The tertiary dike swarms of the Kangerdlugssuaq area, East Greenland
The tertiary dike swarms of the Kangerdlugssuaq area, East Greenland
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东格陵兰 Kangerdlugssuaq 地区的第三级堤坝群
DOI：
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发表时间：
1978
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影响因子：
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通讯作者：
T. F. D. Nielsen
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作者：
T. F. D. Nielsen
通过对Kangerdlugssuaq地区岩脉的详细野外研究，辅以岩石学和岩石化学数据，识别出六个不同的世代，这可能与北大西洋省这一地区的主要构造和岩浆事件有关。按照年龄递减的顺序，这些群体是：1.高Fe和Ti拉斑玄武岩的宽海岸平行岩墙群，被确定为东格陵兰高原玄武岩的供给者，并在海岸弯曲之前侵入。2.具有MORB亲缘关系的放射状拉斑玄武岩岩墙群，在化学和年代学上与主要的辉长岩岩体有关（包括Skærgård），与东格陵兰的海岸平行挠曲准同生。3.海岸平行的碱性岩墙群，最强烈的内陆约20公里，由苦橄质到夏威夷质岩石类型组成，并在弯曲之后侵入。4.在北麻质正长岩的紧邻中发现过碱性韵律，并与主要的5.放射状强碱性岩群，包括多种类型的碱性橄榄玄武岩和分化为过饱和粗面岩的粗面玄武岩; 6.与粗面岩群同时出现的滨岸脉岩群，由分化为流纹质岩石类型的过渡玄武岩组成。
一般来说，海岸弯曲之前的所有岩脉都是拉斑玄武岩，并表现出有限的分异，与辉长岩有关的岩脉表现出分异，趋势与Skærgård侵入体下部相似。挠曲后，所有岩脉都属于碱性更强的岩套，并表现出相当程度的分异。这一相当复杂的演变跨越了从约。58我的36 MY，即该地区大陆分裂的时期。
AbstractDetailed field studies supplemented by petrographic and petrochemical data of dikes in the Kangerdlugssuaq area lead to the recognition of six distinct generations, which may be correlated with the major structural and magmatic events in this part of the North Atlantic Province. In order of decreasing age these swarms are:1.A broad coastparallel dike swarm of high Fe and Ti tholeiitic basalts, identified as feeders for the plateau basalts of East Greenland and intruded prior to coastal flexuring.2.A radial tholeiitic dike swarm with MORB affinities, related both in chemistry and chronology to the major gabbroic plutons (including Skærgård) and penecontemporaneous with the coastparallel flexure of East Greenland.3.A coastparallel alkaline dike swarm, most intense some 20 km inland, composed of picritic to hawaiitic rock types and intruded subsequent to flexuring.4.Peralkaline rhyolites found in the immediate neighbourhood of the nordmarkitic syenites and clearly related to the major period of salic plutonism.5.A radial strongly alkaline swarm, including several types of alkaline olivine basalts and trachybasalts differentiating to oversaturated trachytes.6.Simultaneous with the last, a coastparallel dike swarm composed of transitional basalts differentiating to rhyolitic rock types.
In general, all dikes prior to coastal flexuring are tholeiitic basalts and show limited differentiation, those related to the gabbroic plutons show a differentiation, trend similar to that of the lower part of the Skærgård intrusion. After flexuring all dikes belong to more alkaline suites and show considerable degrees of differentiation. The rather complicated evolution spans the period from ca. 58 to ca. 36 MY, i.e. the period of continental break-up in the area.