亚东-谷露断裂带中北段地热流体碳硫硼同位素特征  

Isotopic characteristics of carbon,sulfur,boron of geothermal fluid in the middle and northern section of Yadong-Gulu rift

作　　者：张健 郝伟林[1] 巴桑元旦 张松[1] ZHANG Jian;HAO Weilin;BANSANG Yuandan;ZHANG Song(CNNC Geothermal Exploration Technology Center Beijing Research Institute of Uranium Geology,Beijing 100029,China;Center of Land Mining Rights Trading and Resource Reserve Evaluation,Xizang Autonomous Region,Lhasa 850011,China)

机构地区：[1]核工业北京地质研究院中核集团地热勘查技术研究中心,北京100029 [2]西藏自治区土地矿权交易和资源储量评审中心,西藏拉萨850011

出　　处：《世界核地质科学》2024年第1期129-140,共12页World Nuclear Geoscience

摘　　要：亚东—谷露断裂带中北段地热系统深循环过程十分复杂,对该区域地热资源的评估具有较大影响。加深对地热水起源、演化和循环过程的研究,对地热资源的勘探和开发具有较大的意义。地热流体中碳硫硼稳定同位素特征分析是研究地热水来源、地热水循环深度和地热水作用过程的方法之一。对亚东—谷露断裂带中北段地热水进行了系统性采样,测量了碳硫硼同位素。进行了碳硫硼同位素分析,结果显示:稳定同位素特征源于地热流体对围岩和地层的淋滤作用和水-岩相互作用。该地热系统中碳的主要来源为碳酸盐的溶解,与区域上分布的碳酸盐地层有关。谷露和续迈地热田δ^(34)S具有较大的分散性,显示出硫来源的非单一性,δ^(34)S均在大气碳酸盐和蒸发碳酸盐范围内,δ^(34)S同位素的来源为大气降水和热储层中的硫酸盐矿物。谷露地热田具有较低的δ^(11)B值和较低的Cl/B比值,较高的硼含量,且硼含量和硼同位素值相对集中,表明硼主要源于地热流体对围岩的淋滤作用。大气降水和冰雪融水中硼含量极少,主要起到对地热水中硼含量的稀释作用,不改变地热水中的δ^(11)B值。本研究的结果验证了亚东—谷露断裂带中北段地热系统地下热水的起源主要为大气降水,在深循环过程中存在少量岩浆流体的混入。The central-northern section of the Yadong-Gulu rift is one of the important geothermal activity areas in the Mediterranean-Himalayan geothermal belt.The deep circulation process of the geothermal system in the central-northern section of the Yadong-Gulu rift is very complex and still unclear,which has a significant impact on the evaluation of geothermal resources in this region.Attracting researcher’s attention to the geological structure and geothermal system of this region.The deep seismic reflection profiles of the Himalaya and Tibetan Plateau confirm the existence of magmatic heat sources in the geothermal system in the middle and northern section of the Yadong-Gulu rift.The central-northern section of the Yadong-Gulu rift is enriched in Li,Rb,and Cs elements in geothermal fluid,which may be derived from deep magmatic hydrothermal fluid or from water-rock interaction during runoff process.Isotopic characteristics are important evidence of material sources and are an important method for clarifying the runoff process.We systematically sampled the geothermal water in the central and northern sections of the Yadong-Gulu fault zone and measured carbon,sulfur,and boron isotopes.Samples of geothermal water were collected and analyzed from typical hot fields and multiple geothermal display areas in the study area.The carbon sulfur and boron isotope analysis of geothermal fluids in the middle and northern section of Yadong-Gulu rift zone shows that the stable isotope characteristics are derived from the leaching of geothermal fluids to surrounding rock and formation and water-rock interaction.The main source of carbon in this geothermal system is the dissolution of carbonates,which is related to the distribution of carbonate strata in the region.Theδ^(34)S values of Gulu and Xumai geothermal fields have a large dispersion,indicating that the source of sulfur is not single.Theδ^(34)S isotopic values are within the range of atmospheric carbonate and evaporative carbonate,indicating that the source of sulfur is atm

关 键 词：亚东—谷露断裂带中北段 地热流体 碳硫硼同位素 水文地球化学过程 水热系统 

分 类 号：P314[天文地球—固体地球物理学] O613.51[天文地球—地球物理学] O613.71[理学—无机化学] O613.81[理学—化学]