摘要
对青岛花岗岩类复式岩基的氧同位素研究表明，各个岩体的氧同位素组成明显受水岩相互作用的影响。根据样品采集位置和氧同位素分析结果，可以恢复其中六个古化石热水体系，它们包括两种类型：内高外低型和内低外高型，其形成可能与当时大气降水的循环方式密切相关。近似模拟计算表明，发生水岩作用的温度多在２５０－４００℃之间，水岩比的变化较大（０．０８％－０．３％）。研究还发现，曾发生过强烈去气作用的岩体与未经去气（或去气较弱）的岩体相比，其氢氧同位素体系受水岩作用影响结果不一样，使用δ１８Ｏ－δＤ图可以对它们进行有效的鉴别。
The oxygen isotopic characteristics of the Qindao granitoid batholith indicate that most of the plutons were evidently affected by the interaction between meteoric water and rocks to different extents. There are six fossil hydrothermal convection systems, which occurred at the time of their formation. According to the distributions of the δ18O values of the rocks in the batholith, two types can be distinguished on the basis of the δ18O contours in each of plutons, one is lower in δ18O in the inner part but higher in the outer part and the other is higher in the inner part but lower in the outer part. They may be related to the circulating patterns of meteoric waters. The results of modelling calculation for the water-rock interaction systems indicate that the temperatures of these systems range from 250℃ to 400℃, and their W/R ratios vary from 0.08% to 0.3%. Meanwhile, it has been found that degassed plutons are different from non-degassed plutons tor weakly degassed plutons) with respect to their hydrogen and oxygen isotopic compositions.Therefore, δ18O-δD diagrams can be uscd as effective measures to distinguish degassed plutons from non-degassed ones.
出处
《地球化学》
CAS
CSCD
北大核心
1994年第1期50-59,共10页
Geochimica
基金
国家自然科学基金
关键词
氧同位素
古化石
热水体系
花岗岩
Water-rock reaction, Oxygen isotope, Fossil geothermal system
