Antonio Garcia-Casco

University of Granada | UGR · Department of Mineralogy and Petrology

The ophiolitic Villa Clara serpentinite-matrix mélange, central Cuba, forms part of the large ophiolitic belt of the Greater Antilles. The composition of ultramafic and mafic rocks allows classifying them into two main groups, revealing a complex multi-stage formation of oceanic lithosphere in varied tectonic settings: i) group 1 matches fertile MO...

Deep Slow Slip and Tremors (SSTs) are a combination of transient clusters of tectonic tremors and slow slip associated with extremely elevated fluid pressures. SSTs are thought to reflect a transition from viscous to brittle plate interface rheology and likely exert a first-order control on megathrust seismicity. Nevertheless, the deformation mecha...

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 northeaste...

Exotic blocks of massive antigorite-serpentinite (antigoritite) document a deep-seated subduction channel in the Villa Clara serpentinite-matrix mélange, central Cuba. The petrological and geochemical characteristics of antigoritite allow distinguishing two types of rock: i) antigoritite and ii) dolomite-bearing antigoritite. Both types are intimat...

In this contribution we report the first systematic study of zircon U-Pb geochronology and δ18O-εHf(t) isotope geochemistry from ten islands of the hot-spot related Galapagos Archipelago. The data extracted from the zircons allow them to be grouped into three types: 1) young zircons (0 – ~4 Ma) with εHf(t) (~5 – 13) and δ18O (~4 – 7) isotopic mantl...

In the most internal zone of the Variscan Orogen, a stack of ophiolites and (ultra)high-P belts hold evidence for c. 60 Myr (c. 400–340 Ma) of almost continuous metamorphism and accretion onto the continental margin of Gondwana. Subduction of the peri-Gondwanan lithosphere led to three successive (ultra)high-P metamorphic episodes prior to the cont...

Platinum-group elements (PGEs) occur in ophiolitic chromitite in the Dominican Republic as platinum-group minerals (PGMs) in spatial association with hydrothermal uvarovite and chromian clinochlore. Bulk-rock total PGE content in a single analyzed chromitite sample is of 6.54 g/t. Three main PGM types are distinguished: euhedral magmatic laurite co...

Ultramafic-hosted volcanogenic massive sulfide deposits (UM-VMS) located in the Havana-Matanzas ophiolite (Cuba) are the only known example of this type of mineralization in the Caribbean realm. UM-VMS from Havana-Matanzas are enriched in Cu, Ni, Co, Au, and Ag. The mineralization consists of massive sulfide bodies mostly composed of pyrrhotite and...

Detailed textural and compositional study of calc-alkaline lamprophyres and minettes from Zeneta, SE Spain Neogene Volcanic Province (NVP) are used to unravel the magma sources and differentiation processes involved in their formation. The presence of xenocrysts of various origins indicates a hybrid nature involving mantle-derived alkaline lamproit...

We present a new U-Pb zircon age and geochemical data from an intermediate calc-alkaline pluton with adakitic affinity from NW Hispaniola (Haiti). The data provide important constraints and offer new insight on the Late Cretaceous (~90 Ma) development and geological evolution of the Greater Antilles Arc (GAA). The pluton intrudes Cretaceous basalts...

Variscite is a rare mineral that offers new opportunities for research on the mobility of raw materials in America during pre-Hispanic times through the provenance study of the source material. In this article we address a detailed characterization of the texture, mineralogy and chemical composition of the variscite beads belonging to the Nahuange...

A U-Pb zircon date of ;113 Ma revealed that a variety of jadeitites and related omphacitite, chloritite and albite-rich rocks from the subduction-related Sierra del Convento block-in-serpentinite-matrix mélange (eastern Cuba) formed nearly synchronously with MORB metabasite-derived anatectic trondhjemitic liquids at high-temperature and pressure in...

The Tampanchi Ultramafic–Mafic Complex (TUMC), located in the central segment of the Cordillera Real (Ecuador), is an oval-shaped intrusive body of approximately 18 km² emplaced within a Cretaceous metavolcano-sedimentary sequence. Field investigations, zircon geochronology, mineral and whole-rock elemental and isotopic compositions constrain the n...

Dense and strong, hydrothermal-metasomatic jadeitite and jadeite-omphacite rocks were used as tools and adornments throughout the wider Caribbean since initial inhabitation. Regionally, rich sources of jadeitite and jadeite-omphacite jade are known only in Guatemala (north and south of the Motagua Fault Zone), eastern Cuba and the northern Dominica...

The Habana-Matanzas ophiolites (western Cuba) host several hydrothermal ultramafic-hosted Cu-Au-Co rich massive sulfide deposits (e.g. Loma Majana and Salomón). The ore mineralogy of these deposits consists of pyrrhotite, pyrite, and chalcopyrite, with minor Co-Fe-Ni arsenides/sulfarsenides (mainly safflorite and cobaltite), gold (electrum), and re...

The Badajoz-Córdoba Unit (BCU, SW Iberian Massif) is a Variscan high-P unit mainly constituted by metapelites, metagreywackes, orthogneisses, Grt-amphibolites, and retrogressed eclogites (high-P metamorphism at c. 377 Ma). Discovery of rare metapelites with well-preserved high-P mineral assemblages, including large garnets up to 1 cm in diameter wi...

The architecture and pressure-temperature conditions reached by a Cretaceous block-in-matrix serpentinite mélange exposed in the Zagros suture resemble those imaged in the active Mariana subduction zone. There, large magnitude-earthquakes (Mw>9) have never been recorded but smaller events – of poorly-constrained physical origin – in the range Mw ~3...

An increasing number of seismological studies report transient seismicity clusters in the mantle wedge several kilometers above the subduction interface. Their physical significance with respect to subduction zone seismo-tectonics remains poorly understood. Jadeitites are known to form and/or be associated with mantle wedge serpentinites in the c....

Mantle plumes are active for long periods of time1,2, however dating the onset of their activity is difficult. The magmatic products of the Galápagos plume, for example, have been subducted and fragmentarily accreted to the Caribbean and South American plates3,4. Based on submarine and terrestrial exposures it is inferred that the plume has been op...

Devolatilization and fluid-rock interaction processes along subduction interfaces, in particular at depths where episodic tremor and slip events (ETS) are inferred, are evidenced by the occurrence of metamorphic veins in exhumed metamorphic terranes. We investigate the late Cretaceous lawsonite blueschist-facies Seghin complex, part of the Zagros s...

The Neoproterozoic Bou Azzer ophiolite in the Moroccan Anti-Atlas Panafrican belt hosts numerous chromitite orebodies within the peridotite section of the oceanic mantle. The chromitites are strongly affected by serpentinization and metamorphism, although they still preserve igneous relicts amenable for petrogenetic interpretation. The major, minor...

We investigate the late Cretaceous blueschist-facies (480 °C-1.8 GPa) segment of the Zagros suture zone, a well-preserved block-in-matrix paleo-subduction channel. We aim to determine the relative chronology, conditions of deformation, and potential fluid sources and processes associated with the widespread occurrence of lawsonite + clinopyroxene +...

The Cubito-Moura Unit is a high-P metamorphic succession that occurs in the southern part of the Ossa-Morena Complex (SW Iberian Massif). It includes a series of metasedimentary, metafelsic and metamafic rocks affected by a high-P, low to intermediate-T metamorphic event during Late Devonian times. Geochemistry of the metabasic rocks reveals that t...

Although experimental work predicts that platinum-group elements (PGE) are soluble in hydrothermal fluids at temperatures <500 ºC during serpentinization in ophiolite complexes, mineralization-mechanisms driving to the formation of hydrothermal epigenetic PGE mineralizations are still poorly understood. In this communication we describe hydrotherma...

The physical and mechanical processes rooted in the hydrated, serpentinized mantle above subduction zones remain insufficiently explored despite fundamental implications on our understanding of rheology and fluid recycling along subduction interfaces. Through a field-based investigation, serpentinized peridotites and jadeitite samples from a fossil...

The Geology of Colombia book provides an updated background of the geological knowledge of Colombia by integrating the most up–to–date research covering paleontology, biostratigraphy, sedimentary basin analysis, sedimentology, sequence stratigraphy, stratigraphy, geophysics, geochronology, geochemistry, thermochronology, tectonics, structure, volca...

Fe-Ti oxide ores are commonly associated with Proterozoic massif-type anorthosite bodies emplaced during the Grenville orogeny (~1.2-1.0 Ga). Some of these anorthositic bodies occur in the northernmost part of the Santa Marta Massif, Colombia. They locally contain crosscutting Fe-Ti(-V) ore bodies between the El Hierro creek and the Don Dieguito ri...

The Havana-Matanzas Ophiolite contains one of the few examples of ophiolitic platinum group minerals (PGM)-rich chromitites associated with orthopyroxenites in the mantle section of ophiolitic complexes. The chromitites occur as veins hosted by ortho-pyroxenite bands within mantle peridotites. The peridotites are mostly harzburgites and their acces...

The amphibolites and associated ophiolitic rocks/metapelites in the Aburrá Valley, Colombian Central Cordillera, are commonly considered oceanic fragments accreted to the Permian-Triassic Cajamarca Complex of the north Andes. Nevertheless, the complex tectonostratigraphic architecture of the Central Cordillera and the general paucity of accurate ge...

New field and petrographic observations, whole-rock major- and trace-element geochemical data, Nd and Sr isotope systematics and U-Pb SHRIMP zircon ages of the Peltetec metaophiolite and related rocks (Ecuador) allow the characterization of the igneous and sedimentary protoliths and the evaluation of the geodynamic evolution of the active western m...

Diamond is commonly regarded as an indicator of ultra-high pressure conditions in Earth System Science. This canonical view is challenged by recent data and interpretations that suggest metastable growth of diamond in low pressure environments. One such environment is serpentinisation of oceanic lithosphere, which produces highly reduced CH 4-beari...

The physical and mechanical processes rooted in the hydrated, serpentinized mantle above subduction zones remain insufficiently explored despite fundamental implications for our understanding of rheology and fluid recycling along subduction interfaces. Through a field‐based investigation, serpentinized peridotites and jadeitite samples from a fossi...

Mid and Late Cretaceous arc-related basaltic rocks in the Camagüey area, East Central Cuba, record an intriguing seemingly random enrichment in alkalis that suggests alkaline affinity, representing an oddity in the Greater Antilles. In this study, the petrology and geochemistry of volcanic rocks from the Camujiro, Piragua and La Mulata Formations h...

Palaeozoic rocks in the Betic Cordillera are widespread in the Maláguide, Alpujárride and Nevado-Filábride complexes of its Internal Domain. The Malaguide stratigraphic successions record a deepening trend during the post-rift evolution of a divergent continental margin that was paleogeographically related to the Northern Paleotethys from the lates...

The exercise of paleogeographic/tectonic reconstruction of past orogenic belts is a complex task that includes the interpretation and integration of multi‐technique approaches such as basin tectonics, structural geology, petrology, geochemistry, geochronology, and geodynamics. Proterozoic geologic records are fragmented and incomplete, which make e...

Chromitite bodies hosted in peridotites typical of suboceanic mantle (s.l. ophiolitic) are found in the northern and central part of the Loma Caribe Peridotite in the Cordillera Central of the Dominican Republic. These chromitites are massive pods of small size (less than a few meters across) and veins that intrude both dunite and harzburgite. Comp...

The Variscan Orogen in Iberia and the Anti-Atlas Mountains in Morocco contains a set of ophiolites formed between Neoproterozoic and Devonian times, during the complex evolution of the NW African–Iberian margin of Gondwana. During this time interval, the margin evolved from an active margin ( c. 750–500 Ma: the Reguibat–Avalonian–Cadomian arc) to t...

The Upper Units of the allochthonous complexes of the NW Iberian Massif constitute a terrane with continental affinity. They represent the vestiges of a Cambrian magmatic arc developed in the periphery of Gondwana (West African Craton) which was involved in the Devonian Variscan collision, undergoing high‐pressure, high‐temperature metamorphism. Th...

High pressure–low temperature metamorphic rocks from the late Paleozoic accretionary wedge exposed in central Chile (Pichilemu region) are characterized by a greenschist-blueschist lithological association with interbedded metasediments that reached peak burial conditions of ~400 °C and 0.8 GPa during late Carboniferous times. We herein combine new...

The Moa-Baracoa ophiolite in eastern Cuba is one of the few known ophiolites that display sulfide mineralization attributable to a magmatic origin in association with podiform-chromite ores hosted in the mantle-crust transition. These sulfide ores chiefly consist of Fe-Ni-Cu sulfides, namely pyrrhotite, pentlandite, chalcopyrite and cubanite partly...

Ti-rich amphibole, Mg-rich ilmenite, baddeleyite, zirconolite, srilankite, and zircon are important high-field-strength elements (HFSE) bearing phases in the Potosí chromitite bodies located in the Moho Transition Zone of the Cretaceous Moa-Baracoa suprasubduction zone ophiolite (eastern Cuba). Such HFSE-bearing phases were found in the interaction...

Recent discoveries at the base of the seismogenic zone, at which episodic tremor and slip occurs, have been proposed that high pressure fluid pulses may travel upwards along the subduction interface involving weakening of the fault and triggering slow slip events (Frank et al., 2015). However, the rock record of those fluids along with its mechanic...

Supplementary Information to López-Quirós et al. 2019. Glaucony authigenesis, maturity and alteration in the Weddell Sea: An indicator of paleoenvironmental conditions before the onset of Antarctic glaciation. Scientific Reports.

Three types of glaucony grains were identified in the late Eocene (~35.5–34.1 Ma) sediments from Ocean Drilling Program (ODP) Hole 696B in the northwestern Weddell Sea (Antarctica). The grains are K2O-rich (~7 wt%) and formed by smectite-poor interstratified ~10 Å glauconite-smectite with flaky/rosette-shaped surface nanostructures. Two glaucony ty...

The Havana-Matanzas ophiolite contains an example of chromitite veins hosted in olivine orthopyroxenites within mantle peridotites. Accessory Cr-spinel in the harzburgite and in the Ol-orthopyroxenite, and chromite in the chromitite vein show a wide range of composition (Cr# 0.39-0.75). However, the chromite in the vein and the Cr-spinel in the Ol-...

Recent advances in understanding the plate tectonics, intracontinental deformation, and flow of partially molten crust have significantly improved our knowledge of collisional tectonics and the way in which we understand complex ancient orogens. The Central Ribeira Belt represents a Neoproterozoic fold‐and‐thrust belt formed in the Brasiliano Oroge...

The tectonic evolution of the Ribeira Belt comprises a protracted history involving several magmatic, deformational and metamorphic events mainly associated with the Neoproterozoic Brasiliano Orogenic Cycle. Most tectonic models relate the evolution of the Ribeira Belt to a protracted orogenic history with diachronous accretion of different terrane...

We are grateful to Massonne (2019) and Yang et al. (2019) for their constructive Comments to our recent publication (Farré-de-Pablo et al., 2018). We appreciate their interest in discussing our results and interpretations, which confirm that our work is a benchmark for future research. We are pleased to have the opportunity to address in further de...

Recent findings of diamonds in ophiolitic peridotites and chromitites challenge our traditional notion of Earth mantle dynamics. Models attempting to explain these findings involve incorporation of diamonds into chromite near the mantle transition zone. However, the occurrence of metastable diamonds in this context has not been considered. Here, we...

En la expresión material de las sociedades prehispánicas que habitaron la Sierra Nevada de Santa Marta (SNSM), Colombia, durante los periodos cronológicos Nahuange (100–1000 dC) y Tairona (1000–1600 dC) se aprecia una amplia variedad de objetos elaborados en piedra verde. Entre estos se destacan placas aladas alargadas, posiblemente talladas con un...

The origin of the assemblage of ultra-high pressure (UHP), super-reduced (SuR) and several crustally derived phases in ophiolitic chromitites is still hotly debated. In this paper, we report, for the first time, this assemblage of phases in ophiolitic chromitites of the Caribbean. We studied the Mercedita chromitite deposit in the eastern Cuban oph...

EPMA and LA-ICP-MS trace-element maps have been acquired from amphibolitized eclogites from the Diego de Almagro Metamorphic Complex (Chile). Several garnet growth pulses and garnet resorption stages are revealed by major elements chemical zoning and by heterogeneous Y and rare earth element (REE) behavior associated subduction and exhumation of th...

Little mineralogical evidence is left of the recycling of continental and oceanic crust into the mantle at subduction zones. Zircon, because of its exceptional robustness, is probably the only surviving phase and the best mineral tracer of this global-scale process. This article combines new in-situ U-Pb dating and O and Hf isotope analyses on Cret...

The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic chromitites are hotly debated. We report a population of zircon grains with ages ranging from Cretaceous (99 Ma) to Neoarchean (2750 Ma), separated from massive chromitite bodies hosted in the mantle section of the supra-subduction (SSZ)-ty...

Models for evaluating the terrestrial carbon cycle must take into account not only soil organic carbon, represented by a mixture of plant and animal remains, but also soil inorganic carbon, contained in minerals, mainly in calcite and dolomite. Thick soil caliches derived from weathering of mafic and ultramafic rocks must be considered as sinks for...