【摘要】 野外构造解析和显微构造分析表明:崇山剪切断裂系北部的崇山剪切断裂带为一条左旋走滑剪切带,变形温度为300～550℃,为绿片岩相至低角闪岩相;而南部的临沧剪切带是一条带有NWW-SEE向地壳缩短变形的左旋走滑剪切带,普遍为绿片岩相,变形温度为300～450℃,存在向SE的推覆事件。对采自崇山和临沧韧性剪切带内糜棱岩样品中矿物的40Ar-39Ar年代学研究表明:崇山韧性剪切带凤庆至小湾公路26km处02DX-139样品中黑云母40Ar-39Ar坪年龄为28.3±0.1Ma,临沧韧性剪切带双江粟义剖面02DX-51样品白云母给出了31.5±0.2Ma的坪年龄。崇山-临沧剪切断裂带变形运动学和变形时序与哀牢山-红河剪切断裂带具有很好的一致性,这为理解滇西地区新生代构造演化和亚欧-印度块体的拼合效应及南海海盆的打开提供了新的信息。更多还原

【Abstract】 All the structural and microstructural observations suggest a tectonic movement of a sinistral strike-slip shearing for the Chongshan-Lincang shear zones. A kinematic scenario was presented for the Chongshan-Lincang shear zones: a sinistral strike-slip transport (top-to-SE extrusion) for the northern Chongshan-Lincang shear zones (Chongshan shear zones) under deformational temperature from ~550 ℃ to ~300 ℃, i.e., from greenschist facies to low amphibolite facies, and a sinistral strike-slip shearing with a WNW-ESE shortening for the southern Chongshan- Lincang shear zones (Lincang shear zones) under deformation temperature from ~450 ℃ to ~300 ℃ and greenschist facies deformational condition as being representative of transition from ductile to brittle condition during progressive deformation. Biotite separated from sample 02DX-139 of mylonitic rocks acquired from Xiaowan in Chongshan shear zones yields well-defined 40Ar- 39Ar plateau age of 28.3±0.1 Ma for about 95% released 39Ar. Muscovite separated from sample 02DX-51 of mylonitic rocks from Xuyi in Lincang shear zones yields well-defined 40Ar- 39Ar plateau age of 31.5±0.2 Ma for about 92% released 39Ar. These ages are interpreted to represent cooling following the synkinematic growth of mica as a consequence of mylonitic overprinting, based on the 40Ar- 39Ar closure temperatures, and to represent the deformation of Chongshan-Lincang shear zones. Chongshan- Lincang shear zones are similar to the Ailaoshan-Honghe shear zones in kinematics and deformation epoch concerning southeastern Tibetan syntaxis. It can offer new information on the Cenozoic structural development of west Yunnan Province and the effect of India-Asia colliding, even on the opening of the South China Sea.更多还原