Collaborative Research: Isotopic constraints on the mineralogy of the MORB source

合作研究：MORB 源矿物学的同位素限制

• 批准号: 0241053
• 负责人: Vincent Salters
• 金额: $ 28.08万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0241053&HistoricalAwards=false
• 关键词: Collaborative; Research; Isotopic; constraints; mineralogy

Under this award, the PIs propose to analyze approximately 50 abyssal peridotites for Nd-isotopes to determine whether variations in Nd-isotopic composition in ridge basalts are also observed in the associated peridotites. Abyssal peridotites are thought to be the residues of melting that lead to mid-ocean ridge basalts, however in a study on two segments of the South West Indian Ridge (SWIR) the PIs showed that the 143Nd/144Nd of abyssal peridotites are more radiogenic than MORB and do not span the range as the basalts. This surprising result may indicate that the peridotite is not the sole source of the basalts, and most likely, a lithology with a lower melting temperature than peridotite (like pyroxenite) is present in the MORB source. The purpose of this study is to confirm and extend these observations. Samples of Normal MORB will come from the Kane and Gibbs fracture zone, Garrett FZ, Hess Deep and the orthogonal spreading segment between 17 degrees and 30 degrees E along the SWIR. In addition samples will be studied from areas that are clearly influenced by hot spots: the Oceanographer fracture zone (Azores plume) the area of the Indian Ocean between 33 degrees - 45 degrees E (Marion hot spot).

根据该奖项，PI提议分析ND同位素的大约50个深处橄榄岩，以确定在相关的橄榄岩中也观察到脊玄武岩中ND同位素组成的变化。深渊橄榄岩被认为是导致中山脊的融化的残留物，但是在一项对西南印度山脊（SWIR）的两段的研究中，PIS表明，第143/144个稀疏的郊区橄榄石是放射线比Morb更具放射性的，并且不超过范围。这种令人惊讶的结果可能表明，橄榄岩不是玄武岩的唯一来源，并且最有可能的熔化温度较低的岩性比橄榄石（如吡乙富）（如pyroxenite）中存在。这项研究的目的是确认和扩展这些观察结果。正常MORB的样本将来自Kane和Gibbs断裂区，Garrett FZ，Hess Deep以及沿SWIR的17度和30度E之间的正交扩散段。另外，将从明显受热点影响的区域研究样品：海洋骨折区（Azores Plume）印度洋的面积在33度-45度E（Marion Hot Sot）之间。