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

南大西洋似乎是一个广阔边界的所在地 在地球地幔的两个主要地球化学区域之间。 的 以南大西洋为中心的DUPAL异常可能是 软流圈的污染， 大陆岩石圈在断裂和分散过程中 冈瓦纳大陆或来自更深的地幔柱的扩散 起源于地球。 为期38天的航行，以疏浚中- 大西洋海岭和邻近的海山从大约41 S到52 S将是 进行。 巡航后的分析程序将提供一种手段， 为了研究DUPAL边界的同位素和地球化学性质， 描述高夫号、发现号和绍纳号可能造成的影响 关于大洋中脊火山活动及其预算的脊外热点， 进一步评估两个相互竞争的假设的优点： 分散模型与次冈瓦纳大陆的拆沉 大陆岩石圈

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.