摘要
本文对我国东南沿海地区温度最高的典型花岗岩裂隙热水盆地——漳州盆地水热系统的地下热水及各类相关的其它类型天然水的氢氧稳定同位素(δD和δ^(18)O)特征进行了研究。对漳州地区的大气降水线、地下热水起源、地下热水的补给源(区)以及影响地下热水同位素成分的形成与演化的海水与大气降水的混合等地球化学作用问题进行讨论。
This paper is resulted from detailed investigation of stable oxygen and hydrogen isotopes on the geothermal and other natural waters from Zhangzhou Basin hydrothermal system, which is typical of a fault basin on a granitic basement in the southeastern coastal area of China and is the highest in thermal water temperature in that area (121.5℃ at a depth of 90 meters or so). δD and δ^(18)O data on 28 water samples are first reported in this paper, based on which problems like the local meteoric water line, the thermal water origin, the recharge source (or area) of the Field and factors affecting the formation and consequent modification of isotope contents of the thermal water, as evidently the mixing process of thermal water with seawater, are discussed.
The following conclusions have been drawn from the results of this study. (1) The local meteoric water line was worked out based on the isotopic data of rain water, river water and the groundwater which does not circulate under the ground for a long distance or a long time. Results show that they still represent the isotopic features of precipitation and this method can be used as an alternative one for the calculation of local meteoric water line. (2) The data points of thermal water samples exhibit very close features in the δD-δ^(18)O plot and statistical analyses also reveal very close linear correlation between thermal water and the local meteoric water, which indicates that the thermal water of the studied area originates from meteoric water. (3) No considerable 'Oxygen Shift' is observed from the isotope data points of the thermal water in the δD-δ^(18)O plot, which implies that the geothermal reservoir is not a high temperature one. (4) The mixing process between the seawater and the meteoric water is a major geothermal-geochemical process in Zhangzhou Basin hydrothermal system, which has a rather strong influence on the isotopic composition of the thermal water. The variation in isotope compositions of the thermal water, which is dominated by seawater-mixing, correlate linearly to the amount of seawater mixed-in. (5) The isotope compositions of the end members calculated from the mixing relation are δD=-52‰ and δ^(18)O=-7.7‰ for dilute water, and δD=-7‰ and δ^(18)O=-0.7‰ for saline water. The mixing ratio of seawater to the meteoric water in the most saline thermal water is approximately 1:2. (6) Based on the isotope composition of the dilute end member calculated from the mixing relation, the elevation of the recharge area was estimated according to the 'Elevation Effect' principle to be 900～1050 meters and the recharge area for the Geothermal Field is therefore concluded to be the Tianbao Mountain and the neighbor mountains to the northwest periphery of the Basin.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1990年第4期75-84,共10页
Acta Petrologica Sinica
基金
中国科学院科学基金
国际原子能机构(IAEA)资助。
关键词
地热
氢氧同位素
水热系统
咸-淡水混合
漳州盆地
Geothermal
Oxygen and hydrogen isotopes
Hydrothermal systems
Mixing between saline and dilute water
Zhangzhou Basin
