georefid:2009-006638SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=10.1093/petrlogy/egn0382008-01-01publicationgeorefid:2009-006638doi:10.1093/petrlogy/egn038Frost, B. RonaldUniversity of Wyoming, Department of Geology and Geophysics, Laramie, WY, United StatesauthorBeard, James S.Virginia Museum of Natural History, United StatesauthorMcCaig, AndrewUniversity of Leeds, United KingdomauthorCondliffe, EricauthorOxford University Press, Oxford, United KingdompublisherdocumentHardcopyJournal of Petrology49 (9)1579-1588Olivine-rich troctolites of Integrated Ocean Drilling Program hole U1309D contain abundant veins along which the olivine has been serpentinized. Where the serpentinite veins cut plagioclase the plagioclase has been altered to prehnite and in many places the prehnite in the core of the vein has been altered to grossular. We show that these Ca-rich assemblages, which we call micro-rodingites, need not have formed by Ca-metasomatism. Instead the micro-rodingites could have occurred during serpentinization as a nearly closed-system process (apart from the addition of water and release of H (sub 2) and Na (super +) ). We argue that in these rocks the alteration of plagioclase occurred as a result of the very low silica activity that accompanies serpentinization. The reaction of plagioclase to prehnite and prehnite to grossular provided a source of SiO (sub 2) that allowed olivine to hydrate to serpentine without producing much brucite. Excess Al (sub 2) O (sub 3) produced by the alteration of plagioclase reacted with serpentine to produce chlorite and additional SiO (sub 2) .completedGeochemistry of rocks, soils, and sedimentsIgneous and metamorphic petrologyAtlantic OceanAtlantisAtlantis SeamountExpedition 304geochemistryIntegrated Ocean Drilling ProgramIODP Site 1309lithogeochemistrymetaigneous rocksmetamorphic rocksmetasomatic rocksmetasomatismMid-Atlantic RidgeNorth Atlanticprocessesrodingiteserpentiniteserpentinizationwater-rock interactionurn:org.iodp:exp:304urnlargerWorkCitationcampaignurn:org.iodp:exp:304:site:U1309urnlargerWorkCitationstudyurn:org.iodp:exp:304urnlargerWorkCitationcampaignurn:org.iodp:exp:305:site:U1309urnlargerWorkCitationstudyurn:org.iodp:exp:305urnlargerWorkCitationcampaignEnglishgeoscientificInformation-42.0700-42.060030.100030.1100