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

缓慢扩张的山脊部分的深成岩基础：凯恩海洋核心复合体（北纬 23 度 30，西经 45 度 20）

• 批准号: 0624408
• 负责人: Henry Dick
• 金额: --
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-11-01 至 2009-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0624408&HistoricalAwards=false
• 关键词: Plutonic; Foundation; Slow; spreading; Ridge

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.

这是对第一个系统样品的岩石学和地球化学研究，代表了一个缓慢扩张的洋中脊的深成基础。岩石来自一个20 × 35 km ~ 370万年的岩心杂岩，对应于凯恩断裂带以南的二级脊段。2004年秋天，ODP利用海床、深拖曳磁学和测深技术、疏浚和Jason ROV进行了现场调查。采集了2667公斤岩石样本。岩石系统地露头于杂岩之上，其中的泥质岩和滑石岩显示出一个约10公里宽的集中地幔熔体流带，为一个古老的南部火山中心提供了食物。这些岩石在北部的稀缺性表明，上覆的辉绿岩和枕状玄武岩可能代表了南部岩浆中心的下轴裂缝喷发。这些观测结果与相对构造板块上的火山壳相吻合，其中轴向火山高对应于岩浆中心的位置。这些样品将首次允许研究熔体产生和地壳增生，在一个末端成员“正常”大西洋中脊扩张段之下。它们可以限制熔融过程，并可以将正常的山脊熔融环境中的橄榄岩组成与可能接近MORB地幔源组成的Gakkel山脊的极低熔融程度的橄榄岩组成进行比较。