Tracking Exhumation of Ultrahigh-pressure Terranes: Linking Thermobarometers and Geochronometers Through REE Chemistry

跟踪超高压地体的折返：通过 REE 化学连接温压计和地质计时器

• 批准号: 1049433
• 负责人: Jane Gilotti
• 金额: $ 20.1万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1049433&HistoricalAwards=false
• 关键词: Tracking; Exhumation; Ultrahigh; pressure; Terranes

When continents collide, as Asia and India are doing today, continental crust can be taken to depths of 100-150 km. The presence of the minerals diamond and coesite in some crustal rocks is evidence that deep, ultrahigh-pressure rocks have been buried deep and then exhumed back to Earth's surface. The time frame in which this exhumation occurs is important for understanding how fast tectonic processes associated with continental collision can take place. A major problem in determining timing is that the minerals used to calculate pressure and temperature (i.e. thermobarometers) at specific depths in the Earth are not the same minerals as the ones used to obtain the ages of the rocks (i.e. geochronometers). The hypothesis to be tested is that the budget of rare earth elements (REEs) in both sets of minerals can be used to find links between the age of the rocks and when the minerals grew at certain depths in order to track the path of these rocks back to the surface in the exhumation process. The exhumation of continental ultrahigh-pressure terranes in collisional orogens is an important process that impacts our understanding of plate tectonics through time, recycling of crustal material into the mantle, subduction zone magmatism and collisional processes in general. Understanding the relationship between geochronometers and metamorphic evolution is currently a very active field of research, which is enabled by recent advances in microanalytical techniques that allow in situ chemical analysis. This project will focus on an excellent example from North-East Greenland where the period of exhumation is long enough - approximately 55 million years - to resolve exchanges in REE along the pressure-temperature path. The results will be easily transported to other metamorphic systems and environments, ultimately influencing petrologic, tectonic and geodynamic models for orogenesis.

当大洲发生冲突时，像亚洲和印度今天所做的那样，大陆地壳可以被带到100-150公里的深度。 在某些地壳岩石中，矿物质钻石和甲铁矿的存在证据表明，深，超压力的岩石已被埋葬在深处，然后回到地球表面。 发生这种挖掘的时间范围对于理解与大陆碰撞相关的构造过程的速度很重要。 确定时间安排的一个主要问题是，用于计算地球特定深度压力和温度的矿物质（即热量计）与获得岩石年龄（即地球制度计）的矿物质不同。 要测试的假设是，两组矿物质中稀土元素（REE）的预算可用于在岩石时代之间找到联系，而当矿物质在某些深度增长时，可以追踪这些岩石的路径，以追踪这些岩石的路径回收到挖掘过程中的表面。 在碰撞orogens中挖掘大陆超高压地层是一个重要过程，它会影响我们对板块构造的理解，随着时间的流逝，将地壳材料回收到地幔中，俯冲带岩浆和碰撞过程。 当前，了解地球工程学与变质演化之间的关系是一个非常活跃的研究领域，这是通过允许原位化学分析的微分析技术的最新进展来实现的。 该项目将重点放在东北格陵兰的一个很好的例子上，该例子足够长的时间（约5500万年），以解决沿着压力温度路径的REE的交流。 结果将很容易地传输到其他变质系统和环境中，最终影响岩石学，构造和地球动力学模型的造成造成。