deepening of subsidence areas. Contrarily, the upper cycle took place during the Neo-Alpine phase, when in the Malaguide and Ghomaride domains, thrustings should become superficial contemporaneous to subduction and stacking of tectonic units. This led to a strong increasing of rising areas reflected in the sedimentation by the occurrence of coarse terrigenous deposits in wedge-top basins. The early Miocene also shows the influence of volcanism in the Mediterranean region, and/or the erosion of magmatic-metamorphic rocks derived from deep tectonic levels affected in the Eo-Alpine phase or belonging to the Hercynian bedrock. This evolution fits well with recent paleogeographic-geodynamic models for the western-central Mediterranean.Research Project PID2020-114381GB-I00 to M. Martín-Martín, F. Perri and S. Critelli, Spanish Ministry of Education and Science; Research Groups and Projects of the Generalitat Valenciana, Alicante University (CTMA-IGA) are acknowledged. Support from Ministero Italiano dell'Università e della Ricerca Scientifica to S. Critelli, is also acknowledged

    Boceprevir is highly effective in treatment-experienced hepatitis C virus-positive genotype-1 menopausal women

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    AIM: To investigate the safety/efficacy of Boceprevirbased triple therapy in hepatitis C virus (HCV)-G1 menopausal women who were historic relapsers, partial-responders and null-responders. METHODS: In this single-assignment, unblinded study, we treated fifty-six menopausal women with HCV-G1, 46% F3-F4, and previous PEG-α/RBV failure (7% null, 41% non-responder, and 52% relapser) with 4 wk lead-in with PEG-IFNα2b/RBV followed by PEGIFNα2b/RBV+Boceprevir for 32 wk, with an additional 12 wk of PEG-IFN-α-2b/RBV if patients were HCV-RNA-positive by week 8. In previous null-responders, 44 wk of triple therapy was used. The primary objective of retreatment was to verify whether a sustained virological response (SVR) (HCV RNA undetectable at 24 wk of follow-up) rate of at least 20% could be obtained. The secondary objective was the evaluation of the percent of patients with negative HCV RNA at week 4 (RVR), 8 (RVR BOC), 12 (EVR), or at the end-of-treatment (ETR) that reached SVR. To assess the relationship between SVR and clinical and biochemical parameters, multiple logistic regression analysis was used. RESULTS: After lead-in, only two patients had RVR; HCV-RNA was unchanged in all but 62% who had ≤ 1 logio decrease. After Boceprevir, HCV RNA became undetectable at week 8 in 32/56 (57.1%) and at week 12 in 41/56 (73.2%). Of these, 53.8% and 52.0%, respectively, achieved SVR. Overall, SVR was obtained in 25/56 (44.6%). SVR was achieved in 55% previous relapsers vs. 41% non-responders (Ρ = 0.250), in 44% F0-F2 vs 54% F3-F4 (Ρ = 0.488), and in 11/19 (57.9%) of patients with cirrhosis. At univariate analysis for baseline predictors of SVR, only previous response to antiviral therapy (OR = 2.662, 95%CI: 0.957-6.881, Ρ= 0.043), was related with SVR. When considering "on treatment" factors, 1 log10 HCV RNA decline at week 4 (3.733, 95%CI: 1.676-12.658, Ρ= 0.034) and achievement of RVR BOC (7.347, 95%CI: 2.156-25.035, Ρ= 0.001) were significantly related with the SVR, al-though RVR BOC only (6.794, 95%CI: 1.596-21.644, Ρ = 0.010) maintained significance at multivariate logistic regression analysis. Anemia and neutropenia were managed with Erythropoietin and Filgrastim supplementation, respectively. Only six patients discontinued therapy. CONCLUSION: Boceprevir obtained high SVR response independent of previous response, RVR or baseline fibrosis or cirrhosis. RVR BOC was the only independent predictor of SVR

    The Miocene deposits of the Cirò Basin in the evolution of the peri-Ionian region, eastern Calabria

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    The Cirò Basin is located in the north-eastern portion of Calabria, between the Ionian Sea and the Sila slopes. In this area, basin successions of the Neogene and Quaternary age overlap the Paleozoic metamorphic basement of the Sila Unit. In particular, there are units consisting of continental clastic facies and coastal facies that are the basis of the Tortonian-Messinian transgression. An accurate geological-structural survey, combined with sedimentological and stratigraphic analysis, has allowed to define the limits of the Cirò Basin and the stratigraphic relationships between the various outcropping Miocene deposits. Five distinct litofacies have been recognized, each of which contains both lateral and vertical variations.The main tectonic structures control the architecture and evolution of main Neogene basins of the Calabrian terranes. From the Neogene to the Quaternary, the history of orogenic building was mainly controlled by the activity of NW-SE oriented faults and shear zones characterised by left-transcurrent kinematics. Deformation is well evidenced in the tectono-sedimentary evolution of the wedge-top basins as well as in the retro-arc domain

    Sandstone Petrology and Provenance in Fold Thrust Belt and Foreland Basin System

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    The sandstone composition of foreland basin has a wide range of provenance signatures, reflecting the interplay between flexed underplate region and abrupt growth of the accreted upper plate region. The combination of contrasting detrital signatures reflects these dual plate interactions; indeed, several cases figure out that the earliest history of older foreland basin infilling is marked by quartz-rich sandstones, with cratonal or continental-block provenance of the flexed underplate flanks. As upper plate margin grows over the underplate, the nascent fold-and-thrust belt starts to be the main producer of grain particles, reflecting the space/time dependent progressive unroofing of the subjacent orogenic source terranes. The latter geodynamic processes are mainly reflected in the nature of sandstone compositions that become more lithic fragment-rich and feldspar-rich as the fold-thrust belt involves the progressive deepest portions of upper plate crustal terranes. In this context sandstone signatures reflect quartzolithic to quartzofeldspathic compositions

    The Messinian evaporite succession of the Crotone Basin, Southern Italy: a Python 3D modelling

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    An interactive 3D visualization of stratigraphic and structural architecture of the Crotone Basin, has been tested by using an open-source Python libraries for machine learning KNN and linear interpolation algorithms, together with Geographic Information Systems (GIS). A preliminary test was performed within the onshore-offshore Crotone area (southern Italy), where due to the presence intense exploration field for hydrocarbons (gas) is enriched by a unique stratigraphic dataset available from well cores and seismic profiles. The analysis of 58 different boreholes, subdivided the stratigraphic succession into three main stratigraphic intervals: Pre-Messinian, Messinian, and Post-Messinian. Three interactive HTML 3D models are constructed with Python tools: (1) surfaces separating the stratigraphic intervals by linear interpolation; (2) surfaces by nearest-neighbor interpolation; and (3) volumes of the three units. These models allow to visualize the stratigraphic and tectonic architecture of the Crotone Basin in a virtual and modelling detail.Financial support for this research derived from ENI-UNICAL funds (Definizione modello geologico e dei fenomeni geodinamici del Bacino Crotonese; Resp. S. Critelli). E.Falsetta was supported by The PhD Course in “Science and Engineering of Environment, Building and Energy” at the University of Calabria and by the PON React-EU “Ricerca e Innovazione” 2014–2020 funds (CUP: H29J21010090006). Research Project PID2020-114381GB-I00 to M. Martín-Martín, M. Bullejos and S. Critelli, Spanish Ministry of Education and Science; Research Groups and Projects of the Generalitat Valenciana, Alicante University (CTMA-IGA) are also acknowledged

    Temporal and spatial significance of volcanic particles in sand(stone): implications for provenance and palaeotectonic reconstructions

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    Volcanic particles have particular geodynamic significance. Despite abundant datasets on volcanicderived sand(stone), the distinction between spatial and temporal distribution of volcanic particles within the sedimentary record is poorly documented. One of the most intricate tasks in optical analysis of volcaniclastic sand(stone) is the distinction of grains eroded from ancient volcanic rocks (palaeovolcanic, noncoeval grains) from grains generated by active volcanism during sedimentation (neovolcanic coeval grains). Petrologic methods are useful for deciphering temporal significance of volcanic particles in detail between palaeovolcanic and neovolcanic, and for active volcanism to decipher syneruptive v. posteruptive processes during deposition in sedimentary basins close to volcanoes. Sedimentary processes during syneruptive, intereruptive and posteruptive phases are well described in continental environments in terms of changing sedimentary facies, for example, the architecture (from body scale to stratigraphic scale), width/depth ratios of palaeochannels, palaeosols and composition of fluvial-channel deposits, whereas they are less documented in deep-marine environments. Examples of volcaniclastic sedimentation derived from both palaeovolcanic and neovolcanic sources are found in diverse geotectonic settings

    The interplay of structural pathway and weathering intensity in forming mass-wasting processes in deeply weathered gneissic rocks (Sila Massif, Calabria, Italy)

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    This paper presents a detailed map (Main Map) showing geology, tectonics, weathering intensity and spatial distribution of landslides in the San Pietro in Guarano study area (about 7.5 km2), located in the north-western sector of Calabria (southern Italy). In this area, deeply weathered high-grade metamorphic rocks and different types/categories of mass movements are widespread. The Main Map, at 1:5000 scale, results from the combination of information gathered via analysis and interpretation of aerial photographs at different times and scales, multi-temporal geostructural and geomorphological surveys, field investigations and mapping of weathering grade in outcrop – through observation of geologically distinctive characteristics and qualitative and semi-quantitative engineering geological tests – integrated by means of the analysis of both weathering profiles on cutslopes and boreholes logs. The Main Map can represent a useful tool for authorities in charge of land-use planning and can profitably concur to typify landslides and to assess quantitative landslide risk
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