Experimental Development and Calibration of (U-Th)/He Thermochronology

Reinerseigh-0073576最近，由于解释上的进步，加上仔细的扩散研究，以及明显成功的构造应用和对其他热年代计的校准，（U-Th）/He定年的兴趣重新抬头。然而，他约会的许多令人兴奋的方面仍然没有探索。这项工作包括一系列的实验研究，开发，扩展和校准新的（U-Th）/He热年代学方法。一个目标是将He测年法扩展到新的相，包括锆石、萤石和石榴石。这是由低T热约束的潜在好处，缺乏这些阶段的丰度，如许多沉积和热液矿化岩石，以及独特的扩散性能和其他阶段的封闭温度（Tc）的岩石的动机。第二个目的是利用的属性，扩散域为他是相当于晶体或晶粒本身。我们将尝试使用它来约束不仅冷却年龄，但晶体的热历史，通过检查的潜在用途1）核心到边缘的He浓度和年龄分带内的单个晶体使用磨损技术，和2）年龄晶粒尺寸的相关性，反映特定的热历史的部分重置晶体。最后一个目标是严格比较（U-Th）/He热年代学与其他方法，主要是多域钾长石40 Ar/39 Ar定年，提供intermethodcalibrations和前所未有的密集的时间-温度采样和热约束。W.S.U.的（U-Th）/He实验室定于2000年5月开始测量年龄和进行扩散实验，这笔资金将与区域裂变径迹和40 Ar/39 Ar热年代学实验室、华盛顿大学经济地质学项目合作，为从事这些方法实验发展的研究生提供支持。和附近的U.I.

ReinersEAR-0073576Recent resurgence of interest in (U-Th)/He dating has been made possible by interpretational advances combined with careful diffusion studies and apparently successful tectonic applications and calibrations against other thermochronometers. Nevertheless, many exciting aspects of He dating remain unexplored. This work comprises a series of experimental studies to develop, extend, and calibrate new (U-Th)/He thermochronologic methods. One objective is to extend He dating to new phases, including zircon, fluorite, and garnet. This is motivated by the potential benefits of low-T thermal constraints in rocks that lack these phases in abundance such as many sedimentary and hydrothermally mineralized rocks, as well as the unique diffusion properties and closure temperatures (Tc) of other phases. A second objective is to exploit the property that the diffusion domain for He is equivalent to the crystal or grain itself. We will attempt to use this to constrain not only cooling ages, but thermal histories of crystals, by examining the potential uses of 1) core-to-rim He concentration and age zonation within individual crystals using abrasion techniques, and 2) age-grain size correlations that reflect specific thermal histories of partially reset crystals. A final objective is to rigorously compare (U-Th)/He thermochronometry with other methods, primarily multi-domain K-feldspar 40Ar/39Ar dating to provide intermethodcalibrations and unprecedentedly dense time-temperature sampling and thermal constraints. The (U-Th)/He lab at W.S.U. is set to begin measuring ages and performing diffusion experiments in May of 2000, and this funding will provide support for graduate students working on experimental development of these methods, in collaboration with with regional fission-track and 40Ar/39Ar thermochronologic labs, the economic geology programs at W.S.U. and the nearby U.I.