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Origin and genesis of post-collisional mafic–ultramafic rocks in the Dabie orogen of China are controversial issues with respect to Mesozoic transport of mass and energy between mantle and crust. Zircon U–Pb age, whole-rock major and trace elements, mineral and whole-rock oxygen isotopes, and carbon concentrations and isotope compositions of apatite and whole-rock were determined for these igneous...
Titanite occurs as an accessory phase in melteigite, ijolite and nepheline syenite from the Alnö alkaline intrusion and is typically associated with Ti-andradite and calcite±perovskite. Titanite from 7 samples was investigated using microanalytical techniques including EMPA, 57 Fe Mössbauer spectroscopy, powder X-ray diffractometry and FTIR-spectroscopy. A common feature of the analysed titanite...
Towards unravelling the geodynamic setting of the northern Sierras Pampeanas (NW Argentina) we describe the tectono-metamorphic and geochronologic evolution of sub-greenschist to granulite facies metamorphic sediments, granitoid plutons, and pegmatites in the Ordovician Sierra de Quilmes metamorphic complex. The protoliths of the metasediments are represented by a sequence of turbidites and minor...
The petrogenesis of the Hercynian magmatic rocks of the Albera Massif (eastern Pyrenees) is investigated in this work, in order to establish spatial and temporal relationships between deformation episodes, high temperature–low pressure metamorphism and igneous activity, by using fieldwork together with petrological and geochemical methods.Hercynian magmatic rocks comprise (i) calc-alkaline granitoids...
Geochemical and petrographical studies of lavas and ignimbrites from the Quaternary Nisyros–Yali volcanic system in the easternmost part of the Hellenic arc (Greece) reveal insight into magma generating processes. A compositional gap between 61 and 68 wt.% SiO 2 is recognized that coincides with the stratigraphic distinction between pre-caldera and post-caldera volcanic units. Trace element...
The Jinbaoshan ultramafic intrusion is a member of the late–middle Permian (260 Ma) Emeishan Large Igneous Province in Yunnan Province, SW China and hosts an economical Pt–Pd–sulphide deposit. The intrusion consists mainly of wehrlite (92 vol.%), with minor olivine clinopyroxenite and clinopyroxenite (8 vol.%). The ores, defined as rocks having >0.5 ppm Pt and Pd, contain abundant chromite (up...
High-P metabasites of the Diahot terrane, NE New Caledonia occur as spatially restricted (cm to km-scale) lenses, boudins and layers in psammitic to pelitic metasediments. Although interlayered, the two rock types preserve distinct, tectonically disrupted metamorphic profiles in the transition from lawsonite blueschist in the SW to low-T eclogite in the NE. As the metabasites experienced comparatively...
Rare earth elements in bulk cumulates and in separated minerals (plagioclase, apatite, Ca-poor and Ca-rich pyroxenes, ilmenite and magnetite) from the Bjerkreim–Sokndal layered intrusion (Rogaland Anorthosite Province, SW Norway) are investigated to better define the proportion of trapped liquid and its influence on bulk cumulate composition. In leuconoritic rocks (made up of plagioclase, Ca-poor...
Calculations of fractional crystallization (FC) and assimilation fractional crystallization (AFC) at 11 kb for a variety of primitive magmatic compositions and a mafic assimilant demonstrate that none of them has a bulk composition suitable to be parental to massif anorthosites. Mafic compositions thought to be parental to massif anorthosites have Mg′ values of 0.6 to 0.4 and form coherent arrays...
The Lovozero alkaline massif (Kola Peninsula, Russia) is composed of three major units. The central unit (80% of the volume) comprises numerous well developed layers composed, from bottom to roof, of an urtite–juvite–foyaite–lujavrite continuous lithological sequence (ijolite–foid-bearing alkali feldspar syenite in IUGS nomenclature). The mode of emplacement of the massif and the mechanism of formation...
The Bjerkreim-Sokndal layered intrusion (BKSK) consists of a >7000-m-thick Layered Series comprising anorthosites, leuconorites, troctolites, norites, gabbronorites and jotunites (hypersthene monzodiorites), overlain by an unknown thickness of massive, evolved rocks: mangerites (hypersthene monzonites; MG), quartz mangerites (QMG) and charnockites (CH). The Layered Series is subdivided into six...
The origin of magmatic layering is still hotly debated. To try to shed some light on this problem, two ultramafic–mafic layered xenoliths from Puy Beaunit (French Massif Central) were investigated in detail. The nodules belong to a stratiform intrusion emplaced in the deep crust during the Permian (257±6 Ma; Féménias, O., Coussaert, N., Bingen, B., Whitehouse, M., Mercier, J.-C., Demaiffe, D., 2003...
To constrain the amount and rate of crustal contamination that is possible in basaltic and jotunitic magma, and to gain an insight into the physical and thermal processes of assimilation in crustal magma chambers, we have modelled published Sr and Nd isotopic data from three layered intrusions. Well-exposed sequences of cumulates with no evidence of magma recharge provide direct records of concurrent...
Whole-rock major element compositions are investigated in 99 cumulates from the Proterozoic Bjerkreim–Sokndal layered intrusion (Rogaland Anorthosite Province, SW Norway), which results from the crystallization of a jotunite (Fe–Ti–P-rich hypersthene monzodiorite) parental magma. The scattering of cumulate compositions covers three types of cumulates: (1) ilmenite–leuconorite with plagioclase, ilmenite...
The Mont Collon mafic complex is one of the best preserved examples of the Early Permian magmatism in the Central Alps, related to the intra-continental collapse of the Variscan belt. It mostly consists (>95 vol.%) of ol+hy-normative plagioclase-wehrlites, olivine- and cpx-gabbros with cumulitic structures, crosscut by acid dikes. Pegmatitic gabbros, troctolites and anorthosites outcrop locally...
The layered mafic intrusion at Sept Iles, Canada, is one of the largest intrusions in the world. A new interpretation of its structure is proposed, based on a review of its geology and a comparison with the Skaergaard intrusion, Greenland. Several different magmatic components are recognized; hence the name Sept Iles Intrusive suite (SIIS) is proposed. Emplacement of the suite may have been preceded...
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