Rock Dredging and Geochemistry of the Mid-Atlantic Ridge from 41 Degrees South to 51 Degrees South

南大西洋似乎是地幔两个主要地球化学省之间广阔边界的中心。以南大西洋为中心的DUPAL异常可能是软流圈受到污染的结果，既可能是冈瓦兰岛解体和散布过程中次大陆岩石圈拆沉的结果，也可能是更深层次的地幔热柱在地球内部扩散的结果。将进行一次为期38天的邮轮，从大约41海里到52海里疏浚大西洋中部海脊和邻近的海山。巡航后的分析计划将提供一种手段来研究DUPAL边界的同位素和地球化学性质，描绘Gough、Discovery和Shona海脊外热点对大洋中脊火山活动及其预算的可能影响，并进一步评估两个相互竞争的假设的优点：烟柱扩散模型和亚冈瓦纳大陆岩石圈的拆沉。

The South Atlantic appears to be the locus of a broad boundary between two major geochemical provinces of the earth's mantle. The DUPAL anomaly centered over the South Atlantic may be the result of contamination of the asthenosphere either by delamination of sub- continental lithosphere during the breakup and scatter of Gondwanaland or from the dispersal of mantle plumes of deeper origin within the earth. A 38-day cruise to dredge the Mid- Atlantic Ridge and adjacent seamounts from about 41S to 52S will be conducted. The post-cruise analytical program will provide a means to study the isotopic and geochemical nature of the DUPAL boundary, delineate the possible effects of the Gough, Discovery, and Shona off-ridge hotspots on mid-ocean ridge volcanism and its budget, and further evaluate the merit of two competing hypotheses: the plume dispersion model and the delamination of the sub-Gondwana continental lithosphere.