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Near the coastal village of As Sifah, NE Oman, eclogite-facies rocks occur in the Saih Hatat window. We investigated a metapelite from this area, which is composed of mm-sized garnet and greenish phengite and minor epidote, blue amphibole, paragonite, albite, quartz, rutile, opaque phases, barite, and carbonate. Garnet exhibits a chemical zonation with Gro 17 Alm 66 Pyr 6 Spe...
Lasail plutonic complex (4.7×3.8km), as a typical example of late stage intrusive rocks, is located to the south of Wadi Jizi, and intrudes into the base of V1 volcanic rocks and sheeted dike complex. The Lasail plutonic complex consists of various rock types ranging from ultramafic cumulates to tonalite, and is associated with minor amounts of axis stage gabbro to quartz diorite. These rocks are...
The Sistan ophiolitic belt, formed by the closure of the N–S trending Sistan Ocean during late Cretaceous times, comprises several branches and basins across a 100×700km area along the Iran–Afghanistan border. One of these, the Ratuk complex, exposes disrupted HP ophiolitic blocks from a paleo-subduction complex generally interpreted as a tectonic “mélange”.In order to better understand its overall...
In the forearc of the Andean active margin in southwest Ecuador, the El Oro metamorphic complex exhibits a well exposed tilted forearc section partially migmatized. We used Raman spectroscopy on carbonaceous matter (RSCM) thermometry and pseudosections coupled with mineralogical and textural studies to constrain the pressure–temperature (P–T) evolution of the El Oro metamorphic complex during Triassic...
The origin of historic potassic basalts (from the 1719 to 1721AD eruption) from the Wudalianchi volcanic field, northeast China, is investigated. The samples examined in this study are aphyric, and contain ~5vol.% olivine microphenocrysts. Geochemical analyses of the samples, along with published data for material from the 1719 to 1721AD eruption, show that the basalts exhibit linear compositional...
Garnet porphyroblasts from a litho-assemblage containing aluminous granulite and quartzofeldspathic gneisses of the Eastern Ghats granulite belt, India contain nanometer- to micrometer-thick ilmenite needles oriented crystallographically. Petrographic and chemical analyses reveal that garnet was formed by dehydration melting reaction(s) of titaniferous biotite in an oxidized condition. Elevated oxygen...
Petrological evidence is provided for partial melting of ultrahigh-pressure (UHP) metamorphic granitic gneiss in the Sulu orogen. Petrographic observations show the occurrence of elongated, highly cuspate feldspars in grain boundaries, interstitial cuspate feldspars in triple junctions, felsic veinlets mainly consisting of K-feldspar+quartz, and feldspar crystal faces against quartz. These features...
Mineral assemblages in spinel lherzolite xenoliths from the Cenozoic alkali basalt of eastern China were analyzed by 57 Fe Mössbauer spectroscopy for Fe 3+ /ΣFe and distribution of Fe 2+ /Fe 3+ in non-equivalent crystal cites. Orthopyroxene, clinopyroxene and spinel have 0.08–0.13, 0.19–0.31 and 0.13–0.23 Fe 3+ /ΣFe, respectively. The cation-exchange equilibrium...
Mesozoic granitoids are ubiquitous in China and have attracted the interests of many geologists not only because of their mineralization potential but also because they carry information on source material, emplacement mechanisms and crustal architecture. Most of the plutons were created by multi-stage magma emplacement and offer particular challenge for unraveling the emplacement and cooling history...
The Grand Forks complex (GFC) is a fault-bounded metamorphic core complex in the southern Omineca Belt of British Columbia, Canada. It experienced prograde metamorphism ranging from upper-amphibolite to granulite facies conditions during the Mesozoic to early Tertiary compressional stage of the Cordilleran orogeny. Peak metamorphism was followed by multi-stage exhumation in the Early Eocene. This...
At Okataina volcano, a caldera-collapse event at 46ka followed by frequent intra-caldera eruptions (every 1–5ka) provides an opportunity to examine the temperature and pressure conditions from amphiboles (and other phases) through the life cycle of a rhyolite magma system. In each of 18 eruptions examined, the amphibole population is heterogeneous (e.g., Al 2 O 3 =4.45–10.88wt.%; and...
In order to characterize the recycled lower continental crust (LCC) in the Dabie orogen, 17 Early Cretaceous low-Mg adakitic (LMA) and 9 normal (non-adakitic) granitoids have been investigated for SrNdPb isotopes. Combined with literature data, LMA have low Ɛ Nd (t) (−27.8 to −14.7) and 206 Pb/ 204 Pb(i) (15.69–17.16) and low to moderately high 87 Sr/ 86 Sr(i)...
Petrogeochemical investigations at the Sahlabad region have revealed that epigenetic listvenite veins occur in sheared zones of metaophiolitic suites of Cretaceous age. The listvenite mineralization developed in three forms, namely (1) the silica-listvenite veins which are chiefly composed of chalcedony, opal, quartz, pyrite, chalcopyrite, serpentine and relicts of chrome spinels, magnetite and fuchsite;...
The petrogenesis of Early Cretaceous adakitic intrusions in the Lower Yangtze River belt (LYRB), central-eastern China, and their genetic association with Cu–Au mineralization have recently been debated. This study presented integrated in-situ zircon U–Pb–Hf–O isotopic and trace elemental data for the LYRB adakites, and a comparison with ore-barren adakites from the south Tan-Lu fault (STLF) adjacent...
The western Kunlun orogen, the northwest Tibet Plateau, occupies a key tectonic position at the junction between the Pan-Asia and the Tethyan tectonic domains. It is related to subduction of Proto- and Paleo-Tethys and terrane collision from early Paleozoic to early Mesozoic. This paper presents the first detailed SHRIMP zircon U–Pb chronology, mineral chemistry, major and trace element, and Sr–Nd–Hf...
The Beiminghe (BMH) iron ore in the southern part of the Taihang Mountain (TM), Hebei province, is one of the largest skarn iron deposits in China. Here we report phlogopite 40 Ar– 39 Ar and zircon U–Pb age data, as well as sulfur, lead, and He–Ar isotope geochemistry of pyrite from the ores and skarnitized rocks in the deposit in an attempt to constrain the timing and mechanism of...
The partitioning of a number of trace elements (LILE, HFSE, REE, Cu, Pb, Co, Ni) between mantle minerals (olivine, pyroxenes and garnet) and silico-carbonate melts was experimentally studied at 6–12GPa and 1300–1700°C. The starting compositions were model kimberlitic with ~30wt.% SiO 2 , which differentiated to carbonatite-like melts with <10wt.% SiO 2 depending on the degree of...
The Chenaillet Ophiolite is one of the best-preserved remnants of the Piemont-Liguria oceanic basin, a branch of the Central Atlantic that opened during the separation of Adria/Africa from Europe. Despite numerous studies of structure, petrology, geochemistry and isotope geochronology, the timing and genesis of various magmatic rocks within the Chenaillet Ophiolite are still controversial. We provide...
The Monashee Mountains of the Canadian Cordillera are thought to expose a classic Barrovian-facies series of isograds. The timing of aluminosilicate growth in the region was determined for four pelitic schist samples by combining textural relationships with monazite compositional zoning and monazite U–Pb geochronology conducted directly on thin-sections by the laser ablation method. Three distinct...
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