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Microstructural evidence for crystallization regimes in mafic intrusions: a case study from the Little Minch Sill Complex, Scotland
Contributions to Mineralogy and Petrology ( IF 3.5 ) Pub Date : 2018-11-09 , DOI: 10.1007/s00410-018-1525-7
Gautier Nicoli 1 , Marian Holness 1 , Jerome Neufeld 1, 2, 3 , Robert Farr 4
Affiliation  

The magma forming the 20 m thick crinanitic/picrodoleritic Dun Raisburgh sill, part of the Little Minch Sill Complex of NW Scotland, comprised a mafic carrier liquid with a crystal cargo of plagioclase and olivine (1 vol%). The olivine component of the cargo settled on the floor of the intrusion while the more buoyant plagioclase component remained suspended during solidification, resulting in a relatively high plagioclase content in the centre of the sill. The settled olivine grains form a lower fining-upwards sequence overlain by a poorly sorted accumulation formed of grains that grew within the convecting magma. The accumulation of olivine on the sill floor occurred over 5–10 weeks, synchronous with the upwards-propagation of a solidification front comprising a porous (~ 70 vol% interstitial liquid) plagioclase-rich crystal mush.

中文翻译:

镁铁质侵入体结晶状态的微观结构证据:苏格兰 Little Minch Sill 复合体的案例研究

形成 20 m 厚的岩浆岩/苦玄岩岩 Dun Raisburgh 岩浆(苏格兰西北部 Little Minch Sill 复合体的一部分)的岩浆由镁铁质载体液体和斜长石和橄榄石晶体 (1 vol%) 组成。货物的橄榄石成分沉降在侵入物的底部,而更具浮力的斜长石成分在凝固过程中保持悬浮,导致基坑中心的斜长石含量相对较高。沉降的橄榄石颗粒形成较低的向上细化序列,其上覆盖着由在对流岩浆内生长的颗粒形成的分类不良的堆积物。橄榄石在窗台上的积累发生了 5-10 周,与包含多孔(约 70 vol% 间隙液体)富含斜长石晶体糊状物的凝固前沿的向上传播同步。
更新日期:2018-11-09
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