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The paper reports comprehensive petrological, geochemical and mineralogical studies of osumilite-bearing andesite-dacitic lavas of Kordieritoviy Volcano (Keli Highland, Greater Caucasus) erupted at the end of the Pleistocene (about 200 ka). The petrographic and microprobe analysis showed that the rocks contain three paragenetic mineral associations: (1) "xenogenic" (metamorphic) association consisting of garnet (XPrp = 0.42, XAlm = 0.51–0.53, XGrs = 0.04–0.05) + hercynite + sapphire + bronzite + pargasite + ilmenite; (2) early magmatic association represented by hypersthene + hercynite + garnet (XPrp = 0.21–0.31, XAlm = 0.52–0.71, XGrs = 0.04–0.13) + ferro-kaersutite + ilmenite; (3) late magmatic association including hypersthene-ferrohypersthene + labradorite + garnet (XPrp = 0.04–0.14, XAlm = 0.65–0.81, XGrs = 0.06–0.18) + osumilite-(Mg) + phlogopite + tridymite + ilmenite + apatite. The osumilite-(Mg) (phenocrysts, xenomorphic aggregates in the rock matrix, and crystals in miarolic cavities), the average formula for dacites of Kordieritoviy Volcano can be written as (K0.73Na0.06Ca0.02 )1.00(Mg1.06 Mn0.04)2.00(Al2.75 Ti0.01)3.00(Si10.34Al1.66)12O30, formed mainly at late magmatic stages – in intermediate chambers immediately prior to the rise of the melt to the surface or after its eruption. Accordingly, this mineral in the studied lavas has a purely magmatic origin. Thermobarometric calculations and petrological modeling showed that the deep magma chamber of Kordieritoviy Volcano was located at a depth of 45–53 km near the Moho discontinuity. The temperature of the melt at the early magmatic stage was no less than 1100°C at 17–23 kbar. Crystallization of osumilite-(Mg) in intermediate magmatic chambers (at depths of 30–40 km) and during the lava ejection occurred at 1030–870°C and pressure progressively decreasing from 14–9 to 1 kbar. A petrogenetic model has been proposed to explain the genesis of exotic osumilite-bearing lavas of Kordieritoviy Volcano. It includes several stages: (1) formation of an enriched upper-mantle source (lithospheric mantle metasomatized by permanent interaction at the Moho discontinuity with the overlying lower crust composed of metamorphosed terrigenous-volcanogenic complexes); (2) generation of "dry" basaltic magmas in the source; (3) crystallization differentiation in the source (fractionation of olivine and chromium spinels) with the formation of a "dry" overheated andesitic melt; (4) limited-scale assimilation of the lower crustal material made up of leucocratic granulites by highly differentiated andesitic melts rising to the surface, with simultaneous fractionation of garnet, orthopyroxene and ilmenite from the melt. [ABSTRACT FROM AUTHOR]

The geologic evolution of the Gondwanide orogen recorded during the late Palaeozoic along the Panthalassan border of Gondwana is related to an active continental margin, though it is still debatable whether it was built by collision or accretion. To disentangle its orogenic processes and provide constraints on the orogen type, we characterize the physicochemical conditions of metamorphism and associated deformation of the Mina Gonzalito Metamorphic Complex from northern Patagonia (41°28’30” S-65°40’30” W). New field mapping and comprehensive petrochronologic analysis constrain the evolution of a thick-skinned fold and thrust belt in a retroarc setting, which is spatially and temporally related to the geometry and kinematics of the right-lateral reverse El Jagüelito ductile shear zone. Metamorphic evolution resulted in a clockwise P‐T‐t-D path reflecting three stages of continuously changing P-T conditions under high-pressure (8.0–9.9 kbar) amphibolite facies (540–680°C) during a single-phase progressive ductile deformation event. Monazite ages ranging from 303 ± 5 to 252 ± 6 Ma account for the single-phase regional tectono-metamorphic event spanning ~ 50 My. Our results, integrated with regional data, led to interpreting the late Palaeozoic Gondwanide orogen developed along the Panthalassan margin of Gondwana as accretionary in advancing-mode. [ABSTRACT FROM AUTHOR]

Granulites exposed in high-grade regional metamorphic belts and exhumed as xenoliths in basaltic pipes are considered as window into the deep crust thus play a key role in constraining models of crustal processes and evolution. Here we present a detailed investigation of the tectono-metamorphic history of the two-pyroxene mafic granulite located in the southern region of the Sonapahar area. This involves conducting monazite chemical dating, analyzing petrological and geochemical characteristics, applying geothermobarometry, performing phase equilibria modeling, and tracing a pressure-temperature (P-T) path. Metamorphic P-T conditions estimated for the mafic granulite using conventional thermobarometer and winTWQ shows temperature in excess of 800°C and pressure of about 8.6 kbar, stand for high temperature granulite facies metamorphism. The metamorphic evolution path obtained from P-T pseudosection suggest a clockwise P-T evolution path, thus signify isothermal decompression and indicate rapid upliftment. Geochemical study of trace and rare earth elements (REE), suggest protolith is of tholeiite basalt in nature that is derived from back arc basin setting near to subduction zone. Additionally, the analyzed rock was examined using primitive mantle-normalized trace element spider diagram. The results indicate an enrichment in large-ion lithophile elements (Th, U, K, Pb) and a depletion in high field-strength elements (Nb, Ta, Ti). The presence of negative anomalies in Nb and Ti, coupled with elevated values of Th, K, and Pb, suggests the possibility of crustal contamination. Monazite chemical data from the studied rock reveals a peak metamorphism age of 521.3 ± 4.20 Ma, which corresponds to the Kuunga Orogeny in the later phase of global Pan-African collision. [ABSTRACT FROM AUTHOR]

The studied Miocene volcanic rocks are observed in the Örenköy, Fındıkköy, and Kızılkaya Tepe regions in and around the Kütahya area. The Örenköy volcanic rocks consist of augite basalt, basaltic andesite and andesite, and show hyalo-microlitic porphyritic and cumulophyric texture, and contain plagioclase (An70-82Ab17-29Or1-2), clinopyroxene (Wo40-44En41-52Fs6-16), orthopyroxene (Wo1-4En64-71Fs27-34) olivine (Fo86-90) and Fe-Ti oxide. The Fındıkköy volcanic rocks include augite trachybasalt, augite basaltic trachyandesite and trachyandesite, and show hyalo-microlitic porphyritic and intersertal texture, and generally contain plagioclase (An58-88Ab12-38Or1-5), clinopyroxene (Wo44-48En38-47Fs8-17), olivine (Fo41-63) and Fe-Ti oxide, while the andesitic ones also contain biotite. The Kızılkaya Tepe volcanic rocks contain augite basalt, augite basaltic andesite and trachyandesite, and exhibit hyalomicrolitic porphyritic, vesicular, intersertal and trachytic texture, and include plagioclase (An53-85Ab14-44Or0-3), clinopyroxene (Wo39-46En41-52Fs8-16), orthopyroxene (Wo2-3En73-75Fs21-25), olivine (Fo52-82) and Fe-Ti oxide. In addition, the pre-eruptive crystallization conditions of the volcanic rocks were estimated using mineral chemistry analyses and thus it was determined that the magmas of the volcanic rocks have evolved by fractionation in magma chambers of the upper continental crust. [ABSTRACT FROM AUTHOR]

Introduction Mineral chemistry data as well as petrography provide a comprehensive picture of magma crystallization conditions that support the conclusions based on geochemical data. In addition, the chemical composition of minerals such as clinopyroxene, olivine, biotite, feldspar, and Fe-Ti oxides reflect physicochemical parameters (pressure, temperature, and oxygen fugacity), crystal growth history, and melt origin. The pressure, temperature and oxygen fugacity parameters are estimated from chemical data of various rock-forming minerals to provide information regarding the crystallization of magmas. The essential purposes of present study are to determine the physicochemical conditions (temperature and pressure), to identify the tectonic environment and to propose an emplacement model for Pargeh mafic magmas formation.Regional GeologyThe Pargeh area is a part of the Central Alborz Magmatic Belt (AMB) (Figure 1). There are extensive magmatic sections in this zone including the Cenozoic calc-alkaline and alkaline (potassic) magmatism generated in an arc and back-arc setting in an extensional environment (post collision). This belt is mainly composed of Upper Precambrian to Eocene sedimentary and volcanic sequences intruded by Mesozoic to Cenozoic plutons, in the central and western parts of the belt. The igneous rocks of the north and northeast of Qazvin were formed during three volcanic phases, of which only two phases can be seen in the study area. These Late Eocene-Oligo-Miocene plutonic rocks are related to post-collisional magmatic activities originated in back-arc extensional basins and have calc-alkaline to high-potassium shoshonitic characteristics. According to U–Pb dating, the age of the syenite and monzonite rocks is Late Eocene. But the exact age of the Pargeh gabbroic rocks is not known, considering that these intrusions were injected into Eocene tuffs, they are Late Eocene and possibly Oligocene.Analytical MethodsThe main minerals were analyzed by an electron microprobe at the Queen’s Facility for Isotope Research (QFIR), Queens University, Kingston, Canada. Operating conditions were as follows: the acceleration voltage was 15 kV, the beam current was 20 nA, and the diameter of the probe was 3 µm (Tables 1 to 6).PetrographyField and petrographic observation show that most of the Pargeh pluton is monzogabbro and olivine gabbros make up only a small part of the pluton. Olivine gabbro is a medium- to coarse-grained mesocratic-melanocratic rock. Olivine gabbro and monzogabbro are texturally varied. In both samples, intergranular, poikilitic, sub-ophitic and granular textures were identified. Olivine gabbro are dominated by olivine (20-25%vol), clinopyroxene (15-20 %vol), plagioclase (50-55 %vol), biotite (~ 5 %vol) and K-feldspar (~ 5 %vol). Accessory minerals include apatite and Fe-Ti oxides. Monzogabbros are characterized by a high proportion of plagioclase (55-60 %vol) and clinopyroxene (20-25 %vol), biotite (5-10%vol) and K-feldspar (8-10%vol).. Fe-Ti oxides and apatite are common accessory minerals in monzogabbros.DiscussionBased on research on the distribution of Ti in silicates and oxides of magmatic rocks, Verhoogen (1962) proposed that the crystallization temperature of clinopyroxene is positively correlated with its Ti content. Therefore, the higher clinopyroxene, crystallization temperature, the more Ti clinopyroxene likely to contain. The TiO2 content of clinopyroxenes in olivine gabbros is slightly higher than that of monzogabbros, pointing to the clinopyroxenes in olivine gabbro having a relatively higher crystallization temperature compared to that of clinopyroxenes in monzogabbro. In the 9-A and B diagram, all the samples are in the range of alkaline basalt, so the parental magma can be an alkaline magma. As mentioned above, clinopyroxenes have high amounts of Al and Ti, consistent with the evolution of an alkaline magma. High amounts of calcium in the studied clinopyroxenes indicate that the parental magma may have an alkaline nature. This tectonic setting discrimination diagram can distinguish basaltic clinopyroxenes from volcanic arc basalt (VAB), ocean floor basalt (OFB), intraplate tholeiite (WPT) and intraplate alkaline environments (WPA). In the F1-F2 tectonic environment discrimination diagram, all the study samples fall within the range of volcanic arc basalts (VAB+OFB), which shows that these rocks are probably formed in a volcanic arc and arc-related tectonic setting environment. In general, all tectonic discrimination diagrams based on clinopyroxene chemistry indicate an arc-related environment for the parental magma.ConclusionThe mafic rocks of Pargeh are composed of olivine gabbro and monzogabbro which are characterized by the presence of olivine, plagioclase, clinopyroxene, biotite and K-feldspar. The mineral chemistry results show the role of fractional crystallization as the main process in the formation of the parental magma of the rocks under study The chemical features of clinopyroxenes point that the parental magma must belong to a silica under-saturated alkaline series, characterized by high temperature, low pressure, low Si and high Ca contents possibly formed in a volcanic arc tectonic setting environment. As the xamined thermobarometers data show, the olivine gabbros generated at higher temperature and pressure than that of monzogabbros indicating that the olivine gabbros probably crystallized at a greater depth.

Mineral chemistry data as well as petrography provide a comprehensive picture of magma crystallization conditions that support the conclusions based on geochemical data. In addition, the chemical composition of minerals such as clinopyroxene, olivine, biotite, feldspar, and Fe-Ti oxides reflect physicochemical parameters (pressure, temperature, and oxygen fugacity), crystal growth history, and melt origin. The pressure, temperature and oxygen fugacity parameters are estimated from chemical data of various rock-forming minerals to provide information regarding the crystallization of magmas. The essential purposes of present study are to determine the physicochemical conditions (temperature and pressure), to identify the tectonic environment and to propose an emplacement model for Pargeh mafic magmas formation. [ABSTRACT FROM AUTHOR]

We present a reconstruction of the physicochemical conditions of melts in the Pleistocene storage and plumbing system of the Doña Juana Volcanic Complex (SW Colombia): a poorly known, potentially active polygenetic volcano of dacitic composition comprising four major edifices and showing periods of long quiescence. Compositional data for plagioclase, amphibole, pyroxene, and Fe-Ti oxides were combined with new and existing whole-rock data from representative eruptive products, allowing for the implementation of equilibrium tests and geothermobarometry calculations within an established stratigraphic, petrographic, and geochronological framework. Textural and geochemical variabilities of all mineral phases suggest the existence of a trans-crustal magmatic system feeding the Pleistocene eruptions of Doña Juana, and cyclic rejuvenation of a crystal mush following each volcano edifice collapse. The assemblage of different crystal cargos before magma recharge and final eruption is attested by (i) the coexistence of equilibrium and disequilibrium textures and variable compositions in crystals of all studied species, (ii) felsic cores in antecrysts, (iii) mafic overgrowth rims, and (iv) significantly less differentiated microcrysts relative to the composition of meso- and macrocrysts. By integrating multiple mineral-only and mineral-liquid geothermobarometers, after careful textural analyses, we estimate the intensive parameters of the mush–melt interaction zone of the plumbing system in the middle crust, providing a preliminary view of the architecture of a trans-crustal magmatic system in a complex tectonic setting at a previously understudied area of the north-Andean volcanic zone. [ABSTRACT FROM AUTHOR]

We combined compositional analyses, crystal size distributions and geothermobarometry of tephra erupted during the 2021 Tajogaite eruption (La Palma, Spain), focusing on samples collected in November 2021 associated with a period of abundant ash emission characteristic of the second half of the eruption (from October onwards). Magma erupted in November exhibits a more primitive basanitic composition than the earlier magma. Crystallisation temperatures range between ~1100–1160 °C (H2O = 1–3 wt.%) for phenocrysts and microphenocrysts, with corresponding pressures indicating depths from ~10 to ~30 km. Crystal size distribution analysis reveals short (minutes) residence times for plagioclase. Finally, magma ascent velocities (~0.01–0.3 m s−1) suggest acceleration and fragmentation in the shallowest part of the conduit. Our results suggest that the trigger of the November explosive activity can be attributed to complex feedback between gas emission rates, changes in conduit geometry, and magma ascent rate.

Based on the proposed numerical model of the stress-strain state of polymineral rocks, which describes the formation of blastomylonites in the Yenisei Regional Shear Zone (YRSZ) in the Yenisei Ridge, the possibility of local tectonic overpressure exceeding the lithostatic pressure in rocks subjected to shear deformations is shown. For tectonites of the southern (Angara–Kan block) and northern (Isakovka terrane and Garevka complex) segments of the YRSZ, estimates of the maximum overpressure were obtained from 2–3 to 4–5 kbar, which range from 25 to 50% of the lithostatic pressure. It is shown that the excess pressures can be preserved in a local volume on a geological time scale sufficient for their fixation in metamorphic minerals. Model values of overlithostatic pressure in the garnet–amphibole tectonites and geobarometric estimates of peak values during stress metamorphism allow us to offer new evidence for pressure inhomogeneity in natural mineral associations. Using the results of numerical modeling for the evolution of metabasite blastomylonites, it was established that the overpressure at the stage of syn-deformation metamorphism in the shear zone is possible at temperatures up to 600–650°C and not reaching 800°C; the presence of fluid or partial melt prevents the occurrence of overpressure. Magnitudes of excess pressure caused by shear stresses depend on the mineral composition and structure of the rock. [ABSTRACT FROM AUTHOR]

A detailed mineral-scale study was conducted on pumices of the latest, dominantly explosive eruption epoch (56–30 ka) of Ciomadul, the youngest, long-dormant volcano in eastern-central Europe for characterizing the magma storage system and for understanding better the changes in eruption style from effusive to explosive. The mineral cargo of dacitic pumices enables us to constrain the conditions of the pre-recharge crystal mush, the recharge magmas and the post-recharge magma prior to eruptions. A careful evaluation of the results yielded by various thermometers, barometers, oxybarometers, chemometers and hygrometers as well as direct comparison with experimental data were necessary to select the appropriate techniques and therefore to constrain the conditions for the Ciomadul magmatic system. Beneath the volcano, a felsic crystal mush body is inferred at 8–12 km depth comprising slightly oxidized (0.5–1.6 ∆NNO), low-temperature (680–750 °C), highly crystalline magma. This zone is underlain by a deep magma storage zone with less evolved, hot (> 900 °C) magma at 16–40 km depth. The dominantly explosive volcanism after the effusive eruptions (160–90 ka) can be explained by the ascent of distinct recharge magmas. They contained high-Mg (MgO > 18 wt%) amphibole, which could have crystallized from ultrahydrous (H2O > 8 wt%) magma at near-liquidus conditions. The rates of amphibole overgrowth and microphenocryst formation require weeks to months for the magma mixing and the eruption events. The hybridized melt became more oxidized and contained dissolved water in around 5.5 wt% at temperature of 790–830 °C calculated from the re-equilibrated Fe-Ti oxides. These magma properties along with the degree of crystallinity (27–38 vol% crystals) favored rapid magma ascent and an explosive style eruption. Thus, the strongly hydrous nature of the recharge magma in addition to the crystallinity and H2O content of the pre-eruption magma plays an important role in controlling the eruption style. [ABSTRACT FROM AUTHOR]

Thermobarometry provides a critical means of assessing locations of magma storage and dynamics in the lead-up to volcanic eruptions and crustal growth. A common approach is to utilise minerals that have compositions sensitive to changes in pressure and/or temperature, such as clinopyroxene, which is ubiquitous in mafic to intermediate magmas. However, clinopyroxene thermobarometry may carry significant uncertainty and require an appropriate equilibrium melt composition. In addition, the degree of magma undercooling (Δ T) affects clinopyroxene composition and zoning, with common sector zoning potentially obfuscating thermobarometry results. Here, we use a set of crystallisation experiments on a primitive trachybasalt from Mt. Etna (Italy) at Δ T  = 25–233 °C, P = 400–800 MPa, H2O = 0–4 wt % and fO2 = NNO + 2, with clinopyroxene crystals defined by Al-rich zones (prisms and skeletons) and Al-poor zones (hourglass and overgrowths) to assess common equilibrium models and thermobarometric approaches. Under the studied conditions, our data suggest that the commonly applied Fe–Mg exchange (cpx-meltKdFe–Mg) is insensitive to increasing Δ T and may not be a reliable indicator of equilibrium. The combined use of DiHd (CaMgSi2O6 + CaFeSi2O6) and EnFs (Mg2Si2O6 + Fe2Si2O6) models indicate the attainment of equilibrium in both Al-rich and Al-poor zones for almost all investigated Δ T. In contrast, CaTs (CaAl2SiO6) and CaTi (CaTiAl2O6) models reveal substantial deviations from equilibrium with increasing Δ T , particularly in Al-rich zones. We postulate that this reflects slower diffusion of Al and Ti in the melt compared with Ca and Mg and recommend the concurrent application of these four models to evaluate equilibrium between clinopyroxene and melt, particularly for sector-zoned crystals. Thermobarometers calibrated with only isothermal–isobaric experiments closely reproduce experimental P–T at low Δ T , equivalent to natural phenocrysts cores and sector-zoned mantles. Models that also consider decompression experiments are most accurate at high Δ T and are therefore suitable for outermost phenocryst rims and groundmass microlites. Recent machine learning approaches reproduce P–T conditions across all Δ T conditions. Applying our experimental constraints to sector-zoned microphenocrysts and groundmass microlites erupted during the 1974 eccentric eruption at Mt. Etna, we highlight that both hourglass and prism sectors are suitable for thermobarometry, given that equilibrium is sufficiently tested for. The combination of DiHd, EnFs, CaTs and CaTi models identifies compositions closest to equilibrium with the bulk melt composition, and results in smaller differences in P–T calculated for hourglass and prism sectors compared with applying only DiHd and EnFs equilibrium models. This provides a framework to assess crystallisation conditions recorded by sector-zoned clinopyroxene crystals in mafic alkaline settings. [ABSTRACT FROM AUTHOR]

Accretionary and collisional orogeny are often accompanied by the disturbance of the geothermal gradient, leading to high-temperature metamorphism. High-temperature metamorphic rocks are significant in their ability to help the reconstruction of the thermal histories of orogenic belts. The Tianshan Orogenic Belt, at the southwest margin of the Central Asian Orogenic Belt, is a record of the long-term subduction–collision–post-collision orogenic process that has taken place in the Phanerozoic Eon. Here, we report the discovery of mafic granulites in the Muzhaerte area, SW Tianshan. Petrographic observation reveals that the mafic granulites underwent two metamorphic stages. The peak mineral assemblage of the first stage is dominated by clinopyroxene + orthopyroxene + plagioclase + quartz + hornblende (hb1) ± biotite, and the post-peak mineral assemblage of the second stage is dominated by clinopyroxene + plagioclase + quartz + hornblende (hb2) + biotite. The calculated results obtained from the two-pyroxene thermobarometers and the Al-in-hornblende barometer for the mafic granulites indicate that the metamorphic conditions of mafic granulites are 760–860 °C, <0.39–0.41 Gpa. The mafic granulites recorded a high-grade granulite facies thermal metamorphic event with the highest temperature limit currently recorded in the Central Tianshan Block. [ABSTRACT FROM AUTHOR]

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The study of individual volcanoes in northwest Java has been largely overlooked. In this study, an investigation of the magma evolution and plumbing system of Gede-Salak Volcano was conducted. A geological survey determined the lava unit and volcanism. The whole-rock geochemistry is utilized to determine the magma type and evolution. Mineral chemistry based on microprobe analysis revealed the magmatic process and phenocryst origin. Geothermobarometry is employed to estimate the temperature and pressure. The volcanism comprised the eruption of lava flows, sector collapse, and the eruption of lava domes. The magma evolution consists of two magma types: type A (lava flow and peripheral dome) and type B (summit dome). The processes identified are amphibole fractionation, magma mixing, and crust assimilation. Phenocryst textures and chemistry implied open-system processes in the plumbing system involving three magma series, namely the felsic, intermediate, and mafic series. Magma type A resulted from multiple mafic recharges on the felsic series, while type B resulted from the mixing of intermediate and mafic series. The felsic and intermediate phenocryst crystallization occurred at 933-948°C and 1010-1011°C in the mid-crust at 14 km to 17 km depth. Meanwhile, the mafic series reside in the lower crust at 21 km depth and of 1065-1087°C temperature. [ABSTRACT FROM AUTHOR]

The petrogenesis of Palaeoarchaean mafic–ultramafic rock suites from the western Iron Ore Group, Singhbhum Craton, eastern India, has been evaluated based on the chemistry of constituent mineral phases. The rock suites include basaltic rocks and mafic (gabbro) to ultramafic (serpentinized peridotite) intrusive rocks, which occur in host rocks covering phyllite, ferruginous shale, banded haematite quartzite and jasper. The constituent clinopyroxene shows dominant uralitization, whereas plagioclase grains are generally saussuritized, being marked by relatively tiny granular aggregates of albite, chlorite, epidote and K-feldspar. The ultramafic intrusive rocks are overwhelmingly serpentinized. Clinopyroxene compositions are augitic, whereas relict plagioclase is typically bytownite. Amphiboles of the investigated rock suites are divisible into the 'uralite' type (occurring peripherally to clinopyroxene) and the 'completely changed-over amphibole' type (with no traces of initial clinopyroxene). Both the amphibole types belong to the 'calcic group', showing a compositional spectrum from actinolite–magnesiohornblende–ferrohornblende–ferroactinolite. Opaque minerals include magnetite (both Cr-magnetite and Al-magnetite), chromite (Al-chromite) and ilmenite, whereas serpentine (belonging to the ultramafic intrusive rocks) corresponds to lizardite. Looking at the mineral compositions of the pyroxene, glass and amphibole, the studied rock suites show a wide equilibration temperature–pressure domain range (∼750 °C to ∼1400 °C at ∼0.26 kbar to ∼21 kbar), which corresponds to an ascending magma that underwent a 'hydration event' at a shallow level. The assessment of the clinopyroxene and spinel chemistry characteristically suggests an arc setting for the parent magma that has undergone both equilibrium and fractional crystallization in the course of magmatic evolution. During differentiation, the magmatic density remains almost constant, with variable oxygen fugacity. [ABSTRACT FROM AUTHOR]

In the sector of San Jose, Macanal, and Tabaquen, in eastern Colombia, granitic rocks cut by pegmatite dikes and quartz veins appear with the presence of magnetite, ilmenite, and ilmenorutile. Using magnetic petrology and geochemistry concepts and methods, the main objective is to determine if these types of rocks are genetically related and how the fluid chemically evolves during its crystallization and cooling. This work was conducted in three stages. Petrography and opaque metallography for identifying the occurrence, paragenesis, and secondary processes that transform the oxides. In a second stage and utilizing an Electron Probe Microanalyzer (EPMA), 214 quantitative analyses (WDS) and four compositional maps for magnetite, ilmenite, and ilmenorutile were performed, measuring the oxides FeO, TiO2, V2O3, MgO, MnO, Nb2O5, Ta2O5, Al2O3, Ga2O3, NiO, CaO, Cr2O3, SnO, and WO3. Since magnetite and ilmenite are favorable geothermometers that also allow the calculation of oxygen fugacity, the ILMAT program was used to calculate these values. In closing, integrate the data with the magnetic susceptibility values. The results determine crystallization temperatures between 358-414 °C for the granitic-host rock and 402-499 °C for pegmatites dykes, in a system where oxygen fugacity increases, the Mn2+ is enriched in the ilmenite, and magnetite preserves a low content of trace elements thorough the evolution of the fluid. Taken together with the martitization and exsolution of hematite and rutile within ilmenite found in the petrography, these results allow us to conclude that an oxide-silicate re-equilibration process controls the evolution of this magmatic-hydrothermal fluid with a KUIlB cooling trend-type reaction. Based on the Al + Mn vs. Ti + V ratio, the signature of the magnetite is like the Lucky Friday mine's signature studied by Nadoll. However, the analysis of the 95th percentile shows a different concentration of trace elements in the magnetite of both sectors. Therefore, a new field of discrimination is proposed for this environment of anorogenic pegmatites of the NYF family. Finally, the magnetic susceptibility is controlled only by the abundance of magnetite in each type of rock. The granitic host rocks have the highest susceptibility values, followed by pegmatites and quartz veins with the lowest. [ABSTRACT FROM AUTHOR]

This research deals with the petrography and mineral chemistry of gabbroic and monzodioritic rocks to characterize the minerals, including their genesis and tectonic evolution. The rocks are dominated by gabbro in Barapaharpur and monzodiorite in Voktipur, and they contain plagioclase, hornblende, biotite, and magnetite, with few epidote and apatite, as well as clinopyroxene and orthopyroxene in gabbroic member. Chemical analyses of minerals were carried out by an electron microprobe analyzer. The chemistry of plagioclases is compositionally oligoclase-andesine and andesine, amphiboles are dominantly magnesiohornblende, biotites are Mg-biotites (phlogopite), and pyroxenes are diopside and enstatite types. The calculated P-T conditions of the gabbroic rocks yielded about 850–957 °C and 5.8–9.3 kbar, which are the highest geothermobarometric values in the region. However, the monzodioritic rocks yielded about 696–723 °C and 5.6–6.2 kbar. The estimated emplacement depths from the calculated highest pressure values equalize at ∼ 20–33 km and at ∼ 19–22 km, respectively. Biotite chemistry provides quantitative fO2 within QFM and HM buffers ranging from −10.6 to −12.0 in gabbroic rocks and −11.6 to −13.5 in quartz monzodiorite, respectively. These data are also echoed by amphibole and pyroxene mineral chemistry, which collectively demonstrate that the source materials were in a relatively higher oxidation state within arc magmatism. The mineral data also offer calc-alkaline I-type suites formed within subduction-related environments. However, gabbroic rocks show a dominantly island arc signature substantiating the suprasubduction zone, and also have the affinity of the island arc tholeiitic and calc-alkaline basaltic equivalents within orogenic environments and marginally boninitic affinities.

Introduction The Kahnouj Fe-Ti ore district is located 25 km southeast of Kahnouj city associated with the large gabbro intrusion of the Kahnouj ophiolitic complex. This ophiolite is one of the largest ophiolite assemblages of Iran (SE Iran), and part of neo-tethyan ophiolites (Kananian et al., 2001; Ghasemi Siani et al., 2021b). The Dar Gaz district is located in the middle part of Kahnouj ophiolitic complex and it is classified as the main ortomagmatic Fe-Ti ore mineralization. Although the geothermobarometric of iron-titanium oxide minerals in the Dar Gaz district has been studied by Karimi Shahraki et al. (2019), the geothermometry of silicate minerals (especially ferromagnesian) in the Dar Gaz gabrroic rocks has not been performed. Therefore, the main aim of this study is to determine the crystallization temperature and replacement of gabbroic rocks hosting Fe-Ti mineralization of the Dar Gaz district, using geothermometry of ferromagnesian silicate mineral. Material and methods A total of 100 thin-polish sections from different parts of the mining area were prepared and studied at the Iran Mineral Processing Research Center (IMPRC) and the Kharazmi University of Tehran with a Zeiss Axioplan 2 microscope. In order to achieve the temperature conditions of gabbroic rocks formation, 64 points (20 points of olivine, 13 points of clinopyroxene, 3 points of orthopyroxene, 14 points of plagioclase and 14 points of amphibole) from ferrogabbro to coarse-grained pyroxene-hornblende gabbro, 42 points (11 points of olivine, 10 points of clinopyroxene, 1 point of orthopyroxene, 8 points of plagioclase and 12 points of amphibole) from pyroxene-hornblende to fine-grained olivine gabbro, 30 points (12 points of clinopyroxene, 10 points of plagioclase, 8 points of amphibole) from fine-grained hornblende gabbro and 20 points (3 points of clinopyroxene, 11 points of plagioclase and 5 points of amphibole) from the diabasic dike of the Dar Gaz district were analyzed using CAMECA SX 100 electron microscopy (EPMA) with 20 kV and 20 nA conditions in the IMPRC. Discussion The mafic rocks of the Dar Gaz district include ferrogabbro to coarse-grained pyroxene-hornblende gabbro, fine-grained pyroxene-hornblende gabbro, hornblende gabbro and diabasic dikes. Ferrogabbro to coarse-grained pyroxene-hornblende gabbro is one of the most important host rocks for Fe-Ti mineralization in the district. According to the thermo-barometers, the formation temperature and pressure of gabbroic rocks in the Dar Gaz district are in the range of 750 to 1258°C and a pressure of 2.5 and 6 kbars (clinopyroxene and amphibole barometers), and dibasic dikes are in the range of 700 to 1145°C and a pressure of 2.5 and 6 kbars were obtained. The highest crystallization temperature related to fine-grained pyroxen-hornblende gabbro unit (754 to 1258 °C) is the base of the sequence. The ascending of asthenosphere in the back-arc tectonic settings are from a magmatic chamber with a depth of about 15.34 to 21.20 km, and a pressure of about 4 to 8 kbars upwards. The average geometric results of pyroxene-ilmenite mineral pair geothermometry and pyroxene geothermometer of these rocks, their equilibrium temperature was determined between 901 to 1228°C, which is close to the magmatic temperatures. With comparison of temperature (700 to 1258°C), pressure (4 to 8 kbars) and oxygen fugacity (-19.25 to -25.25 bars) obtained for gabbroid rocks hosting Fe-Ti oxide mineralization with the temperatures obtained from ilmenite and titanomagnetite by Karimi Shahraki et al. (2019), it can be concluded that oxide mineralization is classified as orthomagmatic and occurs during the replacement, cooling and fraction of basic magma and formation of gabbroid intrusion associated with fractional crystallization. Conclusion Thermometry of pyroxenes at 2.5 kbars pressure indicates a temperature of 750 to 1258 °C for gabbroid bodies and 700 to 1145 °C for diabaic dikes. Thermometry of plagioclase and hornblende-plagioclase at 6 kbars pressure for coarse-grained ferrogabbro, fine-grained pyroxene-hornblende gabbro, hornblende gabbro and diabasic dikes are 868, 884, 776 and 784 °C, respectively. Amphibole thermometers at 6 kbar pressure for coarse-grained ferrogabbro, fine-grained pyroxene-hornblende gabbro, hornblende gabbro and diabasic dikes are 911, 948, 937 and 946°C, respectively. Comparison of temperature, pressure and high oxygen fugacity values obtained for gabbroic rocks and ilmenite and titanium magnetite ores of the Dar Gaz district, indicating oxidation conditions associated with fractional crystallization is the main factor for control of orthomagmatic mineralization in the back-arc environment.

Igneous rock forming minerals carry valuable information from the deep earth that is not directly accessible at the surface. Each mineral represents the physico-chemical conditions at which various magmatic processes have occured over a wide range of depths from upper mantle to shallow crustal levels. These processes are cryptically inscribed in the whole-rock and mineral compositions (e.g. major elements, trace elements and isotopic ratios) and textures (equilibrium vs. disequilibrium features), together with intensive variables (e.g. pressure, P ; temperature, T). Therefore, particular attention should be given to igneous minerals to understand better the processes that took place during their journey from the source through magma chambers and conduit systems to the Earth's surface. MagMin_PT is an Excel© based user-friendly program, designed to calculate mineral formulae and end-members, and to estimate pressure and temperature (e.g. geothermobarometry) from electron microprobe analytical data. The program operates using the most common igneous rock-forming minerals (olivine, pyroxene, amphibole, biotite, feldspar, magnetite, ilmenite, apatite and zircon), resulting in various classification diagrams and P – T diagrams. The program allows for whole-rock or glass composition to be entered together with the EPMA data to evalaute the equilibration status for most P – T calculation models. Fe2+ and Fe3+ estimation is routinely performed in MagMin_PT based on stoichiometric constraints, and to some extent using machine learning methods for different iron-bearing minerals. MagMin_PT is also able to carry calculations of fugacity, magmatic water content and saturation temperature. Graphical and numerical outputs produced by the program can be easily copied to other media for further processing. [ABSTRACT FROM AUTHOR]

This paper presents major and trace element compositions of the clinopyroxene phenocrysts from variably altered basaltic rocks from the Yüksekova Complex from E Anatolia (Elazığ) to reveal the geochemical affinity of the basaltic magmatism and the intensive parameters during magmatic crystallization. The Yüksekova Complex crops out over extensive areas to the north of the Bitlis suture. The investigated samples come from an area of ca. 2500 km2 in the Elazığ province. Petrographically, the basaltic rocks are represented by basalt, porphyric basalt and dolerite. The rocks are characterized by plagioclase, clinopyroxene, magnetite and ilmenite and are devoid of any hornblende and biotite, whereby clinopyroxene and plagioclase form phenocrysts. Generally, the groundmass is variably altered, whereas clinophenocrysts are comparatively fresh. The clinopyroxene is represented by the composition Wo37–48En43–53Fs4–17, with Mg/(Mg + Fe2+) ratios of 0.93–0.73. Compositionally, the clinopyroxenes resemble those from island arc tholeiitic, calc-alkaline and anorogenic tholeiitic rocks. Clinopyroxene-melt geothermobarometry yielded temperatures of 1146 and 1193 °C and pressures of 1.4 to 7.0 kbar, suggesting that the clinopyroxene phenocrysts started to grow at variable crustal depths. There is no apparent difference of magma temperatures between different magma affinities. The Fe–Mg partition coefficient between clinopyroxene and melt (KD Fe−MgCpx-Melt = 0.27) suggests that the parental magmas in equilibrium with clinopyroxene were mostly primitive, with Mg# of 65–79. The REE patterns of parental melts in equilibrium with clinopyroxene phenocrysts resemble those of low-K tholeiitic to middle- to high-K calc-alkaline rocks from the magmatic arcs. The results of this study are mostly consistent with the inferences from the whole-rock geochemistry, and indicate that the major and trace element geochemistry can be effectively used to infer the geochemical affinities of the highly altered basaltic rocks. [ABSTRACT FROM AUTHOR]

The southern Sanandaj-Sirjan Zone (SSZ) forms the core of the Zagros orogen and consists of a stack of four major tectonic units, all of which were thrust southwestward over the Neyriz ophiolites. Precambrian and early Paleozoic rocks were affected by high-grade metamorphism, whilst the late Paleozoic (Carboniferous and Permian) and Mesozoic rocks are of low grade to unmetamorphosed. Geothermobarometric results indicate that the investigated area experienced peak temperature–pressure conditions of ~ 650 °C and 8–9 kbar, before being partly overprinted by greenschist facies conditions. We identified two main deformational phases (D2, D3) and some relics of an older one (D1) in the southern SSZ. D1 is inferred based on local evidence of tight D2 folds that fold a pre-existing schistosity (S1), associated with prograde- and peak metamorphism. D2 shows large-scale, tight-to isoclinal F2 folds and a penetrative S2 foliation, forming the dominant foliation in our study area. The P–T path is clockwise and associated with a geothermal gradient of ~ 20 °C/km, suggesting a collision-related geodynamic setting, preceding D2, and possibly linked to an early stage of D1. D3 is characterized by open folds (F3) and thrusts developed after greenschist facies metamorphism. Based on the metamorphic grade and stratigraphic age of folded units, D2 is inferred to be Eo-Cimmerian, and D3 post-Cretaceous, coeval to the Zagros orogeny. Concerning the oldest phase (D1), for which only circumstantial structural evidence exists, we discuss whether its age is pre-Cimmerian, possibly Variscan, or Eo-Cimmerian as suggested in previous literature. This study uses metamorphic assemblages and structures of the southern SSZ, to retrace its geodynamic evolution, which started with burial associated with high-temperature metamorphism, followed by Eo-Cimmerian shortening, and finally terminated with additional shortening related to the Zagros collisional event. [ABSTRACT FROM AUTHOR]

The Lohit Plutonic Complex (LPC) of Arunachal Trans‐Himalaya represents the northeast extension of Trans‐Himalayan magmatic arc system located in the north of Indus Tsangpo Suture Zone (ITSZ). Field relation, magnetic susceptibility (MS), and phase petrology on the granitoids of LPC was conducted in order to assess the granite series (magnetite, oxidized vs. ilmenite, reduced types), and physico‐chemical conditions of the LPC granitoid magmas. The studied granitoids are well‐exposed in the Dibang and Lohit valleys, and their MS values indicate a bi‐modal patterns corresponding to ilmenite (reduced) series (71%) and magnetite (oxidized) series (29%) granites. The variation of MS in the LPC granitoids is related to the alteration of ferromagnetic minerals, and later tectonic and deformational processes that acted upon them. The amphiboles from the LPC granitoids are calcic (CaB >1.5, Si = 6.30–7.06 apfu) and exhibit tschermak substitutions typical to their evolution in a calc alkaline, metaluminous (I‐type) felsic magmas. Al‐in‐hornblende rims estimate the emplacement of quartz diorite and granodiorite magmas at shallow (~5 km) and mid (~16 km) crustal depths. Geothermometric results point to a regime of magmatic crystallization (940–837°C for quartz diorite; 882–829°C for granodiorite) sufficiently above the solidus of respective melts. Biotites from LPC granitoids are primary to re‐equilibrated, and transitional between magnesio‐ and ferri‐biotites. Quartz diorite and granodiorite biotites evolved under oxidizing magmas (log ƒO2−14 to log ƒO2−13) in a temperature range of ~750–950°C, typical to their formation in a calc alkaline magma of subduction zone environment. However, the biotites from leucogranite appear to have evolved under a mildly reducing magma environment, most likely attained in a collisional setting. The obtained results suggest that the oxidized nature of calc alkaline, subduction‐related magmatic arc rocks of the LPC is largely modified and reduced by post‐magmatic, and later tectonothermal and deformational events that operated during Himalayan and Trans‐Himalayan orogenesis. [ABSTRACT FROM AUTHOR]

The metamorphic conditions and evolution of the Palaeozoic-Mesozoic metamorphic complex of Medvednica Mountain (Zagorje-Mid-Transdanubian zone, Croatia) are still a matter of debate. The results of the investigation of five samples of metapelitic schists with the mineral association of quartz, white mica and chlorite are presented. The studied schists are part of the continental margin of Adria and were metamorphosed under upper greenschist- to amphibolite-facies conditions. The focus of this study is a sample representing the highest metamorphic grade that additionally contains chloritoid blasts. Pressure-temperature pseudosection modelling together with classical geothermobarometric calculations yielded peak metamorphic conditions of 0.94 ± 0.05 GPa and 550 ± 20 °C for chloritoid schist. Monazite in-situ U-Th-total Pb electron microprobe dating indicates two metamorphic events at 167 ± 2 Ma and 143 ± 2 Ma, which are interpreted as the time of monazite growth during two distinct metamorphic phases. The formation of the chloritoid paragenesis is related to the older event (around 167 Ma) and linked with the Middle Jurassic subduction-accretion processes of Neotethys-derived ophiolitic lithologies. The younger metamorphic event (around 143 Ma) is related to the obduction of ophiolites onto the continental margin of Adria. [ABSTRACT FROM AUTHOR]

The Strandja Massif cropping out in NW Turkey is cut by Late Cretaceous intrusives. These are called Strandja Intrusives and they are felsic and mafic coeval intrusives. Felsic intrusives consist of granite, granodiorite, quartz monzonite and syenite, while mafic intrusives consist of diorite and gabbro composition. Main composition of felsic intrusives consists of quartz, alkali feldspar, plagioclase, biotite, amphibole ±pyroxene mineral association, while main composition of mafic ones consists of plagioclase, biotite, amphibole ±pyroxene ±olivine mineral association. Amphiboles hydrated double-chain mineral of the Strandja Intrusives observed in all rocks used as an index mineral in this study to understand the petrological evolution of the rocks. According to Confocal Raman Spectroscopy studies amphiboles were actinolite type and exhibited similar spectrum and results of mineral chemistry reveals that they were calcic/Mg-hornblende types. According to geothermobarometer calculations, amphiboles crystallize in felsic intrusives at a pressure range of 0.49-0.94 kbar and a temperature of 757.52-814.49o C temperature at a depth of approximately 1.34-4.93 km, while in mafic ones at 2.59 kbar pressure and 892.82o C temperature at 9.97 km depth. Different temperatures-depth conditions and overlaps in Raman shift obtained from amphiboles indicate that these intrusives are derived from different sources but crystallized in the same environment. [ABSTRACT FROM AUTHOR]

A recent petrological study on the lesser-known Sholayar alkaline syenite complex (10°17′59.9′′N: 076°47′26.3′′E) accommodated in the high-grade rocks of the Southern Granulite Terrane reveals the presence of three distinct petrographic types namely leuco syenite, melanofelsic syenite and mela syenite. The syenites, in general, have the following constituent minerals, namely alkali feldspar (Or76.8Ab23.2–Or93.4Ab6.6), plagioclase (An4.1–An17.3), calcic amphibole (edenitic hornblende/ferropargasitic hornblende), quad pyroxene (diopside–hedenbergite), biotite and opaque minerals (magnetite and ilmenite). Mode-based statistical studies indicate that a highly significant correlation exists among certain mineralogical parameters including quartz%, total feldspar%, colour index, alteration index and hydration index. Isopleth plots of these parameters strongly suggest maintenance of a magmatic regime throughout, with increasing water content towards the end stage of crystallization. Several geothermobarometric methods point to shallow to moderate level emplacement (~9–23 km) of the alkaline/sub-alkaline syenite magma which was facilitated by a 'hydration event'. The steep change in water gradients (in localized pockets) of the syenite intrusives has been corroborated by textural evidences. Research highlights: First systematic petro-mineralogical report of Sholayar alkaline syenite complex from SGT. Involvement of single magmatic lineage with variable water content. Geothermobarometry suggests a moderate to shallow level of syenite emplacement. [ABSTRACT FROM AUTHOR]

Osorno volcano (41°06'S, 72°20'W) is a composite stratovolcano of the Central Southern Volcanic Zone of the Chilean Andes. It is the southernmost member of a NE–SW trending alignment of volcanic edifices including La Picada and Puntiagudo volcanoes and the Cordón Cenizos chain. According to contemporary descriptions recorded by Charles Darwin in 1835, two eruptive events occurred: the first during January–February, and the second during November–December 1835 and January 1836. The volcano erupted basaltic andesite lavas and tephra fall deposits (52.4 to 52.9 SiO2 wt. %), which contain phenocrysts of olivine, plagioclase, clinopyroxene, and spinel. The compositions of these phenocryst phases, together with those of olivine-hosted melt inclusions, allowed us to constrain intensive parameters for the pre-eruptive magmas. These varied from 1060°C to 1140°C, with an oxygen fugacity buffer of ~ΔQFM +1.1, dissolved water concentrations of up to 5.6 wt. % (average of ~4.2 wt. %) and maximum pressures equivalent to ~7-km depth. Textural relations, such as crystal accumulations and clots, zoning in crystals and other indications of disequilibrium, lead us to infer the involvement of a crystal mush, rich in individual crystals and clots of crystals, which underwent a degree of disaggregation and entrainment into the transiting magma prior to eruption. Comparison of trace element abundances, including rare earth elements, fluid-mobile elements, and relatively fluid-immobile elements, combined with 87Sr/86Sr and 143Nd/144Nd isotope ratios, allows us to consider variations in slab-derived fluid input and the minor role of crustal contamination on the Osorno eruptive products and those from neighboring volcanic systems. Our results suggest both a greater contribution from slab-derived fluid and a higher degree of partial melting in the systems supplying stratovolcanoes (Osorno, Calbuco, and La Picada) relative to those supplying small eruptive centers built over the major regional Liquiñe-Ofqui Fault Zone. [ABSTRACT FROM AUTHOR]

To improve the understanding of the formation and evolution of the sub‐continental lithospheric mantle (SCLM) underlying the South Australian Craton we have conducted a detailed petrological study on >3,000 mantle xenocrysts from 13 kimberlites emplaced across the craton. Pressure (P) and temperature (T) estimates on Cr diopside and garnet have been coupled with their chemical concentrations to constrain lithospheric thickness and chemo‐lithostratigraphy. We show that lithospheric thickness is greatest beneath the Gawler Craton, whereas thinner lithosphere occurs beneath the Adelaide Fold Belt. Mineral compositions highlight two litho‐chemical domains within the shallow and deep SCLM that are separated by a mid‐lithosphere discontinuity (MLD). The shallow SCLM (60–130 km) comprises low Cr2O3 lherzolite and wehrlite. Shallow SCLM xenocrysts record depleted and refertilized compositions enriched in light rare earth elements related to metasomatism by kimberlite or related melts. The mid‐lithosphere (130–160 km) is depleted in garnet and Cr diopside which may relate to a layer of pargasite lherzolite. The deep SCLM (>160 km) comprises high Cr2O3 lherzolite with elevated TiO2 and FeO. We interpret the litho‐chemical stratification of the SCLM to reflect a multi‐stage top‐down growth. The shallow SCLM reflects an amalgamation of Precambrian cratonic nuclei characterized by heterogeneity in geochemical enrichment and depletion. Interaction of the shallow SCLM with mantle plumes accreted melts along the paleo‐lithosphere‐asthenosphere boundary, which now occurs as a MLD. The deep SCLM represents depleted mantle residue formed during mantle plume impingement and thickened during orogenesis. This domain has been metasomatized and refertilized by high‐T melts from the asthenosphere. Key Points: The South Australian Craton comprises three litho‐chemical layers within the shallow, middle and deep lithospheric mantleXenocrysts define a heterogeneously depleted‐kimberlite melt metasomatized shallow sub‐continental lithospheric mantle (SCLM) and fertile‐melt metasomatized deep SCLMThe mid‐lithosphere is a seismic and geochemical discontinuity marked by negative Vp and lower modal proportions of garnet and diopside [ABSTRACT FROM AUTHOR]

Multiple factors may downgrade the mineralization potential of an intermediate-felsic intrusion, such as the commonly invoked inefficient fluid exsolution and lack of ore-forming species (metals and their ligands) in magmas. However, other factors may affect the mineralization potential of a magma body but have poorly understood roles in the formation of magmatic-hydrothermal ore deposits. Here, we present a comparison between two Cu mineralizing plutons and a Cu-poor, Fe mineralizing pluton in the Edong district. Efficient fluid exsolution and extraction occurred during the solidification of all three plutons, as evidenced by extensive skarn alteration around them. The results show that the oxidation state of the three plutons is similar (within a range of ~ΔNNO+0.9 to ΔNNO+2.5). A systematic comparison of the Cu contents of a certain suite of minerals of the three plutons shows that the Cu concentrations of all minerals in the Cu mineralizing plutons are lower than those of the Cu-poor Fe mineralizing pluton. This indicates that the Cu mineralizing plutons underwent more efficient copper extraction. Thus, igneous crystals with anomalously low Cu contents may potentially be used as a tool to identify Cu mineralizing magmatic units in a deposit with multiphase intrusions. We suggest that the inefficient copper extraction from plutons may be ascribed to the lack of reduced S species during fluid exsolution or different evolution paths of Cu and Cl during magma crystallization. [ABSTRACT FROM AUTHOR]

Introduction The study area is located in the Eastern Alborz zone (Gansser, 1951) which is a part of the northern margin of Gondwana during the Paleozoic (Stöcklin, 1974; Salehi Rad, 1979; Berberian and King, 1981; Şengor, 1990; Alavi, 1991, 1996; Stampfli and Borel, 2002; Allen et al., 2003; Horton et al., 2008; Sinha, 2012, 2013). According to studies conducted by Gansser (1951) and Hubber (1957), the gabbro masses of South Gorgan (Nahar Khuran Valley) belong to the ophiolite collection. Meanwhile, 6km South-East of Galougah city, Gorgan schists have been covered by underlying Jurassic sandstones with s steep discontinuity. The parts resulting from the erosion of Gorgan schists were observed in the sequence conglomerate of the underlying Jurassic. At the beginning of the Ziarat Valley, about 800 meters above the Nahar Khuran, two small tectonic masses (the thickness of about 11 meters) are placed on the layers. These masses are mostly metamorphic. The metamorphic rocks (Gorgan schists), as one of the important geological units in Iran, are mainly formed from low-metamorphic rocks such as slate, phyllite, chlorite schist, greenschist and micaschist along with volcanic rocks and gabbrodiorite masses infiltrating them. Materials and Methods To prepare a geological map of the study area, field sampling and fieldwork were first done from the various units in the region. Over 100 samples were collected from the area. Approximately 70 thin cross-sectional samples of the tectonic rocks of the area were selected from them and investigated using a polarizing microscope. In this paper, 11 points of clinopyroxene were selected for microprobe analysis. The point analysis done on these minerals was conducted using the EPMA method using a microprobe analysis set in the Center of Mineral Processing of Iran (Karaj). The structural formula is calculated using the Excel (Spreadsheet) and dividing them was done by the MinPet 2.02 software package. Given that microprobe analysis is unable to distinguish Fe2+ and Fe3+ and given that it reports total iron as FeO*, it is necessary to separate these two from each other in order to calculate the minerals’ structural formula. Results Petrographic studies identified rocks including gabbro, olivine gabbro, monzonite, gabbro to monzogabbro altered, metagabbro, and catalactic porphyry diorite. Mineralogically, these rocks consist of phenocrysts of plagioclase with labradorite composition, clinopyroxene and olivine with accessory minerals of apatite, sphene, biotite, and metal minerals. Secondary minerals are chlorite, sericite, clay mineral and epidote. The dominant textures in these rocks are granular and ophitic. The results of electron microprobe analysis of these clinopyroxenes show that they have augite compositions. In addition, gabbros also mostly show alkaline composition. Discussion To precisely investigate the rocks in the research area, the results of the chemical analyses of minerals were used in determining their petrogenesis. Felsic minerals mainly include altered plagioclase, the main combination of which is labradorite and which is converted to the secondary albite due to hydrothermal alteration processes. The combination of clinopyroxenes available in the volcanic rocks is in Quad range and has a composition of augite. The temperature calculated for the clinopyroxenes in gabbros is 1277.7 to 1353.1°C and the pressure is more than 10 Kbars. (On the baseline of 3.65kbar per 1km in depth), the formation of clinopyroxenes in the parent magma was over 37km. The primary water content of the gabbro magmas is estimated to have been between 0.5 and 5 wt.%. Distribution of aluminum in tetra and octa positions of clinopyroxenes depends on pressure and the amount of water available in the crystallization environment. Accordingly, the amount of AlIV decreases as the amount of water increases. Tectonomagmatic diagrams suggest that the host rocks are alkaline and are related to volcanic arc setting. References Alavi, M., 1991. Sedimentary and structural characteristics of the Paleo–Tethys remnants in northeastern Iran. Geological Society of America Bulletin, 103(8): 983–992. https://doi.org/10.1130/0016-7606(1991)1032.3.CO;2 Alavi, M., 1996. Tectonostratigraphic synthesis and structural style of the Alborz mountain system in northern Iran. Journal of Geodynamics, 21(1): 1–33. https://doi.org/10.1016/0264-3707(95)00009-7 Allen, M.B., Ghassemi, M.R., Shahrabi, M. and Qorashi, M., 2003. Accommodation of late Cenozoic oblique shortening in the Alborz range, northern Iran. Journal of Structural Geology, 25(5): 659–672. https://doi.org/10.1016/S0191-8141(02)00064-0 Berberian, M. and King, G.C.P., 1981. Toward apaleogeography and tectonic evolution of Iran. Canadian Journal of Earth Sciences, 18(2): 210–265. https://doi.org/10.1139/e81-019 Gansser, A., 1951. Geological reconnaissance in the Gorgan and surrounding areas. Geological Survey of Iran, Tehran, report 18, 37 pp. Hubber, H., 1957. Geological reporte on south Gorgan mountain front between Nika and Shah-Pasand. National Iran Oil Company, Tehran, report 164, 39 pp. Salehi Rad, M.R., 1979. Etude géologique de la region de Gorgan (Alborz oriental, Iran). Ph.D. Thesis, University of Paris, Paris, France, 162 pp. Şengor, A.M.C., 1990. A new model for the late Palaeozoic–Mesozoic tectonic evolution of Iran and implications for Oman. Geological Society of London, 49‌(1): 797–831. http://dx.doi.org/10.1144/gsl.sp.1992.049.01.49 Sinha A.K., 2012. Petrological characterization of Proterozoic mafic dykes from the Singhbhum craton, eastern India, 34th International Geological Congress, University of Queensland, Brisbane, Australia. Sinha, A.K., 2013. Geochemistry of distinct mafic dykes from the Damodar valley Gondwana basins and Chhotanagpur gneissic terrain, eastern India: implications for their petrogenesis and tectonic setting. 125th anniversary of The Geological Society of America, Cornell University, New York, USA. Stampfli, G.M. and Borel, G.D., 2002. A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrones. Earth and Planetary science letters 196 (1–2): 17–33. https://doi.org/10.1016/S0012-821X(01)00588-X Stöcklin, J., 1974. Possible ancient continental margins in Iran. In: C.A. Burk and C.L. Drake (Editors), The geology of continental margins. Springer, New York, pp. 873–887. https://doi.org/10.1007/978-3-662-01141-6_64

Abstract To improve the understanding of the formation and evolution of the sub‐continental lithospheric mantle (SCLM) underlying the South Australian Craton we have conducted a detailed petrological study on >3,000 mantle xenocrysts from 13 kimberlites emplaced across the craton. Pressure (P) and temperature (T) estimates on Cr diopside and garnet have been coupled with their chemical concentrations to constrain lithospheric thickness and chemo‐lithostratigraphy. We show that lithospheric thickness is greatest beneath the Gawler Craton, whereas thinner lithosphere occurs beneath the Adelaide Fold Belt. Mineral compositions highlight two litho‐chemical domains within the shallow and deep SCLM that are separated by a mid‐lithosphere discontinuity (MLD). The shallow SCLM (60–130 km) comprises low Cr2O3 lherzolite and wehrlite. Shallow SCLM xenocrysts record depleted and refertilized compositions enriched in light rare earth elements related to metasomatism by kimberlite or related melts. The mid‐lithosphere (130–160 km) is depleted in garnet and Cr diopside which may relate to a layer of pargasite lherzolite. The deep SCLM (>160 km) comprises high Cr2O3 lherzolite with elevated TiO2 and FeO. We interpret the litho‐chemical stratification of the SCLM to reflect a multi‐stage top‐down growth. The shallow SCLM reflects an amalgamation of Precambrian cratonic nuclei characterized by heterogeneity in geochemical enrichment and depletion. Interaction of the shallow SCLM with mantle plumes accreted melts along the paleo‐lithosphere‐asthenosphere boundary, which now occurs as a MLD. The deep SCLM represents depleted mantle residue formed during mantle plume impingement and thickened during orogenesis. This domain has been metasomatized and refertilized by high‐T melts from the asthenosphere.

The geologic record reveals events in which enormous volumes (100–1000s of km3) of magma were erupted in a matter of days to months. Yet, the architecture of magmatic systems that feed supereruptions can only be investigated through the study of ancient systems. For more than 40 years, the Bishop Tuff (Long Valley, California) has been the archetypal example of a single, zoned magma body that fed a supereruption. Early-erupted material is pyroxene-free and crystal poor (< 20 wt%), presumably erupted from the upper parts of the magma body; late-erupted material is orthopyroxene and clinopyroxene-bearing, commonly more crystal rich (up to 30 wt% crystals), and presumably tapped magma from the lower portions of the magma body. Fe-Ti oxide compositions suggest higher crystallization temperatures for late-erupted magmas (as high as 820°C) than for early-erupted magmas (as low as 700°C). Pressures derived from major-element compositions of glass inclusions were used to suggest an alternative model of lateral juxtaposition of two main magma bodies—each one feeding early-erupted and late-erupted units. Yet, this interpretation has proven controversial. We present a large dataset of matrix glass compositions for 227 pumice clasts that span the stratigraphy of the deposit. We calculate crystallization pressures based on major-element glass compositions using rhyolite-MELTS geobarometry and crystallization temperatures based on Zr in glass using zircon-saturation geothermometry. Additionally, we apply the same methods to 1,538 major-element and 615 trace-element analyses from a dataset from the literature. The results overwhelmingly demonstrate that the variations in crystallization temperature and pressure are not consistent with vertical stratification of a single magma body. All crystallization pressures and temperatures are very similar, with modes of ∼150 MPa and ∼730°C. Our results support lateral juxtaposition of three main magma bodies. Magmas represented by smaller stratigraphic units crystallized at similar pressures as the main bodies, which suggests coexistence of larger and smaller magma bodies at the time of eruption. We compare our findings with results for other very large eruptions and supereruptions. We argue that supereruptions typically mobilize a complex patchwork of magma bodies that reside within specific levels of the crust. These eruptions reveal the architecture of the crust during moments of high abundance of eruptible magma, revealing crustal states that differ from what is inferred for magmatic systems currently present on Earth.

Unlike their silicic counterparts, mafic eruptions are known for being on the low-end of the explosivity spectrum with eruption styles commonly ranging from effusive to Hawaiian fire fountaining. However, there are increasing discoveries of large mafic Plinian eruptions, sometimes generating ignimbrites, suggesting that this phenomenon might not be so uncommon. So, what processes lead a mafic magma to fragment violently enough to generate extensive ignimbrites?We sampled pumices from ignimbrites and PDCs with a compositional range from basaltic-andesite (Curacautín ignimbrite, Volcàn Llaima, Chile), andesite (Marapi, Indonesia) to trachyte (Gunungkawi ignimbrite, Batur, Indonesia). We use SEM imagery and X-ray Microtomography on pyroclasts from these deposits to characterize phenocryst, microlite and vesicle textures. From vesicle number densities we estimate fragmentation decompression rates in the range of 0.4–1.6 MPa/s for the three deposits. With a combination of EPMA and SIMS analyses we characterise pre-eruptive storage conditions. Based on the bulk and groundmass compositions, the storage temperature (1,050–1,100°C), pressure (50–100 MPa) and phenocryst content (1.0–2.5 vol%), we conclude that the basaltic-andesitic Curacautín magma was at sub-liquidus conditions, which allowed fast and widespread disequilibrium matrix crystallization (0–80 vol%) during ascent to the surface. Combined with the important decompression rate, this intense crystallization led to a magma bulk viscosity jump from 103 up to >107 Pa s and allowed it to fragment brittlely. Conversely, for the Marapi PDC and Gunungkawi ignimbrite, similar decompression rates coupled with larger initial bulk viscosities of 105–106 Pa s were sufficient to fragment the magma brittlely. The fragmentation processes for these latter two deposits were slightly different however, with the Marapi PDC fragmentation being mostly driven by vesicle overpressure, while a combination of bubble overpressure and intense strain-rate were the cause of fragmentation for the Gunungkawi ignimbrite. We conclude that mafic ignimbrites can form due to a combination of peculiar storage conditions that lead to strongly non-linear feedback processes in the conduit, particularly intense microlite crystallization on very short timescales coupled with intense decompression rates. Conversely, the high viscosity determined by pre-eruptive storage conditions, including temperature and volatile-content, are key in controlling the formation of more evolved magmas PDCs'.

The reliability of eight Fe–Mg exchange geothermobarometers for garnet-bearing peridotites, pyroxenites and eclogites has been examined using a database comprised of more than 300 published peridotite, pyroxenite and eclogite experiments conducted from 10 to 70 kbar and 850 to > 1650 ∘ C . We have tested Fe–Mg exchange geothermometers suitable for a range of mantle lithologies, including websterite, harzburgite, wehrlite and eclogite. All geothermometers maintained an average difference in experimental and calculated temperature (T) Δ T = T exp - T calc of less than ± 50 °C with a standard deviation of Δ T between ± 50 to 150 °C. Most geothermometers performed well across a narrow range in ln Kd Fe - Mg A - B (where Kd Fe - Mg A - B = Fe A × Mg B (Fe B × Mg A) ), however, systematic overestimation and underestimation of T were observed outside of the optimal range of lnKd Fe - Mg A - B . Increases in experimental pressure (P) adversely affected several geothermometers, particularly those calibrated empirically using natural samples. All previously published calibrations of the garnet-clinopyroxene geothermometer were unable to reliably reproduce the experimental T for both peridotite and eclogite experimental compositions, which hinders their confident application to natural datasets. To improve the state of mantle geothermobarometry we have used our experimental database to recalibrate the (1) garnet-clinopyroxene Fe–Mg exchange geothermometer, and (2) garnet-orthopyroxene Fe–Mg exchange geothermometer. Each geothermometer has been recalibrated across an extended P, T, and compositional range. The inclusion of eclogitic experiments in the calibration for the garnet-clinopyroxene geothermometer permits application to both eclogitic and peridotitic/pyroxenitic assemblages equilibrated under a wide range of PT conditions in the upper mantle. Using multiple linear regression to solve for lnKd, we found the following expressions best reproduced the experimental T (℃) of our dataset: T Fe - Mg grt - cpx (∘ C) = 3356.34 - 0.008 × P kbar + 0.259 × X Ca grt + 0.914 × X Mg grt + - 0.159 × Jd cpx + ln Kd Fe - Mg grt - cpx + 1.265 - 273 T Fe - Mg grt - opx (∘ C) = 1851.85 - 0.007 × P kbar + - 1.83 × X Ca grt + ln Kd Fe - Mg grt - cpx + 1.08 - 273 . where, X Ca grt = Ca Ca + Fe + Mg , Kd Fe - Mg grt - opx = Fe grt × Mg opx (Fe opx × Mg grt) , X Mg grt = Mg Ca + Fe + Mg , Jd cpx = Na - Cr - 2 × Ti , Kd Fe - Mg grt - cpx = Fe grt × Mg cpx (Fe cpx × Mg grt) , with all elements calculated on the basis of 12 oxygen anions in garnet and 6 oxygen anions in clino- and orthopyroxene. Fe2+ = total Fe. Our updated calibrations resolve several issues with earlier calibrations, including a poor performance at elevated P and compositional limitations. An improvement in precision and accuracy has been demonstrated through application to the experimental calibration dataset, a second independent set of published experimental data, and to natural peridotites, pyroxenites and eclogites from on and off craton settings. Iterative PT estimates on natural datasets calculated using our updated calibrations compare well with estimates from widely used calibrations such as the Taylor (1998) two-pyroxene solvus geothermometer. We anticipate that this contribution will provide an important reference for the reliability of mantle geothermometers and that our updated calibrations will be used in future studies on peridotite, pyroxenite and eclogite inclusions in diamond and mantle-derived xenoliths. [ABSTRACT FROM AUTHOR]

This study focuses on the nature of giant micas occurring at the contact between the Özvatan (foid‐bearing) syenites and the metamorphic basement in Central Anatolia. The studied micas are dark greenish‐black in color and crystallized within vein shape like bodies as a narrow lens. The origin and processes responsible for the formation of these independent crystals of the giant micas were investigated by mineralogical, petrographical and geochemical analyses with the use of Confocal Raman Spectroscopy (CRS), Fourier Transform Infrared (FTIR) Spectroscopy, X‐Ray Diffraction (XRD), Polarized Energy Dispersive X‐Ray Fluorescence Spectrometer (PED‐XRF) and Electron Probe Micro Analysis (EPMA). According to XRD, CRS, FTIR and EPMA data, the giant micas are phlogopite. EPMA results reveal that studied mica minerals represent the products of re‐equilibrated primary mica characterized by high MgO and FeO and low Al2O3 and TiO2 contents. The trace element concentrations of the giant micas display similar patterns with the upper crust. The giant micas are crystallized within small cubicles from an alkaline magma and their composition is possibly modified by a mixing event between the crust‐ and mantle‐derived magmas and contaminated at varying extent by the basement metamorphic rocks. [ABSTRACT FROM AUTHOR]

Geothermobarometry shows that metapelite samples from Namche Barwa Complex (NBC) reached upper amphibolite to near‐granulite facies during the peak metamorphic stage, with similar conditions of ~700–750°C/8–10 kbar, and then experienced retrograde metamorphism at ~630–700°C/4–7 kbar. In situ monazite laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U–Th–Pb dating suggests divergent metamorphism in the NBC: metapelite on the hanging wall of Namu–La thrust preserved a continuous metamorphic record of >19–3 Ma, whereas metapelite on the footwall yielded age ranges of >18–14 and 8–3 Ma, with a gap in recorded ages between 14 and 8 Ma. Monazite grains in the garnet porphyroblasts, more depleted in the heavy rare earth elements (HREE), yielded the youngest age of ~14 Ma. This is interpreted as the timing of upper amphibolite facies peak metamorphism in the metapelite from the NBC, with the NBC being exhumed coherently thereafter. Furthermore, the discrepancy between reported peak metamorphic ages of high‐pressure granulite (~40–30 Ma, ~25–20 Ma) and mid‐pressure metapelite (~14 Ma, this study) indicate asynchronous subduction–exhumation processes in the NBC. We suggest that crustal flow has played an essential role in exhumation since ~40 Ma, and recent surficial erosion (<8 Ma) intensified the exhumation of the NBC, with young leucogranite (<10 Ma) resulting from decompression melting. From ~3 Ma to the present, the interplay of erosion and tectonic movement caused ubiquitous rapid uplift, resulting in the concomitant exhumation of various types of rocks and the formation of the spectacular high relief between Yarlung Tsangpo Gorge and Namche Barwa Peak. [ABSTRACT FROM AUTHOR]

The eruptions of Campi Flegrei (Southern Italy), one of the most studied and dangerous active volcanic areas of the world, are fed by mildly potassic alkaline magmas, from shoshonite to trachyte and phonotrachyte. Petrological investigations carried out in past decades on Campi Flegrei rocks provide crucial information for understanding differentiation processes in its magmatic system. However, the compositional features of rocks are a palimpsest of many processes acting over timescales of 100–104 years, including crystal entrapment from multiple reservoirs with different magmatic histories. In this work, olivine, clinopyroxene and feldspar crystals from volcanic rocks related to the entire period of Campi Flegrei's volcanic activity are checked for equilibrium with combined and possibly more rigorous tests than those commonly used in previous works (e.g., Fe–Mg exchange between either olivine or clinopyroxene and melt), with the aim of obtaining more robust geothermobarometric estimations for the magmas these products represent. We applied several combinations of equilibrium tests and geothermometric and geobarometric methods to a suite of rocks and related minerals spanning the period from ~59 ka to 1538 A.D. and compared the obtained results with the inferred magma storage conditions estimated in previous works through different methods. This mineral-chemistry investigation suggests that two prevalent sets of T–P (temperature–pressure) conditions, here referred to as "magmatic environments", characterized the magma storage over the entire period of Campi Flegrei activity investigated here. These magmatic environments are ascribable to either mafic or differentiated magmas, stationing in deep and shallow reservoirs, respectively, which interacted frequently, mostly during the last 12 ka of activity. In fact, open-system magmatic processes (mixing/mingling, crustal contamination, CO2 flushing) hypothesized to have occurred before several Campi Flegrei eruptions could have removed earlier-grown crystals from their equilibrium melts. Moreover, our new results indicate that, in the case of complex systems such as Campi Flegrei's, in which different pre-eruptive processes can modify the equilibrium composition of the crystals, one single geothermobarometric method offers little chance to constrain the magma storage conditions. Conversely, combined methods yield more robust results in agreement with estimates obtained in previous independent studies based on both petrological and geophysical methods. [ABSTRACT FROM AUTHOR]

Characterising equilibrium and disequilibrium crystal-melt processes is critical in determining the extent of magma mixing and crystallization conditions in the roots of volcanoes. However, these processes remain poorly investigated in most Pacific intraplate ocean settings that are difficult to access and study. To help address this issue, we investigated crystallization conditions of clinopyroxene phenocrysts in an accreted Palaeogene oceanic island in Panama. Petrographic and geochemical observations, petrological modelling of major and trace elements, and liquid-mineral multicomponent equilibrium tests were carried out using basalts, picrites, and hawaiites of the transitional tholeiitic shield to alkaline post-shield volcanic stages of the island. Five types of clinopyroxene crystals were identified, including (1) microphenocrysts with micron-scale oscillatory zoning, (2) primitive, yet resorbed picrite-hosted phenocrysts, (3) chemically homogeneous, anhedral crystals found in the remaining basalts, (4) Ti–rich euhedral hawaiite-hosted phenocrysts, and (5) evolved sector-zoned phenocrysts. Liquid-clinopyroxene multicomponent equilibrium tests in combination with textural analysis show that ~ 74% of the studied clinopyroxenes are in possible major element equilibrium with one of the available whole rock magma compositions, of which only 21% are equilibrated with their carrier liquid. To deconvolute clinopyroxene-melt pairings and determine plumbing system conditions, we combine rhyolite-MELTS modelling, geothermobarometry, and major- and trace-element equilibrium evaluations, limiting crystallization conditions to crustal levels (< 23 km depth). No migration of magmatic reservoirs to deeper levels is observed during the shield- to post-shield transition. These results suggest the occurrence of an extensive crystal mush system during the late shield to post-shield volcanic stages of this intraplate volcanic system, with both primitive and evolved crystallization domains sampled during eruptions. [ABSTRACT FROM AUTHOR]

The present study focuses on the mineral chemistry data of Early–Cenozoic volcanic rocks in the south of the Tarom-Hashtjin magmatic zone. The Uchbolaq lavas in the north of Zanjan are a part of Oligocene eruptions within the Turkish-Iranian plateau. The microprobe analysis of the andesite-trachyandesites’ samples from this area indicates that the rocks under study composed of, labradorite (An55-66), augite (Wo44 En44 Fs12), Mg-hastangsite ((Na+K)A≥0.50 and Alvi0.3). Based on geo-thermometric calculations, the crystallization temperatures for amphiboles vary from 985 to 941 ºC, and for biotites from 770 to 758 ºC. According to geobarometric measurements, the pressure in amphiboles ranges between 5.3 and 6.5 kbar, and for biotites from 0.9 to1.9 kbar. The mineral chemistry datasets consisting of amphiboles' and biotites' data indicate that the investigated rocks are derived from a calk-alkaline magma with approximately high ƒO2, in a volcanic arc related to the subduction zone and the orogenic setting suites. [ABSTRACT FROM AUTHOR]

The Kahnouj Fe-Ti ore district is located 25 km southeast of Kahnouj city associated with the large gabbro intrusion of the Kahnouj ophiolitic complex. This ophiolite is one of the largest ophiolite assemblages of Iran (SE Iran), and part of neo-tethyan ophiolites (Kananian et al., 2001; Ghasemi Siani et al., 2021b). The Dar Gaz district is located in the middle part of Kahnouj ophiolitic complex and it is classified as the main ortomagmatic Fe-Ti ore mineralization. Although the geothermobarometric of iron-titanium oxide minerals in the Dar Gaz district has been studied by Karimi Shahraki et al. (2019), the geothermometry of silicate minerals (especially ferromagnesian) in the Dar Gaz gabrroic rocks has not been performed. Therefore, the main aim of this study is to determine the crystallization temperature and replacement of gabbroic rocks hosting Fe-Ti mineralization of the Dar Gaz district, using geothermometry of ferromagnesian silicate mineral. [ABSTRACT FROM AUTHOR]

This Data in Brief article presents methods used to acquire and process the data presented and discussed in a research paper co-submitted to the Journal of African Earth Sciences titled: “Comparative geology and metamorphic evolution of the Luswishi Dome, Copperbelt, Zambia: Implications for exploration targeting.” [1]. The dataset includes geographical coordinates, lithological logs of drill holes, rock and mineral chemistry data, and pseudosections. The dataset is hosted in the Mendeley Data repository in relevant sub-folders as supplementary data to the research paper. In order to provide spatial context for the study area map, geographical coordinates and collar information of the studied drill holes obtained from secondary sources are also provided in tabular form. Lithological logs summarize physical characteristics of lithological observations made on drill core. Rock chemistry data were obtained by fusion X-ray fluorescence, XRF (outsourced to the Actlabs, Canada), and mineral chemistry data were obtained by electron probe microanalyzer, EPMA, model JXA-8800R at Hokkaido University in Japan. Pseudosections were computed using Perple_X 6.8.6 software, as a function of rock compositions, temperature and pressure following the methods outlined in the online Perple_X documentation files available on the developer's website. The data maybe of potential use for improving our understanding of the geology, geochemical characteristics, and metamorphic conditions of the study area, with potential to inform further research and explorations works in the Dome's region of the Lufilian Arc.

Although there is a consensus about Pangea assemblage in northwestern Gondwana spanning from the Late Carboniferous to the Early Permian, the tectonics of the Permo–Triassic period, including the onset of Pangea breakup, is still controversial. In this context, three regional tectonic features need to be considered: (1) The Ouachita-Marathon-Sonora suture, (2) east-dipping subduction of the Panthalassa oceanic crust beneath Gondwana, and (3) an extensional setting documented in Colombia, Ecuador, and México suggesting Pangea breakup at ca. 240–220 Ma. A chemical, isotopic, and geochronological dataset is presented in this contribution to constrain the effects of these tectonic processes in the metamorphic basement of the Mérida Andes in western Venezuela. U–Pb Secondary Ion Mass Spectrometry analyses on unpolished surfaces of zircons from orthogneisses yielded an average age of 251 ± 4 Ma. The corresponding δ18O values suggest metamorphic recrystallization of zircon instead of high-T fluid interaction. Rb–Sr and Sm–Nd geochronology in white mica and garnet yielded ages of 234 ± 3 Ma and 249 ± 2 Ma, respectively, whereas a younger Rb–Sr date of 197 ± 1 Ma was obtained from biotite. U–Pb and Sm–Nd ages constrain the latest Permian–earliest Triassic metamorphism in the Mérida Andes at 251 ± 4 Ma. Geothermobarometry data suggest amphibolite-facies peak metamorphic conditions at ~ 685 °C and ~ 6.0 kbar. Metamorphism might be related to post-orogenic collapse, after the collision of Gondwana and Laurentia to form Pangea. Rb–Sr ages suggest retrogression and cooling, possibly caused by thermal relaxation of a tectonically overthickened crust and onset of extensional setting, followed by Pangea breakup during the Late Triassic–Early Jurassic. [ABSTRACT FROM AUTHOR]

In our study we characterize the thermodynamic regimes in the thrust zone of the newly formed Paleoproterozoic continental crust of the Svecofennian mobile belt on the outskirts of the Archean Karelian continent along the sublatitudinal, in modern coordinates, powerful strike-slip zone of the Northern Ladoga area. The Meyeri thrust zone is divided into northern and southern domains, considered allochthonous and autochthonous blocks according to material composition and structural features. The autochthonous block of the northern domain is different from the allochthonous block of the southern one by the presence of gneiss domes with Archean rocks in the cores. The allochthonous block is composed only of Paleoproterozoic rocks. During the formation of the thrust zone 1.86–1.85 Ga ago, the low-temperature amphibolite facies of biotite–muscovite parageneses were developed after the early mineral parageneses of the high-temperature amphibolite and granulite facies. [ABSTRACT FROM AUTHOR]

This study was examined minerological, petrographic and mineral chemistry analyzes of Eocene aged Kışlaköy volcanic rocks (Narman / Erzurum). The data obtained suggest that the physicochemical properties of the magmas such as temperature, pressure, which are effective during crystallization, and physicochemical data were combined with geological data, and the development of the magmas forming these rocks in the crust was examined. The main units in the study area are Eocene aged Kışlaköy Volcanite, Oligo-Miocene aged Oltu Formation, Oligo-Miocene Trout Formation and Alluviums. Kışlaköy volcanic rocks have been examined under three headings as pyroclastics, dykes and lavas according to their volcanic facies characteristics, have compositionally basalt and mainly consist of plagioclase (An49-85), clinopyroxene (Wo40-46 En41-50 Fs5-18), olivine (Fo68-75) and Fe-Ti oxide. These minerals generally exhibit hyalomicrolytic porphyritic, glomera porphyritic, cumulative porphyritic, microlitic porphyritic, poikilitic, intersertal textures. The studied volcanics rocks, disequilibrium texture are observed such as oscillatory zoning, sieve texture and corrosion in plagioclase phenocrysts, zoning, resorbed cores and mantles, rounded crytals, and embayed rims in clinopyroxenes. According to thermobarometric calculations, volcanics have crystallization temperature and pressure values ranging from 489 to 1247 0C, 0.5 to 4.7 kbar respectively. It can be concluded that the studied volcanics were emplaced at mid to shallow crustal depths (~4-12 km). [ABSTRACT FROM AUTHOR]

Like the Moldanubian parts of the Bohemian Massif and the French Massif Central, the Vosges Mts (NE France) comprise an uppermost tectonic unit that consists of retrograded (U)HP/UHT granulites, eclogites and garnet peridotites, originally metamorphosed at pressures of ≥ 4 GPa and temperatures of ≥ 950 °C. Two amphibole–garnet–spinel-bearing peridotite bodies located near to Col des Bagenelles (CB) and Crébimont (CR) show a pronounced retrograde evolution. Primary garnet was completely transformed to a symplectite of orthopyroxene + clinopyroxene + Cr-poor spinel ± amphibole, partially surrounded by a discontinuous outer zone of coarser grains of pyroxenes ± amphibole. Such symplectites are typical for the sliding reaction garnet + olivine ± Na2O ± K2O ± H2O = orthopyroxene + clinopyroxene + spinel ± amphibole. Both peridotites contain ‘primary’ Cr–Al–spinel. In the sample from CB, such grains occur only within the symplectites after garnet, but never in the matrix, while in the sample from CR, Cr–Al–spinel is present as inclusions within the symplectites and as isolated grains within the surrounding matrix. In the peridotite from CR, that is more depleted than that from CB, these Cr–Al–spinel grains show intense chemical zoning with Cr and Fe2+ decreasing, but Al and Mg increasing from core to rim. This pattern is interpreted as retrograde zoning during decompression. Primary P–T conditions deduced from compositions of matrix pyroxenes under the assumption of equilibration with earlier garnet are ≥ 1.6–1.7 GPa/ ≥ 900 °C for sample CB, but ≥ 2.3 GPa/ ≥ 860 °C for sample CR. Temperature conditions during the breakdown of garnet are indicated by pyroxenes from the symplectites and are 833 ± 18 (CB) and 812 ± 11 °C (CR) using the Ca-in-Opx thermometer at a chosen pressure of 1.3 GPa. [ABSTRACT FROM AUTHOR]

Meke Gölü ve Acıgöl kraterleri Konya ili sınırları içerisinde Karapınar ilçesinin 6 km güneydoğusunda yer almaktadır. Bölgede Pliyo-Kuvaterner’de etkili olan volkanizmanın son evresinde oluşan kraterler petrografik olarak karşılaştırıldığında Meke Gölü çevresinde daha çok bazalt ve bazaltik andezit kayalar yer alırken Acıgöl çevresinde andezit ve trakiandezit bileşimli kaya gruplarının yer aldığı belirlenmiştir. Ana mineralojik bileşimi plajiyoklazların (Meke An56-80; Acıgöl An46-68) oluşturduğu volkanitlerde mafik bileşen olarak piroksen (Meke Wo37-51; Acıgöl Wo40-48), amfibol ve biyotit gözlenmektedir. Meke volkanitlerinde ise bu mafik bileşenlere olivinler (Fo70-85) eşlik etmektedir. Bölgede yüzeyleyen kaya gruplarının ana element oksit değerleri SiO2 % 51.32-64.88, K2O%1.16-3.09, Na2O %2.39-3.92, MgO%1.2-3.39, Al2O3 %14.24-17.85, P2O5 %0.18-0.35, CaO %5.59-9.46, MnO %0.09-0.15 ve Fe2O3 ise %5.17-10.21 arasında değişim göstermektedir. Ana Element Oksitlerin dağılım aralıklarına bakıldığında, Meke gölü çevresinde yer alan kayaların daha bazik karakterde olduğu tespit edilmiştir. Bölgedeki kaya gruplarının MORB’a göre normalize edilen iz element dağılımlarında, LIL elementlerce zenginleşmeyi, HFS elementler bakımından ise kısmen tüketilmeyi yansıtan dağılım desenleri gözlenmektedir. Petrografik, jeokimyasal ve jeotermobarometrik çalışmalar, Acıgöl volkanitlerinin 1093-1107 °C-0.9-1 kb; Meke volkanitlerinin ise 1133-1141 °C-4.7-5.3 kb koşullarında kristallenen kıtasal yay karakterli, kalkalkalen bir magmanın ürünleri olabileceğini ortaya koymaktadır.

Meke Gölü ve Acıgöl kraterleri Konya ili sınırları içerisinde Karapınar ilçesinin 6 km güneydoğusunda yer almaktadır. Bölgede Pliyo-Kuvaterner’de etkili olan volkanizmanın son evresinde oluşan kraterler petrografik olarak karşılaştırıldığında Meke Gölü çevresinde daha çok bazalt ve bazaltik andezit kayalar yer alırken Acıgöl çevresinde andezit ve trakiandezit bileşimli kaya gruplarının yer aldığı belirlenmiştir. Ana mineralojik bileşimi plajiyoklazların (Meke An56-80; Acıgöl An46-68) oluşturduğu volkanitlerde mafik bileşen olarak piroksen (Meke Wo37-51; Acıgöl Wo40-48), amfibol ve biyotit gözlenmektedir. Meke volkanitlerinde ise bu mafik bileşenlere olivinler (Fo70-85) eşlik etmektedir. Bölgede yüzeyleyen kaya gruplarının ana element oksit değerleri SiO2 % 51.32-64.88, K2O%1.16-3.09, Na2O %2.39-3.92, MgO%1.2-3.39, Al2O3 %14.24-17.85, P2O5 %0.18-0.35, CaO %5.59-9.46, MnO %0.09-0.15 ve Fe2O3 ise %5.17-10.21 arasında değişim göstermektedir. Ana Element Oksitlerin dağılım aralıklarına bakıldığında, Meke gölü çevresinde yer alan kayaların daha bazik karakterde olduğu tespit edilmiştir. Bölgedeki kaya gruplarının MORB’a göre normalize edilen iz element dağılımlarında, LIL elementlerce zenginleşmeyi, HFS elementler bakımından ise kısmen tüketilmeyi yansıtan dağılım desenleri gözlenmektedir. Petrografik, jeokimyasal ve jeotermobarometrik çalışmalar, Acıgöl volkanitlerinin 1093-1107 °C-0.9-1 kb; Meke volkanitlerinin ise 1133-1141 °C-4.7-5.3 kb koşullarında kristallenen kıtasal yay karakterli, kalkalkalen bir magmanın ürünleri olabileceğini ortaya koymaktadır.

The temperature-dependent exchange of Ni and Mg between garnet and olivine in mantle peridotite is an important geothermometer for determining temperature variations in the upper mantle and the diamond potential of kimberlites. Existing calibrations of the Ni-in-garnet geothermometer show considerable differences in estimated temperature above and below 1100 °C hindering its confident application. In this study, we present the results from new synthesis experiments conducted on a piston cylinder apparatus at 2.25–4.5 GPa and 1100–1325 °C. Our experimental approach was to equilibrate a Ni-free Cr-pyrope-rich garnet starting mixture made from sintered oxides with natural olivine capsules (Niolv ≅ 3000 ppm) to produce an experimental charge comprised entirely of peridotitic pyrope garnet with trace abundances of Ni (10–100 s of ppm). Experimental runs products were analysed by wave-length dispersive electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We use the partition coefficient for the distribution of Ni between our garnet experimental charge and the olivine capsule lnD grt / olv Ni ; Ni grt Ni olv , the Ca mole fraction in garnet ( X grt Ca ; Ca/(Ca + Fe + Mg)), and the Cr mole fraction in garnet ( X grt Cr ; Cr/(Cr + Al)) to develop a new formulation of the Ni-in-garnet geothermometer that performs more reliably on experimental and natural datasets than existing calibrations. Our updated Ni-in-garnet geothermometer is defined here as: T ∘ C = - 8254.568 X grt Ca × 3.023 + X grt Cr × 2.307 + lnD grt olv Ni - 2.639 - 273 ± 55 where D grt / olv Ni = Ni grt Ni olv , Ni is in ppm, X grt Ca = Ca/(Ca + Fe + Mg) in garnet, and X grt Cr = Cr/(Cr + Al) in garnet. Our updated Ni-in-garnet geothermometer can be applied to garnet peridotite xenoliths or monomineralic garnet xenocrysts derived from disaggregation of a peridotite source. Our calibration can be used as a single grain geothermometer by assuming an average mantle olivine Ni concentration of 3000 ppm. To maximise the reliability of temperature estimates made from our Ni-in-garnet geothermometer, we provide users with a data quality protocol method which can be applied to all garnet EPMA and LA-ICP-MS analyses prior to Ni-in-garnet geothermometry. The temperature uncertainty of our updated calibration has been rigorously propagated by incorporating all analytical and experimental uncertainties. We have found that our Ni-in-garnet temperature estimates have a maximum associated uncertainty of ± 55 °C. The improved performance of our updated calibration is demonstrated through its application to previously published experimental datasets and on natural, well-characterised garnet peridotite xenoliths from a variety of published datasets, including the diamondiferous Diavik and Ekati kimberlite pipes from the Lac de Gras kimberlite field, Canada. Our new calibration better aligns temperature estimates using the Ni-in-garnet geothermometer with those estimated by the widely used (Nimis and Taylor, Contrib Mineral Petrol 139:541–554, 2000) enstatite-in-clinopyroxene geothermometer, and confirms an improvement in performance of the new calibration relative to existing versions of the Ni-in-garnet geothermometer. [ABSTRACT FROM AUTHOR]