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通过对采自鄂尔多斯盆地基底西部石榴夕线黑云斜长片麻岩与东部片麻状二云母花岗岩的钻孔样品进行SHRIMP锆石U-Pb定年,分别获得了203110和203510Ma的207Pb/206Pb年龄.两件样品的锆石都显示清楚的韵律环带,具岩浆锆石特征.其中石榴夕线黑云斜长片麻岩中的部分锆石具有较薄的变质增生边,由3个增生边获得的年龄范围约为1850～1630Ma.该岩石的矿物组合显示原岩为泥质-长英质岩石,但其锆石主体为岩浆成因,可能说明其源区为单一的花岗质岩体或火山沉积岩区.因此,鄂尔多斯基底与邻近剥露区域一样,在古元古代2035～2030Ma左右曾有大规模的花岗岩浆侵位,表明存在古元古代活动构造带,这对揭示华北克拉通西部陆块的性质和特征具有重要的意义.
The SHRIMP zircon U-Pb dating of boreholes collected from the slate ancillary plagioclase gneiss and eastern gneissic ductile micas from the west of Ordos Basin resulted in 207Pb / 206Pb ages of 203110 and 203510 Ma, respectively The zircons of both samples show a clear rhythmic ring zone with magmatic zircons, in which some of the zircons in the siphonite plagiogneiss have a thinner metamorphic edge and consist of three hyperplastic edges The ages ranged from 1850 to 1630 Ma. The mineral assemblages of this rock show that the protolith is argillaceous-feldspathic, but its main zircon is magmatic origin, which may indicate that the source area is a single granitic rock mass or Volcanic sedimentary rock area.Therefore, the Ordos basement had large-scale granitic magma emplacement in the period of about 2035 ~ 2030Ma in the Paleoproterozoic, which indicates the existence of Paleoproterozoic active tectonic belts in the Ordos basement. The nature and characteristics of blocks are of great importance.