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Article: The Kennack Gneiss of the Lizard Peninsula, Cornwall, SW England: Commingling and mixing of mafic and felsic magmas accompanying Givetian continental incorporation of the Lizard ophiolite

TitleThe Kennack Gneiss of the Lizard Peninsula, Cornwall, SW England: Commingling and mixing of mafic and felsic magmas accompanying Givetian continental incorporation of the Lizard ophiolite
Authors
KeywordsCornwall England
Kennack Gneiss
Lizard complex
U-Pb, anatexis
Issue Date2000
PublisherGeological Society Publishing House. The Journal's web site is located at http://www.geolsoc.org.uk/gsl/publications/journals/jgs
Citation
Journal Of The Geological Society, 2000, v. 157 n. 6, p. 1227-1242 How to Cite?
AbstractThe Kennack Gneiss comprises a suite of interlayered mafic and felsic igneous rocks that intruded the 397 Ma Lizard Ophiolite Complex, Cornwall, at 376.4 ± 1.7 Ma (U-Pb single-zircon date) and were shortly thereafter (c. 370 Ma) metamorphosed to the amphibolite facies. Weakly deformed examples at the type-locality of Kennack Sands reveal net-veining of the mafic by the felsic component, dispersed enclaves of the former in the latter and flame-like interfingering of the two, features indicative of magmatic commingling and mixing. The silicic components of the Kennack Gneiss range from granodiorite to syenogranite and from metaluminous to peraluminous, the least silicic rocks being the most peraluminous. They were generated through anatexis of a predominantly metasedimentary crustal source having trace element and isotopic compositions comparable to those of the Devonian Gramscatho Group of South Cornwall. The mafic component of the gneiss includes members (group 1) which are weakly enriched in light REE, have minor negative Ta, Nb, P and Ti anomalies in extended trace element plots, and display primitive, time-corrected 143Nd/ 144Nd and 87Sr/ 86Sr values, and others (group 2) which are more strongly enriched in all incompatible trace elements, exhibit more prominent negative Ta, Nb, P and Ti anomalies, and have isotopic ratios intermediate between group 1 mafic components and the associated felsic gneiss. Group 2 represents mixtures of group 1 and granitic melts, whereas group 1 rocks are comparable to EMORB and were probably generated through partial melting of a weakly enriched mantle source. Emplacement of two commingled magmas into the base of the Lizard ophiolite, one representing the products of crustal anatexis, implies that the ophiolite was removed from its oceanic setting and was in the process of obduction in the Givetian.
Persistent Identifierhttp://hdl.handle.net/10722/44691
ISSN
2015 Impact Factor: 2.473
2015 SCImago Journal Rankings: 1.449
References

 

DC FieldValueLanguage
dc.contributor.authorSandeman, HAIen_HK
dc.contributor.authorClark, AHen_HK
dc.contributor.authorScott, DJen_HK
dc.contributor.authorMalpas, JGen_HK
dc.date.accessioned2007-10-30T06:07:52Z-
dc.date.available2007-10-30T06:07:52Z-
dc.date.issued2000en_HK
dc.identifier.citationJournal Of The Geological Society, 2000, v. 157 n. 6, p. 1227-1242en_HK
dc.identifier.issn0016-7649en_HK
dc.identifier.urihttp://hdl.handle.net/10722/44691-
dc.description.abstractThe Kennack Gneiss comprises a suite of interlayered mafic and felsic igneous rocks that intruded the 397 Ma Lizard Ophiolite Complex, Cornwall, at 376.4 ± 1.7 Ma (U-Pb single-zircon date) and were shortly thereafter (c. 370 Ma) metamorphosed to the amphibolite facies. Weakly deformed examples at the type-locality of Kennack Sands reveal net-veining of the mafic by the felsic component, dispersed enclaves of the former in the latter and flame-like interfingering of the two, features indicative of magmatic commingling and mixing. The silicic components of the Kennack Gneiss range from granodiorite to syenogranite and from metaluminous to peraluminous, the least silicic rocks being the most peraluminous. They were generated through anatexis of a predominantly metasedimentary crustal source having trace element and isotopic compositions comparable to those of the Devonian Gramscatho Group of South Cornwall. The mafic component of the gneiss includes members (group 1) which are weakly enriched in light REE, have minor negative Ta, Nb, P and Ti anomalies in extended trace element plots, and display primitive, time-corrected 143Nd/ 144Nd and 87Sr/ 86Sr values, and others (group 2) which are more strongly enriched in all incompatible trace elements, exhibit more prominent negative Ta, Nb, P and Ti anomalies, and have isotopic ratios intermediate between group 1 mafic components and the associated felsic gneiss. Group 2 represents mixtures of group 1 and granitic melts, whereas group 1 rocks are comparable to EMORB and were probably generated through partial melting of a weakly enriched mantle source. Emplacement of two commingled magmas into the base of the Lizard ophiolite, one representing the products of crustal anatexis, implies that the ophiolite was removed from its oceanic setting and was in the process of obduction in the Givetian.en_HK
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dc.format.extent3083 bytes-
dc.format.mimetypeapplication/pdf-
dc.format.mimetypetext/plain-
dc.languageengen_HK
dc.publisherGeological Society Publishing House. The Journal's web site is located at http://www.geolsoc.org.uk/gsl/publications/journals/jgsen_HK
dc.relation.ispartofJournal of the Geological Societyen_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.rightsJournal of Geological Society. Copyright © Geological Society Publishing House.en_HK
dc.subjectCornwall Englanden_HK
dc.subjectKennack Gneissen_HK
dc.subjectLizard complexen_HK
dc.subjectU-Pb, anatexisen_HK
dc.titleThe Kennack Gneiss of the Lizard Peninsula, Cornwall, SW England: Commingling and mixing of mafic and felsic magmas accompanying Givetian continental incorporation of the Lizard ophioliteen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0016-7649&volume=157&issue=6&spage=1227&epage=1242&date=2000&atitle=The+Kennack+Gneiss+of+the+Lizard+Peninsula,+Cornwall,+SW+England:+commingling+and+mixing+of+mafic+and+felsic+magmas+accompanying+Givetian+continental+incorporation+of+the+Lizard+ophioliteen_HK
dc.identifier.emailMalpas, JG: jgmalpas@hku.hken_HK
dc.identifier.authorityMalpas, JG=rp00059en_HK
dc.description.naturepublished_or_final_versionen_HK
dc.identifier.scopuseid_2-s2.0-0033749707en_HK
dc.identifier.hkuros64709-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0033749707&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume157en_HK
dc.identifier.issue6en_HK
dc.identifier.spage1227en_HK
dc.identifier.epage1242en_HK
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridSandeman, HAI=6701319997en_HK
dc.identifier.scopusauthoridClark, AH=13302632500en_HK
dc.identifier.scopusauthoridScott, DJ=13308395600en_HK
dc.identifier.scopusauthoridMalpas, JG=7006136845en_HK

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