河西走廊盆地地下水的氦同位素指示  

Tracing Groundwater with Helium Isotopic Compositions in the Hexi Corridor Basin, Northwestern China

作　　者：赵霞[1] 陈建生[1,2,3] 饶文波[2] 董海洲 盛雪芬[3] 苏治国[3] 陈亮[1] 

机构地区：[1]河海大学岩土工程研究所,南京210098 [2]河海大学科学研究院 [3]河海大学水文水资源与水利工程科学国家重点实验室,南京210098

出　　处：《地质学报》2007年第4期563-569,共7页Acta Geologica Sinica

基　　金：国家自然科学基金面上预研项目(编号50579017);河海大学国家重点实验室开放基金(编号2005406611);江苏省"六大人才高峰"A类项目共同资助成果

摘　　要：详细讨论了河西走廊的张掖、永昌和武威盆地地下水中同位素3He/4He、4He/20Ne和δ13C的组成与分布特征。结果表明,泉水溢出地表后尽管受大气不同程度的混染,其中仍含有明显的深源氦气的组分,包括放射性元素铀和钍的蜕变及锂诱发的核反应生成的壳源4He与地球形成初期储存于地幔中的原始3He。这些氦气挥发份随NNE和WNW向活动断裂带向上迁移,直至被循环的地下水带至地表。The HexiCorridor （37°17＇N to 42°48＇N; 93°23＇E to 104°12＇E） is situated on the arid region of northwestern China. Fault zones in the Hexi Corridor Basin are still active in response to the collision between the Indian Plate and Eurasian Plate together with the northern extrusion since the Cenozoic. We measured helium and carbon isotopic compositions of groundwater to clarify the origins of helium and volatiles in the groundwater and to disclose a relationship between the groundwater system and fault zones within the Hexi Corridor. The R/Ra values indicate that 3^He from the groundwater in the northern boundary fault of the Qilian Mountains is derived from the mantle with a mixture of atmospheric helium. Frequent earthquake activities activated the North Qilian Fault, so that oceanic basalt vitreous or volcanic rocks were molten to magma again. The magma then trapped mantle-source 3^He and carried it along as it rose into the crust along the faults. In contrast, helium in the Xigaze-Langshan Fault Zone is derived mainly from the crust with mixing of atmospheric helium. Caledonian granites widely distribute in the water-bearing layers, resulting in the sharp increase of 4^He contents produced from the decay of radioactive U and Th elements contained in these types of rocks. Furthermore, the slight mantle-source helium injection in the groundwater is probably due to extraction processes of earthquake. Additionally, The δ13^C values show that carbon dioxide is predominately derived from the deep earth. Therefore, helium, neon and carbon dioxide volatiles in the deep earth are released along active fault zones and in turn incorporated in the groundwater, which transported into the ground surface accompanied with the water circulation.

关 键 词：河西走廊 HE同位素 地下水 断裂带 

分 类 号：P315.72[天文地球—地震学]