Collaborative Research: Timescales of Magmatic Differentiation and Crustal Assimilation Beneath Iceland: Combined U-Series and Oxygen Isotope Studies

合作研究：冰岛下方岩浆分异和地壳同化的时间尺度：结合 U 系列和氧同位素研究

• 批准号: 0307691
• 负责人: Kari Cooper
• 金额: $ 13.51万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0307691&HistoricalAwards=false
• 关键词: Collaborative; Research; Timescales; Magmatic; Differentiation

EAR-0307691CooperThis study will measure 226Ra-230Th disequilibria and oxygen isotope compositions in whole-rock samples, groundmass separates and plagioclase separates from recent lavas of Krafla volcano in Iceland. This approach will be applied both on the relatively broad scale of variations in whole-rock (226Ra)/(230Th) and d18O between different eruptions, and also in detail by separating and analyzing more than one size fraction of plagioclase separates from the same lava. Because the fractionation of oxygen isotopes between coexisting plagioclase and silicate liquid is relatively well-known, d18O measured in crystals can be related directly to variations in d18O of the liquids from which they crystallized. Thus, d18O of early-formed crystals can preserve a record of the compositions of liquids before magma mixing or crustal assimilation occurred. The diversity of oxygen-isotope composition of plagioclase in Krafla lavas, both between different eruptions and within a single lava, will provide information on the relative influence of mantle-derived and crustally-derived material and the process of producing intermediate lavas. By dating the same crystal populations, the timing of mixing/assimilation can be established, providing unprecedented information about the rates of these magmatic processes.Intellectual Merit: The results of this project will enhance our understanding of the processes of magmatic differentiation and crustal assimilation by linking information about the timescales over which such processes occur to mass balance of crustally-derived and mantle-derived material. These results will have important implications in terms of the mass and heat balance of crustal reservoir systems, and will be compared to the extensive body of work in Iceland on geophysical observations of crustal structure, reservoir volume, and geothermal activity. These results will provide background and groundwork for future studies of magma mixing and crustal assimilation in other areas of Iceland and in other tectonic settings. Broader Impacts: This project will serve to broaden the participation of underrepresented groups in the geosciences by supporting the early career development of a female PI. Furthermore, we anticipate that a graduate student will be extensively involved in this project as part or all of his or her thesis project, and that an undergraduate will be involved in the technical aspects of this project; funding for this project would therefore support the education and training of the next generation of scientists. Finally, an explicit goal of this collaboration is that the PI Cooper will travel to WHOI with the graduate student in order to gain experience in U-series analyses specifically by PIMMS. She will transfer this expertise to the new analytical facilities at UW, and these techniques will subsequently be applied to a variety of solid earth and oceanographic problems.

EAR-0307691 CooperThis研究将测量全摇滚样品中的226RA-230次不平衡和氧同位素组成，地下质量分离，斜长石与冰岛Krafla火山的最新熔岩分开。这种方法将在整个岩石（226ra）/（230th）的变化相对较大的范围内以及在不同喷发之间的D18O上应用，也将通过分离和分析与同一熔岩分离的斜长石分离的多种斜向分数来详细介绍。 由于共存的斜长石和硅酸盐液之间的氧同位素分馏相对众所周知，因此在晶体中测得的D18O可能与它们结晶的液体的D18O的变化直接相关。因此，早期形成晶体的D18O可以在发生岩浆混合或地壳同化之前保留液体组成的记录。在不同喷发和单个熔岩之间，斜长石熔岩中斜长石的氧相同位素组成的多样性将提供有关地幔衍生和地壳衍生物质的相对影响的信息，以及产生中间熔岩的过程。通过与相同的晶体种群约会，可以建立混合/同化的时间，提供有关这些岩浆过程速率的前所未有的信息。智能优点：该项目的结果将增强我们对磁相差和甲壳同化过程的理解，并通过将这些过程及时弥补这些过程 - 弥漫在这些过程中 - 弥漫在上面 - 弥补 - 弥漫在上面 - 弥补 - 弥补 - 弥补 - 弥补 - 弥漫在上面。这些结果将在地壳储层系统的质量和热量平衡方面具有重要意义，并将与冰岛在地球物理结构，储层体积和地热活动的地球物理观察中的广泛工作进行比较。这些结果将为冰岛其他地区和其他构造环境中的岩浆混合和地壳同化的未来研究提供背景和基础。 更广泛的影响：该项目将通过支持女性PI的早期职业发展，从而扩大代表性群体不足的团体的参与。 此外，我们预计研究生将作为他或全部论文项目广泛参与该项目，并且本科生将参与该项目的技术方面；因此，该项目的资金将支持下一代科学家的教育和培训。 最后，这项合作的明确目标是Pi Cooper将与研究生一起前往Whoi，以便获得PIMMS专门进行U系列分析的经验。 她将把这种专业知识转移到UW的新分析设施中，随后将应用这些技术，以应用于各种固体地球和海洋学问题。