Grain boundary migration of water and carbon dioxide during uplift of garnet‐zone Alpine Schist, New Zealand
Grain boundary migration of water and carbon dioxide during uplift of garnet‐zone Alpine Schist, New Zealand
复制标题
新西兰石榴石带高山片岩隆升过程中水和二氧化碳的晶界迁移
DOI：
10.1111/j.1525-1314.1993.tb00154.x
复制
发表时间：
1993
影响因子：
3.4
通讯作者：
R. Norris
中科院分区：
文献类型：
--
作者：
D. Craw;R. Norris
新西兰活跃高山断层附近的石榴石带片岩中的变形石英脉，沿石英晶界滞留有流体包裹体。纹理表明，内含物是在变形矿脉退火过程中形成的。许多包裹体是空的，但有些包裹体含有密度为 0.16 至 0.80 g cm−3 的二氧化碳。没有检测到水、氮气或甲烷。这些包裹体比原生变质流体（<5% CO2）或相同或相关岩石中与裂缝相关的情况下捕获的流体（<50% CO2）富含更多二氧化碳。据推测，CO2 的富集是由于冷却引起的水-CO2 混合物不混溶后，盐水沿着水湿晶界从包裹体中选择性迁移（芯吸）所致。失水后包裹体体积发生变化。非润湿的二氧化碳仍然被包裹在包裹体中，直到进一步渗滤逐渐去除溶液中的二氧化碳。这种流体运移机制在脆性-韧性转变附近但下方的富含延性石英的岩石中占主导地位。在更深的层面，水力压裂也是流体运移的重要机制，而在较浅的层面，通过开放裂缝的平流在流体流动方式中占主导地位。
Deformed quartz veins in garnet-zone schist adjacent to the active Alpine Fault, New Zealand, have fluid inclusions trapped along quartz grain boundaries. Textures suggest that the inclusions formed in their present shapes during annealing of the deformed veins. Many of the inclusions are empty, but some contain carbon dioxide with densities that range from 0.16 to 0.80 g cm−3. No water, nitrogen or methane was detected. The inclusions are considerably more CO2-rich than either the primary metamorphic fluid (<5% CO2) or fluids trapped in fracture-related situations in the same, or related, rocks (<50% CO2). Enrichment of CO2 is inferred to have resulted from selective migration (wicking) of saline water from the inclusions along water-wet grain boundaries after cooling-induced immiscibility of a water-CO2 mixture. Inclusion volumes changed after loss of water. Non-wetting CO2 remained trapped in the inclusions until further percolation progressively removed CO2 in solution. This mechanism of fluid migration dominated in ductile quartz-rich rocks near, but below, the brittle-ductile transition. At deeper levels, hydraulic fracturing is also an important mechanism for fluid migration, whereas at shallower levels advection through open fractures dominates the fluid flow regime.