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The role of S during high-grade metamorphism is a topic that has not garnered much interest in the literature until recently. In this review, the role of S as an active component in high grade hypersaline fluids is reviewed per a series of regional studies involving orthopyroxene-bearing granulite-facies granitoids. These include the Shevaroy Block and Nilgiri Block, southern India; the Bamble Sector, southwest Norway; the Val Strona traverse of the Ivrea-Verbano Zone, northern Italy; and the Lewisian Complex, northwest Scotland. In each these terranes, S-bearing, high-grade, low H2O activity fluids are conjectured to have been present during granulite-facies metamorphism and to have contributed to the dehydration of the rock, the oxidation state of the rock, and trace element mobility, leaving behind pyrite and/or pyrrhotite as traces of its presence. The various mineral equilibria reactions between the various oxidation states of S in these fluids and the oxide and silicate minerals encountered by the fluid are explored and a coherent framework of interdependent chemical reactions are developed, which describe both oxidation of the rock and the formation of pyrite and pyrrhotite during both peak- and post-peak metamorphism. [ABSTRACT FROM AUTHOR]

Abstract: The ca. 930 Ma Farsund intrusion (SW Norway) belongs to a series of 0.99–0.92 Ga post-collisional plutons from the Sveconorwegian (Grenvillian) orogen. It is made of two rock facies (charnockite and quartz mangerite, and subordinate quartz monzonite and quartz monzodiorite) that show mingling relationships. As shown elsewhere, these two facies belong, respectively, to the two suites of A-type affinity recognized in the Sveconorwegian post-collisional magmatism of Southern Norway, namely the AMC and HBG suites. A structural study of the Farsund intrusion, based on the anisotropy of magnetic susceptibility (AMS) technique, is presented here. The AMS is controlled by the shape-preferred orientation of low-Ti titanomagnetite grains and it can be used as a proxy for the global petrofabric. The AMS data, when combined with micro- to macrostructural observations, unfold the occurrence of a steeply dipping shear zone, straddling the NE border of the pluton and characterized by a likely strike-slip component of shearing. This high-strain zone is roughly coincident with the boundary between the outcrop domains of the AMC and HBG suites, and was formed or, more probably, reactivated during the gravitational collapse of the Sveconorwegian orogen, in an extensional (possibly transtensional) tectonic regime. It would have controlled the ascent and emplacement of the Farsund intrusion, and materializes as well the structural weakness that would have channelled the magmas of the neighbouring and coeval Rogaland anorthosite province. It is also suggested that vertical, gravity-driven movements were recorded in the Farsund intrusion and its close surroundings. They would have been induced in a very hot environment, akin to that prevailing in the Precambrian ultra-hot orogens, but linked in the present case to the emplacement of anorthosites and penecontemporaneous igneous bodies, including the Farsund intrusion. [ABSTRACT FROM AUTHOR]

Abstract: Trace element analyses of quartz from the layered charnockitic Kleivan granite in the Rogaland Igneous Province (Rogaland Municipality, SW-Norway) reveal that the trace element composition of quartz can track igneous evolution during differentiation of the magma. Combined SEM-CL imaging and LA-ICP-MS analyses allow identification and analysis of primary igneous quartz. Al, Ti, Li, and Ge are the most abundant trace elements in the Kleivan quartz and each element shows a characteristic evolution during differentiation of the granitic magma. The Ge/Ti ratio of quartz is a reliable index of the magmatic evolution of granitic igneous systems, since Ti and Ge show pronounced compatible and incompatible characteristics, respectively. The temperature of the quartz crystallisation varies from 850 °C during charnockite formation to 645 °C in the most evolved aplitic–granite and granitic pegmatite. Therefore, the regular evolution of Ti and Ge in quartz during cooling of the melt may be used as an igneous geothermometer. The Li evolution pattern of quartz is mostly controlled by the Li content of the melt hence by the absence or presence of Li-bearing phases forming during solidification of the melt. Al in quartz is controlled by the aluminium saturation index of the melt. Accordingly, Al in quartz is constant during crystallisation of a metaluminous magma and increases during peraluminous conditions. [Copyright &y& Elsevier]

Abstract: 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 megacyclic units that represent the crystallisation products of successive major influxes of magma. We have studied a ca. 2000-m-thick section that straddles the sequence from the uppermost part of the Layered Series to the QMG in the northern part of the intrusion. Mineral compositions in 37 samples change continuously in the lower part of the sequence up to the middle of the MG-unit (plagioclase An37-18; olivine Fo40-7; Ca-poor pyroxene Mg#57-15; Ca-rich pyroxene Mg#65-21). Above this compositions are essentially constant in the upper part of the MG-unit and in the QMG (An21-13; Fo6-4; Mg#opx17-13; Mg#cpx25-20). The amount of interstitial quartz and the amount of normative orthoclase, however, both increase systematically upwards through the QMG-unit, implying that these rocks are cumulates. There is no evidence of a compositional break in the MG-QMG sequence that could reflect influx of relatively primitive magma. Two types of QMG/CH are known in the uppermost part of BKSK. Olivine-bearing types are comagmatic with the underlying Layered Series; the studied stratigraphic sequence belongs to this suite. Two-pyroxene QMG and amphibole CH define a separate compositional lineage related to jotunites. An intrusive unit of dominantly two-pyroxene QMG is discordant to the olivine-bearing jotunite-MG-QMG sequence near Rapstad, confirming the presence of two compositionally distinct suites of QMG and related lithologies in the upper part of BKSK. A xenolith-rich unit near the olivine-bearing MG-QMG boundary represents a major collapse of the roof of the magma chamber during the final stages of crystallisation. [Copyright &y& Elsevier]

Mangerites, charnockites, anorthosites, gabbros and granites occur within a high-grade metamorphic complex in the Lofoten–Vesterålen islands of northern Norway. U–Pb dating of zircon, titanite and monazite indicates a three-stage magmatic history beginning at 1870–1860 Ma with the emplacement of the Lødingen and Hopen plutons, followed by a dominant stage at 1800–1790 Ma that formed the bulk of the suite, and concluded by the emplacement of pegmatites, local rehydration and retrogression between 1790 and 1770 Ma. On the scale of the Baltic Shield the 1870–1860 Ma episode corresponds to contraction, amalgamation of arcs, and regional deformation. By contrast, the episode at 1800–1790 Ma was characterized by major shifts in plate convergence, by intraplate deformation, and by a diversity of magmatic associations including suites derived from the subcontinental mantle and widespread granitoid rocks extracted from the continental crust. The diversity of concurrent magmatic events across the Svecofennian orogen, and the temporal coincidence with collisional events in coeval orogenic belts, suggests that the genesis of the suite of magmatic rocks may have been related to tectonically driven mechanisms of magma generation. [ABSTRACT FROM AUTHOR]

In the Caledonides of Scandinavia a lower part of the nappe pile, the Middle Allochthon, consists of metasedimentary rocks and orthogneisses, transported in a southeastern direction and presumably derived from the rifted margin of pre-orogenic cratonic Baltica. In the Sarek-Kvikkjokk area in northern Sweden, telescoped orthogneisses are composed of lithologies that share characteristics with the autochthonous AMCG (anorthosite- mangerite-charnockite-granite)-suite of the Lofoten Complex in northern Norway. The allochthonous Tielma Magmatic Complex (TMC) consists of syenitic and gabbroic rocks, gabbro dykes and ferrogabbros and contains other noteworthy lithologies, such as anorthosites and Fe-Ti ores, which also occur in the Lofoten Complex. All rock types of this study show strong similarities in their trace element and rare earth element patterns with corresponding lithologies in Lofoten, which could indicate a common source and/or process of formation. U-Pb age determinations on zircons constrain the timing of the magmatic activity in the TMC to between 1776 ± 7 Ma and 1761 ± 9 Ma. Subsequent felsic dykes were dated to 1731 ± 5 Ma. The new geochronological, petrological and structural data from the TMC constrain the geological evolution of these crustal elements, which were probably derived from the outermost cratonic Baltoscandian margin and strengthen a correlation with the Lofoten Complex. This correlation together with structural data on Caledonian transport directions suggest orthogonal transport directions towards ESE during the final phase of nappe emplacement. [ABSTRACT FROM AUTHOR]

Summary ¶Sm–Nd, Rb–Sr and Pb–Pb isotopic compositions of 34 intrusive AMCG (anorthosite–mangerite–charnockite–granite) suite rocks and spatially related ferrodiorites and gabbros from the Lofoten Islands, northern Norway, suggest that almost all Lofoten intrusive rocks can be modelled as a mixture of mainly two components: Archean lower crustal material and an about 1.8 Ga mantle-derived component. Isotopically, the gabbros and anorthosites overlap the mangeritic rocks in all three isotope systems. Hence, the isotopic data are in agreement with a model that relates the mangeritic rocks to the fractionation of crustally contaminated mantle-derived basaltic melts. Overlap in all three isotopic systems indicates that at least part of the assimilation process predates or accompanies fractionation. Whole rock geochemistry supports this model: based on major, minor, and trace element data, primitive 1.79–1.86 Ga mangerites could have formed from anorthosite residual liquids – the ferrodiorites – by fractionation processes involving Fe–Ti oxides, Fe–Mg silicates and apatite combined with contamination of the ferrodiorites with about 50 wt.% crustal anatectic melt. [ABSTRACT FROM AUTHOR]

Sr and Nd isotopic data from the anorthosite-mangerite-charnockite (AMC) suite of the Late-Sveconorwegian (ca. 0.93 Ga) Rogaland anorthosite province of SW Norway are discussed. The study focuses on new data obtained from three distinct rock occurrences: (1) primitive (=MgO-rich and K2O-poor) jotunites that represent the parental magmas of leuconorite and mafic plutons (87Sr/86Sr0.93 Ga=ca. 0.704–0.707, &epsiv;Nd(0.93 Ga)=+3.6 down to +1.2); (2) evolved jotunites that differentiated from the primitive jotunites and constitute the starting components of dyke-scale fractionation trends (87Sr/86Sr0.93 Ga=ca. 0.705–0.713, &epsiv;Nd(0.93 Ga)=+0.4 down to −2.0); and (3) felsic plutons (87Sr/86Sr0.93 Ga=ca. 0.707–0.723, &epsiv;Nd(0.93 Ga)=+1.4 down to −1.7). A comparison of the Sr and Nd isotopic compositions with available geochemical data (major and trace elements) is also made. Fractionation of the primitive to the evolved jotunites, below the intrusion level of the anorthosite province, is shown to have involved crustal contamination. A case of fractional crystallization and simultaneous contamination/assimilation is substantiated in the felsic cap of a layered intrusion (the Bjerkreim-Sokndal intrusion). It is further proposed that the Sr and Nd isotopic compositions of the various felsic occurrences result from fractional crystallization of primitive jotunitic melts, with or without contamination/assimilation; this strengthens the possibility for large volumes of silica-rich magmas to have been produced by fractionation, through evolved jotunites, of primitive jotunites. The entire range in Sr and Nd isotopic compositions of the Rogaland anorthosite province is interpreted as reflecting a mixing of crustal contaminants, having variable 87Sr/86Sr0.93 Ga ratios and (negative) &epsiv;Nd(0.93 Ga) values, with a more isotopically primitive source. The crustal end members of that mixing array are represented by moderately to strongly LILE-enriched high-grade gneisses from the Pre-Sveconorwegian basement of southernmost Norway, that have a crustal history extending back to 1.5–1.9 Ga in the surroundings of the anorthosite province. The primitive end member is either an unusual LREE-depleted and Rb-enriched component, possibly corresponding to an originally depleted source subsequently modified by metasomatic fluids, or a more classical depleted component; it corresponds to a gabbronoritic rock of the deep crust, as shown by recent experimental data, with a quite short crustal residence time (<0.4–0.2 Ga). If that mafic end member is the lower granulitic crust itself, this would imply the presence in the deep continental crust of southwesternmost Norway of a crustal material strongly different from the 1.7- to 1.9-Gyr-old, moderately LILE-enriched component that is supposed to constitute the largest volume of the present deep continental crust in southern Norway. [Copyright &y& Elsevier]

Crystallization temperatures of the 1.8 Ga Lofoten anorthosites are estimated from pyroxene thermometry, and pressure is derived from solving simultaneously the equilibria CaAl2SiO6(in cpx)+SiO2=CaAl2Si2O8(in plag)NaAlSi2O6(in cpx)+SiO2=NaAlSi3O8(in plag) and Mg2SiO4(in ol)+SiO2=2MgSiO3(in opx) These calculations indicate that the calcic Flakstadøy anorthosite [FBC, Cpx ± Ol ± Opx + Mtss + Ilmss + Plag (An57–47)] crystallized under polybaric conditions at pressures between 4 and 9 kbar and at temperatures between 1140 and 1185°C. The sodic Eidsfjord complex [Cpx + Opx + Mtss + Ilmss + Plag (An48–44)] crystallized at 1100–1135°C at a maximum pressure of 7.3 kbar. This technique may provide a means to estimate crystallization pressure and aSiO2 in many types of intrusive and extrusive rocks. Coeval mangerites and charnockites intruded subsequently at ∼4 kbar and temperatures between greater than 925°C and 800°C, respectively, indicated by the succession of the mafic phase assemblages (Cpx + Opx; Cpx + Opx + Ol; Cpx + Pig + Ol; Cpx + Ol) that reflect continuous fractionation to higher Fe/Mg ratios. The evidence for polybaric crystallization of the FBC quantitatively supports the common model that generation of Proterozoic anorthosites involves initial crystallization at depth (crust–mantle boundary) and intrusion as a crystal-rich mush. Detailed estimation of intrinsic parameters (P, T, fO2, aSiO2, fHCl) indicates a systematic relationship between the phase assemblages in anorthosites, ferrodiorites, mangerites and charnockites, which is compatible with fractional crystallization of a mafic parental magma. [ABSTRACT FROM AUTHOR]

The upper part of the Bjerkreim–Sokndal layered intrusion (BKSK) comprises a suite of charnockitic granitoids (mangerite, quartz mangerite and charnockite) with some jotunites. The petrology and geochemistry (major and trace elements) of eight main rock types (88 samples) are considered. The rocks form a suite of K20-rich alkali–calcic granitoids of A-type, deriving from jotunitic magma. Two trends of inferred liquids are distinguished: the main liquid line of descent which passes from jotunites through two-pyroxene quartz mangerites to amphibole charnockites, the second one which encompasses olivine-bearing quartz mangerites and charnockites and is rooted into mangeritic liquids. Comparison with the Tellnes rock series reveals that contamination by leucogranitic material has taken place simultaneously with fractional crystallization in both BKSK trends. Zr, Rb, Cs and Th are particularly sensitive to assimilation and the higher water content in BKSK. Zircon and apatite have saturated at the liquidus of quartz mangerite around 900°C, close to the fayalite-magnetite-quartz (FMQ) buffer. The two-pyroxene quartz mangerites cannot have been equilibrated with the mangerite cumulates on which they rest. A major influx of magma took place when mangeritic cumulates were being deposited. It mingled and partly mixed with the resident contaminated magma. [ABSTRACT FROM AUTHOR]