Search

The Middle-to-Upper Paleolithic transition in Europe covers the last millennia of Neanderthal life together with the appearance and expansion of Modern Human populations. Culturally, it is defined by the Late Middle Paleolithic succession, and by Early Upper Paleolithic complexes like the Châtelperronian (southwestern Europe), the Protoaurignacian, and the Early Aurignacian. Up to now, the southern boundary for the transition has been established as being situated between France and Iberia, in the Cantabrian façade and Pyrenees. According to this, the central and southern territories of Iberia are claimed to have been the refuge of the last Neanderthals for some additional millennia after they were replaced by anatomically Modern Humans on the rest of the continent. In this paper, we present the Middle-to-Upper Paleolithic transition sequence from Cova Foradada (Tarragona), a cave on the Catalan Mediterranean coastline. Archaeological research has documented a stratigraphic sequence containing a succession of very short-term occupations pertaining to the Châtelperronian, Early Aurignacian, and Gravettian. Cova Foradada therefore represents the southernmost Châtelperronian–Early Aurignacian sequence ever documented in Europe, significantly enlarging the territorial distribution of both cultures and providing an important geographical and chronological reference for understanding Neanderthal disappearance and the complete expansion of anatomically Modern Humans. [ABSTRACT FROM AUTHOR]

The Los Pedroches batholith (SW Spain) is one of the most salient igneous alignments of the Iberian massif. The batholith is considered one of the best examples of post-collisional batholiths of Iberia and is dominated by a biotite granodiorite that was emplaced in the shallow crust postdating the main deformation phases of the Variscan orogeny. In the Quintana de la Serena area, to the northwest of the batholith, granodiorites were partially emplaced into dacites characterized by the presence of abundant orthopyroxene. The quality of outcrops and abundant quarries in the area, together whit the near absence of local crustal contamination, make this zone an ideal location for petrogenetic studies about the origin of granodiorite magmas and their related microgranular enclaves. We present in this paper new SRHRIMPII-based zircon geochronology data that indicate orthopyroxene-bearing subvolcanic rocks emplaced and cooled at the age of 310 ± 2 Ma, slightly earlier than the intrusion and cooling of the massive granodiorites (307 ± 1 Ma and 306.6 ± 0.7 Ma) and their related mafic microgranular enclaves (307.8 ± 0.8 Ma). Whole rock geochemistry demonstrates that the three groups of rocks, dacites, granodiorites and mafic microgranular enclaves, define a coherent geochemical trend indicating that they are cogenetic and related by fractionation of a common parental magma. This study proves the role played by intermediate magmas of sanukitoid affinity in the generation of the most abundant and massive granodiorite rocks that form large post-collisional batholiths in Iberia. • Granodiorites, enclaves and subvolcanic orthopyroxene-bearing rocks form a continuous series. • All rocks were emplaced at ca. 307 Ma, postdating Variscan orogenic episodes. • Granodiorites were generated by fractionation of a parental sanukitoid magma. • Intrusive and subvolcanic rocks of Quintana form part of a large post-collisional batholith. [ABSTRACT FROM AUTHOR]

New palynological results from the Gafo Formation (southern sector of the Pulo do Lobo Domain, South Portuguese Zone) are integrated with recently studied sections and drillholes from the Portuguese and Spanish sectors. A total of 44 samples were studied, 27 of which were positive for palynomorph taxonomy. This research revealed well preserved palynological assemblages, including 73 spore species allocated to 28 genera, four acritarch genera, three prasinophyte algae genera plus common chitinozoan remains. Some additional forms were retained under open nomenclature. From this, the first complete age determination for the Gafo Formation in Portugal and Spain was achieved, indicating a middle Famennian (Grandispora gracilis–Grandispora famenensis, GF Biozone) to a late Famennian (Grandispora echinata, VH Biozone) age. A greywacke sample from the same Gafo Formation was dated by U–Pb zircon geochronology and a maximum depositional age of 369 ± 2.5 Ma was obtained. A correlation between these palynological and U–Pb zircon data and the palynoflora assemblages of previous authors was made, as well as with the ages of felsic volcanic rocks found intercalated in the Gafo Formation, confirming the complex stratigraphy of Pulo do Lobo Domain. The results are consistent with stratigraphic mapping and structural interpretations, allowing a middle–late Famennian age (GF and VH Biozone) to be assigned to the Gafo Formation sedimentary rocks. This work has also contributed to a reinterpretation of Gafo Formation depositional facies correlatives (e.g. the Santa Barbara Group in Spain) as being the same lithological unit. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents new geochronological, geochemical and isotopic data for Late Ordovician magmatism (455±2Ma) from the Variscan massifs in the northeastern Iberian Peninsula. This magmatism is mainly composed of aluminous and metaluminous plutonic rocks and a sequence of calc-alkaline ignimbrites and epiclastic volcanic rocks, which were deformed and metamorphosed during the Variscan orogeny. The metaplutonic rocks are located in the lower part of a Neoproterozoic/Early Cambrian metasedimentary sequence in the Canigó massif (Eastern Pyrenees). Aluminous orthogneisses have isotopic signatures that indicate a crustal origin, whereas metaluminous orthogneisses originate from a mixture of juvenile and crustal melts. The metavolcanic rocks define a calc-alkaline ignimbritic sequence of crustal origin located in the lower part of the Late Ordovician sequence in the Les Gavarres massif (Catalan Coastal Ranges). T DM ages for all the studied Late Ordovician rocks range from Mesoproterozoic to Paleoproterozoic (1.3Ga, 1.5Ga, 1.7Ga and 2.2Ga), suggesting a Neoproterozoic crust with Paleoproterozoic components and an arc signature, as the most probable source for the crustal melts. The isotopic similarities between the studied samples and other Early Ordovician magmatic rocks of the Central and Western Iberian Massif suggest repeated melt extractions from a common basement as the source for the Early and Late Ordovician magmatism in the Iberian realm. However, the studied massifs are more closely linked to other massifs from the Mediterranean realm. The most probable tectonic setting for the emplacement of the Late Ordovician volcanic and plutonic bodies is that of an extensional regime, which postdates a previous Ordovician contractional event and the opening of the Rheic Ocean. [Copyright &y& Elsevier]

From Permian to Late Cretaceous, the northern Bohemian Massif experienced a complex intra-plate tectono sedimentary evolution involving development of at least four generations of sedimentary basins in different settings. We examine this protracted evolution using stratigraphic changes in sediment provenance, analyzed through heavy mineral assemblages and U–Pb detrital zircon geochronology (by laser-ablation ICP–MS) in Permian, Jurassic, and Late Cretaceous successions. The provenance data point to multiple, temporally evolving sources ranging from local (e.g., the ʽWest Sudetic Islandʼ) through more distant from elsewhere in the Bohemian Massif to exotic, likely derived from Baltica. The latter is interpreted as a trace of now completely eroded Late Jurassic to Early Cretaceous basin that once covered the Lusatian (Lausitz) Block and received the Baltica-derived detritus from northerly fluvial and deltaic depositional systems. We suggest that fill of this basin was recycled into the Bohemian Cretaceous Basin during progressive unroofing of the West Sudetic Island. A time-slice reconstruction of the paleogeographic and tectono sedimentary evolution of the northern Bohemian Massif is then developed to show that periods of basin development and deposition (early Permian, late early Permian to Early Triassic, Middle Jurassic–Early Cretaceous, and Late Cretaceous) were interrupted by major depositional gaps (Middle Triassic–Early Jurassic, mid-Cretaceous, and post-early Campanian). The Mesozoic depositional episodes resulted from reactivation of major NW–SE strike-slip fault zones due to stress transfer from the North Atlantic Rift during Jurassic to Early Cretaceous, overridden by the far-field effect of convergence of Iberia, Africa, and Europe during Late Cretaceous. [ABSTRACT FROM AUTHOR]

The origin of plutonic complexes that stitch suture zones developed during collision is not well understood. In southern Iberia, the Pulo du Lobo suture zone (PDLZ) is intruded by the syn- to postcollisional Gil Marquez pluton (GMP), thought to be part of the Sierra Norte Batholith. U-Pb (LA-ICPMS, zircon) data on various phases of the GMP yield from oldest to youngest: (1) a 354.4 ± 7.6 Ma unfoliated gabbro; (2) a 345.6 ± 2.5 Ma foliated intermediate phase; (3) a 346.5 ± 5.4 Ma unfoliated porphyritic granite; (4) a 335.1 ± 2.8 Ma unfoliated biotite granite. This sequence is consistent with cross-cutting relationships observed in the field. The range in ages is consistent with interpretations that the GMP is part of the composite (ca. 350-308 Ma) SNB. Inherited ages preserved in the GMP intermediate and felsic phases indicate that its magmas traversed through South Portuguese Zone and PDLZ crust during emplacement. The ca. 345 Ma emplacement of the late kinematic foliated intermediate phase constrains the age of late-stage strike slip deformation within the PDLZ, and the lack of a foliation in the older gabbro indicates that is was not proximal to a shear zone neither at the time of emplacement, nor during its subsequent history. The unfoliated porphyritic granite and unfoliated biotite granite cut the foliation of the intermediate phase indicating emplacement during the waning stages of collision, while the ca. 335 Ma biotite granite intrudes the Santa Ira Flysch, thereby providing a tight constraint for the latest stage of deformation in the PDLZ. [ABSTRACT FROM AUTHOR]

The Spanish Central System (SCS) batholith, located in the Central Iberian Zone, is one of the largest masses of granite in the European Variscan Belt. This batholith is a composite unit of late- and post-kinematic granitoids dominated by S- and I-type series granite, with subordinate leucogranite and granodiorite. Zircon trace element contents, from two representative S-type and three I-type granitoids from the eastern portion of the SCS batholith, indicate a heterogeneous composition due to magma differentiation and co-crystallisation of other trace element-rich accessory phases. In situ, U-Pb dating of these zircons by SHRIMP and LA-ICP-MS shows 479-462-Ma inherited zircon ages in the I-type intrusions, indicating the involvement of an Ordovician metaigneous protolith, while the S-type intrusions exclusively contain Cadomian and older zircon ages. The zircon crystallisation ages show that these granites have been emplaced at ca. 300 Ma with a time span between 303 ± 3 Ma and 298 ± 3 Ma. Precise dating by CA-ID-TIMS reveals a pulse at 305.7 ± 0.4 Ma and confirms the major pulse at 300.7 ± 0.6 Ma. These ages match the Permo-Carboniferous age for granulite-facies metamorphism of the lower crust under the SCS batholith and coincide with a widespread granitic event throughout the Southern Variscides. Ti-in zircon thermometry indicates temperatures between 844 and 784°C for both the S- and I-type granites, reinforcing the hypothesis that these granites are derived from deep crustal sources. [ABSTRACT FROM AUTHOR]

Terra Nova, 24, 283-294, 2012 Abstract The Bazar Ophiolite, one of the ophiolitic units involved in the Variscan suture of NW Iberia, is mainly formed by metagabbroic high T amphibolites with N-MORB affinity. The ophiolite appears accreted under an arc-derived upper terrane affected by intermediate-P granulite facies metamorphism dated at 496-484 Ma. U-Th-Pb geochronology and Lu-Yb-Hf isotope geochemistry of zircons allow recognizing two growth stages. The first occurred during crystallization of the gabbroic protolith and has been dated at 495 ± 2 Ma, whereas the second one, interpreted as dating the high T metamorphism, yielded an age of 475 ± 2 Ma. The chronology of the Bazar Ophiolite and its accretionary history suggest that this unit is a relic of the Cambrian ocean located to the North of Gondwana, the Iapetus-Tornquist Ocean, accreted to a dissected arc during or before the early stages in the opening of the Rheic Ocean. [ABSTRACT FROM AUTHOR]

A number of hydrocarbon discoveries have been made recently in the Flemish Pass Basin and Central Ridge, offshore Newfoundland, Canada, but there is only limited geological information available. The primary goal of this study was to determine the sedimentary provenance and paleodrainage patterns of mudstones and sandstones from the Upper Jurassic Rankin Formation, including the Upper and Lower Kimmeridgian Source Rock (organic-rich shale) members and Upper and Lower Tempest Sandstone Member reservoirs, in this area. A combination of heavy mineral analysis, whole-rock geochemistry and detrital zircon U-Pb geochronology was determined from cores and cuttings from four offshore wells in an attempt to decipher provenance. Detrital heavy minerals in 20 cuttings samples from the studied geologic units are dominated by either rutile + zircon + apatite ± chromite or rutile + apatite + tourmaline, with minor zircon, indicating diverse source lithologies. Whole rock Zr-Th-Sc trends suggest significant zircon recycling in both mudstones and sandstones. Detrital zircon U-Pb ages were determined in two mudstone and four sandstone samples from the four wells. Five major U-Pb age groups of grains were found: A Late Jurassic group that represents an unknown source of syn-sedimentary magmatism, a Permian–Carboniferous age group which is interpreted to be derived from Iberia, a Cambrian–Devonian group derived from the Central Mobile Belt of the Newfoundland–Ireland conjugate margin, and two older age groups (late Neoproterozoic and >1 Ga) linked to Avalonia. The Iberian detritus is abundant in the Central Ridge and southern Flemish Pass region and units containing sizable populations of these grains are interpreted to be derived from the east whereas units lacking this population are interpreted to be sourced from the northeast and possibly also the west. The Upper Tempest Sandstone contains Mesozoic zircons, which constrain the depositional age of this unit to be no older than Late Tithonian. [ABSTRACT FROM AUTHOR]

Enicocephalomorpha, also known as uniqueheaded bugs, are a seldom-collected infraorder of heteropteran insects whose evolutionary relationships have puzzled entomologists for more than a century. Unique-headed bugs are exceptionally rare in the fossil record, which hinders our understanding of the morphological transformations of the lineage across time and also affects the calibration of molecular clock estimates used to date the origins of the infraorder. Here, we report the discovery of Enicocephalinus ibericus sp. nov. from Iberian amber in the Ari~no deposit in Spain, early Albian (Early Cretaceous) in age. The new species represents the second oldest fossil enicocephalomorphan to date, and the second record of this infraorder from European deposits. Remarkably, the closest relative of E. ibericus is the congeneric E. acragrimaldii Azar from Lebanese amber that is c. 20 myr older (Barremian), indicating a long-term persistence of the Enicocephalinus lineage across geological time. A review of the existing literature enabled us to record a total of 20 congeneric insect species that have been found in both Lebanese and Iberian ambers, suggesting the existence of previously underappreciated entomofaunal connections between southern Laurasia (the European archipelago) and northern Gondwana during the Cretaceous. We show that the palaeoentomological record holds remarkable potential for elucidating the faunistic exchanges and palaeobiogeographical patterns in the peri-Tethyan region during the Cretaceous. [ABSTRACT FROM AUTHOR]