Mount Girnar is one of the most conspicuous alkaline complexes (gabbro-diorite-syenite-lamprophyre), which intrude some of the earliest erupted basalts (ca. 69 Myr) of the Deccan Large Igneous Province (Deccan LIP) in the Kathiawar plateau of NW India. Petrography, bulk-rock geochemistry, Sr and Nd isotopes and 40Ar/39Ar mineral ages of fractionated (Mg#: 36.3–43.6) lamprophyre dykes (younger intrusives)

Back-arc magmatism is perhaps extremely rare in a Paleoproterozoic mobile tectonic regime. The present study provides a detailed account on the petrogenesis of basalts that are interleaved with marine sedimentary rocks in the Agori Formation, which overlies the Chitrangi Formation in the ~2.1 Ga Mahakoshal supracrustal belt within the Central India Tectonic Zone. The basalts are sub alkaline, tholeiitic

Syn-exhumation partial melting of the deeply subducted continental crust commonly occurs in collisional orogenic settings. The resulting felsic melts not only form granitoids, but can also modify the composition of the mantle wedge above continental subduction zones. This study investigates crustal anatexis and its role in granitoid formation and crust–mantle interaction during continental collision

The Hongge layered intrusion in Emeishan Large Igneous Province (ELIP), SW China, contains the largest Fe-Ti-V oxide deposit in China (4500Mt ore reserve). The mechanism by which million tons of Fe-Ti-V oxide concentrated is debated. In this study, new petrography, mineral chemistry (~3600 microprobe analyses for olivine, clinopyroxene and plagioclase) and bulk rock major element chemistry (108 samples)

Primary FeMn phosphates from four pegmatites (Cañada, Palermo#1, Palermo#2 and Palermo#11) typical of the beryl-columbite-phosphate subtype have been characterized texturally and geochemically. Most of the common FeMn phosphates (triphylite, sarcopside, ferrisicklerite, wagnerite and wolfeite) are extremely poor in trace elements, with the exception of Zn for all them, Li for sarcopside, and Nb and

The Yilgarn Craton of Western Australia is one of the largest Archean cratons in the world and is well-known for its metal endowment. In order to provide new insights into its metallogenic fertility and the nature of the upper mantle that lies underneath the craton, this study investigates the poorly constrained platinum-group element (PGE) and gold signatures of a selected suite of calc-alkaline lamprophyres

Graphite in Ordovician ultramafic intrusions through Neoproterozoic country rocks in West Aberdeenshire, NE Scotland attests to the mobility of carbon into subduction-related magmas. Pelites in the country rock contain up to 5% organic carbon, and are consequently also sulphide-rich. This occurrence is one of many examples of graphite in ultramafic intrusions. The sedimentary origin of the graphite

A unique scapolite-rich gabbro has been found in the Cho Don complex (north-eastern Vietnam) and investigated using cathodoluminescence microscopy and spectroscopy, electron-microscopic observations, and Raman micro-spectroscopy. The scapolite, occupying up to ca. 30 vol% of rock matrix, displays distinctive brownish to greenish (S2_activated) luminescence, while its chemical composition is marked

The new discovery of Fe-monticellite in serpentinized peridotites of the Happo ultramafic complex, central Japan, shows it replacing olivine and coexisting with antigorite. The monticellite occurs in several forms: as discrete grains; partially disconnected rings or circular ribbons; fringing mantles or in veins cutting olivine; or as aggregates of small equant grains. It shows a textural contrast

Cathaysia Block in South China had accreted tremendous amounts of Mesozoic magmatic rocks. Recent zircon UPb age results revealed existence of some Early Jurassic gneissic granites (200–190 Ma) in the Pingtan-Dongshan Metamorphic Belt (PDMB), coastal SE China which corresponds one stage of magmatic quiescence in the rest part of East Cathaysia. To better understand Mesozoic thermal evolution of the

The phases of CaAl2O4 and Ca2Al6O11 were synthesized at 15 GPa and 1600 °C. Microprobe data gave formulae Ca1.003Al1.998O4 and Ca2.05Al5.97O11, on the basis of 4 and 11 oxygen atoms. The crystal structures have been refined by single-crystal X-ray diffraction. Orthorhombic unitcell parameters for CaAl2O4 are a = 8.8569(10) Å; b = 2.8561(4) Å; c = 10.2521(11) Å; V = 259.34(5) Å3; Z = 8 (space group

The Doldrums transform system offsets the Equatorial Mid Atlantic Ridge by ~630 km at 7–8° N. This transform system consists of four intra-transform spreading centers (ITRs) bounded by five transform faults. The northernmost ITR is linked to the MAR axis by a ~ 180 km-long transform. Here, during two R/V A. N. Strakhov expeditions (S06 and S09), mantle peridotites were dredged along the transverse

In this study, we present new mineralogical and petrological data from fifteen eruptive products erupted at Vulcano Island (Aeolian Arc, Italy) over a period of time from 54 to 8 ka and representative of the Eruptive Epochs from 5 to 8 of this volcanic system. These rocks show shoshonitic (SHO) to high-K calc-alkaline (HKCA) affinity, with compositions changing from primitive basalts-shoshonites (Mg#35–60)

The evolution of continental crust in convergent margins can be explored in southernmost South America (54-56°S). Plutonic rocks of the Fuegian Batholith and the rear-arc satellite Ushuaia Pluton were emplaced within the magmatic arc and the Fuegian fold-and-thrust belt, respectively. They record subduction zone processes in two distinct tectonic settings during the evolution of the Rocas Verdes Basin

Kohistan, an intra-oceanic arc, formed due to the India-Asia collision-related tectonics. The arc is comprised of mafic-ultramafic and crustal lithologies. Chilas Complex, one of the major mafic-ultramafic body that lies at the base of the Kohistan arc, is dominantly composed of massive gabbronorites with local ultramafic-mafic intrusive bodies. The ultramafic rocks were considered as the products

The mineral chemistry of titanite has been studied in hydrothermally altered syenite preserved as blocks in a salt wall within a regional intracontinental shear zone. The study focusses on the controls on temporal variation in REEs, Zr, Nb, U and Th. Several generations of titanite are recognised on the basis of morphology, chemistry, and relationship to other secondary minerals. Magmatic euhedral

Kimberlites are the surface manifestation of deeply-derived (>150 km) and rapidly ascended magmas. Fresh kimberlite rocks are exceptionally rare, as most of them are invariably modified by pervasive deuteric and/or post-magmatic fluids that overprint the original mineralogy. In this study, we examined fresh archetypal kimberlite from the Mark pipe (Lac de Gras, Canada), which is characterised by well-preserved

The Ntem Complex represents the northwestern margin of Congo Craton in southern Cameroon. It consists mainly of charnockites, TTG suites, potassic grantitoids, minor supracrustal and mafic rocks. The latter include gabbronorite enclave or sill, gabbro and dolerite dykes. The metagabbro are basaltic to andesitic in composition and show geochemical features of low-La Archean tholeiitic basalts, and LREE-depleted

One of the most debated issues about the Carajás Mineral Province in Brazil is the tectonic setting that prevailed at the time of the major Neoarchean (ca. 2.7 Ga) volcanic event, with views ranging from subduction- to rift-related. During this event, thick lava flows of mainly basaltic and basaltic-andesitic composition extruded at the Earth's surface, cooled and underwent significant alteration by

The Khamal complex is an Ediacaran post-collisional gabbro-anorthosite igneous complex that intruded Tonian and Cryogenian subduction-related island arc and ophiolitic rocks and syn-tectonic granitic rocks. The complex is reminiscent of massif-type anorthosites. It has an elliptical shape and is unmetamorphosed and undeformed. The Khamal complex is differentiated into four lithological units, marginal

Large quartz pebbles erupted with the Escorial ignimbrite provide insight into the late-magmatic evolution of the shallow, cooling magmatic-hydrothermal system below the Cerro Escorial volcano of the Southern Central Volcanic Zone in the Argentine Andes. The ignimbrite is of relatively small volume, crystal-rich, dacitic in composition, and not particularly water-rich, as amphibole is absent. Eruption

New tectono-metamorphic data along the Alaknanda-Dhauli Ganga valleys in the Garhwal Himalaya (NW India) are presented focusing on sheared rocks of the Main Central Thrust zone (MCTz), one of the first order regional structures in the Himalaya. In regard of large hot orogens (LHOs), the MCTz corresponds to the base of the low-viscosity infrastructure. Our new findings support that the MCTz is a c.

In the Bushveld Complex of South Africa, numerous granitic and granophyric rocks termed the Lebowa Granite and Rashoop Granophyre Suites, respectively, overlie the layered ultramafic-mafic rocks of the Rustenburg Layered Suite. Despite their close spatial and temporal association, the granites and granophyres are often interpreted as being unrelated to the Rustenburg Layered Suite. This paper describes

New Guinea has acted as the boundary between the Australian and Pacific plates for hundreds of millions of years. Strike-slip movement and arc–continent collisions along this boundary during the Cenozoic have shuffled rocks of different age and composition in a series of terranes along the plate boundary making mapping them a considerable challenge. Here we report results of SrNd isotopic data obtained

Here we present synchrotron-based X-ray diffraction experiments combined with diamond anvil cell on the nitrogen-bearing compounds Si3N4 and TiN up to ~53 GPa and ~51 GPa, respectively. The pressure-induced phase transition of Si3N4 is evidenced at 42.3 GPa at room temperature and a new monoclinic high-pressure phase assigned to the P2, Pm, or P2/m space group was observed. The pressure-volume relationship

Zinc and lead smelting slags from Ruda Śląska are unique in their chemistry and phase composition, which resemble rare natural rocks such as paralavas and melilitolites. Moreover, considering its size, we can treat a pyrometallurgical slag dump as a geological body. In slags from Ruda Śląska the assemblage melilite ± pseudowollastonite ± wollastonite ± plagioclase was discovered in glassy slag. High-temperature

Neoproterozoic Li–Cs–Ta (LCT) pegmatites and pegmatitic sheeted leucogranites (SLGs) of the Damara Belt, Namibia, although coeval, are variably mineralized and have intruded multiple tectono-stratigraphic units. Major and trace element data together with oxygen and hydrogen isotopes were used to identify possible sources for these pegmatite melts. Two groups of pegmatites can be identified on the basis

The 1.49 Ga Norra Kärr complex (Sweden) consists of deformed and metamorphosed peralkaline nepheline syenites that contain eudialyte-group minerals as the major host of high field strength elements and rare earth elements. Earlier studies revealed the presence of distinct generations of eudialyte-group minerals and clinopyroxene of magmatic and metamorphic origin. Here, we present the trace element

The Mushgai-Khudag alkaline‑carbonatite complex, located in southern Mongolia within the Central Asian Orogenic Belt (CAOB), comprises a broad range of volcanic and subvolcanic alkaline silicate rocks (melanephelinite-trachyte and shonkinite-alkaline syenite, respectively). Magnetite-apatite rocks, carbonatites, and fluorite mineralization are also manifested in this area. The complex formed between

The recovery of melt inclusions (MI) in peritectic phases of metamorphic rocks demonstrates their anatectic origin even in the absence of other textural or field evidences, and gives the opportunity to retrieve the chemical composition of primary melts and infer melt entrapment conditions. Here we report the first recovery of such inclusions in a medium-grade schist from the Edixon Metamorphic Complex

Characterizing island arc and back arc basin system through detailed magmatic profile remains a pivotal task in any regional paleotectonic and supercontinental reconstructions along ancient convergent plate margins, as is of paramount importance for the northern China–southern Mongolia (NCSM) tract along the eastern Central Asian Orogenic belt (CAOB). Here we document episodic Late Carboniferous intermediate

We present detailed major-, trace-element and Sr-Nd-Mg isotopic geochemistry for a suite of pyroxenite xenoliths entrained in Oligocene basalts in Yangyuan county, North China Craton, to reveal their origins and to further constrain the evolution of the lithospheric mantle beneath this area. The Yangyuan pyroxenites exhibit a lithologic spectrum ranging from orthopyroxenite, through orthopyroxene-rich

The continental crust of NW Iran is intruded by Late Cretaceous I-type granites and gabbro-diorites as well as Paleocene A-type granites. SIMS and LA-ICPMS UPb analyses of zircons yield ages of 100–92 Ma (Late Cretaceous) for I-type granites and gabbro-diorites and 61–63 Ma (Paleocene) for A-type granites. Late Cretaceous gabbro-diorites (including mafic microgranular enclaves; MMEs) from NW Iran show

Structural, geochronological and geochemical studies of pre-3.75 Ga rocks of volcano-sedimentary protoliths in the Inukjuak domain in the Superior Province in Québec have been mostly focused on the Nuvvuagittuq Supracrustal Belt (NSB). The Porpoise Cove outcrops – at the southwestern limit of the NSB – are the de-facto “type locality” for the supracrustals of the Inukjuak Complex. Yet, it remains unclear

Determination of metamorphic pressure (P) – temperature (T) conditions of metapelitic assemblages sometimes suffers from low-CaO content of garnet and/or plagioclase, thus the garnet-plagioclase-related geobarometers lose their usage under such circumstances. Therefore, calibration of garnet-plagioclase-absent geobarometers is very useful. In this paper, the biotite-muscovite geobarometer was empirically

In the Argentera-Mercantour Massif, swarms of high-K calc-alkaline lamprophyres intruded into Carboniferous migmatites and early Permian granites, likely in Permian-Triassic times. The dykes collected multiple magmatic injections, the latest of which of alkaline affinity. Syn-intrusive vesicles and straight chilled margins suggest that the lamprophyres emplaced at a shallow crustal level. Lower greenschist

Metamorphic P–T paths provide valuable constraints on the tectonics of collisional orogens and many such paths have been deduced from analysis of chemical zoning in garnet. Inclusion barometry (e.g. quartz-in-garnet or QuiG) provides complementary and sometimes contradictory information regarding the interpretation of garnet zoning and the P–T paths derived therefrom. For example, QuiG barometry on

The eruptive products of continental arc volcanoes provide wide-ranging insights into the processes governing storage, differentiation, and final eruption (or emplacement) of magmas from trans-crustal magmatic systems. The important role and fractionation of amphibole in continental arc magmatic systems is well documented even if amphibole is generally absent as a prevalent phenocrystic phase in erupted

A comprehensive understanding of the magmatic system evolution and petrogenetic environment is crucial for the correct interpretation of magmatic zircon age spectra. In the Central Andes, a protracted Late Paleozoic period of collisional to post-collisional magmatism was followed by Late Triassic emplacement of post-orogenic plutons and associated mantle precursors. Some of these magma products are

Arc magmas are generated by complex geological processes in subduction settings. Due to the complexity of source materials and geological processes, the genesis of arc magmatic rocks can be difficult to disentangle. Here, we report on diorites from the Kenama area of the middle-eastern part of the Bangong–Nujiang suture zone in central Tibet. New SIMS and LA–ICP–MS zircon UPb dating for three diorite

Recent studies have shown that the Mesozoic metallogenic event in the southern margin of the North China Craton (NCC) is related to the coeval magma activities generated by the lithospheric thinning and asthenosphere upwelling. However, the reason why some Mesozoic magmatic systems in this area are barren is not clear. In this study, we report new geochronological and geochemical data for a Mesozoic