Identifying Multiple Thermal Events in Polymetamorphic Rocks: Electron and Ion Microprobe Analysis of Complexly Zoned Titanite

识别多变质岩中的多个热事件：复杂分区钛矿的电子和离子微探针分析

• 批准号: 9909410
• 负责人: Robert Wintsch
• 金额: $ 17万
• 依托单位: Indiana University
• 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 2003-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909410&HistoricalAwards=false
• 关键词: Identifying; Multiple; Thermal; Events; Polymetamorphic

9909410WintschThe ability to decipher and date multiple thermal events in metamorphic terranes would be a major tool in understanding orogenic events and paleotectonic settings. However minerals with moderate closure temperatures to radioactive isotopes useful for age determination commonly lose some or all of the accumulated time-dependant isotopic products, causing ambiguous results, whereas high closure temperatures invite inheritance and multiple overgrowths. This project will explore the utility of using the U-Pb pair in titanite to date polymetamorphic events. Titanite has a high closure temperature with respect to this system, but unlike zircon and other accessory minerals, is composed of major components and therefore it can be more easily linked to specific metamorphic reactions occurring in a particular metamorphic event or phase. The study will involve petrologic characterization of titanite-bearing rocks of New England to determine the causes and ages of growth. These results will be applied to understanding the distribution and intensity of the Acadian Orogeny and overprinting by the Alleghanian Orogeny.

[90942 . 10]破译变质地体中多个热事件并确定其年代的能力将是理解造山事件和古构造环境的主要工具。然而，对年龄测定有用的放射性同位素具有中等封闭温度的矿物通常会失去部分或全部累积的随时间变化的同位素产物，导致结果不明确，而高封闭温度会导致遗传和多次过度生长。该项目将探索使用钛矿中的U-Pb对来确定多变质事件的年代的效用。钛矿相对于该体系具有较高的闭合温度，但与锆石和其他副矿物不同，钛矿由主要成分组成，因此更容易与特定变质事件或相中发生的特定变质反应联系起来。这项研究将涉及新英格兰含钛岩石的岩石学特征，以确定其生长的原因和年龄。这些结果将用于了解阿卡迪亚造山运动的分布和强度以及阿勒卡尼亚造山运动的叠加作用。