Acquisition of a Solid-State 193-nm Laser-Ablation System

高能、聚焦的激光束可以用来“烧蚀”固体表面的微小区域，释放出亚微观碎片，供等离子体源质谱仪分析，以确定同位素比率和痕量元素组成。这种微取样技术以高空间分辨率高效地进行地质年代学和地球化学测量。激光技术的最新进展导致了短波长固态激光系统的发展，这些系统显着提高了这些测量的准确度，精度和分辨率。 在这个项目中，一个现代化的193纳米激光烧蚀系统将被集成到德克萨斯大学奥斯汀分校现有的质谱仪设施中，以使这种强大的技术能够用于一系列地球科学调查。 地质年代学的应用将集中在确定世界各地沉积岩中捕获的大量单个锆石颗粒的年龄。 这将使研究人员能够限制沉积物积累的年龄，沉积物的来源，以及潜在相关的沉积包的相关程度;这些结果反过来将允许测试岩石起源的构造和沉积学假设。 对基底岩石的类似应用将允许快速筛选岩石圈块体的年龄和鉴别古造山带中的同位素储层。地球化学应用将集中于空间分辨的痕量元素和同位素测量，以解决各种科学问题，如地幔中的挥发性再循环，火山岩浆混合和结晶的动力学，地质材料中的固态扩散速率，和洞穴沉积物的最佳取样用于古气候研究。

A high-energy, tightly focused laser beam can be used to "ablate" tiny areas on the surface of a solid, liberating submicroscopic fragments for analysis by plasma-source mass spectrometers to determine isotopic ratios and elemental compositions at trace levels. This micro-sampling technique produces geochronological and geochemical measurements at high spatial resolution with great efficiency. Recent advances in laser technology have led to the development of short-wavelength solid-state laser systems that significantly improve the accuracy, precision, and resolution of these measurements. In this project, a modern 193-nm laser-ablation system will be integrated into existing mass-spectrometry facilities at the University of Texas at Austin to bring this powerful technology to bear on a range of earth-science investigations. Geochronological applications will center upon determining the ages of large numbers of individual grains of zircon trapped in sedimentary rocks from localities around the world. This will permit investigators to constrain the ages of sediment accumulation, the sources of the sediments, and the degree of correlation of potentially related sedimentary packages; these results in turn will permit testing of tectonic and sedimentological hypotheses for the rocks' origins. Similar applications to basement rocks will allow rapid screening of ages of lithospheric blocks and discrimination of isotopic reservoirs in ancient orogens.Geochemical applications will focus on spatially resolved trace-element and isotopic measurements to address scientific questions as diverse as volatile recycling in the mantle, the dynamics of volcanic magma mixing and crystallization, rates of solid-state diffusion in geologic materials, and optimal sampling of cave deposits for paleoclimate studies.