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

Zircon from 14 representative granite samples of the late-Variscan Cornubian Batholith in SW England was analysed for W, P, As, Nb, Ta, Si, Ti, Zr, Hf, Th, U, Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, Al, Sc, Bi, Mn, Fe, Ca, Pb, Cu, S and F using electron probe microanalyses. Zircons from the biotite and tourmaline granites are poor in minor and trace elements, usually containing 1.0–1.5 wt.% HfO2, <0.5 wt.% UO2 and P2O5, <0.25 wt.% Y2O3, <0.2 wt.% Sc2O3 and Bi2O3 and <0.1 wt.% ThO2. Zircon from topaz granites from the St. Austell Pluton, Meldon Aplite and Megiliggar Rocks are slightly enriched in Hf (up to 4 wt.% HfO2), U (1– 3.5 wt.% UO2) and Sc (0.5–1 wt.% Sc2O3). Scarce metamictized zircon grains are somewhat enriched in Al, Ca, Fe and Mn. The decrease of the zircon Zr/Hf ratio, a reliable magma fractionation index, from 110–60 in the biotite granites to 30–10 in the most evolved topaz granites (Meldon Aplite and Megiliggar Rocks), supports a comagmatic origin of the biotite and topaz granites via long-lasting fractionation of common peraluminous crustal magma. In comparison with other European rare-metal provinces, the overall contents of trace elements in Cornubian zircons are low and the Zr/Hf and U/Th ratios show lower degrees of fractionation of the parental melt.

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Mineral Deposits Study Group 40th Annual Winter Meeting, 2016-12-19, 2016-12-21, University of BristolThe Hemerdon W-Sn deposit, being worked at Drakelands Mine near Plymouth by Wolf Minerals is centred upon a subvertical, NNE-SSW striking, 100+ m wide Early Permian granite dyke hosted by Devonian metasedimentary and metavolcanic rocks. Mineralisation is overwhelmingly associated with moderately to steeply NW-dipping greisen-bordered quartz-wolframite ± cassiterite sheeted veins. The resource size and dyke host are, to date, unique in SW England. We have undertaken a preliminary evaluation of mine and near mine-site geology in order to place the deposit into a regional geological framework and understand some of the factors that have contributed to the development of such a unique resource. There has been no systematic BGS re-mapping of the Ivybridge sheet since the 1890s, but the adjacent Plymouth sheet has been recently mapped to modern standards (Leveridge et al., 2002) and provides an insight into the Upper Palaeozoic regional tectonic evolution (Shail and Leveridge, 2009). Mapping of new exposures created during site enabling works in summer 2015 has been supplemented with near mine-site mapping in 2015-16, using Tellus South West radiometric, LiDAR and magnetic data as well as historical AMAX and BGS data. These data shave allowed the Plymouth sheet lithostratigraphy to be correlated further east. The key issues that contribute to W prospectivity in the Hemerdon area are: (1) The Hemerdon Granite is an old muscovite granite sourced by early (low-T) muscovite-dominated partial melting (Simons et al., 2016); (2) Proximity to major NW-SE fault zones that controlled migration of early melts from lower / middle / upper crust; dilation along an earlier NNE-SSW segment allows emplacement of the Hemerdon Dyke and forms persistent ‘chimney’ (magmatic-hydrothermal fluid pathway) during continued crystallisation of deeper magma batches; faults repeatedly reactivated as transfers; (3) Proximity to the Landulph High influences the development of extensional fault zones and tensile fractures in the Hemerdon Dyke and surrounding host rocks during Early Permian post-Variscan extension; repeated movements create effective permeability networks (fault-fracture meshes) during the continued release of magmatic-hydrothermal fluids. References [1] Leveridge, B.E., Holder, M.T., Goode, A.J.J., Scrivener, R.C., Jones, N.S. and Merriman, R.J. (2002) Geology of the Plymouth and south-east Cornwall area. Memoir of the British Geological Survey, Sheet 348 (England and Wales). [2] Shail, R.K. and Leveridge, B.E. (2009) The Rhenohercynian passive margin of SW England: Development, inversion and extensional reactivation. Comptes Rendus Geoscience, 341, 140-155. [3] Simons, B.J., Shail, R.K. and Andersen, J. (2016) The petrogenesis of the Early Permian Variscan granites of the Cornubian Batholith: Lower plate post-collisional peraluminous magmatism in the Rhenohercynian Zone of SW England. Lithos, 260, 76-94