【作者】 尹周勋； 滕吉文； 熊绍柏；

【Author】 Yin Zhouxun Teng Jiwen Xiong Shaobai (Institute of Geophysics,Chinese Academy of Sciences)

【机构】 中国科学院地球物理研究所；

【摘要】 为了研究攀枝花-西昌构造带的地壳与上地幔顶部结构,在西起丽江东至者海全长350km的测线上进行了爆炸地震探测.本文利用所取得的6条地震记录剖面的P_g波组,研究测线下方地壳浅层结构.采用层状垂直梯度和横向不均匀模型,用理论走时和射线追踪方法来拟合实测P_g走时资料.得到深度为10 km范围的地壳浅层结构和速度分布.结果表明,该区地表P波速度以渡口至华坪一带为最高,达6.00 km/s.向东西两侧逐步减小,东至者海为5.20 km/s,西至丽江降为3.50 km/s.局部地段因构造影响速度值有些起伏.从浅层结构和速度分布可见,该区存在箐河-程海、绿汁江、安宁河和甘洛-小江等深断裂带,并向地壳深部延伸.等速度线图表明,该区上地壳中有一高速岩体存在.攀枝花钒、钛、铁矿的富集以及其它热液型矿床的分布很可能与此有关.更多还原

【Abstract】 In order to study the deepcrustal structure in the Pan-Xi tectonic belt,a explosion seismic sounding along a profile of 350 km long in the Dukou region was conducted in 1984.The east-west profile from Lijiang to Zhehai was arranged and six seismic sections in the profile were obtained.In this paper,first seismic phases in records are analysed to study the upper crustal structure beneath Dukou in detail.In data processing,different methods,such as theoretical travel time andray tracing,were used for a model with lateral inhomogeneity and vertical velocity gradient to fit the observed travel time data.Fine structures of the upper crust and velocity distributions down to 10 km deep are obtained. In the upper crust there exist several deep faults which extend to the lower crust.The P wave velocity of 6.00 km/ s between Dukou and Huaping is higher than those at the two ends of the profile(5.20 km / s in Zhehai and 3.50 km / s in Lijiang).The lateral variation of ve- locity seems to be attributed to tectonic processes.It is noted that there is a geological body with high velocity in the region between Dukou and Huaping,which is probably related to the upward movement and concentration of magma from the upper mantle.It can be inferred that a great deal of mineral of sefstromite deposited in the Panzhihua zone have somewhat relations with the above geodynamic processes.更多还原