Evolution of fluid phases associated with lithium pegmatites from SE Ireland
Evolution of fluid phases associated with lithium pegmatites from SE Ireland
复制标题
与爱尔兰东南部锂伟晶岩相关的流体相演化
DOI：
10.1180/minmag.1989.053.371.01
复制
发表时间：
1989
影响因子：
2.7
通讯作者：
A. Rankin
中科院分区：
文献类型：
--
作者：
M. P. Whitworth;A. Rankin
与爱尔兰东南部莱因斯特花岗岩伴生的内部分带贫瘠和含锂辉石伟晶岩中的石英流体包裹体代表了多种早期和晚期的热液流体，对伟晶岩的发育起到了作用。显微测温和光学检查揭示了包裹体的两种主要类型。第一类(类型1)由低-中盐度卤水组成，其均一温度最高可达400℃左右；第二类(类型2)似乎晚于第一代，盐度较高，大部分温度低于250℃，均一化温度大多低于250℃。模型1型包裹体流体等温线表明，675℃和2.5kbar的莱因斯特花岗岩形成了晚期岩浆/早期热液，并等压冷却到锂辉石稳定区，伟晶岩在那里完全结晶。后来，更多来源不明的含盐二型流体可能促成了锂辉石向白云母和钠长石的转变，并伴随着锂从锂辉石晶格中释放出来。
Abstract Fluid inclusions in quartz from internally zoned barren and spodumene-bearing pegmatites associated with the Leinster granite of SE Ireland represent a variety of early and late hydrothermal fluids responsible for the development of pegmatites. Microthermometry and optical examination reveal two main populations of inclusions. The first (Type 1) comprises low-moderate salinity brines which homogenized at temperatures up to about 400 °C. The second (Type 2) appear to postdate the first population and are characteristically more saline and homogenized at temperatures mostly below 250 °C. Isochores for model type 1 inclusion fluids indicate that a late-magmatic/early-hydrothermal fluid developed from the Leinster granite at 675 °C. and 2.5 kbar and cooled isobarically into the spodumene stability field where complete crystallization of the pegmatites took place. Later, more saline, type 2 fluids of unknown origin may have contributed to the alteration of spodumene to muscovite and albite with the accompanying release of lithium from the lattice of spodumene.