U-Th-Pb Geochronology and Mineral Pb Systematics of Quaternary Basalt

第四纪玄武岩U-Th-Pb年代学及矿物铅系统学

• 批准号: 9909590
• 负责人: Donald DePaolo
• 金额: $ 18.97万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909590&HistoricalAwards=false
• 关键词: Th; Pb; Geochronology; Mineral; Systematics

EAR-9909590DePaoloDevelopment will continue on a new method for determining the ages of young basaltic volcanic rocks, the most abundant lava type erupted on the earth. The research involves measurements of Pb isotopic composition combined with measurements of U/Pb and Th/Pb ratios in minerals, glass and groundmass in volcanic rocks. The research requires a special approach to measuring Pb isotope ratios. The approach had been developed with a previous grant, but we hope to improve the resolution. With this new technique it will be possible to better understand the processes by which magma is produced in the earth and transported to the surface for eruption. The work will focus on application of the technique to submarine mafic lavas, particularly those with low potassium concentrations. Low-K lava is widespread on the earth, and particularly difficult to date by other methods. Preliminary work shows that Pb isotopes in minerals of many basalts are more variable than expected. The causes and implications of these variations will befurther investigated as well. The rocks and minerals that will be measured will be collected from Hawaii, the western U.S., and Italy, and additional submarine lavas will be obtained from other sources. To help interpret the Pb isotope data, analyses of Sr and Nd isotopes will also be made.

DePaolo将继续开发一种新的方法来确定年轻玄武质火山岩的年龄，这是地球上喷发的最丰富的熔岩类型。该研究包括火山岩矿物、玻璃和基质中Pb同位素组成的测量，以及U/Pb和Th/Pb比值的测量。 这项研究需要一种特殊的方法来测量铅同位素比值。 这种方法是用以前的赠款开发的，但我们希望提高分辨率。 有了这项新技术，就有可能更好地了解岩浆在地球上产生并输送到地表喷发的过程。 这项工作将侧重于将这项技术应用于海底镁铁质熔岩，特别是那些钾浓度低的熔岩。 低钾熔岩在地球上广泛分布，特别难以通过其他方法确定年代。 初步研究表明，许多玄武岩矿物中的铅同位素比预期的更易变。 这些变化的原因和含义也将进一步研究。 将被测量的岩石和矿物将从美国西部的夏威夷收集，和意大利，并将从其他来源获得更多的海底熔岩。为了帮助解释Pb同位素数据，还将进行Sr和Nd同位素分析。