Continued Used of Cosmogenic 3HE and 21 NE in Dating Geomorphic Surfaces

我们将继续提高生产率， 宇宙成因的3 He和21 Ne，通过收集额外的样品， 我们会延长生产时间 通过分析富含钾的熔岩， 可以使用激光聚变39 Ar/40 Ar来测定流量 法 我们将分析这些最近的流量为3 He和 21 Ne，以建立超过14 C年表的生产率。 我们还将测量石英中的21 Ne生产率， 长石来自全新世和晚更新世流。 在 此外，我们将测量共存的21 Ne含量 矿物，以建立21 Ne的成分依赖性 生产 此外，我们将开始集中努力， 确定冰川期结束时的冰川消退 威斯康星州的两个地区：美国西部和 加拿大和南部的安第斯山脉。 我们将集中精力 火山地形，因为3 He和21 Ne是定量的 保留在火山辉石和橄榄石中;深成地体 将在我们建立21 Ne生产率后进行分析 并能将其与成核21 Ne分离 产于古老的（20 Ma）深成岩中。 西北 美国和南部安第斯山脉将被研究，因为它是 在这两个地区，我们已经建立了生产 率的3 He和21 Ne（北美），并将延长它 回到过去（南美洲）。 这种限制性的研究 将有助于建立北方和南半球 冰盖是否同时消退， 年轻的仙女木在西部北部和南部 美国参考

We will continue to refine the production rate of cosmogenic 3He and 21Ne by collecting additional samples of well-dated lava flows, and we will extend the production rate determination back in time by analyzing K-rich lava flows that can be dated using the laser fusion 39Ar/40Ar technique. We will analyze these recent flows for 3He and 21Ne to establish the production rate beyond 14C chronology. We will also measure 21Ne production rates in quartz and feldspar from Holocene and late Pleistocene flows. In addition we will measure the 21Ne contents of co-existing minerals to establish the compositional dependency of 21Ne production. In addition , we will begin a concentrated effort on determining the mountain deglaciation at the end of the Wisconsin of two regions: the western United States and Canada, and the southern Andes. We will concentrated on volcanic terrains because 3He and 21Ne is quantitatively retained in volcanic pyroxene and olivine; plutonic terrains will be analyzed after we establish the 21Ne production rate in quartz and can separate it from nucleogenic 21Ne production in old (20 Ma) plutonic rocks. Western North America and the southern Andes will be studied because it is in those two regions that we have established the production rate of 3He and 21Ne (North America), and will extend it back in time (South America). Such constrasting studies will help to establish the Northern and Southern Hemisphere ice sheets were retreating at the same time or not and if the younger Dryas is to be found in western North and South America.