辽宁瓦房店金刚石矿床50号岩管地质特征及找矿预测

Geological characteristics and prospecting predictions of No.50 kimberlite pipe in Wafangdian diamond deposit of Liaoning Province

以辽宁瓦房店金刚石矿床50号岩管为例,系统分析了该矿床的地质特征。通过对斑状富金云母金伯利岩、含围岩角砾斑状金伯利岩和金伯利凝灰角砾岩进行岩石地球化学分析发现碳酸盐化金伯利凝灰角砾岩超基性成分较少,滑石化、蛇纹石化及碳酸盐化混合金伯利凝灰角砾岩超基性成分较多;铬、镍、钛在金伯利凝灰角砾岩中的含量较低,在含围岩角砾斑状金云母金伯利岩中的含量略高,在斑状富金云母金伯利岩和斑状金伯利岩中的含量最高。该矿床主要为含围岩角砾斑状金伯利岩和斑状富金云母金伯利岩,其次为金伯利凝灰角砾岩、含围岩角砾斑状金云母金伯利岩和含金伯利物质角砾岩。含铬镁铝榴石、铬铁矿和碳硅石是金刚石的伴生矿物。水平方向上,金伯利岩含矿品位西部较富,东部较贫;垂直方向上,金伯利岩含矿品位变化较小。通过三维建模,推测50号岩管不是根部相,而是受EW向推覆构造作用影响发生的断层错位,在其东侧600 m深处存在50-1号金伯利岩体。

Taking No.50 kimberlite pipe of Wafangdian diamond deposit in Liaoning Province as an example,the authors systematically analyzed its geological characteristics.Based on the petrogeochemical analysis of porphyry phlogopite kimberlite,breccia porphyry kimberlite with surrounding rocks and kimberlite tuff breccia,it is found that there are less ultrabasic components in carbonated kimberlite tuff breccia and more ultrabasic components in kimberlite tuff breccia mixed with steatitization,serpentinization and carbonation.The content of Cr,Ni and Ti is relatively lower in kimberlite tuff breccia,slightly higher in breccia porphyrg phlogopite kimberlite with surrounding rocks and the highest in porphyry phlogopite kimberlite and porphyry kimberlite.This deposit is mainly composed of breccia porphyry kimberlite with surrounding rocks and porphyry phlogopite kimberlite,followed by kimberlite tuff breccia,breccia porphyry phlogopite kimberlite with surrounding rocks and kimberlite breccia.Chromite bearing pyrope,chromite and moissanite are associated minerals of the diamond deposit.The kimberlite ore-bearing grade is high in the western part and low in the eastern part in the horizontal direction,while the kimberlite ore-bearing grade changes little in the vertical direction.Through the three-dimensional modeling,it is inferred that instead of the root phase,No.50 kimberlite pipe is the fault dislocation caused by the EW nappe structural force with the No.50-1 kimberlite body at the depth of 600 m in the eastern pipe.