U.S. Argentina Cooperative Research on Cenozoic Volcanism inthe Argentine Puna: Relation of Magmatic Source Areas to Evolving Tectonics

该奖项支持康奈尔大学的苏珊娜·M·凯博士与阿根廷胡胡伊国立大学的比阿特丽斯·L·科伊拉教授开展的一项合作研究计划，该计划旨在将地球表面的可见变化--例如，反映在山脉或高原形成中的相邻“板块”之间的碰撞--与火成岩的地球化学联系起来。将对阿根廷中部高高原地区非常古老和相对年轻的岩石进行主元素和微量元素化学分析，在某些情况下还将进行同位素组成分析，结果将与高原抬升有关的过程相关联，并概括为山脉和高高原的形成。通过研究地壳板块交界处火山岩的分布和地球化学，可以加深我们对地壳生长和演化的理解，因为这种地球化学是地壳形成的时间尺度、热历史和构造力学的函数。阿根廷高原是研究这种地球化学的绝佳地点，因为那里过去集中了火山活动，但现在那里停止了火山活动。此外，该地区在陆地和卫星上的地质测绘都很好，当地地质学家都很熟悉。拟议的火山岩分析应提供有关高原形成地质过程中涉及的时间尺度和温度的信息，以及形成高原本身的地壳演化化学的信息。总体而言，拟议的研究将极好地补充利用美国首席调查员在地球化学分析技术方面的专业知识和阿根廷合作者在野外岩石学方面的专业知识，并应导致对山区和高原地区总体形成过程的更全面了解。

This award supports the participation of Dr. Suzanne M. Kay of Cornell University in a program of cooperative research with Prof. Beatriz L. Coira of the Universidad National de Jujuy, Argentina, aimed at relating visible changes on the surface of the earth--collisions between adjacent "plates" reflected in the formation of mountain ranges or plateaus, for example--to the geochemistry of igneous rocks. Both very old and relatively young rocks from the high plateau region of central Argentina will be analyzed for major and trace element chemistry, and in some cases for isotopic composition, and the results will be correlated to the processes that were involved in the uplift of the plateau and generalized to the formation of mountain ranges and high plateaus generally. Our understanding of the growth and evolution of the earth's crust may be improved by studying the distribution and geochemistry of the volcanic rocks found at the intersections of the plates which form the earth's crust, since this geochemistry is a function of the time scale, thermal history, and structural mechanics of the formation of the crust. The high plateau of Argentina is an excellent location for the study of this geochemistry, due to the past concentration but current cessation of volcanic activity there. In addition, the area is well mapped geologically, both terrestrially and from satellites, and is well-known to local geologists. The proposed analysis of volcanic rocks should yield information on time scales and temperatures involved in the geological processes of the plateau's formation, and on the evolving chemistry of crust forming the plateau itself. Overall, the proposed study will make excellent complementary use of the U.S. principal investigator's expertise in geochemical analysis techniques, and the Argentine collaborator's expertise in field petrology, and should result in obtaining a fuller understanding of the processes that occur in the formation of mountain and high plateau regions in general.