Criteria for Recognit

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Recognition of Extension-Rifting Environments inAncient SuccessionsPetrochemical Criteria:Ancient rift successions have a chemostratigraphy defined bydistinct petrochemical assemblages of mafic and felsic rocks that areindicative of an extension that differ somewhat with geodynamicsetting and, therefore, with Lithostratigraphic Deposit TypeA VMS productive rift succession should contain high-temperaturefelsic (e.g., FIII-FII, HFSE-enriched) and mafic (e.g., BON-LOTI,MORB) volcanic (intrusive) rocks
Lithostratigraphic Classification of VMS DepositsType Typical Facies Petrochemical Assemblages Tectonic Setting(Inferred for Archeanexamples)MaficDominantly mafic flows and, 10% felsicflows/domes. Mafic sills and dikescommon, minor argillite and chert.(Ophiolitic assemblages)MORB- LOTI-boninite basaltsMature intra-oceanicbackarcsExamplesSouth Urals, RussiaCentral Newfoundland, CanadaTroodos, CyprusSemail, OmanPontides, Turkey and AlbaniaPelitic-maficMafic sills, subordinate flows withargillite, carbonaceous argillite subequalor dominant, minor chert and trace toabsent felsic volcanic facies.MORB, EMORB basalts,Alkaline basalt (OIB)Sedimented mid-oceanridges, transforms orbackarcsOutokumpu, FinlandLabrador Trough, Windy Craggy, CanadaMid and South Urals, RussiaBesshi district, JapanBimodal-mafic Dominantly mafic flows with up to 25%felsic flows/domes and subordinatefelsic/mafic volcaniclastic rocks andterrigenous sedimentary rocks (wackes,argillites)Bimodal-felsic Felsic flows/domes, volcaniclastic rocksdominant with 10-40% mafic flows andsills and /= FII rhyolitesMORB, OIB-Alkalic basaltFII (
Page 1 and 2: The Role of Extension and Rifting i
Page 3 and 4: OutlineExtension and Rifting - defi
Page 5 and 6: Extension and Rifting(McKenzie and
Page 7 and 8: Seafloor Hydrothermal Vents and Rel
Page 9 and 10: Examples from Modern Geodynamic Env
Page 11 and 12: Arc-frontVolcanoesBrothers VolcanoS
Page 13: Early Arc Rifting and Proto-Backarc
Page 18 and 19: The Manus Back-arc Basins (4 m.y. o
Page 20 and 21: Lau Back-Arc BasinNorthFijiLauSouth
Page 22 and 23: Lau BasinHawkins →general trendfr
Page 24 and 25: Distribution of Western Pacific Hyd
Page 26 and 27: Sibuet et al.,1998
Page 28 and 29: Recognition of Extension-Rifting En
Page 30 and 31: Altay-Sayan DistrictBathurst Distri
Page 32 and 33: Dikes in FlowsDikes in volcaniclast
Page 34 and 35: 1 st Generation2 nd Generation
Page 36 and 37: Basalt DikePillowFB BasaltDike
Page 38 and 39: PillowedBlockMega-Breccia - Evidenc
Page 40 and 41: Recognition of High-Temperature Sem
Page 42 and 43: .Subvolcanic Plutons
Page 44 and 45: Caldera Recognition• Multiphase,
Page 48 and 49: VMS- and Rift-Related Mafic Rocks
Page 50 and 51: Piercey and Gibson, 2005
Page 54 and 55: VMS- and Rift-Related FelsicRocks
Page 56 and 57: FI-FIV RhyolitesAfter Hart et al.,
Page 58 and 59: after Piercey and Gibson, 2005
Page 60 and 61: VMS- and Rift-Related FelsicRocks:

Criteria for Recognit

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