岩浆热源型地热系统及其水文地球化学判据  

Magma-heated geothermal systems and hydrogeochemical evidence of their occurrence

作　　者：郭清海[1,2] GUO Qinghai(State Key Laboratory of Biogeology and Environmental Geology,Wuhan,430074;School of Environmental Studies,China University of Geosciences,Wuhan,430074)

机构地区：[1]中国地质大学(武汉)生物地质与环境地质国家重点实验室,武汉430074 [2]中国地质大学(武汉)环境学院,武汉430074

出　　处：《地质学报》2020年第12期3544-3554,共11页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41861134028、41772370、41572335、40702041)资助的成果。

摘　　要：在各类地热系统中,岩浆热源型地热系统具有突出的科学研究意义和开发利用价值。自岩浆热源释出的岩浆流体富含多种强酸性气体,有极强的岩石溶蚀能力,是发生于岩浆热源型地热系统内的水文地球化学过程大异于非岩浆热源型地热系统的根本原因。浅埋或深埋岩浆热源型地热区内均普遍发育三种不同类型的地热水:酸性SO4型、SO4-Cl型或Cl-SO4型水,中性Cl-Na型或Cl-HCO3-Na型水,弱碱性HCO3-Cl-Na型或HCO3-Na型水;是否同时出现以上类型地热水也成为以非碳酸盐岩为热储围岩的水热型地热系统是否具有岩浆热源的水文地球化学判据。在中国,藏南-滇西地热带和台湾地热带是岩浆热源型地热系统集中分布的区域;藏南高原的高温水热型地热系统下的岩浆囊可能是地壳增厚过程中发生局部熔融的结果,也可能与印度大陆岩石圈向北消减后在拉萨地体下形成的近东西向地幔楔的上涌有关。Of various types of geothermal systems, magma chamber-heated geothermal systems are of great scientific significance and high exploitation value. Magmatic fluids released from a magma chamber serving as the heat source of a geothermal system are rich in strongly acidic gases, and therefore are capable of altering reservoir hostrocks substantially, which is the fundamental reason why hydrogeochemical processes occurring in a magmatic geothermal system is quite different from those in a non-magmatic geothermal system. In general, three types of geothermal waters are expected to occur in a geothermal area with either a shallow or a deep magmatic heat source, i.e. acidic SO4, SO4-Cl, or Cl-SO4 waters, neutral Cl-Na or Cl-HCO3-Na waters, and weakly alkaline HCO3-Cl-Na or HCO3-Na waters. Correspondingly, concurrence of these three geothermal waters turns out to be a useful hydrogeochemical criterion to judge if a hydrothermal system hosted by non-carbonate rocks is being heated by magma chambers. In China, magmatic geothermal systems are basically distributed in the southern Tibet-western Yunnan geothermal belt and the Taiwan geothermal belt. The magma chambers below the high-temperature hydrothermal systems in southern Tibet were formed probably due to the partial melting of Tibetan crust induced by crustal thickening, or resulted from the occurrence of a near E-W trending mantle wedge during the northward subduction of the Indian continental lithosphere and its further upwelling.

关 键 词：岩浆热源 岩浆流体 地热系统 地热水 水文地球化学 

分 类 号：P314[天文地球—固体地球物理学] P641.3[天文地球—地球物理学]