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对蚌埠隆起区庄子里和磨盘山钾长花岗岩进行了系统的年代学和地球化学以及锆石Hf同位素的研究,以便对其岩石成因进行约束.研究结果表明,庄子里和磨盘山钾长花岗岩中锆石发育震荡生长环带,且具有较高的Th/U比值(0.13～1.47),反映了岩浆成因特征.对庄子里和磨盘山钾长花岗岩中岩浆锆石进行的LA-ICP-MSU-Pb定年结果(上交点年龄)分别为2104±20Ma和2196±190Ma,这表明蚌埠隆起区钾长花岗岩的形成时代为古元古代.钾长花岗岩的SiO2和K2O含量分别介于69.65%～77.95%和4.98%～5.17%之间;该类岩石富集轻稀土元素和Zr、Hf、Rb、Th、U等元素,明显亏损Ba、Sr、Eu、P和Ti等元素;它们的εNd(t)值变化于-3.4～+3.2之间,Nd的模式年龄变化于2.31～2.79Ga之间;钾长花岗岩中锆石的εHf(t)值和Hf同位素两阶段模式年龄分别介于-5.1～+7.8和2.26～2.83Ga之间.上述特征表明,蚌埠隆起区钾长花岗岩的原始岩浆起源于有少量古老地壳物质涉入的新生下地壳的部分熔融.庄子里和磨盘山钾长花岗岩为A型花岗岩,形成于伸展的构造背景.
We systematically studied the geochronology and geochemistry of zircons and the Hf isotopes of zircons in the Zhuangzi ri and the Mopanshan potash-bearing granites in the Bengbu uplift so as to constrain the genesis of the rocks. The results show that the Zhuozili and Mopanshan k- The zircons developed an oscillatory growth zone with high Th / U ratio (0.13-1.47), reflecting the genetic characteristics of magma.The LA-ICP-MSU-MS data of magmatic zircons in the Zhuangzili and Mopanshan k- The results of Pb dating (dating point) are 2104 ± 20Ma and 2196 ± 190Ma, respectively, which indicates that the formation of the potash-bearing granite in the Bengbu uplift is Paleoproterozoic.The contents of SiO2 and K2O in the potash-bearing granites range from 69.65% to 77.95% And 4.98% -5.17%. These rocks are enriched in LREE, Zr, Hf, Rb, Th, U and other elements and obviously depleted in Ba, Sr, Eu, The value of Nd varies from -3.4 to +3.2, and the Nd-type ages vary from 2.31 to 2.79Ga. The εHf (t) values and Hf isotopic two-period ages of zircons from K-bearing granites range from -5.1 to + 7.8 and 2.26 ~ 2.83Ga between the above characteristics show that the Bengbu uplift potassium-bearing granite protolith Originated in the partial melting of a small amount of old newborn crust crust involved. Zhuangzi and Mopanshan moyites type A granite, is formed extending in the background structure.