Feraud, Gilbert; Beslier, Marie-Odile; Cornen, Guy (1996): (super 40) Ar/ (super 39) Ar dating of gabbros from the ocean/continent transition of the western Iberia Margin; preliminary results. Texas A&M University, Ocean Drilling Program, College Station, TX, United States, In: Whitmarsh, Robert B., Sawyer, Dale S., Klaus, Adam, Beslier, Marie-Odile, Collins, Eric S., Comas, Maria Carmen, Cornen, Guy, de Kaenel, Eric, Pinheiro, Luis de Menezes, Gervais, Elisabeth, Gibson, Ian L., Harry, Dennis L., Hobart, Michael A., Kanamatsu, Toshiya, Krawcyzk, Charlotte M., Liu, Li, Lofts, Jeremy C., Marsaglia, Kathleen M., Meyers, Philip A., Milkert, Doris, Milliken, Kitty L., Morgan, Julia K., Ramirez, Pedro, Seifert, Karl E., Shaw, Timothy J., Wilson, Chris, Yin, Chuan, Zhao, Xixi, Proceedings of the Ocean Drilling Program; scientific results, Iberia abyssal plain; covering Leg 149 of the cruises of the Drilling Vessel JOIDES Resolution; Balboa Harbor, Panama, to Lisbon, Portugal; sites 897-901, 10 March-25 May 1993, 149, 489-495, georefid:2007-088109

Ocean Drilling Program Hole 899B on the Iberia Abyssal Plain penetrated a thick serpentinite breccia flow underlain by smaller breccia flows, all separated by sediments containing weathered basalt and diabase (microgabbro) clasts. The basalt and diabase clasts, some with discolored weathering rinds, recovered with Early Cretaceous sediments below the thick upper serpentinite breccia, have the compositional characteristics of mid-ocean ridge basalt (MORB) modified by weathering on the seafloor. Seafloor weathering has added MgO and K (sub 2) O and removed CaO from the clasts, resulting in strongly modified major element compositions. However, the more immobile trace elements remain largely unaltered, and all basalt and diabase clasts have rare-earth element and spidergram patterns similar to transitional to enriched MORB (E-MORB). The E-MORB clasts are similar to the type of mid-ocean ridge volcanism that later produced the Atlantic Ocean floor in the region of the present Azores Plateau. The incompatible element enrichment necessary to produce E-MORB indicates a plume contribution and suggests that Early Cretaceous rifting on the Iberia Abyssal Plain was plume initiated despite the lack of extensive volcanism.
West: -12.1604 East: -12.1604 North: 40.4622 South: 40.4622
Expedition: 149
Site: 149-899
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.2973/odp.proc.sr.149.225.1996 (c.f. for more detailed metadata)
Data download: application/pdf
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