Rock Classification Scheme (BGS).pdf - The Water, Sanitation and ...

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level 5 level 6 level 7 level 8HIERARCHICAL LEVELFIELDCLASSIFICATIONrhyolitic-rockdacitic-rockQAPF CLASSIFICATIONalkali-feldspar-rhyoliterhyolitedacitequartz-alkali-feldspar-trachyteQAPFFIELD234,56*felsitealkali-feldspar-trachyte6Note that the terms felsiteand mafite are intended tobe used in the fieldclassification of generallylight and generally darkaphanitic rocks, respectively.However, the compositionof such rocks may notalways correspond to one ofthe rock types at level 7 or 8to which they are attachedon this diagram.trachytic-rockfoid-bearingalkali-feldspar-trachytequartz-trachytetrachytefoid-bearing-trachytequartz-latite6'7*77'8*latite8FINE-GRAINEDNORMALCRYSTALLINEROCKSandesitic-rockbasaltic-rockfoid-bearing-latiteandesitebasalt8'9, 109, 10Where the name of agroup of minerals appearsin a root name, it may bereplaced by a moredefinitive mineral name,where appropriate. Forexample sanidine-rhyoliteinstead of alkali-feldsparrhyolite,and nephelinebearing-latiteinstead offoid-bearing-latite.phonolitic-rocktephritic-rockphonolitetephritic-phonolitephonolitic-basanitephonolitic-tephritebasanite1112131314mafitetephritephonolitic-foidite1415afoiditic-rockbasanitic-foiditetephritic-foidite15b15bfoidite15cultramafitite16Figure 17a Hierarchical classification of fine-grained normal crystalline rocks with QAPFclassification at level 8.40
level 5 level 6level 7level 8level 9FIELDCLASSIFICATIONTAS CLASSIFICATIONrhyolitic-rockrhyolite (TAS)dacitic-rockdacite (TAS)felsitetrachyte (TAS)trachydaciteNote that the terms felsiteand mafite are intended tobe used in the fieldclassification of generallylight and generally darkaphanitic rocks, respectively.However, the compositionof such rocks may notalways correspond to one ofthe rock types at level 7 or 8to which they are attachedon this diagram.trachytic-rockandesitic-rocktrachyandesitebasaltic-trachyandesitetrachybasaltandesite (TAS)basaltic-andesitebenmoreitelatite (TAS)mugeariteshoshonitehawaiitepotassic-trachybasaltboninite *FINE-GRAINEDNORMALCRYSTALLINEROCKSbasaltic-rockphonolitic-rocktephritic-rockbasalt (TAS)phonolite (TAS)tephri-phonolitephono-tephritebasanite (TAS)* The term 'picritic rocks'was recommended by LeMaitre et al. (1989) toinclude the rock namespicrite, komatiite andmeimechite. These,together with boninite,are 'high-Mg' rocks andtherefore cannot beclassified using TAS alone.See section 5.2.5.1mafitetephrite (TAS)foiditic-rockfoidite (TAS)picritepicritic-rock *komatiitemeimechitepicrobasaltFigure 17b Hierarchical classification of fine-grained normal crystalline rocks with TASclassification at levels 8 and 9.41
Page 1 and 2: BRITISH GEOLOGICAL SURVEYRESEARCH R
Page 3 and 4: Contents1 Introduction1.1 Principle
Page 5 and 6: 1 INTRODUCTIONThe use of computers
Page 7 and 8: tion of these rocks (Figure 2b), ha
Page 9 and 10: vi The use of 0.032 mm as an import
Page 11 and 12: to 75% are angular, in a block-bomb
Page 13 and 14: Field 3Field 4Field 5Fields 6Field
Page 15 and 16: (ii) If an accurate mineral mode ca
Page 17 and 18: Field S1 Rocks with the root name t
Page 19 and 20: esulting from the presence of macro
Page 21 and 22: still be a granite in the sense of
Page 23 and 24: increasing abundance. This usage in
Page 25 and 26: REFERENCESBELLIENI, G, VISENTIN, E
Page 27 and 28: kersantite lamp 31kimberlitekimbkom
Page 29 and 30: level 1 level 2 level 3 level 4Grou
Page 31 and 32: PhiunitsClast orcrystalsize in mm.L
Page 33 and 34: Figure 5 Classification andnomencla
Page 35 and 36: level 5 level 6 level 7HIERARCHICAL
Page 37 and 38: QquartzoliteLevel 790 90alkali-feld
Page 39 and 40: level 7 level 8HIERARCHICAL LEVELga
Page 41: Level 8duniteOI90 904040peridotitep
Page 45 and 46: QLevel 890906060alkali-feldspar-rhy
Page 47 and 48: 4 Na 2 O + K 2 O wt %3foidite (TAS)
Page 49 and 50: level 5 level 6 level 7COARSE-GRAIN
Page 51 and 52: 'Old name' phl cpx leu kal melolgls
Page 53 and 54: Q = 60 - 20 Q = 20 - 5P'0-10 10-65

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