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.

Strongly SiO2-undersaturated alkalic rocks (Mg# > 50, SiO2 ≤ 45 wt%, Na2O + K2O ≥ 3 wt%) occur in three early-stage (Sarnu-Dandali, Mundwara, Bhuj) and one late-stage (Murud-Janjira) rift-associated volcanic complexes in the Cretaceous-Paleogene Deccan Traps flood basalt province of India. Thermobarometry based on clinopyroxene-liquid equilibrium suggests that they mostly crystallized beneath the Moho

Centrifuge-assisted piston cylinder experiments were conducted on plagioclase in basaltic melt at 1140–1250 °C, 0.42–0.84 GPa and mostly 1000 g. One set of experiments assesses the settling velocity of a dilute plagioclase suspension; a second sinks or floats plagioclase in a MORB-type melt exploring conditions of neutral buoyancy; and a third set examines floatation of plagioclase from an evolved

Internal textures, multiple sulfur isotopic compositions, and contents of gold, selenium, and molybdenum of ore-related pyrites from a Neoarchean carbonate-facies BIF-hosted gold deposit in Quadrilátero Ferrífero were investigated to elucidate the source(s) of sulfur. Sodium hypochlorite etching and BSE imaging revealed pervasive zoning in pyrites. Five different growth zones (Py1a, Py1b, Py2, Py3

Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 m (West-Muren) crosscut continental flood basalts in the Antarctic extension of the ~ 180 Ma Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. The dikes exhibit unusual geochemical profiles; most significantly, initial (at 180 Ma) εNd values increase from the dike interiors towards the hornfelsed

The metastable paragenesis of corundum and quartz is rare in nature but common in laboratory experiments where according to thermodynamic predictions aluminum–silicate polymorphs should form. We demonstrate here that the existence of a hydrous, silicon-bearing, nanometer-thick layer (called “HSNL”) on the corundum surface can explain this metastability in experimental studies without invoking unspecific

We investigate the coupling between H, minor, trace, and ultra-trace element incorporations in 17 olivines from ten different locations covering various petrological origins: magmatic, hydrothermal, and mantle-derived context. Concentrations in major element are determined by micro X-ray fluorescence. Minor, trace, and ultra-trace elements are determined by laser ablation inductively coupled plasma

Electrical micro-junctions in metal sulfides drive electrochemical reactions with passing gold-bearing fluids, resulting in the deposition of gold, even from under-saturated ore fluids. Understanding the role micro-junctions play in the deposition of gold requires (a) imaging the electric field distribution of a galvanic couple near the surface to qualify the existence of an active micro-geo-battery

Clinopyroxene and orthopyroxene are the two major repositories of rare-earth elements (REE) in spinel peridotites. Most geochemical studies of REE in mantle samples focus on clinopyroxene. Recent advances in in situ trace element analysis have made it possible to measure REE abundance in orthopyroxene. The purpose of this study is to determine what additional information one can learn about mantle

The new biotite activity model and standard-state thermodynamic properties of Ann, Phl, and Eas presented in part-I were used to make pseudosections of bulk compositions representing experimental Fe–Mg exchange equilibria and (model) pelitic bulk rock compositions in the system K2O–FeO–MgO–Al2O3–SiO2–H2O (KFMASH), using mainly the software Perple_X. These pseudosection calculations (termed ‘our calculation(s)’

Replacement reactions occur during metamorphism and metasomatism in response to changes in pressure, temperature and bulk rock and fluid compositions. To interpret the changes in conditions, it is necessary to understand what phases have previously been present in the rocks. During fluid-mediated replacement, the crystallography of the replacement phases is often controlled by the parent reactant phase

A new activity model for Fe–Mg–Al biotites is formulated, which extends that of Mg–Al biotites (Dachs and Benisek, Contrib Mineral Petrol 174:76, 2019) to the K2O–FeO–MgO–Al2O3–SiO2–H2O (KFMASH) system. It has the two composition variables XMg = Mg/(Mg + Fe2+) and octahedral Al, and Fe–Mg and Mg–Al ordering variables resulting in five linearly independent endmembers: annite (Ann, K[Fe]M1[Fe]2M2[Al0

The petrogenesis of the Eocene (43–42 Ma) Nb-rich granitoid dykes from the Kohistan–Ladakh island arc provides insights into melting of the down-going Indian continental crust during the Indian-Eurasian continental collision. These Nb-rich granitoids (SiO2 = 53.8–72.3 wt%, Nb = 24.0–44.1 ppm) have high Sr/Y (41.2–76.8) and (La/Yb)N (15.6–36.8) ratios. Their geochemical and Sr–Nd–Hf isotopic compositions

Equilibria between Ti oxides and silicate melt lead to Ti isotope fractionation in terrestrial samples, with isotopically light Ti oxides and isotopically heavy coexisting melt. However, while Ti is mostly tetravalent in terrestrial samples, around 10% of the overall Ti is trivalent at fO2 relevant to lunar magmatism (~ IW-1). The different valences of Ti in lunar samples, could additionally influence

Zircon inheritance is a common phenomenon in igneous rocks, although more frequent in granitoids. Zircons inherited from granite magmas mostly come from the source, not from wall rocks or xenoliths. Consequently, they can provide invaluable information about the source materials, melting temperature, and melt segregation conditions. Miller et al. (Geology 31:529–532, 2003) divided granite rocks according

Graphite capsules are commonly used in high-temperature, high-pressure experiments, particularly for nominally anhydrous experiments and iron-bearing silicate samples. Due to the presence of graphite in the sample assembly, the oxygen fugacity for these experiments is thought to be relatively low, typically at or below the graphite-CO-CO2 buffer (CCO). The detailed mechanism and kinetics of redox control

The Loch Bà ring-dyke and the associated Centre 3 granites represent the main events of the final phase of activity at the Palaeogene Mull igneous complex. The Loch Bà ring-dyke is one of the best exposed ring-intrusions in the world and records intense interaction between rhyolitic and basaltic magma. To reconstruct the evolutionary history of the Centre 3 magmas, we present new major- and trace-element

The interaction of trace elements, fluids and crystal defects plays a vital role in a crystalline material’s response to an applied stress. Fluid inclusions are typically known to facilitate crystal-plastic deformation in minerals. Herein we discuss a model of fluid hardening, whereby dislocations are pinned at fluid inclusions during crystal-plastic deformation, initiating pipe diffusion of trace

The Voltri Unit and adjacent Tertiary Piedmont Basin, Western Alps, preserve complementary bedrock and sedimentary archives of Alpine subduction and exhumation. Combined PT modeling and phengite Rb–Sr geochronology of bedrock and clast samples shows that Fe–Ti metagabbros and metasediments preserve a record of protracted high-pressure metamorphism, between ~ 50 and ~ 40 Ma. Bedrock and clast Fe–Ti

Dacite lavas erupted from Kameni Islands volcanic centre (Greece) during the last 2000 years have a limited range in chemical composition (SiO2 = 64.0–68.5%) which contrasts with their wide range in plagioclase abundance (3–22%) and crystal size distributions. Most plagioclase crystals have simple zoning and occur independently or in loose clusters with finer-grained cores. We propose that magmatic

The pressure dependence of the exchange of Cr between clinopyroxene and garnet in peridotite is applicable as a geobarometer for mantle-derived Cr-diopside xenocrysts and xenoliths. The most widely used calibration (Nimis and Taylor Contrib Miner Petrol 139: 541–554, 2000; herein NT00) performs well at pressures below 4.5 GPa, but has been shown to consistently underestimate pressures above 4.5 GPa

Porphyry Cu ore deposits are a rare product of arc magmatism that often form spatiotemporal clusters in magmatic arcs. The petrogenetic evolution of igneous rocks that cover the temporal window prior to and during porphyry Cu deposit formation may provide critical insights into magmatic processes that are key in generating these systems. This study documents the magmatic evolution of the Palaeocene–Eocene

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