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核素积累的研究。将研究两种材料来源：1)基岩上方的绿泥岩巨石和2)正下方的花岗质/闪长质巨石。这项工作的总体目标是证明宇宙核素对冰盖下物质定年的效用。如果最后一个无冰期很长，大约有几万年，那么这些样本暴露在宇宙辐射下的时间就足够长，足以积累可测量数量的宇宙核素。在这种情况下，测量这些核素的浓度应该可以得到格陵兰冰盖开始形成的时间的信息：本质上是现在格陵兰冰盖的年龄。如果暴露的时间不长，那么就只能得到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模式的重要参数，也是模式古环境演化的重要约束条件。

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.