georefid:2007-075929SEDIS 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=10.1130/G23741A.12007-01-01publicationgeorefid:2007-075929doi:10.1130/G23741A.1Ingle, StephanieTokyo Institute of Technology, Department of Earth and Planetary Sciences, Tokyo, JapanauthorMahoney, John J.University of Hawaii, United StatesauthorSato, HiroshiSenshu University, JapanauthorCoffin, Millard F.University of Tokyo, JapanauthorKimura, Jun-IchiShimane University, JapanauthorHirano, NaotoChiba University, JapanauthorNakanishi, MasaoauthorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyGeology (Boulder)35 (7)595-598Numerous large igneous provinces formed in the Pacific Ocean during Early Cretaceous time, but their origins and relations are poorly understood. We present new geochronological and geochemical data on rocks from the Manihiki Plateau and compare these results to those for other Cretaceous Pacific plateaus. A dredged Manihiki basalt gives an (super 40) Ar- (super 39) Ar age of 117.9+ or -3.5 Ma (2sigma ), essentially contemporaneous with the Ontong Java Plateau approximately 2500 km to the west, and the possibly related Hikurangi Plateau approximately 3000 km to the south. Drilled Manihiki lavas are tholeiitic with incompatible trace element abundances similar to those of Ontong Java basalts. These lavas may result from high degrees of partial melting during the main eruptive phase of plateau formation. There are two categories of dredged lavas from the Danger Islands Troughs, which bisect the plateau. The first is alkalic lavas having strong enrichments in light rare earth and large-ion lithophile elements; these lavas may represent late-stage activity, as one sample yields an (super 40) Ar- (super 39) Ar age of 99.5+ or -0.7 Ma. The second category consists of tholeiitic basalts with U-shaped incompatible element patterns and unusually low abundances of several elements; these basalts record a mantle component not previously observed in Manihiki, Ontong Java, or Hikurangi lavas. Their trace element characteristics may result from extensive melting of depleted mantle wedge material mixed with small amounts of volcaniclastic sediment. We are unaware of comparable basalts elsewhere.completedIgneous and metamorphic petrologyGeochemistry of rocks, soils, and sedimentsabsolute ageaffinitiesAr/ArAustralasiabasaltsCentral PacificcoresCretaceousdatesDeep Sea Drilling Projectdredged samplesDSDP Site 317East PacificgeochemistryHikurangi Troughigneous rockslarge igneous provinceslavaLeg 33lithophile elementsLower CretaceousManihiki Plateaumantlemantle wedgesmarine sedimentsMesozoicmetalsNew ZealandOntong Java PlateauPacific Oceanrare earthssedimentsSouth PacificSoutheast Pacifictholeiitic basalttrace elementsvolcanic rocksvolcaniclasticsWest Pacificurn:org.iodp:exp:33urnlargerWorkCitationcampaignurn:org.iodp:exp:33:site:317urnlargerWorkCitationstudyurn:org.iodp:exp:33urnlargerWorkCitationcampaignEnglishgeoscientificInformation-170.0000-160.0000-15.0000-5.0000With GSA Data Repository Item 2007150