Collaborative Research: Origins of the Ontong Java Plateau, SW Pacific: A Stratigraphic and Geochemical Study of Exposed Plateau Basement in the Solomon Islands, Part 2

9628252尼尔这个项目是为了继续研究世界上最大的海洋高原的起源和演变，Ontong Java高原（OJP）在西南太平洋。 以前资助的研究补充了大洋钻探计划（ODP）钻探的海底OJP熔岩的工作，重点是所罗门群岛的圣伊莎贝尔和马莱塔的高原基底部分。 这项研究涉及以下任务。 现场工作：在Makira南部和东南部进行详细的地层控制取样，预计这将是Makiran剖面的最深处。 ~（40）Ar-~（39）Ar测年：需要对整个Makiran剖面的样品进行测年，以确定是否存在90 Ma和/或122 Ma熔岩，并确定这些熔岩的意义和厚度。 34马和 64 Ma事件。 地球化学和岩石学：系统的主要和微量元素，和Nd-Pb-Sr同位素分析，需要确定Makiran地球化学地层学，特别是，地球化学变化的OJP型熔岩与深度，广泛的MORB类玄武岩的性质和地层范围，和性质和原因的夹层的两种类型。 铂族元素（PGEs）：从以前的研究结果表明，从Malaita和ODP钻井现场的熔岩富含亲铁元素W和Mo，并可能表明OJP的地幔源的核幔边界起源。 进一步评估这一假设需要确定丰度的超嗜铁铂族元素的一个子集的OJP熔岩。

9628252 Neal This project is for a continuation of research into the origin and evolution of the world's largest oceanic plateau, the Ontong Java Plateau (OJP) in the SW Pacific. Previously funded study, complementing work on submarine OJP lavas drilled by the Ocean Drilling Program (ODP), focused on plateau basement sections on Santa Isabel and Malaita, Solomon Islands. This research involves the following tasks. FIELDWORK: Detailed, stratigraphically controlled sampling in south and southeastern Makira, in what is expected to be the deepest part of the Makiran section. 40Ar-39Ar DATING: Dating of samples from throughout the Makiran section is required to determine if 90 Ma and/or 122 Ma lavas are present, and to establish the significance and thickness of the 34 Ma and 64 Ma events. GEOCHEMISTRY AND PETROGRAPHY: Systematic major and trace element, and Nd-Pb-Sr isotopic analyses are required to define Makiran geochemical stratigraphy; in particular, the geochemical variation of OJP-type lavas with depth, the nature and stratigraphic extent of the broadly MORB-like basalts, and the nature and causes of intercalation of the two types. PLATINUM GROUP ELEMENTS (PGEs): Results from previous study show that lavas from Malaita and ODP drill sites are enriched in the siderophile elements W and Mo, and may indicate a core-mantle boundary origin for the OJP's mantle source. Further evaluation of this hypotheses requires determination of abundances of the ultra-siderophilic PGEs for a subset of OJP lavas.