Shallow Laccolithic Emplacement of the Land's End and Tregonning
Shallow laccolithic emplacement of the Land’s End and Tregonning granites, Cornwall, UK: Evidence from aureole fi eld relations and P-T modeling of cordierite-anthophyllite hornfels Jonathan M. Pownall1,*, David J. Waters1, Michael P. Searle1, Robin K. Shail2, and Laurence J. Robb1 1Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK 2Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK ABSTRACT evidence for stoping of the country rocks by end-member concepts for granite genesis: an outward-migrated sill and dyke network, (1) the diapiric emplacement of igneous-derived The Land’s End and Tregonning-Godol- and uplift and doming of the host rocks can “I-type” granites typifi ed by the Andean batho- phin granites of the >250 km-long Perm- be partially attributed to laccolith infl ation. liths (e.g., Pitcher, 1979; Petford and Atherton, ian Cornubian Batholith are heterogeneous Host meta-siltstones of the Devonian Mylor 1996); and (2) the emplacement of sheeted medium- to coarse-grained peraluminous Slate Formation formed a contact aureole complexes of crustal-melt- (or sedimentary-) biotite-, tourmaline-, and lithium-mica gran- of cordierite + biotite + chlorite ± andalusite derived “S-type” granites typifi ed by the Hima- ites traditionally thought to be emplaced as “spotted slates.” Several interspersed pillow layan leucogranites (e.g., Harris and Massey, massive magmatic diapirs. Although S-type basalts and dolerites, previously affected 1994; Harris et al., 1995; Searle, 1999; Searle et characteristics are dominant (quartz + by hydrothermal alteration, underwent iso- al., 2009).
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