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区域之间广阔边界的所在地。以南大西洋为中心的DUPAL异常可能是由于冈瓦纳大陆分裂和分散期间次大陆岩石圈的分层或地球内部更深起源的地幔柱的分散而造成的软流层污染的结果。将进行为期38天的航行，在南纬41度至南纬52度之间疏浚中大西洋岭及邻近的海山。该项目将为研究DUPAL边界的同位素和地球化学性质提供一种手段，描绘Gough、Discovery和Shona离海热点对洋中脊火山活动及其收支的可能影响，并进一步评估两种相互竞争的假设的优点：羽散模型和亚冈瓦纳大陆岩石圈的分层。

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.