Chemical Interactions Between Gabbros and Their Host Rocks: Field and Laboratory Studies of the Tertiary Macrodikes of the Kangerdlugssuaq Area, East Greenland

东格陵兰Kangerdlugssuaq地区的大型岩墙是北大西洋盆地第三纪裂谷初期侵位于东格陵兰边缘太古宙地壳和第三纪火山岩中的大量拉斑玄武岩之一。这些侵入岩惊人地暴露在布洛斯维尔海岸的冰川地带，保存了与其火山、沉积和片麻岩寄主岩石复杂相互作用的证据。关于这些侵入岩的现有化学数据表明，这些岩浆受到下地壳成分和热液蚀变的镁铁质火山岩的选择性混染，岩浆作用导致了这些侵入岩中的化学分层。沿着侵入性接触，揭示了不同规模和方式的地壳混染。这些暴露允许对杂交过程进行详细的结构和化学研究。建议对这些侵入岩进行野外和地球化学研究，以评估分馏和同化作用在这些岩浆化学演化中的作用，并将开发适当的模型来描述这些关系，这些关系受实验相平衡和利用大型岩脉天然物质获得的动力学数据的制约。这一“案例研究”的结果将被用来评估地壳污染在伴生的辉长岩杂岩和同期东格陵兰玄武岩的化学演化中的作用，并对这些岩浆的源区施加限制。

The macrodykes of the Kangerdlugssuaq area, East Greenland are among a large number of tholeiitic intrusions emplaced into Archean crust and Tertiary volcanic rocks along the East Greenland margin during the initial stages of Tertiary rifting of the North Atlantic basin. These intrusions are spectacularly exposed in the glaciated terrain along the Blosseville Coast and preserve evidence of complex interaction with their volcanic, sedimentary and gneissic host rocks. The available chemical data on these intrusions indicate that these magmas were selectively contaminated by components of the lower crust and hydrothermally altered mafic volcanics and that magmatic processes led to chemical stratification within these intrusions. Various scales and modes of crustal contamination are revealed along the intrusive contacts. These exposures permit detailed structural and chemical study of the hybridization process. Field and geochemical studies of these intrusions are proposed to assess the roles of fractionation and assimilation in the chemical evolution of these magmas and appropriate models will be developed to describe these relations as constrained by experimental phase equilibria and kinetic data obtained using natural materials of the macrodykes. The results from this "case study" will be used to evaluate the role of crustal contamination during chemical evolution of associated gabbroic complexes and contemporaneous East Greenland basalts and place constraints on the source regions for these magmas.