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

研究人员将继续研究确定年轻玄武岩火山岩年龄的新方法，玄武岩火山岩是地球上喷发过的最丰富的熔岩类型。该研究包括测量Pb同位素组成，并测量矿物、玻璃和火山岩中接地块中的U/Pb和Th/Pb比率。这项研究需要一种特殊的方法来测量铅同位素比率。这种方法是在以前的资助下开发的，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被运送到地表进行喷发的过程。这项工作的重点是将这项技术应用于海底基性熔岩，特别是钾浓度低的海底基性熔岩。低钾熔岩在地球上分布广泛，特别难以用其他方法确定年代。初步研究表明，许多玄武岩矿物中的铅同位素变化比预期的要大。这些变化的原因和影响也将进一步研究。将被测量的岩石和矿物将从夏威夷、美国西部和意大利收集，另外的海底熔岩将从其他来源获得。为了帮助解释Pb同位素数据，还将对Sr和Nd同位素进行分析。

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.