金刚石指示矿物的找矿意义研究—以江苏张集地区发现金刚石原生矿为例

Study on the Prospecting Significance of the Diamond Indicator Minerals—Setting the Discovery of Primary Diamond Ore in Zhangji Area of Jiangsu Province as an Example

摘要:

金伯利岩中的石榴子石、铬铁矿和铬透辉石是寻找金刚石原生矿的重要指示矿物。根据主要化学成分TiO2,Cr2O3,FeO,MgO,CaO的含量，将石榴子石分成G1～G12十二组。该次研究区内石榴子石为橙色系列，经电子探针测试，G5组31粒，G4组18粒，G8组7粒，G3组1粒，其中G4组中Na2O含量＞0.07%的有4粒，属含钠镁铝铁铝榴石，且15csy034石榴子石为含金刚石金伯利岩。研究区内1粒铬铁矿为S5组贫钛富镁高铝铬铁矿，属非金伯利岩和非钾镁煌斑岩铬铁矿；研究区内发现的2粒铬透辉石，为低铬富镁透辉石。在研究指示矿物特征的基础上，在四山村北新发现编号分别为1,2,3号3个煌斑岩岩管和编号为4号的1个煌斑岩脉，并在2号岩管角砾岩中，选获直径为0.2mm左右的金刚石1粒。尤其是石榴子石标型矿物的研究为煌斑岩岩体的发现起到重要指导意义，进一步明确了找矿方向，减少了找矿的盲目性。

Abstract:

The garnet, chromite and chrome diopside in the kimberlite are important indicator minerals to search for primary diamond ore. According to the contents of TiO2, Cr2O3, FeO, MgO and CaO, garnet is divided into G1~G12 groups. The garnet belongs to orange series in the study area. Through electron probe test，31 grains belong to the G5 group，18 grains belong to G4 group, 7 grains belong to G8 group，and 1 grain belong to G3 group. There are 4 grains in G4 group with the content of Na2O % > 0.07%. It belongs to sodium magnesium aluminumalmandine type. The 15csy034 garnet belongs to diamond containing kimberlite. 1 chromite in the study area belongs to S5 group，which is chromite with poor titanium but rich magnesium and high aluminum. It is nonkimberlite and nonkalierite chromite. The two chrome diopside found in the study area are low chromium and rich magnesium diopside. Based on the study of the characteristics of indicator minerals, three new types of lamprophyre pipes and lamprophyre dyke, respectively numbered as 1, 2, 3 and 4 have been discovered in the north of Sishancun, and one diamond which diameter is 0.2mm has been selected from No. 2 pipe breccia. Especially, the study of garnet type minerals plays an important guiding role in the discovery of lamprophyre rock mass, and further clarifies the prospecting direction and reduces the blindness of prospecting.