新疆北部早石炭世陆屑建造研究

陆屑建造为地槽沉积旋回中一种重要的建造，作者利用大量的第一手野外实测剖面资料和室内分析测试数据，对新疆北部早石炭世陆屑建造的物质组分，相型特征、层序特征等进行综合分析研究，在此基础上划分出了５个亚建造，并综述了它们的主要特点，最后探讨了形成陆屑建造的大地构造环境。

THE EARLY CARBONIFEROUS TERRIGENOUS CLASTIC FORMATION IN NORTHERN XINJIANG

The lithological compositions of Early Carboniferous terrigenous elastic formation is complicated in northern Xinjiang, dominating sandstone, siltstone and mudstone, and also combining with a certain proportion of conglomerate, volcanoclastic and carbonate rocks, as well as thin coalbed occassionally. In particular, there are some carbonate rocks(about 515% in volume) in many sections. Sedimentary environments of the formation is also variable, and the major lithofacies are littoral and neritic factes as well as a few fluciolacustrine factes. The terrigeous factes developed at the bottom or middle and upper of the formation. The SiO2 concentration of the sandstone in the formation is lower than its average value in the crust, but Al,O,, Fe2O3, FeO, MgO, CaO, NaO, K2O are higher. The abundance of the trace elements of mudstones in the formation is close to the Clark value of the mudstone. However, Zn, Mn, Cu, Ph, V concentrations of sandstone and limestone are several times higher than the average value of sandstone in the crust, especially for Co, Ph. The formation shapes in a long-belt and dominates the littoral-and(or) neritic-factes sequence schemes with a few of terrigeous ones. According to the differences in its composition, forming environments, factes and seqLlence schemes, the formation can be classified into five sub formations in the region. The terrigeous elastic formation in northern Xinjiang, in general, formed in an active geosynclinal region. But there are great differeces in the tectonic settings for its subformations. For instance. neritic fine elastic subformation occurred in a marginal sea; littoral-neritic greywacke-limestone-mudstone sub formation in a foreland basin, littoral-neritic greywacke and intermediate-acid volcanic rock subformation formed in a magmatic back-arc basin and littoral-neritic greywacke and basicintermediate volcanic rock subformation came from an extensive marginal foreland.