Investigation of Biotite/Sanidine Age Discordance

黑云母/Sanidine 年龄不一致的调查

• 批准号: 0126144
• 负责人: Matthew Heizler
• 金额: $ 7.63万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0126144&HistoricalAwards=false
• 关键词: Investigation; Biotite; Sanidine; Age; Discordance

AbstractEAR-0126144Heizler and McIntoshNew Mexico Institute of Mining and TechnologyCogenetic biotite and sanidine from volcanic rocks often yield discordant 40Ar/39Ar ages. The typical age discordance is between 0.2 and 1.0 Ma. The discordance has important implications for detailed, high precision volcanic history studies, for intercalibration of K/Ar with U/Pb and other geochronological methods, and the age of flux monitor standards. This proposal will investigate the causes of the biotite/sanidine discordance through detailed geochronological analyses of two well-studied Mid-Tertiary volcanic sequences from the Mogollon-Datil volcanic field of New Mexico. The expected outcome of this study could be far reaching, if it is shown that biotite ages are plagued by inaccuracy that is not evident in individual analyses. Because biotite is the most commonly dated volcanic and plutonic mineral phase and it often yields highly precise apparent ages, determination of accuracy of biotite ages is essential to a wide variety of tectonic, volcanic, and geological studies.

Heizler和McIntoshNew Mexico采矿和技术研究所火山岩中的同生黑云母和透长石经常产生不一致的40 Ar/39 Ar年龄。典型的年龄不一致在0.2 ~ 1.0Ma之间。这种不一致性对详细的、高精度的火山历史研究、K/Ar与U/Pb和其他地质年代学方法的相互校准以及通量监测标准的年龄具有重要意义。 该建议将通过对新墨西哥州Mogollon-Datil火山岩区两个研究充分的中第三纪火山岩序列进行详细的地质年代学分析，调查黑云母/透长石不一致的原因。这项研究的预期结果可能是深远的，如果它表明，黑云母年龄的困扰是不准确的，这是不明显的个别分析。 由于黑云母是最常见的火山岩和深成岩矿物相，它往往产生高度精确的表观年龄，确定黑云母年龄的准确性是必不可少的各种构造，火山和地质研究。