Cosmogenic Nuclides in Erratics below the Greenland Ice Sheet at GISP ll Site

该奖项支持对格陵兰岛GISP2站点冰下岩石中宇宙成因核素积累的调查。将研究两种物质来源：1)基岩上方的绿泥质巨石和2)正下方的花岗岩/闪长岩巨石。这项工作的总体目标是展示宇宙成因核素对冰盖下物质测年的效用。如果上一次的无冰期很长，大约有数万年之久，那么这些样本将暴露在足够长的宇宙辐射中，以积累可测量的宇宙源核素。在这种情况下，测量的这些核素浓度应该会得出关于格陵兰冰盖开始形成的时间的信息：基本上就是现在的格陵兰冰盖的年龄。如果暴露的时间不长，那么只会产生关于冰盖年龄的定性信息。现今格陵兰冰盖的年龄是气候和冰动力学模型的重要参数，也是古环境演化模型的重要约束条件。

This award supports an investigation of cosmogenic nuclide accumulation in rocks beneath the ice at the GISP2 site on Greenland. Two sources of material will be studied: 1) the chloritic boulder above the bedrock and 2) the granitic/dioritic boulder directly below. The overall goal of this work is to demonstrate the utility of cosmogenic nuclides to dating materials beneath the ice sheet. If the last ice-free period was long, on the order of tens of thousands of years, the samples would have been exposed to cosmic radiation long enough to accumulate measurable amounts of cosmogenic nuclides. In this case, measured concentrations of these nuclides should yield information about the time when the Greenland ice sheet began to build up: essentially the age of the present Greenland ice sheet. If the duration of exposure is not long, then only qualitative information about the age of the ice sheet will be produced. The age of the present Greenland ice sheet is an important parameter for climate and ice dynamics models as well as being an important constraint for models paleoenvironmental evolution.