【摘要】 金沙江-红河断裂带是青藏高原东南缘地热活动强烈、地震活动水平高、各种矿产丰富的深大断裂带。为了探索该断裂带的温泉气体地球化学时空变化特征,2015年3月～2019年7月,经过5次野外考察,采集了54个温泉逸出气体样品,对其化学组分和氦、氖与碳的同位素变化的测试结果表明:(1)金沙江-红河断裂带内温泉气体氦同位素比值(3He/4He)变化范围是0.04～0.62Ra(Ra=空气3He/4He=1.39×10-6),计算获得的幔源氦最大比例达到7.5%,揭示该断裂带内的地质流体主要来自于壳源,幔源氦有从北向南呈现增加的趋势。以CO2为主要组分的温泉,其δ13CCO2值变化范围是-23.6‰～-1.9‰(vs. PDB)。结合区域地质条件分析,这些CO2主要来自三叠系灰岩,所占比例范围是70.1%～89.7%,而幔源CO2的比例最高可以达到4.2%。(2)金沙江-红河断裂带温泉气体的氢气浓度和氦同位素在三处断裂交汇区都出现高峰值,分别是金沙江断裂与巴塘断裂、中甸断裂与红河断裂、红河断裂与小江断裂和奠边府断裂的交汇处。与区域地震活动性的对比分析结果表明,金沙江-红河断裂带内深部流体上涌相对强烈的区域,深部流体对区域地震活动性具有重要的控制作用。更多还原

【Abstract】 The Jinshajiang-Red River fault zone（ JSJ-RRFZ） is a deep and large in scale with high level seismic activity and strong hydrothermal activity,and also rich in mineral resources. In order to elucidate spatial-temporal variations of geochemical features of hot spring gases along the JSJ-RRFZ,chemical composition,He,Ne and C isotropic ratios of 54 bubbling gas samples along the JSJ-RRF were analyzed along with 5 field investigations from March 2015 to July 2019. The analytical data indicated that:（ 1） the isotopic ratios of helium（3 He/4 He） in hot springs varied from 0. 04 to 0. 92 Ra（ Ra = air3 He/4 He = 1. 39 × 10-6）,with mantle-derived He up to7. 5%（ assuming R/Ra = 8 for mantle）,indicating the JSJ-RRF as a crustal-scale fault acting as a conduit for deep fluid from the mantle. The hot springs with CO2 as the majority of gas（ ≥75 vol. %） had δ¹³C_CO2 values from -23. 6‰ to -1. 9‰（ vs. PDB）. The proportions of mantle-derived CO2 varied from 0 to 4. 2%. The crustal marine limestone of Triassic System could be the major contributor（ 70. 1% ～ 89. 7%） to the carbon inventory of hot spring gas samples.（ 2） There were three areas with high values of H₂ concentration and helium isotopic ratios at three fracture junctions of the Jinshajiang fault with the Batang fault,the Zhongdian fault with the Red River fault,the Red River fault with the Xiaojiang fault and the Dianbianfu fault,respectively. The gas geochemical data suggested that the upwelling mantle fluids into the crust played an important role in regional seismic activity in the strike-slip faults along the JRFZ in the Southeast Tibetan Plateau.更多还原