Ancient,highly heterogeneous mantle beneath Gakkel ridge,Arctic Ocean
作者单位：Max-Planck Institut für ChemieAbteilung GeochemieMainz55020Germany Department of GeosciencesUniversity of HoustonHoustonTexas 77204USA. Max-Planck Institut für ChemieAbteilung GeochemieMainz55020Germany.
会议名称：《中国科学院地质与地球物理研究所2008学术年会》
会议日期：2009年
学科分类：070904[理学-构造地质学] 0709[理学-地质学] 07[理学]
摘 要：The Earth’s mantle beneath ocean ridges is widely thought to be depleted by previous melt extraction;but well homogenized by convective *** inference of homogeneity has been complicated by the occurrence of portions enriched in incompatible *** we show that some refractory abyssal peridotites from the ultraslow-spreading Gakkel ridge (Arctic Ocean) have very depleted Os/Os ratios with model ages up to 2 billion years;implying the long-term preservation of refractory domains in the asthenospheric mantle rather than their erasure by mantle *** refractory domains would not be sampled by mid-ocean-ridge basalts because they contribute little to the genesis of *** thus suggest that the upwelling mantle beneath mid-ocean ridges is highly heterogeneous;which makes it difficult to constrain its composition by mid-ocean-ridge basalts ***;the existence of ancient domains in oceanic mantle suggests that using osmium model ages to constrain the evolution of continental lithosphere should be approached with caution.