This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The Early Permian Variscan Cornubian Batholith is a peraluminous, composite pluton intruded into Devonian and Carboniferous metamorphosed sedimentary and volcanic rocks. Within the batholith there are: G1 (two-mica), G2 (muscovite), G3 (biotite), G4 (tourmaline) and G5 (topaz) granites. G1-G2 and G3-G4 are derived from greywacke sources and linked through fractionation of assemblages dominated by feldspars and biotite, with minor mantle involvement in G3. G5 formed though flux-induced biotite-dominate melting in the lower crust during granulite facies metamorphism. Fractionation enriched G2 granites in Li (average 315 ppm), Be (12 ppm), Ta (4.4 ppm), In (74 ppb), Sn (18 ppm) and W (12 ppm) relative to crustal abundances and G1 granites. Gallium (24 ppm), Nb (16 ppm) and Bi (0.46 ppm) are not significantly enriched during fractionation, implying they are more compatible in the fractionating assemblage. Sb (0.16 ppm) is depleted in G1-G2 relative to the average upper and lower continental crust. Muscovite, a late-stage magmatic/subsolidus mineral, is the major host of Li, Nb, In, Sn and W in G2 granites. G2 granites are spatially associated with W-Sn greisen mineralisation.\ud \ud Fractionation within the younger G3-G4 granite system enriched Li (average 364 ppm), Ga (28 ppm), In (80 ppb), Sn (14 ppm), Nb (27 ppm), Ta (4.6 ppm), W (6.3 ppm) and Bi (0.61 ppm) in the G4 granites with retention of Be in G3 granites due to partitioning of Be into cordierite during fractionation. The distribution of Nb and Ta is controlled by accessory phases such as rutile within the G4 granites, facilitated by high F and lowering the melt temperature, leading to disseminated Nb and Ta mineralisation. Lithium, In, Sn and W are hosted in biotite micas which may prove favourable for breakdown on ingress of hydrothermal fluids. Higher degrees of scattering on trace element plots may be attributable to fluid–rock interactions or variability within the magma chamber. The G3-G4 system is more boron-rich, evidenced by a higher modal abundance of tourmaline. In this system, there is a stronger increase of Sn compared to G1-G2 granites, implying Sn in tourmaline-dominated mineral lodes may represent exsolution from G4 granites.\ud \ud G1-G4 granite abundances can be accounted for by 20–30% partial melting and 10–40% fractionation of a greywacke source. G5 granites are analogues of Rare Metal Granites described in France and Germany. These granites are enriched in Li (average 1363 ppm), Ga (38 ppm), Sn (21 ppm), W (24 ppm), Nb (52 ppm) and Ta (15 ppm). Within G5 granites, the metals partition into accessory minerals such as rutile, columbite-tantalite and cassiterite, forming disseminated magmatic mineralisation. High observed concentrations of Li, In, Sn, W, Nb and Ta in G4 and G5 granites are likely facilitated by high F, Li and P, which lower melt temperature and promote retention of these elements in the melt, prior to crystallisation of disseminated magmatic mineralisation.This study was supported by the European Regional Development Fund and European Social Fund as part of the convergence funding for Cornwall and the Isles of Scilly supporting a PhD for BS (Combined Universities in Cornwall project number11200NCO5) and the European Union (Horizon 2020 project 641650 FAME). The LA-ICP-MS work was supported by a grant from the Natural Environment Research Council (NERC, NE/L001896/1). The Cornwall Heritage Trust are thanked for providing additional funds for analysis. The Natural History Museum, London, UK are thanked for loan of samples from collection BM.2004,P14, specimen numbers 1, 7, 8, 10, 21, 23, 24, 30 and 31 and thin sections P11849, P11851, P11864, P12400 and P12399. Samples GG6, GG15, GG28, and GG44 from the study of Darbyshire and Shepherd (1994) came from Peter Floyd, University of Keele. Steve Pendray, Sharon Uren and Joe Pickles assisted with the sample preparation and analysis at Camborne School of Mines. Sam Hammond assisted with LA-ICP-MS analysis at the Open University. De Lank, Carnsew and Castle-an-Dinas quarries, Richard Scrivener, Nick LeBoutillier and Ben Thompson (Imerys) are thanked for help with sampling. Karel Breiter and one anonymous reviewer are thanked for their generous and constructive comments which have helped to improve the manuscript

The pre-Himalayan magmatic events along the northern margin of Indian plate in north-western Pakistan have been investigated and correlated with analogous magmatism in other Himalayan and northern Gondwana regions. The samples from Utla and Mansehra regions of NW Pakistan are dominantly megacrystic two mica granites, strongly peraluminous (A/CNK > 1.1) and intruded by aplite dykes and quartz-rich veins. The high precision zircon U-Pb ages (471-479 Ma) show their emplacement in early Paleozoic. These granites are enriched in light rare-earth elements (LREEs) and show similar chondrite normalized REE patterns with negative Eu anomalies (Eu/Eu* = 0.07–0.73). The geochemical signature and REE based modelling indicate that the granites are derived mainly from the partial melting of pelitic source followed by the evolution of melt via fractional crystallization resulting in the formation of aplites. Tourmaline occurrences in distinct modes show post-magmatic alteration of these granites triggered by hydrothermal fluids from different sources. Enrichment of Sn in certain alteration zones and trace elements ratios suggests a strong mineralization potential for these granites. The analogous composition, source rock characteristics and geochronology represent their regional association with other Cambro-Ordovician granitoids from northern Gondwana. Due to these similarities, an early Paleozoic orogenic event has been anticipated for these granitoids initiated due to subduction of Proto-Tethys oceanic lithosphere beneath the northern Gondwana supercontinent.\ud Dykes of basic composition that intrude these granites and other lithologies are divided into dolerites and amphibolites on the basis of their distinct mineralogical and geochemical composition. Major elements composition suggests alkaline to sub alkaline character of both dykes with intraplate tectonic setting, however, amphibolites (>3%) are markedly enriched in TiO2 relative to dolerites (<3%). Trace element ratios designates the origination of dolerites from subcontinental lithosphere with significant crustal contamination. They show analogous geochemical character to Panjal traps which represent a regional scale rift related basic magmatism in Himalayan terrane during Permian. The geochemical signature of amphibolites, however, show similarities to high-Ti Qiangtang dykes which originates from asthenospheric source via deep mantle plume. The sporadic distribution of both dykes in similar aged host rocks represent their evolution from distinct sources in separate but synchronous magmatic pulses during extensional tectonism related to separation of Cimmeria from Gondwana.\ud Granites with distinct petrographic features have been tested to examine the influence of textural characteristics on the variation of their respective strength. Comparison of petrographic observations before and after the strength tests and the relationship of fracture propagation with mineral boundaries specifies vital impact of textural variation in evaluating the mechanical behaviour of granites. The important textural features include average grain size of rock, grain boundary recrystallization, maximum grain size of major rock forming minerals, mean grain size of cleaved minerals, mineral exsolution and variation of grain size within a rock. The petrographic observations, however, are more effective to describe the strength variation of granites having analogous weathering grade as change in degree of weathering has a dominant effect on rock mechanics.Commonwealth Scholarship Commissio

The Skaergaard intrusion, Greenland, is the type locality for Skaergaard-type mineralizations. Mineralization levels are perfectly concordant with igneous layering, up to 5 m thick, internally fractionated, and contain crystallized sulphide droplets and precious metal alloys, sulphides, arsenides and telluride. Immiscible Cu-rich sulphide droplets, formed in a mush zone below the roof, scavenged precious metals. They were subsequently dissolved and transported to the floor in late-formed, immiscible, Fe-rich mush melts. Mineralized stratigraphic intervals of floor gabbro formed in ‘proto-macrolayers‘, owing to local sulphide saturation in melt concentrated between floating plagioclase and sinking clinopyroxene. The floor mineralization is divided into four stratigraphic sections. Formation of the Lower Platinum Group Element Mineralization (LPGEM) involved: (1) crystallization of the bulk liquid liquidus paragenesis and in situ fractionation; (2) sulphide saturation and formation of sulphide droplets in melt in the upper part of ‘proto-macrolayers‘. After further in situ fractionation, the following steps occurred: (3) the onset of silicate–silicate immiscibility and the consequent loss of buoyant and immiscible Si-rich melt; (4) dissolution of unprotected droplets of sulphide melt present in the Fe-rich mush melt; (5) compaction-driven upwards loss of residual mush melt enriched in, for example, Au. The LPGEM preserves upward increasing bulk Pd/Pt (∼6–13) owing to a continued supply of PGE and Au, with high Pd/Pt. The further development of the LPGEM ceased as the supply of precious metals to the floor waned. The Upper PGE Mineralization (UPGEM) subsequently formed from precious metals recycled in the floor. The UPGEM is characterized by increasing Au substitution in PGE phases, and a decrease in total PGE and Pd/Pt owing to upward fractionation in migrating mush melts and exhaustion of Pd and Pt. An upper Au-rich mineralization level (UAuM) was caused by late remobilization of Au and deposition on grain boundaries in fully crystallized gabbro. Cu concentrations (∼150 ppm) are not correlated with PGE and Au. Repeated Cu mineralization levels (CuM), attaining >1000 ppm, occur above the Au levels, caused by local mush layer sulphide saturation. PGE, Au and Cu distributions in the floor mineralization reflect sub-liquidus, but supra-solidus, processes and reactions in mushes at the roof, wall and floor. Constraints provided by a new model for the mineralization provide the basis for re-evaluation of the solidification processes in the Skaergaard intrusion. We have identified the importance of extensive in situ fractionation and intrusion-wide elemental redistributions in immiscible Fe- and Si-rich silicate melts. Our model characterizes the floor cumulates as bulk liquid orthocumulates containing an upwards-increasing proportion crystallized from Fe-rich, immiscible mush melt. The roof-rocks are complementary to the floor, with downwards increasing proportions crystallized from the conjugate Si-rich melt. Petrographic observations and the relative timing of crystallization support the hypothesis that crystallization was restricted to marginal mush zones. Bulk melt remaining in the magma chamber evolved not, as generally assumed, as a result of loss of crystals grown from the bulk melt, but as the consequence of mixing with recycled and evolved melt expelled from the mush by compaction. Redistribution of Fe in immiscible melts may be common to mafic intrusions and puts into question the validity of petrogenetic modelling of bulk liquids in mafic intrusions based only on consideration of floor cumulates.