Collaborative Research: Magma-Host Rock Interaction Processes of Assimilation in the Mid-Crustal Hortavaer Intrusive Complex, North Central Norway

456 Ma Hortavar侵入杂岩是挪威中北部加里东时代Bindal基的一部分。它由碱性岩石组成，形成数百或数千个脉状体，嵌入不同的寄主岩石（混辉岩、石英岩、大理石和钙硅酸盐片麻岩）中。从橄榄辉长岩到正长岩的火成岩范围、化学变化特征和碳同位素特征表明岩浆对钙硅酸盐和硅酸盐岩具有原位同化作用。对Hortavar的原位同化作用的认识使其成为研究控制岩浆与中地壳寄主岩石之间相互作用机制的理想场所：寄主岩石是否整体同化？或者固体是根据它们在岩浆中溶解的能力被同化的？或者，寄主岩石是否先部分熔化，只吸收熔化部分？我们将采用综合野外和微观分析的方法验证碳酸盐岩+硅酸盐同化作用在岩浆早期演化中起重要作用，而硅酸盐同化作用在后期演化中起主导作用的假设。由于封闭系统中的碳酸盐同化是无效的，我们也将测试这种同化在开放系统中发生的可能性。这项研究将涉及一个由教师和学生组成的国际团队。它将在新的文化和学术环境中为所有参与者提供丰富的合作冒险。它还将涉及与挪威地质调查局和挪威科技大学的科学家和学生，以及当地一名中学教师和业余地质学家的合作。

The 456 Ma Hortavar intrusive complex is part of the Caledonian-age Bindal Batholith in north-central Norway. It consists of alkaline rocks emplaced as hundreds or thousands of dike-like bodies into diverse host rocks (migmatite, quartzite, marble, and calc-silicate gneiss). The range of the igneous rocks, from olivine gabbro through syenite, their chemical variation, and their carbon isotope signatures indicates that the magmas assimilated calc-silicate and silicate rocks in situ. Recognition of in situ assimilation at Hortavar makes it an ideal place to address the mechanisms that control interactions between magmas and their host rocks in the middle crust: Are host rocks assimilated en masse? Or are solids assimilated according to their ability to dissolve in the magma undergoing contamination? Alternatively, are host rocks partly melted first, with only the melt component assimilated? We will use integrated field and microanalytical methods to test the hypothesis that carbonate + silicate assimilation was important during early magma evolution, but that silicate assimilation dominated later evolution. Because carbonate assimilation in a closed system is ineffectual, we will also test the likelihood that such assimilation occurred in an open system. The research will involve an international team of faculty and students. It will provide all participants with a rich, collaborative venture in new cultural and academic environments. It will also involve collaboration with scientists and students from the Norwegian Geological Survey and the Norwegian University of Science and Technology, and a local middle school teacher and amateur geologist.