The campsite dykes: A window into the early post-solidification history of the Skaergaard Intrusion, East Greenland
The campsite dykes: A window into the early post-solidification history of the Skaergaard Intrusion, East Greenland
复制标题
露营地堤坝：了解东格陵兰斯卡尔加德侵入早期凝固后历史的窗口
DOI：
10.1016/j.lithos.2013.10.007
复制
发表时间：
2013
期刊：
影响因子：
3.5
通讯作者：
Holness M
中科院分区：
文献类型：
--
作者：
Holness M
东格陵兰岛的斯卡加德入侵被几代堤坝切断，其中最早的堤坝被认为是在斯卡加德凝固后不久入侵的。在斯卡加德半岛Homestead湾附近的营地地区，发现了2 ~ 6 m宽的最早一代白云岩岩脉。其中一条岩脉（营地岩脉）局部含有丰富的橄榄岩包体。另一个（斜长石-辉岩岩）含有丰富的大斜长石斑晶。两个堤坝之间的横切关系没有暴露出来。营地岩脉斜长石-斜长石-斜长石的中位二面角Θcpp为88 ~ 89.5°，斜长石-长石岩脉的中位二面角为79°。利用经验关系Θcppand（源自白云岩的结晶持续时间），他们观察到Θcppsuggests营地堤坝是两者中较古老的，当它冷却到920-970°C时侵入了斯卡加德。当斯卡加德的温度降到670°C以下时，斜长石岩脉侵入。滑石捕虏体分为两组。A型捕虏体的微观结构与Skaergaard层状系列相似，尽管矿物成分通常比暴露的堆积物更原始——这种类型的捕虏体可能来自Skaergaard侵入体的较深层或来自密切相关的下伏岩浆室。1个A型捕虏体具有矿物组成和Θcppconsistent，其来源为层状系LZb，该捕虏体中含有部分倒置鸽岩，表明层状系下部低钙辉石的倒置发生在侵入体完全凝固后。B型捕虏体以斜长石为特征，内含大量的熔体包裹体。与冰岛玻璃晶结核的显微结构比较表明，B型捕虏体有多阶段的冷却历史，与深室中部分结晶物质的逐步夹带一致。B型捕虏体不太可能来自斯卡加德洞穴的更深层。
The Skaergaard Intrusion of East Greenland is cut by several generations of dykes, the earliest of which is thought to have intruded shortly after solidification of the Skaergaard. Two ~ 6 m wide doleritic dykes from the earliest generation are exposed in the campsite area near Homestead Bay of the Skaergaard Peninsula. One of the dykes (the Campsite Dyke) locally contains abundant xenoliths of troctolitic cumulate. The other (the Plagioclase-phyric Dyke) contains abundant large plagioclase phenocrysts. Cross-cutting relationships between the two dykes are not exposed. The median clinopyroxene–plagioclase–plagioclase dihedral angle, Θcpp, in the Campsite Dyke is 88–89.5°, whereas that of the Plagioclase-phyric Dyke is 79°. Using an empirical relationship between Θcppand the duration of crystallisation derived from dolerite sills, the observed Θcppsuggests that the Campsite Dyke is the older of the two, intruding the Skaergaard when it had cooled to 920–970 °C. The Plagioclase-phyric Dyke intruded later, once the Skaergaard had cooled below 670 °C. The troctolitic xenoliths divide into two separate groups. Type A xenoliths have microstructures similar to those of the Skaergaard Layered Series although mineral compositions are generally more primitive than those of the exposed cumulates — this type of xenolith is likely to have been derived from either deeper levels in the Skaergaard Intrusion or from a closely-related underlying magma chamber. One Type A xenolith has mineral compositions and Θcppconsistent with an origin in LZb of the Layered Series — this xenolith contains partially inverted pigeonite, suggesting that inversion of low-Ca pyroxene in the lower part of the Layered Series took place after the intrusion had completely solidified. Type B xenoliths are characterized by plagioclase containing large and abundant melt inclusions. Comparison with the microstructures of glassy crystalline nodules from Iceland points to a multi-stage cooling history for Type B xenoliths, consistent with step-wise entrainment of partially crystallised material from a deep chamber. Type B xenoliths are very unlikely to have been derived from deeper levels in the Skaergaard chamber.
登录
查看更多内容
东格陵兰斯卡尔加德侵入岩早期和中期分馏阶段的辉石
DOI：
--
发表时间：
1957
期刊：
影响因子：
--
作者：
G. Brown
通讯作者：
G. Brown
影响因子：
3.9
作者：
H. Taylor;R. W. Forester
通讯作者：
H. Taylor;R. W. Forester
英格兰北部 Whin Sill 辉石中的亚显微外溶片层
DOI：
--
发表时间：
1972
期刊：
影响因子：
--
作者：
A. C. Dunham;P. Copley;V. Strasser
通讯作者：
V. Strasser
东格陵兰 Kangerdlugssuaq 地区的第三级堤坝群
DOI：
--
发表时间：
1978
期刊：
影响因子：
--
作者：
T. F. D. Nielsen
通讯作者：
T. F. D. Nielsen
使用自动扫描电子显微镜 (QemSCAN) 进行快速定量矿物和物相分析；
DOI：
--
发表时间：
2004
期刊：
Geological Society Special Publication
影响因子：
--
作者：
D. Pirrie;A. R. Butcher;M. Power;P. Gottlieb;G. Miller
通讯作者：
G. Miller