中文摘要：

上面的二叠的 Xuanwei 形成广泛地发生在西方的贵州， unconformably overlying Emeishan 暗岩，并且主要由黑页岩组成。它是在 Cuyudong 村庄厚的 170 m， Weining 县，韦斯特贵州，中国，在黑页岩的样品和沙的页岩镇定、分析的地方。页岩主要包含 SiO2， 18.9%44.1% ， Al2O3， 14.8%52.8% ， Fe2O3， 1.0%41.2% ， LOI， 3.2%21.1% ， TiO2， 1.0%6.7% ，和 MgO， 0.2%2.5% 。所有另外的主要元素的内容比 1.0% 低。黑页岩比正常页岩有 Fe2O3 和 LOI 的更高的内容，这被显示出。陨铁与 Fe2O3 的更高的内容发生在黑页岩，它可以在 seafloor 上被归因于热水的活动。所有分析页岩样品有极其高的 Ga， 47.8 ?? ㄠ ?????? ㈠吗？？

英文摘要：

The Upper Permian Xuanwei Formation widely occurs in western Guizhou,unconformably overlying the Emeishan basalts,and mainly consists of black shales.It is～170 m thick at Cuyudong Village,Weining County,West Guizhou,China,where the samples of black shale and sandy shale were collected and analyzed.The shales mainly contain SiO2,18.9%-44.1%,Al2O3,14.8%-52.8%,Fe2O3,1.0%-41.2%,LOI,3.2%-21.1%,TiO2,1.0%-6.7%,and MgO,0.2%-2.5%.The contents of all other major elements are lower than 1.0%.It is shown that the black shales have higher contents of Fe2O3 and LOI than normal shales.The siderites occurred in the black shales with higher contents of Fe2O3,which may be attributed to hydrothermal activities on seafloor.All analyzed shale samples have extremely high Ga,47.8×10^-6-109.9×10^-6（70.5×10^-6 on average）,higher than the industrial mining standard of Ga Resource Industry Standard.The total contents of rare-earth elements（REE） of 9 black shale samples vary from 213×10^-6 to 1460×10^-6,suggesting that these black shales are enriched in REE.The shale-normalized REE patterns display both positive and negative Ce anomalies（Ce/Ce＊ from 0.5 to 1.7）,revealing that the Xuanwei shales were precipitated under oxic and anoxic conditions.The Rb-Sr chronological diagram of 6 shale samples in the Xuanwei Formation shows an age of 255±12 Ma.Strontium isotopic ratios（87Sr/86Sr）t0 range from 0.70635 to 0.70711,suggesting that these Xuanwei black shales might be derived from chemical weathering of the Emeishan basalts.