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

我们将继续通过收集更多的测年熔岩流样本来精炼宇宙成因的3He和21Ne的产生率，我们将通过分析可以使用激光聚变39Ar/40Ar技术测得的富K熔岩流来延长产生率的测定时间。我们将分析3He和21Ne的这些近期流动，以建立14C年代学之后的生产率。我们还将测量全新世和晚更新世流体中石英和长石的21Ne产率。此外，我们还将测量共生矿物中的~(21)Ne含量，以建立~(21)Ne的成分依赖关系。此外，我们将开始集中精力确定威斯康星州末端的两个地区的山脉冰川消融：美国西部和加拿大，以及南安第斯山脉。我们将重点研究火山地体，因为3He和21Ne定量地保留在火山辉石和橄榄石中；深成地体将在我们建立石英中的21Ne产率后进行分析，并可以将其与古老(20 Ma)深成岩中的成核21Ne产物分开。将研究北美西部和安第斯山脉南部，因为正是在这两个地区，我们已经建立了3He和21Ne的产量(北美)，并将把它延长到过去(南美洲)。这样的约束性研究将有助于确定北半球和南半球的冰盖是否同时消退，以及是否要在北美西部和南美洲发现较年轻的仙女木。

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.