Cadomian metabasites of the Eastern Pyrenees revisited

This study presents a new geochemical, petrological, and geochronological U-Pb dataset from Ediacaran metabasites and associated rocks of the Canigó and Cap de Creus massifs, Eastern Pyrenees. Metabasites are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452-482ºC and 5.2-7.7kbar, which suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#<0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43-416ppm). The rocks are moderately enriched in Light Rare Earth Elements (LREE) relative to Heavy Rare Earth Elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33–0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82-3.05) of the studied metabasites preclude a notable contribution from an older continental crust. Detrital zircon U-Pb dating Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma and apparent maximum age of deposition at ca. 550Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the Low-Pressure High-Temperature (LP-HT) metamorphism classically described in the Pyrenees.Spanish Government CGL2017-87631-P PGC2018-093903-B-C22Ministerio de Ciencia, Innovacion y Universidades/Agencia Estatal de Investigacion/Fondo Europeo de Desarrollo Regional, Union EuropeaMargarita Salas grantUniversitat de BarcelonaMinisterio de Universidades/NextGenerationEU/PRTR/Plan de recuperacion, transformacion y resilienci

The Discovery of the Romero VMS Deposit and Its Bearing on the Metallogenic Evolution of Hispaniola during the Cretaceous

The recently discovered Romero deposit, located in the Tres Palmas district, Cordillera Central of the Dominican Republic, has probable reserves of 840,000 oz gold, 980,000 oz silver and 136 Mlb copper. Mineralization is hosted by intermediate volcanic and volcaniclastic rocks of the lower stratigraphic sequence of the Cretaceous Tireo formation. The andesitic host rocks yield a U-Pb zircon concordia age of 116 ± 10 Ma. Au–Ag–Cu(–Zn) mineralization is divided into: (1) an upper domain with stacked massive sulfide lenses and sulfide dissemination within a 20-m-thick level of massive anhydrite-gypsum nodules, and (2) a lower domain with a high-grade stockwork mineralization in the form of cm-scale veins with open space fillings of fibrous silica and chalcopyrite, sphalerite, pyrite (+electrum ± Au–Ag tellurides). The γ34S values of sulfides from the upper (-7.6 and +0.9‰) and lower (-2.4 and +5.6‰) domains are consistent with a heterogeneous sourcing of S, probably combining inorganically and organically induced reduction of Albian-Aptian seawater sulfate. Despite this, a magmatic source for sulfur cannot be discarded. The γ34S (+19.2 and +20.0‰) and _18O (+12.5 and +14.2‰) values of anhydrite-gypsum nodules are also consistent with a seawater sulfate source and suggest crystallization in equilibrium with aqueous sulfides at temperatures higher than 250ºC. These data point to a classification of Romero as a volcanogenic massive sulfide (VMS) deposit formed in an axial position of the Greater Antilles paleo-arc in connection with island arc tholeiitic magmatism during a steady-state subduction regime. Circulation of hydrothermal fluids could have been promoted by a local extensional tectonic regime expressed in the Tres Palmas district as a graben structure.This research has been financially supported by the Spanish projects CGL2012-36263 and CGL2015-65824, the Dominican project 2014-1B4-132, the Catalan projects SGR 2014-1661 and 2007-707 and by Goldquest Mining Corp

Cadomian metabasites of the Eastern Pyrenees revisited

This study presents a new geochemical, petrological, and geochronological U–Pb dataset from Ediacaran metabasites of the Canigó and Cap de Creus massifs, Eastern Pyrenees. The rocks are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452–482ºC and 5.2–7.7kbar. These intermediate P-T conditions suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#&lt;0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43–416ppm). The rocks are moderately enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33–0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82–3.05) of the studied metabasites preclude a notable contribution from an older continental crust. U-Pb dating (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the HT-LP metamorphism classically described in the Pyrenees

Cadomian metabasites of the Eastern Pyrenees revisited

This study presents a new geochemical, petrological, and geochronological U–Pb dataset from Ediacaran metabasites of the Canigó and Cap de Creus massifs, Eastern Pyrenees. The rocks are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452–482ºC and 5.2–7.7kbar. These intermediate P-T conditions suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#<0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43–416ppm). The rocks are moderately enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33–0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82–3.05) of the studied metabasites preclude a notable contribution from an older continental crust. U-Pb dating (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the HT-LP metamorphism classically described in the Pyrenees.This research was financially supported by the Spanish Projects CGL2017-87631-P and PGC2018-093903-B-C22, Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional, Unión Europea. Additional funding was provided by a Margarita Salas grant to NPS by the Universitat de Barcelona with funds from the Ministerio de Universidades/NextGenerationEU/PRTR/Plan de recuperación, transformación y resiliencia

Cadomian metabasites of the Eastern Pyrenees revisited

This study presents a new geochemical, petrological, and geochronological U-Pb dataset from Ediacaran metabasites and associated rocks of the Canigó and Cap de Creus massifs, Eastern Pyrenees. Metabasites are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452-482ºC and 5.2-7.7kbar, which suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#&lt;0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43-416ppm). The rocks are moderately enriched in Light Rare Earth Elements (LREE) relative to Heavy Rare Earth Elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33–0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82-3.05) of the studied metabasites preclude a notable contribution from an older continental crust. Detrital zircon U-Pb dating Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma and apparent maximum age of deposition at ca. 550Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the Low-Pressure High-Temperature (LP-HT) metamorphism classically described in the Pyrenees

Petrology, metallogeny and U-Pb geochronology of the paleoproterozoic mafic-ultramafic Hamutenha intrusion, Angolan Shield

The Hamutenha intrusion (Huíla province, SW Angola) is a 3-km-long elongated magmatic body defined by a set of two intrusive units. The northern unit is formed by alternating bands of dunites and olivine gabbros, while the southern unit is composed of amphibole diorites. The Hamutenha body is hosted by the Paleoproterozoic Epupa Complex in the Angolan Shield, SW margin of the Congo Craton. A mineralogical, petrological and geochemical study of the Hamutenha intrusion has been performed. The constrained compositional features of the parental melt suggest interaction of tholeiitic magmas with a significant enrichment in Fe and Ti. Although disseminated Fe–Ni–Cu-(Co) secondary sulphides are observed, both the crustal contamination parameters and generally low bulk-rock metals contents indicate that these elements were most likely previously extracted from the parental melt. U–Pb zircon dating of amphibole diorite samples from the southern unit yields a date of 1844 ± 14 Ma. These data suggest that the emplacement of these rocks was previous to the KC emplacement and it was probably related to the Paleoproterozoic Epupa Complex magmatism.This work has been supported by the project CGL2009-13758 of the Spanish Government and the projects SGR-444 and SGR-589 of the Catalan Governmen

Cadomian metabasites of the Eastern Pyrenees revisited

Acknowledgement. This research was financially supported by the Spanish Projects CGL2017-87631-P and PGC2018-093903-B-C22, Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional, Unión Europea. Additional funding was provided by a Margarita Salas grant to NPS by the Universitat de Barcelona with funds from the Ministerio de Universidades/NextGenerationEU/PRTR/Plan de recuperación, transformación y resiliencia. We are deeply indebted to María José Aguilar Pérez for sample preparation and processing. Reviewers Antonio Castro and M. Francisco Pereira, and editor Martim Chichorro are deeply acknowledged for their constructive criticism and their very useful comments, which have helped to greatly improve the quality of the present manuscript.This study presents a new geochemical, petrological, and geochronological U-Pb dataset from Ediacaran metabasites of the Canigó and Cap de Creus massifs, Eastern Pyrenees. The rocks are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452-482ºC and 5.2-7.7kbar. These intermediate P-T conditions suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#<0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43-416ppm). The rocks are moderately enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33-0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82-3.05) of the studied metabasites preclude a notable contribution from an older continental crust. U-Pb dating (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the HT-LP metamorphism classically described in the Pyrenees

Quantification of potentially toxic elements in food material by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) via pressed pellets

Here, we validated a protocol for the elemental analysis of plant and food materials using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and pressed pellets in compliance with the Green Chemistry principles, i.e. avoiding the use of hazardous reagents. The protocol included sample pre-treatment, preparation of pellets, and LA-ICP-MS optimisation for the food sample matrix using leaf certified reference materials. Sample homogenisation and particle size reduction (∼10 µm) for samples with larger initial particle sizes proved crucial in improving signal stability and analytical results, whereas the raster mode was preferred over spot mode for greater accuracy. The validation of the technique was successful for determination of Mn, Ni, Cu, Zn, As, Se, Cd and Pb (z-score values ≤2). We propose LA-ICP-MS using pressed pellets as an alternative to ICP-MS in food analysis.We thank I. Martínez Segura and R. Reyes-González for their help in sample preparation and assistance in laboratory work. Dr. A. Parviainen acknowledges the ‘Juan de la Cierva – Incorporación’ (IJCI-2016-27412) Fellowship and Dr. C. Marchesi the “Ramón y Cajal” (RYC-2012-11314) Fellowship financed by the Spanish Ministry of Economy and Competitiveness (MINECO). Dr. C.J. Garrido acknowledges funding from Spanish MINECO-CSIC grant RECUPERA-2020 (“Monitorización de contaminantes en la cadena agroalimentaria-Hito 2”). Fellowships, research and infrastructure grants leading to this research have been (co)funded by the European Social Fund (ESF) and the European Regional Development Fund (ERFD) of the European Commission. We would also like to thank the anonymous reviewers for their support and comments that significantly improved the quality of the original paper

Alkaline Silicate Metasomatism Recorded through Fe-Ti-Rich Mantle Xenoliths from the Calatrava Volcanic Field (Spain)

Much of the lithospheric subcontinental mantle (SCLM) sampled in the Calatrava Volcanic Field (CVF) shows refertilization by alkaline metasomatic agents. The Cerro Pelado and El Palo ultramafic xenolith suites record the best evidence of this type of metasomatism in this volcanic field. Several groups of peridotite (lherzolite, wehrlite, and dunite) and pyroxenite (clinopyroxenite and websterite) xenoliths have been distinguished. Despite having scarce phlogopites and amphiboles as modal metasomatic phases, all studied xenoliths present a variable cryptic metasomatism, highlighted by the strong Fe-Ti enrichment and fractionated REE patterns in the most evolved wehrlite and pyroxenite varieties. They show a common trend of an Fe-Ti-Ca increase, whereas the pyroxenites are more depleted in Fe compared to the lherzolites and wehrlites. Trace-element (REE and multi-trace) patterns are roughly similar among them, suggesting different interactions and refertilization degrees by alkaline silicate melts. The same Sr–Nd isotopic EAR composition, combined with trace-element chemistry of metasomatic xenolith phases and phenocrysts from the Calatrava volcanics, highlights the main role of this magmatism in percolation processes beneath Central Iberia. These mantle xenoliths also show variable amounts of interstitial glass that originated by in situ partial melting, favored by the enriched chemical nature of cryptically metasomatized clinopyroxene during their volcanic transport. This alkaline-refertilized mantle type represents the main domain within the SCLM beneath Central Iberia, as was also recorded in other Western European Cenozoic volcanic fields.Ministerio de Ciencia e InnovaciónDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Turonian-coniacian definition of the Caribbean plate: tectonic and metamorphic record in the Median Belt, Dominican Republic

Uplift and unroofing of Jurassic-Cretaceous, mantle and crust, arc- and plume-related rock units in the Median Belt of the Dominican Republic exposed basement rocks with a protracted record of tectono-thermal events delineating the evolution of the northern edge of the Caribbean plate. In this article we focus on crustal rock units in the north-eastern half of the Median Belt. First Ar/Ar dating of metamorphic ferri-winchite (86.4 ± 2.5 Ma; crystallization date) and albite (82.3 ± 5.8 and 79.8 ± 1.6 Ma; cooling dates) in metabasites of boninitic photolith from the Aptian-Albian Maimón Formation in the Ozama shear zone points to a tectono-metamorphic event in the Upper Cretaceous. Beltwide, this event caused syn-metamorphic N- to NNE-directed, simple-shear dominated, mylonitic and phyllonitic deformation of the Maimón Formation at peak metamorphic conditions of 8.2 kbar and 380°C. Such conditions are consistent with subduction of a coherent portion of forearc (represented by the Maimón Formation) to depths of ~25-29 km. The tectono-metamorphic event dated here overlaps with the inception of Turonian-Coniacian SW-dipping subduction and metamorphic sole formation in a back-arc position recorded in the Moa-Baracoa ophiolite complex in neighboring Eastern Cuba. Contemporaneity between the subduction inception of forearc and back-arc portions of the Caribbean arc and the main pulse of plume activity recorded in the Caribbean Large Igneous Province (CLIP) suggests that plume activity promoted general plate instability leading to a regional-scale plate reorganization. This mantle-plume-induced plate margin reorganization was coeval with the inception of the NE-dipping subduction of the Farallón plate beneath Central America leading to the definition of the Caribbean Plate by double-verging subduction zones along its northern and southwestern margins.This research was financially supported by Grant PID2019-105625RB-C21 funded by MCIN/AEI/ 10.13039/501100011033 and the Catalan project 2014-SGR-1661, and received support for analyses at CIC from the University of Granad