Antonio Acosta-Vigil

Spanish National Research Council | CSIC · Instituto Andaluz de Ciencias de la Tierra (IACT)

This study presents the first precise evaluation of the extent of chem-ical equilibrium between felsic melt and crystalline residuum during the crustal anatexis of metasediments. The high precision of these results stems from the fact that, in this case, the melts are repre-sented by pristine glasses that occur in the matrices of partially melted m...

With less than two decades of activity, research on melt inclusions (MI) in crystals from rocks that have undergone crustal anatexis – migmatites and granulites – is a recent addition to crustal petrology and geochemistry. Studies on this subject started with glassy inclusions in anatectic crustal enclaves in lavas, and then progressed to regionall...

The study of the composition of primary melts during anatexis of high-pressure granulitic migmatites is relevant to understand the generation and differentiation of continental crust. Peritectic minerals in migmatites can trap droplets of melt that forms via incongruent melting reactions during crustal anatexis. These melt inclusions commonly cryst...

We explore the controls, mechanisms and timing of generation of primary melts and their compositions, and show that the novel studies of melt inclusions in migmatites can provide important insights into the processes of crustal anatexis of a particular rock. Partial melting in the source region of granites is dependent on five main processes: (i) s...

This study tests experimentally the hypothesis that calculated bulk compositions of multiphase solid inclusions present in minerals of ultrahigh pressure rocks, can be equated to the composition of the former trapped fluids. We investigated samples from the ultrahigh pressure garnet peridotites of the Bohemian Massif, spatially associated with ultr...

The El Robledal deposit is a Mg-Fe-B skarn hosted in a dolomitic marble from the footwall contact of the Ronda peridotites, in the westernmost part of the Betic Cordillera. The skarn is subdivided into two different zones according to the dominant ore mineral assemblage: (1) the ludwigite–magnetite zone, and (2) the magnetite–szaibelyite zone hoste...

The Meseta Goaïda magmatism, which occurs as gabbro, dolerite and rhyolitic intrusions in the Neoproterozoic basement and Cambrian platform sedimentary series of the Moroccan Hercynian orogen, has been ascribed to the Variscan orogenesis in the late Palaeozoic. Here, we provide new LA–ICP-MS U-Pb zircon ages – ranging from c. 519 Ma to c. 479 Ma –...

The Egéré terrane (Central Hoggar, South Algeria) includes mafic eclogite lenses boudinaged in metapelitic rocks with high-pressure relicts. These metapelites show textural records of partial melting, mainly primary melt inclusions enclosed in garnet crystals and later crystallized as “nanogranitoids.” Garnet porphyroblasts also contain inclusions...

The solubility of apatite in anatectic melt plays an important role in controlling the trace-element compositions and isotopic signatures of granites. The compositions of glassy melt inclusions and nanogranitoids in migmatites and granulites are compared with the results of experimental studies of apatite solubility to evaluate the factors that inf...

Despite melt inclusions in migmatites and granulites provide a wealth of information on crustal anatexis in different geological scenarios, a complete compositional study (including trace elements and H2O) is yet to be made for the Himalayan rocks. In this contribution, we focus on nanogranitoids occurring in peritectic garnet of migmatites from Ka...

Metamorphosed mafic igneous rocks (blueschists and eclogites) of the Nevado-Filábride Complex mainly occur as subparallel, multiple-injection dikes crosscutting shallow marine, Permo-Triassic metasediments or, locally, metaperidotites (rodingites). Radiometric data yields magmatic ages for zircons at around 185 ± 3 Ma. Chemical data indicate an E-M...

Alpine metamorphism in the Betic Internal Zones was developed with different age and intensity depending on the affected complex. The Maláguide Complex shows mineral parageneses typical of very low metamorphic grade. In the lower Alpujárride Complex, the P–T conditions of metamorphism range between 0.8–1.4 GPa and 350–800 °C and record a HP-LT subd...

The garnet-biotite-sillimanite enclaves from El Hoyazo are quenched anatectic metapelites found within peraluminous dacites (Betic Cordillera, SE Spain), representing a residual lower crust in the area after 40–60% of melt extraction. Anatexis occurred concomitantly with deformation in a regional metamorphic setting during the Upper Miocene at the...

The Moroccan Meseta, a vagabond terrain or a fragmented margin of the Panafrican belt (North WAC)? OUABID, Muhammad1,2, Houssa Ouali1, Carlos J. Garrido2, Antonio Acosta-Vigil2,3, Manuel J. Román-Alpiste2, Jean-Marie Dautria4, Claudio Marchesi2,5, Károly Hidas2 1 Geology Department, Faculty of Sciences, Moulay Ismail University, P.O. Box 11201 Zito...

We present new Sr-Nd-Pb isotope data of the western Alpujárride metamorphic basement and the pre-Miocene Flysch sediments of the Betic Cordillera (southern Spain). Nd model ages are consistent with an increasing detrital input from the Alborán domain to the Flysch Trough in the western Mediterranean during the late Oligocene. The Alpujárride metamo...

Spinel (± plagioclase) peridotite xenoliths from the Tallante and Los Perez volcanic centres in the eastern Betics (SE Spain) range from depleted (clinopyroxene-poor) harzburgites to fertile (clinopyroxene-rich) lherzolites and orthopyroxene-free wehrlites. Significantly, only one harzburgite, which is depleted in heavy rare earth elements (HREE),...

Mantle xenoliths in Pliocene alkali basalts of the eastern Betics (SE Iberia, Spain) are spinel±plagioclase lherzolite, with minor harzburgite and wehrlite, displaying porphyroclastic or equigranular textures. Equigranular peridotites have olivine crystal preferred orientation (CPO) patterns similar to those of porphyroclastic xenoliths, but slight...

The trace-element thermometers Ti-in-quartz, Zr-in-rutile and Ti-in-zircon are successfully applied to polymetamorphic rocks to estimate their peak and post-peak temperatures. In this study we apply these thermometers to the metapelitic granulites from the Jubrique sequence (Betic Cordillera, S Spain), which contain quartz, zircon and rutile in equ...

This review presents a compositional database of primary anatectic granitoid magmas, entirely based on melt inclusions (MI) in high-grade metamorphic rocks. Although MI are well known to igneous petrologists and have been extensively studied in intrusive and extrusive rocks, MI in crustal rocks that have undergone anatexis (migmatites and granulite...

We investigate the stress regimes acting during serpentinization and faulting of the largest known subcontinental lithospheric peridotite body, namely the Ronda peridotites (Betic Cordillera, S. Spain). Petrological and structural analyses on serpentinites grown along fault planes crosscutting the peridotite slab, reveal that they were developed du...

Anatexis in the crustal footwall of Ronda peridotites (Betic Cordillera, S Spain) is apparently related to the hot emplacement of this mantle slab over metasedimentary rocks. In this study we combine the analysis of melt inclusions (MI) and phase equilibria calculations on quartzo-feldspathic mylonites (former migmatites) occurring at the contact w...

This review presents a compositional database of primary anatectic granitoid magmas, entirely based on melt inclusions (MI) in high-grade metamorphic rocks. Although MI are well known to igneous petrologists and have been extensively studied in intrusive and extrusive rocks, MI in crustal rocks that have undergone anatexis (migmatites and granulite...

The development of zones within granitic pegmatites stems from magmatic processes that have been elucidated by experimental and numerical simulations. Understanding the origins of zonation in pegmatites aids in the exploration of gem minerals within them. Liquidus Undercooling. The crystallization of pegmatites commences at ~ 450°-500°C, ~ 200°C be...

The application of melt inclusion (MI) studies to migmatitic and granulitic terranes is a recent, small-scale approach for a better understanding of melting in the continental crust. In order to show the role of anatectic MI in providing a wealth of microstructural and compositional information on high-temperature metamorphism and crustal anatexis,...

We report a new occurrence of melt inclusions in polymetamorphic granulitic gneisses of the Jubrique unit, a complete though strongly thinned crustal section located above the Ronda peridotite slab (Betic Cordillera, S Spain). The gneissic sequence is composed of mylonitic gneisses at the bottom and in contact with the peridotites, and porphyroblas...

This study investigates the age of anatexis of a crustal sequence constituting the footwall of the Ronda peridotite slab, in the hinterland of the Betic Cordillera (S Spain, region of Istán). These rocks represent a polymetamorphic basement involved in the Alpine orogeny and show an increase in the proportion of melt towards the peridotites. Metamo...

Quantification of H2O contents of natural granites has been an on-going challenge owing to the extremely fugitive character of H2O during cooling and ascent of melts and magmas. Here we approach this problem by studying granites in their source region (i.e. the partially melted continental crust) and we present the first NanoSIMS analyses of anatec...

In this work, we have reviewed a large com-positional dataset (571 analyses) for natural and experi-mental glasses to understand the physico-chemical and compositional conditions of magmatic cordierite crystalli-zation. Cordierite crystallizes in peraluminous liquids (A/CNK C1) at temperatures C750 °C, pressures B700 MPa, variable H 2 O activity (0...

Melt inclusions (MI) are small droplets of silicate liquid trapped by minerals growing either with or from the melt [1]. Most MI in anatectic terranes appear partially or totally crystallized due to slow cooling at depth, and have been named “nanogranites” [2]. MI represent a new and powerful method to study anatexis, because they can give informat...

Stromatic metatexites occurring structurally below the contact with the Ronda peridotite (Ojén nappe, Betic Cordillera, S Spain) are characterized by the mineral assemblage Qtz+Pl+Kfs+Bt+Sil+Grt+Ap+Gr+Ilm. Garnet occurs in low modal amount (2–5 vol.%). Very rare muscovite is present as armoured inclusions, indicating prograde exhaustion. Microstruc...

Nanogranites represent totally crystallized inclusions of anatectic melt trapped within peritectic minerals of migmatites and granulites. They have recently been discovered in several locations. This discovery opens new possibilities for investigating crustal melting processes, provided that an appropriate method for retrieving the information cont...

Nanogranites represent totally crystallized inclusions of anatectic melt trapped within peritectic minerals of migmatites and granulites. They have recently been discovered in several locations. This discovery opens new possibilities for investigating crustal melting processes, provided that an appropriate method for retrieving the information cont...

Several tectonic scenarios have been proposed for the Tertiary evolution of the Betic-Rif chain in the westernmost Mediterranean. Recent studies on late, mantle-derived Cr-rich websterite dykes in the Ronda peridotite have revealed recycling the involvement of sources of continental detrital sediments in the waning magmatic stage of the Ronda perid...

download at: http://geology.geoscienceworld.org/cgi/content/full/41/2/115?ijkey=odGw9gDsxS9jA&keytype=ref&siteid=gsgeology Using a metatexite from the Spanish Betic Cordillera as an example, we show that in situ and otherwise impossible to retrieve compositional information on natural anatectic melts can be reliably gained from experimentally reho...

Crustal anatexis, coupled with melt extraction and ascent, is the main mechanism by which the continental crust differentiates. During diffusion-controlled melting, and in the absence of melt flow and mechanical mixing, diffusion is the main process by which the melt phase ultimately homogenizes and mineral residuum and melt equilibrate. Knowing th...

Assimilation of foreign material into a granitic magma body entails mixing between two end-member com-ponents: the initially solid assimilant, and the original magma, whose composition is mostly represented by a granitic liquid. In this study, we assess the interactions between a haplogranite liquid made to the composi-tion of the minimum at 200 MP...

The occurrence of crystallized and glassy melt inclusions (MI) in high-grade, partially melted metapelites and metagraywackes has opened up new possibilities to investigate anatectic processes. The present study focuses on three case studies: khondalites from the Kerala Khondalite Belt (India), the Ronda migmatites (Spain), and the Barun Gneiss (Ne...

Journal of the Virtual Explorer, Electronic Edition, ISSN 1441-8142, volume 38, paper 2 In: (Eds. of individual contributions. Individual authors may use a single figure and/or a table and/or a brief paragraph or two of text in a subsequent work, provided this work is of a scientific nature, and intended for use in a learned journal, book or other...

To shed light on the mechanisms of crustal anatexis, a detailed geochemical study has been conducted on minerals and glasses of quenched anatectic metapelitic enclaves and their host peraluminous dacites at El Hoyazo, SE Spain. Anatectic enclaves, composed of plagioclase + biotite + sillimanite + garnet + glass ± K-feldspar ± cordierite + graphite,...

This study examines the systematics and rate of alkali transport in haplogranite diffusion couples in which a chemical potential gradient in Al is established between near water-saturated metaluminous and peraluminous liquids that differ only in their initial content of normative corundum. At 800°C, measurable chemical diffusion of alkalis occurs t...

In the restitic crustal enclaves in the Neogene volcanics of El Hoyazo and Mazarrón (SE Spain), associations of fluid and silicate melt inclusions indicative of immiscibility are frequently observed in the Bt-poor, Crd-rich graphitic metapelites. These occurrences, extremely rare for anatectic crustal rocks, have been studied by microthermometry, m...

This article reports microstructures and compositions of melt inclusions in anatectic metapelites found as enclaves within El Hoyazo dacites, in the Neogene Volcanic Province of southeastern Spain. The enclaves represent fragments of continental crust partially melted at ∼800–850 °C and 5–7 kbar, and brought to surface rapidly within the host volca...

We have experimentally investigated the kinetics of melting of an aplitic leucogranite (quartz+sodic plagioclase of ≈Ab90+K-feldspar+traces of biotite) at 690, 740, and 800°C, all at 200 MPa H2O. Leucogranite cylinders, 3.5 mm in diameter and 7 mm in length, were run in the presence of excess H2O using cold-seal pressure vessels for 11–2,925 h. At...

We have conducted experiments on dissolution of quartz, albite, orthoclase, and corundum into H 2 O-saturated haplogranite melt at 800 C and 200 MPa over a duration of 120–1488 h with the aim of ascertaining the diffusive transport properties of granitic melts at crustal anatectic temperatures. Cylinders of anhydrous starting glass and a single min...

This study examines hydration–diffusion in the metaluminous haplogranite system at 200MPa H2O and 800–300C. At 800C hydration is accompanied by melting and uphill diffusion of sodium from anhydrous glass toward the region of hydration and melting, whereas potassium diffuses away from the hydration front and into anhydrous glass. Silicon and aluminu...

We have studied the controls on the Aluminum Saturation Index (ASI = molec. Al2O3/[(CaO)+(Na2O)+(K2O)]) and the concentration of normative corundum of granitic liquids saturated in alumina by equilibrating peraluminous minerals with initially metaluminous haplogranitic minimum composition liquids at 700–800C and 200MPa, at, and below H2O saturation...

Intrusion of the Serranía de Ronda peridotite massif, in southern Spain, during the Alpine orogeny caused partial melting of the Hercynian migmatites lying below and generation of leucogranitic magma that intruded the peridotite as subvertical dikes. Incorporation of B, Cl and Br from marble and evaporite country-rocks account for a high content of...

With the aim of investigating the diffusive transport properties of granitic melts at crustal anatectic conditions and obtaining some constraints on speciation and coordination in the melt, we conducted albite, K-feldspar and quartz dissolution experiments in H2O-saturated metaluminous haplogranitic glass (nominal composition of the 200 MPa H2O-sat...

The mechanisms and kinetics of equilibration between peraluminous minerals and granitic melt were investigated experimentally by the dissolution of corundum and andalusite into H 2 O-saturated metaluminous haplogranitic melt at 800°C and 200 MPa. Mineral and haplogranitic glass rods were juxtaposed inside platinum capsules, and then subjected to ex...

The study of volatile elements in crustal anatectic terranes may provide information about the role of fluid flow and fluid pathways during high temperature metamorphism. We have studied the distribution of Li and B in two migmatitic areas: the Peña Negra Anatectic Complex (central Spain) and the migmatites and leucogranites associated with the Ron...

The study of volatile elements in crustal anatectic terranes may provide information about the role of fluid flow and fluid pathways during high-temperature metamorphism. We have studied the distribution of B in migmatites and leucogranites associated with the Ronda peridotites, Betic Cordilleras (SE Spain). The migmatites underlie the Ronda perido...