georefid:2006-066604georefid:2006-066600SEDIS 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=10.2973/odp.proc.sr.195.103.20052006-01-01publicationgeorefid:2006-066604doi:10.2973/odp.proc.sr.195.103.2005Savov, Ivan P.University of South Florida, Department of Geology, Tampa, FL, United StatesauthorGuggino, SteveGeological Survey of Canada, CanadaauthorRyan, Jeffrey G.Ocean Drilling Program, United StatesauthorFryer, Patricia B.Japan Agency for Marine-Earth Science and Technology, JapanauthorMottl, Michael J.University of Leicester, United KingdomauthorTexas A&M University, Ocean Drilling Program, College Station, TX, United StatespublisherdocumentDigitalIn: Shinohara, Masanao (editor), Salisbury, Matthew H. (editor), Richter, Carl (editor), Araki, Eiichiro, Barr, Samantha R., D'Antonio, Massimo, Dean, Simon M., Diekmann, Bernhard, Edwards, K. Michelle, Fryer, Patricia B., Gaillot, Philippe J., Hammon, William S., III, Hart, David, Januszczak, Nicole, Komor, Stephen C., Kristensen, Mette B., Lockwood, John P., Mottl, Michael J., Moyer, Craig L., Nakahigashi, Kazuo, Savov, Ivan P., Su Xin, Wei, Kuo-Yen, Yamada, Tomoaki, Proceedings of the Ocean Drilling Program; scientific results; seafloor observatories and the Kuroshio Current; covering Leg 195 of the cruises of the drilling vessel JOIDES Resolution; Apra Harbor, Guam, to Keelung, Taiwan; Sites 1200-1202; 2 March-2 May 2001195New geochemical data on serpentinite muds and metamorphic clasts recovered during Ocean Drilling Program Legs 195 (Holes 1200A-1200E) and 125 (Holes 778A and 779A) provide insights into the proportions of rock types of various sources that compose the serpentinite mudflows and the fluid-rock interactions that predominate in these muds. We interpret the metamorphic rock fragments as derivatives of mostly metamorphosed mafic rocks from the descending Pacific oceanic crust. Based on their mid-ocean-ridge basalt (MORB)-like Al (sub 2) O (sub 3) , TiO (sub 2) , CaO, Si/Mg, and rare earth element (REE) systematics, these metamorphic rocks are classified as metabasalts/metagabbros and, therefore, approximately 30-km depths represent an active subduction zone setting. The serpentinite muds from Holes 1200A and 1200E have slightly lower REE when compared to Hole 1200D, but overall the REE abundance levels range between 0.1-1 X chondrite (CI) levels. The chondrite-normalized patterns have [La/Sm]N approximately 2.3 and [Sm/Yb]N approximately 2. With the exception of one sample, the analyzed metamorphic clasts show flat to slightly depleted light REE patterns with 1.0-15 X CI levels, resembling MORBs. Visually, approximately 6 vol% of the serpentinized muds are composed of "exotic" materials (metamorphic clasts [schists]). Our mixing calculations confirm this result and show that the serpentinite muds are produced by additions of approximately 5% metamafic materials (with flat and up to 10 X CI REE levels) to serpentinized peridotite clast material (with very low REE abundances and U-shaped chondrite-normalized patterns). The preferential incorporation of B, Cs, Rb, Li, As, Sb, and Ba into the structure of H (sub 2) O-bearing sheet silicates (different than serpentine) in the Leg 125 and Leg 195 metamorphic clasts (chlorite, amphibole, and micas) have little effect on the overall fluid-mobile element (FME) enrichments in the serpentinite muds (average B = approximately 13 ppm; average Cs = approximately 0.05 ppm; average As = approximately 1.25 ppm). The extent of FME enrichment in the serpentinized muds is similar to that described for the serpentinized peridotites, both recording interaction with fluids very rich in B, Cs, and As originating from the subducting Pacific slab.completedGeochemistry of rocks, soils, and sedimentsIgneous and metamorphic petrologybasaltsclastic sedimentsConical Seamountgeochemistryigneous rocksLeg 125Leg 195Mariana Trenchmarine sedimentsmetaigneous rocksmetalsmetamorphic rocksmetasomatic rocksmid-ocean ridge basaltsmudNorth PacificNorthwest PacificOcean Drilling Programocean floorsODP Site 1200ODP Site 778ODP Site 779Pacific Oceanpatternsrare earthsseamountssedimentsserpentiniteSouth Chamorro Seamountvolcanic rocksWest Pacificurn:org.iodp:exp:125urnlargerWorkCitationcampaignurn:org.iodp:exp:195urnlargerWorkCitationcampaignurn:org.iodp:exp:195:site:1200urnlargerWorkCitationstudyurn:org.iodp:exp:195urnlargerWorkCitationcampaignurn:org.iodp:exp:125:site:778urnlargerWorkCitationstudyurn:org.iodp:exp:125urnlargerWorkCitationcampaignurn:org.iodp:exp:125:site:779urnlargerWorkCitationstudyurn:org.iodp:exp:125urnlargerWorkCitationcampaignEnglishgeoscientificInformation146.0000146.414513.470019.3045Available only on CD-ROM in PDF format and on the Web in PDF or HTMLapplication/pdfunknownSEDIS Publication Catalogue

ana.macario@awi.de

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