Migration of the Pacific-Indian Isotopic Boundary and Evolution of the Australian-Antarctic Discordance: A Drilling Site Survey

太平洋-印度同位素边界的迁移和澳大利亚-南极不一致的演变：钻探现场调查

• 批准号: 9403395
• 负责人: David Christie
• 金额: $ 17.87万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-10-01 至 1998-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9403395&HistoricalAwards=false
• 关键词: Migration; Pacific; Indian; Isotopic; Boundary

9403395 An improved understanding of the systematics of mantle circulation is a high scientific priority in solid earth geophysics. By mapping the areal distribution of crustal compositions over key areas of ocean floor, quantitative information about the size, composition, and distribution of mantle reservoirs, variations in mantle temperatures, the efficiency of convective stirring in the mantle, and the longevity of mantle reservoirs can be obtained. One very important problem of this type, which can be addressed by surficial sampling and crustal drilling, concerns the origin and evolution of the distinctive isotopic and geochemical signature of the Indian Ocean spreading centers are isotopically distinct from those of the Pacific. A unique and sharp boundary between Pacific and isotopic provinces has been identified within the Australian- Antartic Discordance along the spreading ridge. The objective of the present project is to map this boundary away from the ridge crest, since limited available data tends to indicate a westward migration of the boundary over time. Seismic reflection, gravity and magnetic data and dredge samples will be collected in the off-axis area during a 40 day research cruise in early 1996. These data will also provide site-survey information in support of a proposal to the Ocean Drilling Program to sample old crust in an attempt to map the history of the boundary. The project involves scientists from the University of Washington, Oregon State University, and Woods Hole Oceanographic Institution.

9403395 提高对地幔环流系统学的认识是固体地球物理学中的一个高度优先的科学问题。 通过绘制海底关键区域地壳成分的区域分布图，可以获得有关地幔储层的大小、组成和分布、地幔温度变化、地幔对流搅动的效率以及地幔储层寿命的定量信息。 这种类型的一个非常重要的问题，这可以通过表层取样和地壳钻探来解决，涉及印度洋扩张中心独特的同位素和地球化学特征的起源和演变，这些中心在同位素上与太平洋扩张中心不同。 在沿着扩张脊的澳大利亚-南极不一致区内，太平洋区和同位素区之间有一条独特而尖锐的边界。 本项目的目标是绘制远离脊顶的边界图，因为有限的现有数据往往表明，随着时间的推移，边界会向西迁移。 1996年初为期40天的研究航行期间，将在轴外区域收集地震反射、重力和磁力数据以及疏浚样本。 这些数据还将提供现场勘测资料，以支持向大洋钻探方案提出的一项建议，即对旧地壳进行取样，以绘制边界的历史图。 该项目涉及来自华盛顿大学、俄勒冈州州立大学和伍兹霍尔海洋研究所的科学家。