Temporal and Spatial Geochemical Variations in Patagonian Plateau Basalts: Implications for the Evolution of the Continental Lithosphere

巴塔哥尼亚高原玄武岩的时空地球化学变化：对大陆岩石圈演化的影响

• 批准号: 8903732
• 负责人: Suzanne Kay
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-06-15 至 1991-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8903732&HistoricalAwards=false
• 关键词: Temporal; Spatial; Geochemical; Variations; Patagonian

Continental back-arcs and within-plate basaltic volcanic provinces provide a view into the evolution of the mantle and lower crust beneath continents and the mass flux of materials that are subducted, but not extracted by arc volcanism. One of the largest of these continental basaltic provinces is the Patagonian basalt field in southern South America which extends discontinuously for 1800 km. east of the Andes and in places almost reaches the Atlantic coast. Basaltic volcanism ranges continuously in age from late Paleocene to Recent with activity concentrated in different places at different times. The geographical distribution of the basalts, their spectrum of ages, and their variable basement make the Patagonian plateau an excellent place to examine the cause and effect of varying tectonic conditions on the evolution of the basalts and more indirectly, the crust and mantle. An understanding of the source region of both arc and back-arc rocks is dependant on understanding which components change due to variable tectonic conditions and which are the result of long term mantle and crustal heterogeneities. This project is to examine temporal geochemical variation (using major and trace element chemistry; Nd, Sr and Pb isotopes; and some mineral chemistry) in two regions of the plateau. It complements the detailed studies being done in the Andean arc and the more limited studies of the late-Pliocene to Recent evolution of the plateau. ***//

大陆后弧和板内玄武岩火山省提供了大陆下地幔和下地壳的演化以及被俯冲但未被弧火山作用提取的物质的质量通量的视角。其中最大的大陆玄武岩省之一是南美洲南部的巴塔哥尼亚玄武岩油田，它不连续地延伸了1800公里。安第斯山脉以东，在一些地方几乎到达大西洋海岸。玄武岩火山活动的年龄从古新世晚期到近代不断变化，活动集中在不同的地点和不同的时间。玄武岩的地理分布，它们的年龄谱，以及它们可变的基底，使巴塔哥尼亚高原成为研究不同构造条件对玄武岩演化的原因和影响的绝佳场所，更间接地，地壳和地幔的演化。对弧和弧后岩石源区的了解取决于了解哪些成分因不同的构造条件而变化，哪些是长期地幔和地壳非均质性的结果。该项目旨在研究青藏高原两个地区的时间地球化学变化(使用常量和微量元素化学；Nd、Sr和Pb同位素；以及一些矿物化学)。它补充了安第斯弧区正在进行的详细研究，以及对晚上新世到最近高原演化的更有限的研究。*//