The Use of Phosphorus Contents in Yielding Estimates of the Proportion of Trapped Liquid in Cumulates of the Upper Zone of the Bushveld Complex
The Use of Phosphorus Contents in Yielding Estimates of the Proportion of Trapped Liquid in Cumulates of the Upper Zone of the Bushveld Complex
复制标题
磷含量在布什维尔德杂岩上层堆积物中截留液体比例产量估算中的应用
DOI：
10.1180/minmag.1988.052.364.07
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发表时间：
1988
影响因子：
2.7
通讯作者：
Kevin L. Walsh
中科院分区：
文献类型：
--
作者：
R. Cawthorn;Kevin L. Walsh
堆积岩中的磷含量接近南非布什维尔德杂岩基性岩中磷灰石的出现水平，为计算这些岩石中的堆积成分比例提供了一种方法。以前的实验研究已经准确地限制了当磷灰石变得稳定时岩浆中的磷含量。在磷灰石外观正下方的堆积物中的磷含量与该液体成分的比率定义了捕获液体的比例。将这种方法应用于布什维尔德杂岩最上层的岩石，得出的结论是，存在1%至6%的积云间成分。其中许多岩石是多相堆积体，在这种岩石中，根据结构标准估计积云成分是困难的。如果晶体就地生长在岩浆房的底部，就可以产生如此小比例的间隙成分，而不会引起岩浆通过松散的晶体堆积的过度扩散和循环。侵入体的几何形状以及其大小可能对最终凝固在积云岩石中的液体的比例有重大影响。
Phosphorus contents in cumulus rocks occurring close to the level of apatite appearance in the basic rocks of the Bushveld Complex, South Africa, provide a method of calculating the proportion of intercumulus component in these rocks. Previous experimental studies have accurately constrained the phosphorus content of magmas when apatite becomes stable. The ratio of the phosphorus content in the cumulates immediately below the appearance of apatite to this liquid composition defines the proportion of trapped liquid. Application of this method to rocks from the uppermost marie rocks of the Bushveld Complex leads to the conclusion that there is from 1 to 6 per cent intercumulus component. Many of these rocks are muttiphase cumulates and in such rocks estimation of intercumulus component from textural criteria is difficult. If crystals grow in situ on the floor of the magma chamber such small proportions of interstitial component can be produced without appealing to excessive diffusion and circulation of magma through an unconsolidated crystal pile. The geometry of the intrusion as well as its size might have a major influence on the proportion of the liquid ultimately solidifying within a cumulus rock.