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We report the first finding of equilibrium sapphirine+quartz assemblage from the Palghat-Cauvery Suture Zone (PCSZ) in southern India providing unequivocal evidence for extreme crustal metamorphism at ultrahigh-temperature (UHT) conditions associated with the collisional assembly of the Gondwana supercontinent in the Late Neoproterozoic–Cambrian. The sapphirine and quartz occur as coronas around Mg-rich...
The main effect of magma–carbonate interaction on magma differentiation is the formation of a silica-undersaturated, alkali-rich residual melt. Such a desilication process was explained as the progressive dissolution of CaCO 3 in melt by consumption of SiO 2 and MgO to form diopside sensu stricto. Magma chambers emplaced in carbonate substrata, however, are generally associated with...
Simultaneously in-situ analyses of U–Pb isotopes and trace elements were carried out for zircons, in combination with the in-situ analyses of trace elements in coexisting minerals, from low-T/UHP metagranite in the Dabie orogen. The results provide geochemical evidence for the existence of supercritical fluid during continental subduction-zone metamorphism. The zircons are categorized into three types...
This study provides new 40 Ar/ 39 Ar geochronological constraints on the age of the Alpine tectonics in the Aspromonte Massif (southern part of the Calabrian–Peloritan belt). This massif exposes the upper units of the Calabride Complex which originated from the European continental margin. The Calabride Complex was incorporated in the Alpine orogenic wedge and then integrated into...
Leucogranites display petrological and geochemical heterogeneities that can be related to either primary processes in the source of melts or to secondary processes such as fractional crystallization. In the Armorican Massif, a Hercynian domain in western France, syntectonic leucogranites were emplaced along major shear zones, the so-called South Armorican Shear Zone. The Lizio and Questembert massifs...
Post-collisional (26–10Ma) high Sr/Y and HREE-depleted intrusive rocks occur in an E–W trending belt paralleling the Yarlung–Zangbo suture in south Tibet. Their petrogenesis has been a subject of debate. Here, we present chronological, geochemical and Sr–Nd–Hf isotopic data for two newly discovered large-volume high Sr/Y granitoids (the Pagu granodiorite and the Nanmuqie granite) and three high Sr/Y...
Garnet peridotite in oceanic subduction complexes has been reported only in two locations in the world. One of these examples occurs in the late Cretaceous to early Tertiary subduction complex in northern Dominican Republic. The garnet peridotite (wehrlite and olivine-bearing clinopyroxenite) occurs as large (≤4m) boulders together with boulders of eclogites and serpentinites along a narrow (<10m)...
Plagioclase crystals with an anorthite content up to An 99 have been discovered in mantle peridotites from the Yungbwa ophiolite, which crops out along the Indus–Yarlung Zangbo Suture, southwestern Tibetan Plateau. Amphiboles of pargasitic composition also occur in these plagioclase peridotites. Microtextures support the view that both plagioclase and amphibole were formed metasomatically...
Using the HyMap instrument, we have acquired visible and near infrared hyperspectral data over the Maqsad area of the Oman ophiolite (~15×60km). This survey allowed us to identify and map the distribution of clinopyroxene-rich cumulates (inter-layered clinopyroxenites and wehrlites) whose occurrence was previously undocumented in this area. The cumulates reach several hundred meters in thickness and...
Major, trace element and isotopic (Sr, Nd, Pb) data and unspiked K–Ar ages are presented for Quaternary (0.90–0.95Ma old) basalts from the Hayyabley volcano, Djibouti. These basalts are LREE-depleted (La n /Sm n =0.76–0.83), with 87 Sr/ 86 Sr ratios ranging from 0.70369 to 0.70376, and rather homogeneous 143 Nd/ 144 Nd (ε Nd =+5.9–+7.3) and Pb...
Neogene igneous activity in the Aegean region comprised both extrusive volcanism and intrusive granitoid plutonism. Granitoid plutonism in the Cyclades was established in the mid-Miocene period and lasted until late Miocene (18 to 9Ma). The timing of granitoid intrusion was associated with the initiation of extensional tectonics in the Aegean. These intrusions form a broad belt about 200km long running...
The Antalya ophiolites (AO) in SW Turkey comprise remnants from the southern branch of the Neotethyan oceanic basins. The mantle peridotites of the AO include spinel lherzolite, harzburgite, and dunite. Harzburgites are dominant over spinel lherzolites in the AO, whereas dunites occur exclusively as ‘envelopes’ surrounding chromitite pods hosted by harzburgite. Petrographic and geochemical data from...
Post-orogenic granitic and associated mafic rocks from northeastern (NE) China consist of granodiorite and gabbro intrusions. We report here upon new U–Pb zircon ages, geochemical data and Sr–Nd–Hf isotopic data for these rocks. LA-ICP-MS U–Pb zircon analysis yields an age of 262.8±1.0Ma for the granitic rocks, and a uniform age of 262.1±0.7Ma for the gabbro. Most of the granitic and mafic rocks are...
The Srednogorie Zone in Bulgaria and its eastern continuation in NW Turkey, the Strandja Zone, consist of a Late Cretaceous magmatic belt comprised of plutonic, volcanic and associated volcano–sedimentary rocks. The Demirköy Igneous Complex is the biggest Cretaceous pluton within the Strandja Zone, and its age is between 71 and 84Ma. The Demirköy pluton and additional smaller plutons are intruded...
In the Huangling region of the northern Yangtze Block, South China, the 820-Ma Huangling felsic pluton was intruded by ∼800-Ma mafic dikes. These dikes are composed of fine- to medium-grained diabase, porphyritic diabase and olivine gabbro. Quartz xenocrysts occur locally in the olivine gabbro. The rocks are alkaline to sub-alkaline in composition and have SiO 2 ranging from 43.3 to 57.2wt...
We thank Mitchell and Tappe for giving us the opportunity to discuss the nature of kimberlite magmas. We agree with Mitchell and Tappe about the importance of mineralogy, but the mineralogy of interstitial phases in kimberlites can shed little light on the origin of kimberlite magmas. Our use of cation units enables the interpretation of kimberlite whole-rock compositions in terms of the stoichiometry...
We present major element and PGE (platinum-group-element) abundances in addition to Re–Os isotope data for 11 spinel-facies whole rock peridotites from a single maar from the Middle Atlas Mountains, Morocco.Major element systematics of these xenoliths are generally correlated with indices of depletion. FeO–MgO systematics appear to suggest spinel-facies melting in the range of 5 to 25%. However, Al...
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