地处南秦岭海西—印支褶皱带南沿的陕西南部的勉(县)—略(阳)—宁(强)地区是我国石棉矿床集中产地之一。在南北分别受阳(平关)—勉(县)和略(阳)—勉(县)大断裂控制的三角形地块的下构造层(碧口群)中,断续产出有数十个规模不等的超基性岩体。其中含棉岩体有四个——黑木林纯橄—辉橄岩型岩体、煎茶岭辉橄岩型岩体、王家山辉橄岩型岩体和杨家山辉橄—纯橄岩型岩体(图1)。其同位素年龄值(全岩样,钾—氩法)为564— Located in the southern Qinling Hercynian - South of the Indochina fold belt in southern Mian (county) - slightly (Yang) - Ning (strong) is one of the concentrated areas of asbestos deposits in China. In the lower tectonic layer (Bikou Group) of the triangular block controlled by the north-south major faults (Mian (county) and slightly (Yang) -Mian (county) respectively), there are dozens of intermittent outputs Unequal ultramafic rocks. Among them, there are four cotton-bearing rock masses: Hemuilin-Oligochorite type, Jianchaling pumice type rock mass, Wangjiashan pumice type rock mass and Yangjiashan faiou-dunite rock type Body (Figure 1). The isotopic ages (total rock sample, potassium-argon method) were 564-