Acquisition of a Laser Furnace System to Develop U-Th-He Dating in the UCLA Noble Gas Laboratory

EAR-0132997Grove激光加热金属包裹的副矿物已成为实现高通量、低空白和易追踪的(U-Th)/He测年的最可行的氦分析技术。该合同将为用于自动光束衰减的连续波TEMoo模式、Nd-YAG激光器和光学机械设备提供资金，以开发用于加州大学洛杉矶分校惰性气体实验室氦分析的温度控制、激光加热炉系统。激光系统将成为新翻新的VG3600提取线的重要组成部分，该线现在正在建立以进行3He同位素稀释测量。新开发的(U-Th)/He测年能力将支持NSF赞助的一些项目，这些项目需要对磷灰石和辉石进行有效的(U-Th)/He分析。这些研究大多是构造研究，依靠低温热年代学来探测和描述晚新生代地壳形变的规模和时间。计划活动的行程很广，从研究间歇泉热液系统从水为主向以蒸汽为主的条件转变的时间，到研究与构造活动区接壤的盆地的碎屑热年代学。在所有这些活动中，最主要的考虑因素是我们希望开发包含40Ar/39Ar K长石和(U-Th)/He磷灰石/辉石热力学计时仪的自洽解释模型，以得出从地壳中部到地表条件下几乎连续的热历史。

EAR-0132997GroveLaser heating of metal-encapsulated accessory minerals has emerged as the most viable technique for accomplishing high-throughput, low-blank, and readily-tracked helium analysis for (U-Th)/He dating. This award will provide funds for a CW TEMoo mode, Nd-YAG laser and optomechanical equipment for automated beam attenuation to develop a temperature controlled, laser-heated furnace system for helium analysis in the UCLA noble gas laboratory. The laser system will become an essential component of the newly refurbished VG3600 extraction line that is now set up to perform 3He isotope dilution measurements. The newly developed (U-Th)/He dating capabilities will support a number of NSF-sponsored projects that require efficient (U-Th)/He analysis of apatite and sphene. The majority of these investigations are structural studies that rely upon low-temperature thermochronology to detect and characterize the magnitude and timing of Late Cenozoic crustal deformation. The itinerary of planned activities is broad and ranges from studies of the timing of the transition from water to steam-dominated conditions at The Geysers hydrothermal systems to detrital thermochronology in basins that border tectonically active areas. An overarching consideration in all this activity is our desire to develop self-consistent interpretive models that incorporate both 40Ar/39Ar K-feldspar and (U-Th)/He apatite and sphene thermochronometers to derive nearly continuous thermal histories from middle crustal to surface conditions.