Rocks of the lower sheeted dike complex of Hole 504B, sampled during Leg 140, were analyzed for trace element compositions (Li, Sc, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Nb, Mo, REE, Hf, Ta, Bi, Th, U, and Cs) using a multielement ICP-MS (inductively coupled plasma mass spectrometry) method. The rocks are relatively uniform in composition and similar to the shallower dikes in Hole 504B. Previous investigations showed systematic depletions in centimeter-sized patches for REE, Zr, Y, TiO2, and P2O5. Data of this study similarly show that Nb, Hf, Sc, Mo, and, to a lesser extent, Li, and Th are also depleted relative to the host rocks. Whereas Rb shows a systematic increase in centimeter-sized patches, elements such as Cr, Co, Ni, Zn, Ga, and Sr show no significant changes compared to adjacent less altered diabases.
Date of initial receipt: 5 August 1994
Date of acceptance: 15 November 1994
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