New U-Pb zircon SHRIMP determinations from magmatic silicic rocks adjacent to the NE part of the Upper Silesia Coal Basin (USB) are provided and compared with earlier data obtained by K-Ar dating. The zircon samples studied came from the same boreholes and depth intervals previously sampled for K-Ar datings. Recalculations of the earlier K-Ar values for biotites yielded isochron ages in the range of 297–309 Ma. The zircon U-Pb SHRIMP values gave more precise ages between 300.1 ±1.2 Ma and 292.6 ±1.3 Ma (1σ) consistent with U-Pb and Re-Os determinations. In two cases, the recalculated results of K-Ar dates were nearly identical with those obtained from the SHRIMP isotopic analyses. In this context, the granitoids and porphyries of the USB area, once assigned to the Carboniferous-Permian based on the older K-Ar studies, actually are of the same age as other felsic igneous rocks from the vicinity of the Krakow-Lubliniec Fault Zone, with a higher dating precision, however. The new data underline the importance of Late Carboniferous- Early Permian felsic magmatism at the SW margin of the Trans-European Suture Zone in southern Poland. In the zircon populations dated, besides the dominant Late Paleozoic ages, there are some inherited zircon cores, likely remnant detrital grains from a sediment component in the source rocks, that reveal much older ages which range from ~2051 to 569 Ma.

中文翻译：

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Kraków-Lubliniec 断裂带（波兰南部）附近的长英质岩石的 K-Ar 和新 U-Pb 年龄数据的重新评估

提供了上西里西亚煤盆地 (USB) NE 部分附近岩浆硅质岩的新 U-Pb 锆石 SHRIMP 测定结果，并与 K-Ar 测年获得的早期数据进行了比较。所研究的锆石样品来自先前为 K-Ar 测年采样的相同钻孔和深度间隔。对黑云母早期 K-Ar 值的重新计算产生了 297-309 Ma 范围内的等时线年龄。锆石 U-Pb SHRIMP 值给出了更精确的年龄介于 300.1 ±1.2 Ma 和 292.6 ±1.3 Ma (1σ) 之间，与 U-Pb 和 Re-Os 测定一致。在两种情况下，重新计算的 K-Ar 日期结果与从 SHRIMP 同位素分析获得的结果几乎相同。在这种情况下，USB 地区的花岗岩和斑岩，曾经根据较早的 K-Ar 研究被分配到石炭纪-二叠纪，实际上，它们与来自克拉科夫-卢布林尼茨断裂带附近的其他长英质火成岩的年代相同，但具有更高的年代测定精度。新数据强调了波兰南部跨欧洲缝合带西南边缘晚石炭世-早二叠世长英质岩浆作用的重要性。在已测年的锆石种群中，除了占主导地位的晚古生代之外，还有一些继承的锆石核，可能是烃源岩中沉积物组分的残余碎屑颗粒，揭示了更古老的年龄，范围从~2051 到 569 Ma。