鄂尔多斯盆地西南缘铜城一带碱性岩地质特征及找矿前景浅析

GEOLOGICAL CHARACTERISTICS AND PROSPECTING POTENTIAL OF ALKALINE ROCKS IN TONGCHENG AREA,SOUTHWESTERN ORDOS BASIN

鄂尔多斯盆地西南缘铜城一带的碱性岩地学界主要是对岩体的时空分布、岩石学和岩石地球化学特征、形成时代及其与油气成藏关系等方面进行了研究。本次研究根据国内对含钾岩石的某些研究成果,通过对碱性岩资料的收集、分析,发现碱性岩具有较高的w(Al_(2)O_(3))(18.40%~20.00%)、w(K_(2)O)(9.69%~10.2%)和较低的w(SiO_(2))(45.42%~55.61%)、w(Na_(2)O)(0.38%~1.53%)、w(MgO)(0.27%~0.53%)等,岩石整体表现出富钾、铝、钙,贫硅、镁等的强碱性硅不饱和的特征。岩石的K_(2)O含量与《矿产资源工业要求手册》中关于含钾岩石制取钾肥一般工业指标及中国富钾正长岩中K_(2)O含量相当,从理论上认为该碱性岩具有非水溶性钾矿资源的找矿前景。

The Tongcheng area is located in the southwest margin of Ordos Basin and studies of alkaline rocks exposed in this region mainly focus on time-space distribution,petrology,petrochemistry,age and its relationship with hydrocarbon accumulation.On the basis of the research of potash-bearing rocks in China,the data of alkaline rocks are collected and analyzed in this paper.Results show that the alkaline rocks are characterized by high Al_(2)O_(3)(18.40%~20.00 wt.%),K_(2)O(9.69%~10.2 wt.%)and low SiO_(2)(45.42%~55.61 wt.%),Na_(2)O(0.38%~1.53 wt.%),MgO(0.27%~0.53 wt.%).Generally,compositions of rocks is rich in potassium,aluminum,calcium,and poor in silicon and magnesium,which manifests themselves as peralkaline silicon unsaturated series.The K_(2)O content of the rocks is equivalent to the general industrial index of potash fertilizer extracted from potash-bearing rock in the’Handbook of industrial requirements for mineral resources’.Also,the K_(2)O content is the same as potassic syenite in China.So it is theoretically considered that the alkaline rock has the prospecting prospect of insoluble potash resources.