【作者】 魏斯禹； 邓肖粤； 金志翰； 胡忠义； 余武元；

【Author】 Wei Siyu Deng Xiaoyue Jin Zhihan Hu Zhongyi Yu wuyuan (Institute of Geophysics,Chinese Academy of Sciences)

【机构】 中国科学院地球物理研究所；

【摘要】 攀-西地带构造复杂,地震频繁,并且是古老岩浆岩沿构造带轴部规则分布的狭长地带,历史上与现今均遗留下了较多的地壳运动痕迹,并形成了规则的构造体系.为了研究这一地带的地热活动、热流分布及其与该区构造运动关系,对地表温泉分布及水温等资料作了分析,采集了标本,测定了岩心的热导率,并依此及深井温度梯度的测量结果进行了数据处理.在攀-西所测之井位,分布于:西昌太和、米易县、会理红格、盐源县.所求得的热流值分布在1.0-1.2H.F.U.范围之内.这一地区地表温泉均与断裂相关.西昌附近温泉水温为20—48℃,渡口及红格附近为30—44℃,米易附近为38℃,普格、宁南、巧家一线则为65℃、48℃和53℃左右,但在北部康定附近则可达60℃左右.在攀-西构造带东西两侧,泉水温度亦达30—40℃与25—40℃.这便表明,在攀-西构造带的轴部,从总的趋势看来,温泉水温相对于东西两侧略高5—10℃.六口深钻井中的热流值并不高,低于一般大陆与海洋地区正常的平均热流值.基于上述地热活动与热流值的分布特征表明:在攀-西构造地带,地热流值为1.2—1.8H.F.U.,温泉活动又多与断层有关.对比世界裂谷系表明,攀-西地区的热流值要比东非裂谷、贝加尔裂谷、莱茵裂谷和美国盆地山脉省等处低,但却比北欧奥斯陆古裂谷的热流平均值(1.1 H.F.U.)高,即介于新生代裂谷和古裂谷之间.由此推断:攀-西地区乃属于中元古代时期形成的古裂谷,尔后经多次运动的改造,古裂谷已闭合,但由于海西-燕山期地壳的构造运动和印度板块与欧亚板块碰撞后,西藏高原的壳幔物质自北东转向西南运移,对康滇构造带的挤压,形成了与华南板块碰撞的格局,构成了这一构造带的近代"复苏"与断裂带周围应力重新分配与运动.然而由于这里是青藏高原与华南板块碰撞的古板块边界带,且走向北东;而现今断裂带走向近南北,这便证明现今地表构造与岩相格局仍是后期构造运动与作用的结果.在现今南北走向的轴部和上地幔的热物质埋藏较深,不易上升,故地表温度不会很高,热流值也必然会低.近代地震活动主要集中在康定、鱼鲊、普格、巧家、西昌各处的构造交汇部位,则仍是该区相邻构造体系作用的结果.更多还原

【Abstract】 In order to investigate the relationship between geothermal activity,heat flow distribution and the tectonic movement in Pan-Xi region,the data of surfacial hot spring distribution and water temperaturc have been analyzed,rock sample at deep well has been selected,thermal conductivity of the rock core has been measured according to above data;the data and the measured result of temperature gradient at deep well have been processed.The locations of wells measured in Pan-Xi region are:Taihe of Xichang,Miyi county,Hongge and Lala of Huili county,Yah Yuan county and Yanbian county.The obtained heat flow values range from 1.0 to 1.2 H.F.U.. The surficial hot spring at this zone is related to the fracture.The water temperature of hot spring near Xichang is 20-48℃,near Dukou and Hongge is 30-44℃,near Miyi is 38℃,at Puge,Ningnan,and Qiaojia are 65℃,48℃and 53℃or so respectively,but in the vicinity of northern Kang Ding is up to 60℃or so.The temperature of spring water at the east and west sides of Pan-Xi tectonic zone is also up to 30-40℃and 25-40℃.This shows that on the whole the water temperaturc of the hot springs at the axis of Pan-Xi tectonic zone is 5-10℃higher than that of the west and east sides.The heat flow values at 6 deep bore-holes are not high,and lower than the normal average heat flow value at the continental and oceanic regions. The distributional features of the above mentioned geothermal activity and heat flow value indicate that the geothermal activity at Pan-Xi tectonic zone is not very strong,but most hot spring activities are connected with faulting.Compared with the world rift system,the heat flow value at Pan-Xi region is much lower than those of at East African rift,Baikal rift,Rhine rift and American Basin and Range,but it corresponds to the average heat flow value of 1.1 H.F.U. at Oslo ancient rift.Thus it is inferred that Pan-Xi region belongs to the ancient rift formed from Meso-Proterozoic era and then after many movements and transformations the ancient rift has already closed.But the crustal tectonic motion during Hercvrian-Yanshan Period and the migration of the crustal and upper mantle substances at Tibetan plateau from northeast to southwest after the collision between Indian plate and Euracian plate compressing on the Kangdian tectonic zone formed the pattern colliding with south China plate.Therefore recent"activition"of this tectonic zone and renewable stress adjustment and movement surrounding the fracture zone have been constituted.更多还原