Pervasive mantle plume head heterogeneity: Evidence from the late Cretaceous Caribbean-Colombian oceanic plateau Public Deposited

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  • In SW Colombia picritic pillow lavas and tuffs, as well as breccias composed of picritic clasts, occur interspersed with basalts of the Central Cordillera and represent accreted portions of the similar to 90 Ma Colombian/Caribbean oceanic plateau (CCOP). We present new geochemical data for these picrites and high-MgO basalts from SW Colombia, along with new data from Deep Sea Drilling Project Leg 15 drill sites. The Ar-40/Ar-39 ages for the CCOP in the Central Colombian Cordillera range from 87 to 93 Ma. Both SW Colombia picrites and Leg 15 basalts are compositionally diverse and range from reasonably enriched ((La/Nd)(n) > 1 and (ε(Nd))(i) < +4.1) to relatively depleted ((La/Nd)(n) < 1 and (ε(Nd))(i) > +8.0). Nb/Y and Zr/Y systematics suggest that the depleted component is not depleted MORB mantle, but is an intrinsic part of the plume. The bulk of the CCOP compositions can be explained by mixing between this depleted mantle and a HIMU component. However, radiogenic isotope systematics indicate the presence of an EM2 (or possibly EM1) component within the plume. Mantle melt modeling suggests that the enriched magma types are the product of deeper, small degree melting of a pervasively heterogeneous plume comprising a refractory matrix with enriched streaks/blobs, whereas shallower, more extensive melting, results in the formation of relatively depleted magmas.
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  • Kerr, A.C., Tarney, J., Kempton, P.D., Spadea, P., Nivia, A., Marriner, G.F., Duncan, R.A., 2002, Pervasive mantle plume head heterogeneity: Evidence from the late Cretaceous Caribbean-Colombian oceanic plateau. Journal of Geophysical Research, Vol. 107, pg.2-1--2-13
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  • description.provenance : Submitted by Linda Lamb (llamb@coas.oregonstate.edu) on 2010-04-12T23:39:25Z No. of bitstreams: 1 Kerr_et_al_JGR_2002.pdf: 1100745 bytes, checksum: c60a6bd5938ec8c0c0a28c5f83f24b61 (MD5)
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  • 0148-0227

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