A Detailed Chemical and Isotopic Investigation of Mesozoic Atlantic MORB

摘要/ abstract摘要：本文提出了对中、北大西洋中生代MORB进行详细化学和Sr、Nd、Pb同位素研究的建议。大多数钻探点的玄武岩以前都没有被详细研究过，只有两个钻探点的样本有同位素数据。该项目的目的是扩大我们目前对全球白垩纪中期地幔柱岩浆活动对海洋上地幔组成的影响的研究。中生代太平洋MORB资料表明，在120 Ma左右的中白垩世喷发式造山火山活动开始后不久，太平洋上地幔迅速而广泛地富集了高不相容元素和放射性成因Sr。我们希望限制这种上地幔富集“脉冲”的幅度和地理范围，因为它将提供有关广泛的白垩纪板内火山活动性质的关键信息，并将使我们能够测试火山事件起源与核心-下地幔或下地幔-上地幔边界相互作用的模型。

A DETAILED CHEMICAL AND ISOTOPIC INVESTIGATION OF MESOZOIC ATLANTIC MORB (NSF OCE96-17676) This is a proposal to conduct a detailed chemical and Sr, Nd and Pb isotopic investigation of Mesozoic MORB from the central and North Atlantic. Basalts from most of these drill sites have not been investigated in detail before, and samples from only two drill sites have any isotopic data. The objective of the project is to expand our current investigation of the effects of global mid-Cretaceous plume magmatism on the composition of the oceanic upper mantle. Data for Mesozoic Pacific MORB suggest that the Pacific upper mantle underwent rapid and widespread enrichment in highly incompatible elements and radiogenic Sr soon after the initiation of effusive plateau- and seamount-building volcanism in the mid-Cretaceous around 120 Ma. We wish to constrain the magnitude and geographic extent of this upper mantle enrichment "pulse", as it will provide critical information on the nature of the widespread Cretaceous intraplate volcanism, and will allow us to test models relating the origin of the volcanic event to interactions at the core-lower mantle or lower mantle-upper mantle boundaries.