摘要
青藏高原是我国地热活动最强烈的地区,传统观点认为其东北部地区处于相对稳定的地块,地热赋存条件一般。青海省位于青藏高原东北部,地热资源种类齐全,以往研究主要集中在勘查程度较高或单个温泉温度较高的区域,而区内大部分地区研究程度较低,地热资源整体分布特征和热源机制不清。本文依据主要控热活动断裂和温泉集中区将温泉自东北向西南划分为11个区,利用水文地球化学和同位素分析手段对温泉的分布特征和成因进行了综合研究。结果表明,温泉补给来源均为其附近大气降水和冰雪融水。温泉水化学特征与热储的地层岩性相关,花岗岩热储中地热水阳离子以Na^(+)为主,阴离子以SO_(4)^(2-)和Cl^(-)为主;灰岩热储中地热水阳离子以Ca^(2+)和Mg^(2+)为主,阴离子以HCO_(3)^(-)为主;砂岩热储中地热水主要阳离子有Ca^(2+)、Na^(+)和Mg^(2+),主要阴离子有Cl^(-)、SO_(4)^(2-)和HCO_(3)^(-)。温泉主要沿活动断裂展布方向呈串珠状分布,且主要密集在不同构造体系的交接复合部位和同一构造体系的转折部位;分布于一、二级断裂结合部位的热储循环深度最大,径流路径最长、水岩反应较充分;而分布于被少量小规模断裂切割的三级断裂沿线的温泉循环深度相对较小,径流路径较短,水岩反应程度较低。热储温度从东北向西南整体呈现出中部和西南部高、南部和东北部低,中高温热储主要分布于共和、贵德、乌兰和唐古拉山一带,温度在89.0~139.0℃,平均117.7℃。温泉热源主要来自大地热流传导增热、放射性元素衰变生热、岩浆余热和活动断层摩擦生热,以及低速高导熔融体和地幔通道流传热等。此次主要聚焦于青海省水热型地热资源的分布规律和地热成因等方面的研究,可为后期青海省地热资源开发利用提供参考依据。
The Tibetan Plateau is the most active geothermal area in China,and its northeastern region is traditionally considered to be on a relatively stable landmass with average geothermal endowment conditions.Within this region,Qinghai Province possesses a complete range of geothermal resources.Previous studies have been mainly focused on the areas with high levels of exploration or with high-temperature hot springs,yet the overall distribution characteristics of geothermal resources and the heat sources are poorly understood.In this paper,the hot springs are divided into 11 districts from NE to SW according to the main heat-control activity fractures and hot springs areas,and the distribution characteristics and formation of hot springs are comprehensively studied by means of hydrogeochemistry and isotope analysis.The results showed that atmospheric precipitation and snow/ice melt were the source of hot springs recharge.The chemical characteristics of hot spring water were related to the stratigraphy of the hot springs.In granite,chert and sandstone hot springs the dominant cation/anions were Na+/SO_(4)^(2-)-Cl^(-),Ca^(2+)-Mg^(2+)/HCO_(3)^(-) and Ca^(2+)-Na^(+)-Mg^(2+)/Cl^(-)-SO_(4)^(2-)-HCO_(3)^(-),respectively.Hot springs were mainly distributed along the fracture lines-resembling a string of beads,and concentrated at intersections of different tectonic units,or at bends of tectonic units.Areas between the primary and secondary fractures had the largest thermal-storage depth,the longest runoff path,and more adequate water-rock reactions;whilst the opposites were found along the ternary fractures.From NE to SW,the temperatures of geothermal reservoirs were high in the central areas and SW,and low in the S and NE,and the medium-and high-temperature reservoirs mainly distributed in Gonghe,Guide,Wulan and Tanggula Mountain areas,with the reservoir temperatures ranging from 89.0℃to 139.0℃,averaging 117.7℃.The heat sources of hot springs included heat gain by conduction of Earth heat flow;heat from the decay of radi
作者
刘玲霞
路睿
谢文苹
刘博
王亚茹
姚海慧
蔺文静
LIU Lingxia;LU Rui;XIE Wenping;LIU Bo;WANG Yaru;YAO Haihui;LIN Wenjing(Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang 050061,China;Technological Innovation Center of Geothermal&Hot Dry Rock Exploration and Development,Ministry of Natural Resources,Shijiazhuang 050061,China;Qinghai Geological Survey Bureau,Xining 810000,China;Technology Innovation Center for Exploration and Exploitation of Strategic Mineral Resources in Plateau Desert Region,Ministry of Natural Resources,Xining 810000,China;School of Civil Engineering,Xuchang University,Xuchang 461000,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2024年第6期173-195,共23页
Earth Science Frontiers
基金
国家重点研发计划项目(2021YFB1507401)
青海省清洁能源矿产专项(2022013004qj004)
河南省科技攻关项目(212102310383)
河南省安阳市科技攻关项目(2022C01SF086)。
关键词
青藏高原东北部
水文地球化学
地球化学温标
硅焓图解
控热活动断裂
northeastern Tibetan Plateau
hydrogeochemistry
geothermometer
silica-enthalpy diagram
thermal control fractures
