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

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

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

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

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

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

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

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

Tectono-stratigraphic architecture of the Ionian piedmont between the Arso Stream and Nicà River catchments (Calabria, Southern Italy)

Along the northern Ionian margin of Calabria, three Neogene basins comprise wedge-top depozones containing syntectonic deposits which cover the frontal part of the fold-thrust belt. One of the best exposed onshore allochthonous siliciclastic successions is represented by the Cariati Nappe, cropping out in the Cirò Basin. Field geological mapping and aerial interpretations were used to characterize the stratigraphy and tectonics of the area between the Arso Stream and Nicà River catchments (about 170 km2), including a Paleozoic metamorphic basement complex unconformably overlain by Upper Oligocene to Quaternary siliciclastic deposits and minor carbonates. This paper presents a 1:25,000 scale map of the Ionian study area, providing lithological and structural data towards reconstructing its tectono-sedimentary evolution

Mn- and Fe-carbonate rich layers in Meso-Cenozoic shales as proxies of environmental conditions: A case study from the southern Apennine, Italy

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Weathering grade in granitoid rocks: The San Giovanni in Fiore area (Calabria, Italy)

This paper illustrates the methodology and techniques for the compilation of a thematic (engineering) geological map based on detailed mapping of the weathering grade of crystalline rocks occurring in a portion of the Sila Massif close to the San Giovanni in Fiore Village (Calabria, Italy). The map (1:5000 scale), covering an area of about 20 km2, was compiled combining new geological and structural data with the results of a weathering grade field survey. The methodology, used to distinguish and map the weathering grade classes, was performed using qualitative criteria, semi-quantitative tests, and petrographic analysis of weathered rock samples. The Main Map, presented in this paper, aims to provide a useful tool for land-use planning, for geological hazard assessment and engineering perspectives

Facies, composition and provenance of the Agnone Flysch in the context of the early Messinian evolution of the southern Apennine foredeep (Molise, Italy)

Clastic wedges deposited in deep-marine turbidite systemsalong the circum-Mediterranean region represent key tectonic elements that record the structural growing of the Apennine orogenic belt over the Adria margin. One of these clastic wedges is represented by the Agnone Flysch turbidite succession deposited in the Lagonegro-Molise foredeep basin in the early Messinian, for which the depositional facies and the related processes, as well as the sandstone and mudstone composition are poorly known. A combined sedimentology and sedimentary petrology study has been conducted on this turbidite succession that provides new insight to define the basin architecture and the provenance of the Agnone Flysch during late Miocene. Facies analysis suggests that this turbidite succession is constituted by depositional lobes that were emplaced in a sector of the basin showing a variable morphological confinement with frontal and lateral slope on which turbidite deposits onlapped. Consequently, this topographic context controlled the lateral and vertical distribution of turbidite facies, which record the effects of erosive processes, as well as impact, rebound and reflection processes, in turn related to the flow deceleration induced by structurally-controlled basin confinement. Detailed sandstones compositional analysis indicates a complex unroofing history that reflects structural changes in the source rock units and depositional basin physiography. By combining the sandstone composition with information deduced from the X-ray diffraction (XRD) patterns after thermo-chemical treatments (heating and ethylene glycol treatments), it was possible to explain and predict the sedimentary evolution and geological processes affecting fine grained sediments and, thus, the relationship developed between source area and sedimentary basin. In particular, clay minerals data show that Agnone Flysch experienced an early diagenetic condition as showed by the occurrence of the I/S R0 and I/S R1 on the XRD pattern of the glycolated specimens. The sandstone composition (mainly quartzofeldspathic) shows an increase in the metamorphic rock fragments and a decrease of sedimentary lithics up-section. This compositional trend records, together with the paleocurrents data, a derivation of this material from a mountain range located in the Tyrrhenian sector and from the Calabrian arc terranes