Tourmaline-quartz-cassiterite mineralization of the Land's End Granite at Nanjizal, west Cornwall

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Tourmaline-quartz-cassiterite mineralization of the Land's End Granite at Nanjizal, west Cornwall

Show simple item record LeBoutillier, N.G. en_US Camm, G.S. en_US Shail, R.K. en_US Bromley, A.V. en_US Jewson, C. en_US Hoppe, N. en_US 2011-12-19T11:53:12Z en_US 2012-09-28T18:13:53Z en_US 2013-03-20T12:58:35Z 2002 en_US
dc.description.abstract Nanjizal is one of the few locations in the southern segment of the Land's End Granite (Early Permian) where magmatic-hydrothermal tin mineralization has been worked. Three principal mineralization episodes are recognized. The first episode comprises steeply dipping ENE-WSW striking tourmaline quartz veins precipitated from magmatic-hydrothermal fluids during regional NNW-SSE extension; they are not associated with metalliferous mineralization. The second episode is represented by two sets of vertical/subvertical tourmaline veins striking, respectively, 280degrees and 340degrees. The NNW striking set hosts tourmaline-quartz-cassiterite ( alkali feldspar, apatite, zircon) mineralization and was worked for tin during the 19(th) Century. The first generation of tourmaline in these veins is dominated by the Mg-rich end-member, dravite. The subsequent two generations of tourmaline are dominated by the Ferich end-member, schorl, together with zoned cassiterite with Fe-rich cores and Fe-poor rims. The NNW striking tourmaline-quartz-cassiterite veins at Nanjizal have a similar orientation to cassiterite-bearing veins within the St. just Mining District further north. It is possible that the mineralization at Nanjizal was contemporaneous with mineralization in the St. Just Mining District and hence related to a later magmatic episode and the renewed release of magmatic-hydrothermal fluids during ENE-WSW extension. The third mineralization episode is dominated by steeply dipping WNW-NNW striking quartz-limonite-chalcedonyveins that are associated with wall rock hematisation and kaolinisation. Schorl-quartz-cassiterite mineralisation is relatively uncommon in S.W. England but there are remarkable similarities between the vein parageneses at Nanjizal and the Birch Tor-Vitifer area of Dartmoor; both are likely to have been sourced from predominantly magmatic-hydrothermal fluids. en_US
dc.identifier.citation Vol. 10 (3), pp. 312 - 318 en_US
dc.identifier.uri en_US
dc.publisher The Ussher Society en_US
dc.relation.replaces en_US
dc.relation.replaces 10036/3332 en_US
dc.relation.url en_US
dc.subject Southwest England en_US
dc.subject Cornubian batholith en_US
dc.subject Variscan structures en_US
dc.subject Pluton en_US
dc.subject Coast en_US
dc.title Tourmaline-quartz-cassiterite mineralization of the Land's End Granite at Nanjizal, west Cornwall en_US 2011-12-19T11:53:12Z en_US 2012-09-28T18:13:53Z en_US 2013-03-20T12:58:35Z
dc.contributor.editor Pirrie, D. en_US
dc.identifier.issn 0566-3954 en_US
exeter.contacts.depositing-owner-email Shail, Robin <> en_US
exeter.contacts.owner-email Shail, Robin <> en_US
dc.identifier.journal Geoscience in South-West England en_GB

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