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Involvement of Continental Crust in the Formation of the Cretaceous Kerguelen Plateau: New Perspectives from ODP Leg 120 Sites |
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| Authors: | FREY FREDERICK A; WEIS DOMINIQUE; BORISOVA ANASTASSIA YU; XU G |
| Institution: | 154-1226, DEPARTMENT OF EARTH, ATMOSPHERIC AND PLANETARY SCIENCES, MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, MA 02139, USA 2DEPARTMENT OF EARTH AND ENVIRONMENTAL SCIENCES, CP 160/02, UNIVERSITÉ LIBRE DE BRUXELLES, AV. F. D. ROOSEVELT, 50, B-1050 BRUSSELS, BELGIUM 3VERNADSKY INSTITUTE OF GEOCHEMISTRY AND ANALYTICAL CHEMISTRY, KOSYGIN ST. 19, 117975, MOSCOW, RUSSIA |
| Abstract: | The basaltic basement of the large igneous province formed bythe Kerguelen Plateau and Broken Ridge in the southeastern IndianOcean has been sampled by three Ocean Drilling Program cruises(Legs 119, 120 and 183). Although the Cretaceous parts of thisplateau formed in the embryonic Indian Ocean basin, presumablyby melting associated with the Kerguelen plume, trace elementabundances and isotopic ratios of Sr, Nd and Pb of Cretaceousbasalt from several drill sites indicate that continental lithospherewas involved in their petrogenesis. On the basis of relativedepletions in Nb, Ta and Th, and isotopic characteristics similarto those of EMI ocean island basalt, lavas from Leg 120 Site747 in the Central Kerguelen Plateau contain a component derivedfrom lower continental crust. On the basis of relative abundancesof Sr and Eu and EMI-like Pb isotopic ratios, the source ofbasalt from Leg 120 Site 750 in the northeastern part of theSouthern Kerguelen Plateau also contained a component derivedfrom lower continental crust; in this case, the crustal componentformed as a plagioclase-rich, clinopyroxene-bearing cumulate.Basalts from Leg 120 Site 749 define two distinct isotopic (Sr,Nd and Pb) groups which differ from the isotopic fields forSite 747 and 750 basalts. Among Site 749 lavas, there is subtleevidence for a continental component, broadly similar (i.e.moderate 206Pb/204Pb |
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