Whiteschists from the Monte Rosa Nappe were examined in the field as well as with petrographic, geochemical, and isotopic methods to constrain the controversial origin of these rocks in their Alpine metamorphic context. Whiteschists occur as ellipsoidal-shaped, decametric-sized bodies, within a Permian metagranite, and consist mainly of chloritoid, talc, phengite, and quartz. The transition from whiteschist

Volcanic gas emission is considered to reflect the degassing of magma beneath volcanoes. The combined observations of gas measurement and petrological study are expected to constrain the volatile concentrations and storage depths of the pre-eruptive and primitive magma. Aso volcano (Japan) is a constantly-monitored, persistently-degassing volcano, and an ideal site to acquire gas and petrologic data

Granite batholiths record the processes that occur during the formation and differentiation of the continental crust. The ~ 4000 km2 composite Neoproterozoic Jiuling batholith is one of the largest batholiths in southern China and consists of four peraluminous granitoid intrusions that were emplaced at ca. 828–810 Ma. These granitoids define a trend that moves from the terrestrial towards the seawater

This study compares four sets of solution (or activity-composition) models using two internally consistent thermodynamic datasets for calculating isochemical phase diagram sections of six partial melting experiments covering a wide range of metasedimentary bulk compositions. Compared parameters are: (1) biotite-breakdown temperatures; (2) parageneses of Fe–Mg phases and Ti-oxides; (3) proportion of

Phase egg (AlSiO3OH), an important hydrous phase in the Al2O3–SiO2–H2O ternary system, was found in the superdeep diamond from the mantle transition zone. Here, we have investigated the compressibility and the crystal structural evolution of phase egg using the synchrotron-based single-crystal X-ray diffraction and infrared spectroscopy combined with diamond anvil cells up to 32 GPa and 900 K. Present

Zircon occasionally crystallizes in evolved melt pockets in mafic large igneous province (LIP) magmas, and in these cases, it is used to provide high-precision age constraints on LIP events. The precision and accuracy of high-precision ages from LIPs are crucially important, because they may be implicated in mass extinctions. However, why zircon crystallizes in these magmas is not clearly understood

Orthopyroxenite cumulates throughout the Critical Zone of the Bushveld Complex commonly contain prominent euhedral crystals of bottle-green augite, typically around 1 cm in size and surrounded by “haloes” of nearly pure plagioclase. On close examination, the augite grains can be seen to be oikocrysts, containing extensively resorbed chadacrysts of orthopyroxene, indicating an effective peritectic reaction

Bushveld anorthosites commonly contain the so-called “mottles” comprising irregular, typically centimetric domains of oikocrystic pyroxene or olivine enclosing small, embayed plagioclase grains. The mottles were traditionally interpreted to result from solidification of trapped intercumulus liquid or via in situ crystallisation at the top of the crystal mush. Here, we present microtextural and compositional

The Izu–Bonin–Mariana volcanic arc is situated at a convergent plate margin where subduction initiation triggered the formation of MORB-like forearc basalts as a result of decompression melting and near-trench spreading. International Ocean Discovery Program (IODP) Expedition 352 recovered samples within the forearc basalt stratigraphy that contained unusual macroscopic globular textures hosted in

Reactive fluid flow can control the mineralogical, mechanical and chemical evolution of the Earth’s crust. When rocks are exposed to differential stresses (i.e., vertical stress ≠ horizontal stress ≠ pore-fluid pressure (Pf)) during reactive fluid flow, effective pressure is usually assumed to control the overall reaction process. Here, we show that fluid pressure can play an important role in mineral

The interplay between stress and chemical processes is a fundamental aspect of how rocks evolve, relevant for understanding fracturing due to metamorphic volume change, deformation by pressure solution and diffusion creep, and the effects of stress on mineral reactions in crust and mantle. There is no agreed microscale theory for how stress and chemistry interact, so here I review support from eight

Mafic enclaves preserve a record of deep differentiation of primitive magmas in arc settings. We analyze the petrology and geochemistry of mafic enclaves from Shiveluch volcano in the Kamchatka peninsula to determine the differentiation histories of primitive magmas and to estimate their pressures, temperatures, and water contents. Amphibole inclusions in high forsterite olivine suggest that the primitive

Subsurface magmatic–hydrothermal systems are often associated with elevated electrical conductivities in the Earthʼs crust. To facilitate the interpretation of these data and to allow distinguishing between the effects of silicate melts and fluids, the electrical conductivity of aqueous fluids in the system H2O–HCl was measured in an externally heated diamond anvil cell. Data were collected to 700 °C

Coexisting fine-grained (meta-volcanic) and coarse-grained (meta-plutonic) mafic rocks in a high-pressure (P)/low-temperature (T) complex (Sivrihisar, Turkey) preserve different prograde, peak, and retrograde mineral assemblages, providing an opportunity to evaluate controls on mineral assemblages in metabasites that experienced the same P–T conditions. Fine-grained metabasalts are garnet-bearing lawsonite

The Khammam Schist Belt (KSB), southeastern India, represents a part of the collision zone that is sandwiched between the Eastern Dharwar Craton to the west and the Eastern Ghats Mobile Belt (EGMB) to the east. Quartzofeldspathic gneisses of the EGMB and garnet–kyanite metapelites of the KSB have been investigated to characterize P–T–t evolution of the Khammam region. Pseudosection modeling reveals

The formation of phosphorus–iron oxide (P–Fe) immiscible melts and their possible connection to the genesis of Kiruna-type and Nelsonite deposits was experimentally investigated by adding phosphoric acid (H3PO4), water, and sulfur, to andesite at 100–450 MPa, 500–900 °C, at the NiNiO and magnetite-hematite fO2 buffers using internally heated gas vessels. The addition of up to 8.02 wt% of H3PO4 to the

Accessory mineral thermometry and thermodynamic modelling are fundamental tools for constraining petrogenetic models of granite magmatism. U–Pb geochronology on zircon and monazite from S-type granites emplaced within a semi-continuous, whole-crust section in the Georgetown Inlier (GTI), NE Australia, indicates synchronous crystallisation at 1550 Ma. Zircon saturation temperature (Tzr) and titanium-in-zircon

Subduction zones represent one of the most critical settings for fluid recycling as a consequence of dehydration of the subducting lithosphere. A better understanding of fluid flows within and out of the subducting slab is fundamental to unravel the role of fluids during burial. In this study, major and trace element geochemistry combined with oxygen isotopes were used to investigate metasediments

The formation of diamonds within eclogitic rocks has been widely linked to the fate of carbon during subduction and, therefore, referred to conditions of pressure, temperature, and oxygen fugacity (fo2). Mantle-derived eclogite xenoliths from Udachnaya kimberlite pipes represent a unique window to investigate the formation of carbon-free, graphite–diamond-bearing and diamond-bearing rocks from the

Strain accommodation in upper crustal rocks is often accompanied by fluid-mediated crystallization of phyllosilicates, which influence rock strength and shear zone formation. The composition of these phyllosilicates is frequently used for pressure–temperature–time constraints of deformation events, although it is often highly heterogeneous, even in mylonites. This study investigates the reactions producing

We present a new dataset on the composition of high-density fluids (HDFs) in cloudy (n = 25), coated (n = 10) and cuboid (n = 10) diamonds from the Nyurbinskaya kimberlite pipe. These diamonds represent different populations each showing distinct growth histories. The cores of coated diamonds display multiple growth stages and contrasting sources of carbon. Fibrous coats and cuboid diamonds have similar

The Fe–Mg exchange coefficient between olivine (ol) and melt (m), defined as \({\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}\) = (Feol/Fem)·(Mgm/Mgol), with all FeT expressed as Fe2+, is one of the most widely used parameters in petrology. We explore the effect of redox conditions on \({\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}\) using experimental, olivine-saturated basaltic glasses with variable

The Magma Chamber Simulator (MCS) is a thermodynamic tool for modeling the evolution of magmatic systems that are open with respect to assimilation of partial melts or stoped blocks, magma recharge + mixing, and fractional crystallization. MCS is available for both PC and Mac. In the MCS, the thermal, mass, and compositional evolution of a multicomponent–multiphase composite system of resident magma

The Magma Chamber Simulator (MCS) is a thermodynamic model that computes the phase, thermal, and compositional evolution of a multiphase–multicomponent system of a Fractionally Crystallizing resident body of magma (i.e., melt ± solids ± fluid), linked wallrock that may either be assimilated as Anatectic melts or wholesale as Stoped blocks, and multiple Recharge reservoirs (RnASnFC system, where n is

Tonalite–trondhjemite–granodiorite (TTG) gneiss forms a major component of Archean continental crust. Resolving the origin of TTG gneisses and the secular change in their compositions is critical for better understanding how the continental crust has evolved and when a global plate tectonic regime began on Earth. Archean TTGs were generated by partial melting of hydrous basalts, although the geodynamic

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The Ditrău Complex of the Carpathian Mountains in Romania is a Mesozoic igneous complex (~ 200–230 Ma) generated in a continental rift environment. Felsic rocks of the Ditrău Complex consist of nepheline syenite, syenite, quartz syenite, quartz monzonite, monzonite and granite. The Ditrău rocks have mantle-like ɛNd values that range from + 0.8 to + 5.5 ‰. High-temperature equilibrium O-isotope fractionations

Primitive subduction zone magmas provide information about the composition and thermal structure of the underlying mantle wedge. In the Colima Graben, Mexico, primitive lavas erupted from cinder cones range from high magnesium calc-alkaline basalts to high-K trachybasalts. This chemical diversity suggests that the sub-arc mantle wedge from which they derive is heterogeneous. To explore the conditions

The 35 paired diamond intergrowths of rounded colorless transparent and gray opaque crystals from the placers of northeastern Siberian Platform were investigated. Mineral inclusions (KFsp, Coe, E-Grt, Po) detected in studied samples belong to eclogitic paragenesis. The majority of studied samples have uniform ranges of nitrogen content (1126–1982 at. ppm) and carbon isotope composition (− 16.8 to − 23

U–Pb petrochronology of deep crustal xenoliths and outcrops across northeastern Tanzania track the thermal evolution of the Mozambique Belt and Tanzanian Craton following the Neoproterozoic East African Orogeny (EAO) and subsequent Neogene rifting. At the craton margin, the upper–middle crust record thermal quiescence since the Archean (2.8–2.5 Ga zircon, rutile, and apatite in granite and amphibolite

The 1.26 Ma Tshirege Member of the Bandelier Tuff is the second of two major (~ 400 km3, dense rock equivalent) compositionally zoned rhyolitic eruptions from the Valles caldera. Here we analyze 25 samples of a minor component of compositionally and texturally variable silicic dacite pumice (~ 67 to 72% SiO2) that is widely distributed through the unit. The dacite has a phenocryst assemblage dominated

Plagioclase hosted, oriented magnetite micro-inclusions are a frequently observed phenomenon in magmatic and metamorphic rocks. Understanding the orientation relationships between these inclusions and the plagioclase host is highly relevant for interpreting paleomagnetic measurements. The systematics of the shape and crystallographic orientation relationships between needle- and lath-shaped magnetite

Antigorite is considered as the most important source of water in subduction zones, playing a key role during arc magma genesis. Although, these magmas seem more oxidized than mid-oceanic ridge basalts (MORB), the possible inherent link between the oxidation state of arc magmas and serpentinite-derived hydrous fluids is still not well established. Here, we have performed dehydration experiments of

The stability field and composition of immiscible sulfate melts in equilibrium with silicate magmas has been determined using experiments over a range of crustal pressures, allowing an assessment of their possible role in transporting sulfur into the sub-volcanic arc and porphyry copper deposit systems. Experimental starting materials were based on natural trachyandesite and trachydacite compositions

Forsterite crystals produced during metamorphism of siliceous dolomites in the Alta, Utah contact aureole were investigated in-situ and with crystal separates to constrain their aureole-scale textural and morphological variability. As the contact is approached, forsterite crystals increase in abundance but decrease in average size, suggesting greater kinetic influence on forsterite nucleation and growth

Serpentinization processes occur at geological settings notably during oceanic subduction and obduction, where mantle rocks interact with water. Different types of serpentine minerals form according to temperature and pressure conditions, and potentially chemical exchanges. Therefore, the characterization of serpentine minerals, and the possible occurrence of multiple serpentine generations in mantle

The Rum Layered Suite, NW Scotland, hosts Cr-spinel seams at the bases of peridotite–troctolite macro-rhythmic units in the eastern portion of the intrusion. Here, we present detailed field observations together with microstructural and mineral chemical analyses for the Unit 7–8 Cr-spinel seam and associated cumulates in the Eastern Layered Intrusion. Detailed mapping and sampling reveal significant

The Andean margin of the South American continent has been magmatically and tectonically active for over 330 million years. It is the type location where “Cordilleran-type” magmatism and orogenesis are manifest. In Argentina and Chile, between the latitudes of 28° and 40° S, magmatism related to the Gondwanan “Cordilleran-type” orogeny is reflected in a series of Carboniferous to Triassic intrusions

Mafic–ultramafic layered rocks of the Lower and Critical Zones of the Bushveld Complex are believed to have formed from a parental magma usually labelled B1 with SiO2 content at 55 wt.%, MgO at about 12 wt.% and Cr2O3 concentration at 0.15 wt.%. Previous experimental study at 300 MPa and nominally dry conditions showed that this composition had orthopyroxene on liquidus between 1250 and 1300 °C, and

Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex

Clinopyroxenes from the Pico Volcano (Pico Island, Azores Archipelago) have been used as a proxy to define the water content of primitive magmas and the volcanological history of the erupted rocks. This very young volcano (53 ± 5 ka) is at a primordial stage of its evolution in comparison with the other volcanoes of the Azores. Clinopyroxenes from Pico Volcano underwent important dehydration processes

Crustal storage and transit play a critical role in the compositional evolution of arc magmas; however, the enigmatic nature of lower crustal magma storage and early differentiation limit our understanding of the connections between the physical processes of subduction zones and the architecture of the arc crust. We present new geochemical data and applications of existing barometric and chronometric

The Onano eruption (~ 0.17 Ma) is the second to last caldera-forming eruption of the Latera volcano, in the northernmost sector of the Roman Comagmatic Province (Latium, Italy). The stratigraphic sequence, from base to top, includes ash and pumice-rich flow deposits, spatter-rich flow deposits and lag breccias associated with ash-rich flow deposits. By combining major and trace element compositions

The original article can be found online.

In this study the first viscosity measurements in the glass transition range of melts from highly explosive large-volume eruptions from the Colli Albani Volcanic District (CAVD) are presented. The magmas are ultrapotassic, rich in iron and CaO and characterised by a low silica content (< 45 wt%). Melt compositions range from tephri-phonolitic to foiditic. The Colli Albani eruptions appear anomalous

Peralkaline granites and pegmatites are a prime repository of REE and HFSE, critical raw materials. Although it is accepted that magmatic processes are fundamental in concentrating these metals, the role of hydrothermal fluids in concentrating and fractionating these elements remains unclear. This paper investigates the global reproducibility of the magmatic-hydrothermal evolution of alkaline silica-saturated

Accurate geochemical models of magmatic processes require an understanding of crystal-melt partitioning of trace elements. Many major igneous processes at different tectonic environments in Earth occur in the presence of garnet as a residual phase. Since the pioneering crystal lattice-strain model, several attempts have been made to quantify garnet-melt partitioning coefficients over a wide range of

Slow-slip events frequently occur, but regular earthquakes are much less active on the H2O fluid-rich subduction interface at depths of ~ 40 km. The characteristic duration for silent earthquakes, which are categorized as the great slow-slip events, is more than five orders of magnitude longer than that for regular earthquakes. Such phenomena are often attributed to the slippage of the softer part

Thermodynamic modeling is an important technique to simulate the evolution of metamorphic rocks, particularly the poorly preserved prograde metamorphic reactions. The development of new thermodynamic modeling techniques and availability of updated thermodynamic databases and activity–composition (a–X) relations, call for an evaluation of best practices for modeling pressure–temperature (P–T) paths

Diffusion profiles in olivine crystals from the final mafic eruption products of the compositionally zoned Laacher See tephra deposit were measured to identify recharge and eruption-triggering events prior to the eruption of the Laacher See volcano (12.9 kyr). These products represent the hybrids of mixing between phonolite and intruding basanite at the bottom of the reservoir, which is likely related

Supercritical fluids in rock–H2O systems have been proposed to be important agents of mass transfer in subduction zone environments. New experimental studies were conducted on the simple model granite system NaAlSi3O8 (Ab)–H2O in order to investigate phase relations and to develop the thermodynamic mixing properties between aqueous fluid (a.k.a. vapor, V) and silicate melt (a.k.a. liquid, L) at pressures

Coexistence of baddeleyite and zircon is rarely documented in metacarbonate rocks and poorly understood. In this study, metamorphic baddeleyite and zircon were recognized in marbles from the Tongbai orogen, central China. We carried out high spatial resolution analysis of trace element geochemistry and U‒Pb‒Lu‒Hf‒O isotope systematics for the zircon and baddeleyite. SIMS (Secondary Ion Mass Spectroscopy)

Translating burial and exhumation histories from the petrological and geochronological record of high-pressure assemblages in subduction channels is key to understanding subduction channel processes. Convective return flow, either serpentinite or sediment hosted, has been suggested as a potential mechanism to retrieve rocks from significant depths and exhume them. Numerical modelling predicts that

Carbonatite compositions resulting from melting of magnesian calcite + olivine + clinopyroxene were experimentally determined in the system CaO–MgO–SiO2–CO2–H2O as a function of temperature and bulk H2O contents at 1.0 and 1.5 GPa. The melting reaction and melt compositions were found to be highly sensitive to H-loss or -gain during experiments. We hence designed a new hydrogen-trap technique, which

Ba zonation patterns in sanidine phenocrysts from mafic and intermediate phonolite and crystal-rich cumulates from the Laacher See volcano (12.9 ka) in western Germany document diffusion times suggestive of periodic recharge events throughout the magma reservoir’s entire lifespan of ~ 24 ky. Phenocrysts analysed from samples that formed late at the base of the compositionally zoned magma reservoir

The 156–138 Ma Chidliak kimberlites on the Eastern Hall peninsula (EHP) of Baffin Island entrained mantle xenoliths interpreted to have been a part of the Archean North Atlantic Craton (NAC) lithospheric mantle. We studied 19 Chidliak eclogite xenoliths that comprise 10 bimineralic, 5 rutile-bearing, 3 orthopyroxene-bearing and 1 kyanite-bearing eclogites. We report major and trace element compositions

Magma mixing and contamination are among the dominant processes in the building of the isotopic diversity of granite rocks. Felsic microgranular enclaves (FMEs) are remnants of magma mixing and they often carry xenocrysts that also record contamination and assimilation in crystallization fronts disrupted during replenishment events. In addition to isotopic changes, contamination may alter the redox

The geochemistry of biotite crystals from thirty fertile and barren Silurian–Devonian granitoids of New Brunswick, Canada, was studied in situ using electron microprobe and laser ablation inductively coupled plasma-mass spectrometry to investigate the suitability of biotite geochemistry as a diagnostic fertility index among these intrusions. The Fe2+/(Fe2+ + Mg2+) ratio of biotite varies as a function

To investigate the petrogenesis of cyclic units in layered intrusions, we examined chromitite, dunite, poikilitic harzburgite and bronzitite from the Ultramafic Zone of the Stillwater Complex and measured stable isotopes of Li and O in their major minerals. The Li isotopes in olivine range from 4 to 26‰ in δ7Li with uniform Li contents of 1–3 ppm, whereas orthopyroxene and clinopyroxene have Li contents

To better investigate the behavior of titanium (Ti) isotopes during magmatic processes, we report high-precision Ti isotope compositions for 60 terrestrial igneous rocks from different geological settings worldwide. Based on their major element compositions and petrographic descriptions, these samples can be subdivided into two groups: Fe-Ti oxide unsaturated and Fe-Ti oxide saturated. The Fe-Ti oxide