Tracing Pre-Mesozoic Tectonic Sutures in the Crystalline Basement of the Protocarpathians : evidence from the Exotic Blocks from Subsilesian Nappe, Outer Western Carpathians, Poland

Pre-Mesozoic exotic crystalline blocks within the Outer Carpathian flysch have potential to unravel the nature of their eroded basement source(s) and to reconstruct the Paleozoic–Precambrian history of the rotocarpathians. Strongly tectonized Campanian–Maastrichtian grey marls in the Subsilesian Nappe of the OuterWestern Carpathians in Poland contain a variety of different lithology types, including granitoids and andesites. Petrological investigations coupled with zircon and apatite U-Pb dating were performed on crystalline (subvolcanic) exotic blocks from a locality in the Subsilesian Nappe. U-Pb zircon dating yields magmatic crystallization ages of c. 293 Ma for the microgranitoid and c. 310 Ma for the andesite block, with inherited zircon cores yielding Archean, Paleoproterozoic, Mesoproterozoic and Cadomian ages. Whole rock trace element and Nd isotope data imply that the melt source was composed of a significant Neoproterozoic crustal component in both the microgranite and andesite. The Late Carboniferous–Permian magmatic activity likely continues outside the Carpathian Belt and can be linked to a Late Paleozoic transtensional zone, which is a continuation of the Lubliniec–Kraków Zone that extends under the Carpathians to Moesia. This Late Paleozoic transtensional zone was probably reactivated during the Late Cretaceous under a transpressional regime within the Z˙ egocina tectonic zone, which caused the uplift of the Subsilesian Ridge and intensive erosion

Magmatic arc evolution during the tectonic closure of the Rocas Verdes basin: insights from Cretaceous–earliest Paleocene intrusive rocks of Navarino Island (55°S), Fuegian Andes

Navarino Island is located in the southernmost part of the Fuegian Andes, south of the Beagle Channel. Its geological record documents the complex tectonic history of Tierra del Fuego that includes the opening and closure of the Rocas Verdes basin, Cordillera arc collision and subsequent subduction processes. The geology of the island is mostly comprised of the Cretaceous Yahgan Formation, a marine meta-sedimentary sequence, which is intruded by diverse plutons that are mostly exposed on the northwestern tip of the island. We herein present a new dataset that shows the presence of three Cretaceous-earliest Paleocene magmatic suites of active margin magmatism emplaced during the early stage of the Fuegian Andes, which are referred to as (i) the Dientes de Navarino Microdioritic Sills, a suite of pre-tectonic microdioritic sills that formed during ~101-97 Ma; (ii) the Castores Plutonic Complex, a series of pre- to syn-tectonic gabbroic to tonalitic plutons emplaced during ~90-87 Ma and (iii) the Samantha Monzonites, a suite of isolated monzonitic to monzodioritic post-tectonic plutons that formed at ~66-65 Ma. These distinct magmatic episodes are recognised by field observations, geological mapping, petrography and whole-rock geochemistry integrated with amphibole and biotite 40Ar/39Ar and U-Pb zircon LA-ICP-MS geochronology. The geochemical compositions of these rocks are consistent with a continental arc setting that formed during the interval ~101-65 Ma. While the three pulses spatially overlap in Navarino Island, the arc magmatism shows a migration (or expansion) throughout the Late Cretaceous. The locus of the arc then migrated at ~68-66 Ma towards the southwest. We suggest that this trench-ward migration at ~68-66 Ma may be associated with a change in the subduction angle. The three Cretaceous- earliest Paleocene plutonic pulses recorded in Navarino Island formed during the early stages of development of the Fuegian Andes, and are pre-, syn-and post-tectonic with respect to a major compressional event caused by the collision and obduction of the back-arc Rocas Verdes oceanic floor.Fil: Velásquez, Ricardo. Servicio Nacional de Geología y Minería;Fil: Bastías, Joaquín. Universidad Andrés Bello; Chile. Trinity College; IrlandaFil: Salazar, Esteban. Servicio Nacional de Geología y Minería;Fil: Poblete, Fernando. Universidad de Chile; Chile. Universidad de O Higgins;Fil: Gonzalez Guillot, Mauricio Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; ArgentinaFil: Chew, David. Trinity College; IrlandaFil: Peña, Matías. Universidad Mayor.; ChileFil: Tapia Silva, Felipe Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Ramirez, Adán. Servicio Nacional de Geología y Minería;Fil: Drakou, Foteini. Trinity College; Irland

Silesian Ridge in the light of petrological analyses and LA-ICP MS U-Pb analyses of the cohesive debrites from the Istebna Formation (Silesian Nappe, Outer Western Carpathians, Poland)

Exotic clasts present in flysch deposits of the Western Outer Carpathians enable investigation and reconstruction of the eroded crystalline basement of the Silesian Ridge. The flysch rocks of the Istebna Formation (Jasnowice Member: Paleocene) in the Silesian Nappe contain magmatic and metamorphic clasts derived from the Silesian Ridge basement. The crystalline rock fragments acquired from cohesive debrites were analyzed petrographically and geochemically, and zircon and rutile crystals were subject to LA-ICP-MS U-Pb dating. Granitoid clasts yielded Meso-Variscan U-Pb zircon ages (325.7 and 330.6 Ma), with older (Neoproterozoic to Paleoproterozoic) inherited cores and eNd330 = –12.0 (TDM age of 1.98 Ga). The orthogneiss clast yielded a protolith age of 1635 Ma and fingerprint of thermal reworking at ~288 Ma. Zircon crystals from the detrital clasts yielded similar U-Pb zircon ages to the granitoid clasts (311.5 to 391 and 331 Ma). The rutile crystals from sandstone yielded concordia age of 344.7 Ma. Zircon crystals from paragneiss, interpreted as a granitoid envelope, yielded 238U/206Pb ages between 557 and 686 Ma and include an inherited core of age ~1207.4 ±33.8 Ma. Age data from exotic clasts and the detrital zircon and rutile fraction suggest the core part of the Silesian Ridge was a Neoproterozoic to Mesoproterozoic envelope intruded by Meso-Variscan granitoid plutons

Recurrent E - W oscillations of the ice flow confluence of the East and West Antarctic ice sheets in the central Ross Sea, Antarctica, from the Middle Miocene to the present day

We present a multidisciplinary provenance study on legacy cores drilled in the 1970s during DSDP Leg 28 at sites 271 and 272, in the central Ross Sea, Antarctica. The two sites combined provide a discontinuous glaciomarine sedimentary record covering 18 myr, from the Middle Miocene to the present day. The two boreholes are located on the continental shelf and near the edge of the Ross Ice Shelf, in the middle of the Ross Sea, at a key site close at 180° longitude that is considered to represent the present confluence between ice flows fed by West Antarctica and East Antarctica. The study employs U Pb dating of detrital zircons and apatites, coupled with apatite fission-track dating and trace element and REE compositions. Based on the sedimentary provenance, our data show a recurrent E-W oscillation of the confluence of the West Antarctica and East Antarctica ice flows, allowing phases of advance and retreat of the West Antarctic Ice Sheet to be inferr

Variscan magmatic evolution of the Strandja Zone (Southeast Bulgaria and Northwest Turkey) and its relationship to other North Gondwanan margin terranes

The Strandja Zone, straddling the border between Bulgaria and Turkey, is often assigned to either the Balkanide or the Pontide thrust belts of the Alpine orogen in the Black Sea region. Previous studies have considered this zone, which originated on the North Gondwanan margin, as part of a Late Carboniferous to Triassic magmatic arc associated with the subduction of the Paleo-Tethys Ocean beneath Eurasia. Magmatism has been regarded as representing one continuous or two separate stages occurring under different tectonic settings. We present new LA-ICP-MS U-Pb zircon ages together with field, petrographic and geochemical studies of variably deformed granites from the Sakar Batholith and Levka Pluton of the Sakar Unit in the Strandja Zone. The new U-Pb ages from Sakar Batholith (ca. 306 Ma) and Levka Pluton (ca. 319 Ma) demand a re-evaluation of previously published U-Pb crystallisation ages from these magmatic bodies. The U-Pb age reported for the Levka Pluton also provides an upper age limit for the timing of Variscan metamorphism. The Late Carboniferous to Early Permian magmatic evolution of the Strandja Zone displays a strong resemblance to that of the Sredna Gora Zone. Both units, probably together with Serbo-Macedonian Metamorphic Complex and Sakarya Zone, were part of the metamorphic core of the Variscan Orogen

Ice volume variations and provenance trends in the Oligocene-early Miocene glaciomarine sediments of the Central Ross Sea, Antarctica (DSDP Site 270)

Since the early Oligocene, the descent into global colder conditions has led to the stepwise growth of the Antarctic Ice Sheets. However, ocean and air temperatures were not sufficiently cold enough to maintain a large and stable continental ice sheet and associated marine ice shelf, and therefore during the Oligocene to Miocene the glaciation waxed and waned. However there is limited geological evidence for the extent of these early glacial episodes. Here we present a multi-proxy single-grain provenance study on the glaciomarine sediments in DSDP Site 270, from the Central High in the central Ross Sea to determine the extent of such ice volume variations. The Ross Sea embayment is a key region in Antarctica for preserving geological evidence on the early glacial events, because glaciation was synchronous with continuous sea-floor subsidence and uplift of the surrounding mountain ranges. The Central High in the central Ross Sea was drilled by the DSDP project in the 1970s (Site 270) and a sequence of c. 400 m of Oligocene to lower Miocene glaciomarine sediments was recovered, underlain by a few meters of granitic talus breccia and gneissic basement rocks. The sediments evolve from a non-glacial, continental environment to a glaciomarine environment characterized by variable ice-rafted debris content and several diamictite units. Our approach combines information on crystallization ages in the source region (U-Pb detrital zircon dating), medium- and low-temperature thermochronology constraints (detrital apatite U-Pb and fission-track dating on the same grains), information on the source bedrock type (detrital apatite trace element analysis) and petrological analysis of gravel-size clasts. We provide new constraints on the ice sheet evolution since the earliest phases of glaciation, and show a transition from local to regional-scale ice sheets in the central Ross Sea region in the late Oligocene and early Miocene. In addition, our data can identify the source of sediment transported by ice streams to the central Ross Sea from different areas in the Transantarctic Mountains (TAM) and within the West Antarctic Rift System (WARS). In particular, the provenance data show the late Oligocene diamictite strata were sourced from a distant region, likely southern West Antarctica, indicating a substantial continental ice sheet already existed in the late Oligocene. These new data provide robust geological constraints for modeling of ice sheet volumes and ice drainage patterns in the late Oligocene-early Miocene

U-Pb isotope ratios and trace element concentrations of carbonate-fluorapatite from phosphate nodules in Carboniferous sedimentary rocks in northern Co. Clare, Ireland

These data are trace element concentrations and U-Pb isotope ratios from phosphate nodules in Carboniferous-age carbonates, shales and phosphorites in Co. Clare, western Ireland. Sampling locations (both in degrees and as UTM coordinates) are also included. Mineralogically, the analysed material is apatite (species: carbonate-fluorapatite). These data are being used to support a paper which is currently under review. Data were collected by LA-Q-ICPMS in the National Centre for Isotope Geochemistry in University College Dublin, and at the iCRAG Lab @ Trinity College Dublin. Both labs are in Dublin, Ireland. Spots or portions of ablations intercepting inclusions of non-apatite phases have been excluded to ensure the accuracy of reported data. Appropriate reference materials (RMs) were used to reduce and quality-control data, including: Madagascar Fluorapatite; NIST612 glass; BHVO2G glass; Durango Fluorapatite; McClure Mountain Fluorapatite; and Bamble 2 Flour/Chlor-apatite. All secondary RMs reproduced their respective U-Pb isotopic ages or element concentrations within acceptable ranges. These processed data were reduced from raw data using Iolite 3 software. The analysis was chiefly funded under an Irish Research Council Postdoctoral Fellowship Award awarded to Gary J O'Sullivan (GOIPD/2019/906)

Signatures of sulfide remobilization in the Kiruna mining district: a SIMS sulfur isotope and LA-ICP-MS trace element study

The Kiruna mining district in northern Norrbotten, Sweden, is situated in a region that is broadly described as an iron oxide-copper-gold (IOCG) district. Kiruna is well known for the iron oxide-apatite (IOA) deposits (Kiruna-type), but also hosts several Cu-bearing prospects including the Viscaria and Eastern Pahtohavare stratabound-stratiform Cu-(Fe-Zn), the Rakkurijärvi IOCG, and the Pahtohavare epigenetic Cu ± Au prospects. However the genesis of the Cu mineralization in the district has not been studied from a structural perspective in relation to the tectonic evolution of the region. Utilizing recent structural characterization of the Svecokarelian orogenic cycle as a framework, Cu- and Fe-bearing sulfides have been identified from the pre-, early, and late orogenic phases and assessed for primary and overprinting signatures with in situ δ34S and trace element data. Results indicate that the youngest stage of epigenetic mineralization (late orogenic) in the Pahtohavare area precipitated vein-hosted pyrite from a strongly Co-enriched hydrothermal fluid with δ34S values between 2‰ and 6 ‰. The late mineralization event occurred syn- to post-folding of the host rocks together with remobilization of sulfides from the younger Eastern Pahtohavare deposit. This remobilization is characterized by a fractionation of sulfur isotopes towards heavier values and dispersion of Co and Ni data towards higher and lower concentrations, respectively, and indicates redistribution of metals occurred as a result of the late orogenic mineralization and deformation. This implies a distinct Cu-forming event occurred in the late Svecokarelian orogeny both that introduced new metals and redistributed (and possibly incorporated) metals from a preexisting source. Metamorphic and low temperature remobilization is also recorded in samples from the district characterized by increases in Co and Ni, respectively.

Signatures of sulfide remobilization in the Kiruna mining district: a SIMS sulfur isotope and LA-ICP-MS trace element study

The Kiruna mining district in northern Norrbotten, Sweden, is situated in a region that is broadly described as an iron oxide-copper-gold (IOCG) district. Kiruna is well known for the iron oxide-apatite (IOA) deposits (Kiruna-type), but also hosts several Cu-bearing prospects including the Viscaria and Eastern Pahtohavare stratabound-stratiform Cu-(Fe-Zn), the Rakkurijärvi IOCG, and the Pahtohavare epigenetic Cu ± Au prospects. However the genesis of the Cu mineralization in the district has not been studied from a structural perspective in relation to the tectonic evolution of the region. Utilizing recent structural characterization of the Svecokarelian orogenic cycle as a framework, Cu- and Fe-bearing sulfides have been identified from the pre-, early, and late orogenic phases and assessed for primary and overprinting signatures with in situ δ34S and trace element data. Results indicate that the youngest stage of epigenetic mineralization (late orogenic) in the Pahtohavare area precipitated vein-hosted pyrite from a strongly Co-enriched hydrothermal fluid with δ34S values between 2‰ and 6 ‰. The late mineralization event occurred syn- to post-folding of the host rocks together with remobilization of sulfides from the younger Eastern Pahtohavare deposit. This remobilization is characterized by a fractionation of sulfur isotopes towards heavier values and dispersion of Co and Ni data towards higher and lower concentrations, respectively, and indicates redistribution of metals occurred as a result of the late orogenic mineralization and deformation. This implies a distinct Cu-forming event occurred in the late Svecokarelian orogeny both that introduced new metals and redistributed (and possibly incorporated) metals from a preexisting source. Metamorphic and low temperature remobilization is also recorded in samples from the district characterized by increases in Co and Ni, respectively.