河北北部四处温泉的水化学特征及成因分析

Hydrochemical Characteristics and Formation of Four Hot Springs in Northern Hebei

以河北北部承德地区的4处温泉,漠河沟温泉(A10)、三道营温泉(A11)、山湾子温泉(A12)和北大坝温泉(A13)为研究对象,根据2010年与2018年的温泉水样测试数据,分析温泉的水化学特征,并总结其成因模式。研究区出露地层主要有中新元古界、二叠系、三叠系、侏罗系、白垩系和新近系以及第四系,并伴随有大量侵入岩岩体。温泉的出露温度为36~75℃,p H值为7.2~8.2,TDS均小于1 g/L。研究区温泉阳离子均以Na+占绝对优势,毫克当量百分数在90%以上,阴离子主要以HCO_(3)-和SO_(4)^(2-)为主,4处温泉的水化学类型分别为SO_(4)·HCO_(3)-Na型、HCO_(3)·SO_(4)-Na型、HCO_(3)-Na型和SO_(4)·HCO_(3)-Na型,且温泉的偏硅酸和F^(-)含量高。研究区温泉稀土元素总含量(∑REEs)为0.030~15.525μg/L,主要以碳酸盐络合物和F的络合物形式存在;地下热水的稀土元素球粒陨石标准化配分模式较为平缓,轻稀土元素略显富集。研究区温泉水补给主要源于大气降水,利用SiO_(2)温标估算的温泉地下热储温度为85~125℃,地下热水经深循环后通过接触带、破碎带或导水断裂上升出露地表。

This study examined four hot springs in northern Hebei,namely Mohegou(A10),Sandaoying(A11),Shanwanzi(A12)and Beidaba(A13).Through analyzing hot-spring water samples in 2010 and 2018,we unravel the hydrochemical characteristics of the springs and elucidate their formation.Local stratigra-phy comprises mainly the Mesoproterozoic,Permian,Triassic,Jurassic,Cretaceous,Neogene and Quaternary sequences,with large number of plutonic units.The hot spring temperatures range from 26 to 75℃,and the p H and TDS is 7.2-8.2 and<1 g/L,respectively.The cations of the local hot springs are dominated(>90%)by Na+,whilst the anions are dominated by HCO_(3)-and SO_(4)^(2-).The hydrochemical types of the four hot springs are of SO_(4)·HCO_(3)-Na,HCO_(3)·SO_(4)-Na,HCO_(3)-Na and SO_(4)·HCO_(3)-Na type.The local hot springs have generally high H_(2)SiO_(3) and F^(-)concentrations,and their total REE contents range from 0.030 to 15.525μg/L,existing mainly as carbonate and fluorine complexes.The chondrite-normalized REE patterns of the hot water samples are relatively gentle with LREE enrichment.The local hot springs are mainly recharged by atmospheric precipitation,and the geothermal reservoir temperatures are estimated to be 85-125℃with the SiO_(2)geother-mometer.The thermal groundwater may have undergone deep circulation,rises along the contact zone,fracture zones and faults,and emerges as hot springs on the land surface.