The Plutonic Foundation of a Slow-spreading Ridge Segment: The Kane Oceanic Core Complex (23 degrees 30'N, 45 degrees 20' W)

这是对第一批系统样品的岩石学和地球化学的研究，这些样品代表了缓慢扩张的洋中脊的深成基础。 这些岩石来自一个20 × 35 km ~ 370万年的核杂岩，对应于凯恩断裂带以南的二级脊段。 2004年秋季，海洋开发计划署与Seabeam、深拖磁力学和测深学、疏浚和Jason号一起进行了现场调查，绘制了地图。 采集了2667公斤岩石样本。 岩石系统地出露在杂岩上，纯橄榄岩和橄榄岩表明一个约10公里宽的集中地幔熔体流区，为一个古老的南部火山中心提供了补给。 北部这些岩石的稀缺性表明，上覆的闪长岩和枕状玄武岩可能代表南部岩浆中心的轴向裂缝喷发。 这些观测结果与相对构造板块上的火山壳相匹配，其中轴向火山高压对应于岩浆中心的位置。 这些样品将使人们能够第一次研究“正常”大西洋中脊扩张段下的熔体生成和地壳增生。 它们可以限制熔融过程，并允许比较橄榄岩的组成，从一个正常的山脊熔融环境，那些代表极低程度的熔融在加克尔岭，可能是接近MORB地幔源组成。

This is a study of the petrology and geochemistry of the 1st systematic samples representing the plutonic foundation of a slow-spreading mid-ocean ridge. The rocks are from a 20 by 35 km ~3.7 million year old core complex corresponding to the 2nd order ridge segment south of the Kane Fracture Zone. An ODP Site Survey with Seabeam, deep-tow magnetics and bathymetry, dredging and the Jason ROV mapped it in fall 2004. 2667 kg of rock were sampled. Rocks outcrop systematically over the complex, with dunite and troctolite indicating a ~10 km wide focused mantle melt flow zone that fed an ancient southern volcanic center. The scarcity of these rocks to the north indicates that the overlying diabase and pillow basalt likely represent down-axis fissure eruptions from the southern magmatic center. These observations match the volcanic carapace on the opposing tectonic plate, where an axial volcanic high corresponds to the position of the magma center. The samples will allow the study of melt generation and crustal accretion beneath an end-member "normal" Mid-Atlantic Ridge spreading segment for the first time. They can constrain the melting process, and allow comparison of peridotite compositions from a normal ridge-melting environment to those representing extreme low-degrees of melting at the Gakkel Ridge that may lie close to the MORB mantle source composition.