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

9909410温茨能够破译变质地体中的多次热事件并确定其发生时间，这将是理解造山事件和古构造背景的主要工具。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丢失部分或全部累积的依赖时间的同位素产物，造成不明确的结果，而较高的封闭温度会导致遗传和多次过度生长。这个项目将探索利用钛铁矿中的U-Pb对来确定多变质事件的年代。相对于这一体系，钛铁矿具有较高的闭合温度，但与锆石和其他副矿物不同，它由主要组分组成，因此更容易与特定变质事件或阶段中发生的特定变质反应联系在一起。这项研究将涉及新英格兰含钛矿岩的岩石学特征，以确定生长的原因和年龄。这些结果将用于了解阿卡迪亚造山带的分布和强度，以及阿勒格尼亚造山带的叠印。

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.