摘要
采用生物地层、岩石地层学方法,主要利用钻孔岩心及部分地表露头,在矿区中深部原认为属早二叠世早期地层中,发现头足类、牙形石、笔石等化石,确定其为早古生代地层。在浅部原认为属早二叠世晚期地层中,发现不同时代化石并鉴别出不同类别原岩断块,初步确定其为构造岩,属非地层划分单位。
The studied area is situated about 15 km to the southwest of Jiayu, Hubei being a gold ore area discovered by No. 4 Geology Party in recent years. The strata cropping out on the surface and revealed by drilling in the ore area may be originally divided into Qixia Formation and Maokou Formation from bottom to top; the former means the argillaceous nodular lime-stone, micrite, bioclastic limestone, dolomite, etc. at the middle depth in the ore area, the inferred age of which belongs to the early stage of Early Permian Epoch; the latter may be subdivided into two parts, i. e., the lower part named the pied mudstone(also called the mud-stone mineralized bed) and the upper part, siliceous rock(also called the silicon hat) correlat-ing with Gufeng Formation of the Ningzhen mountain range based on the lithological charac-teristics. In addition, there are still some different cognitions on whether the strata at shal low part are of Quaternary sediments or Mesozoic—Cenozoic basin margin sediments, etc. Through studies in the office and field for about two years and by using mainly the bios-tratigraphical and petrostratigraphical methods, some new cognitions on the stratigraphy of the ore area are as follows: 1. Based on the discovery and study on a large amount of palaeontological fossils, the as-certained age of the strata at middle depth in the ore area belongs to Late Cambrian Epoch-Ordovician Period(the main). 2. Shallow″strata″(mineralized bed) are preliminarily ascertained the argillized tectonite and silicified tectonite respectively, but could not be divided into formal or informal petros-tratigraphical units. 3. The foot—wall strata(autochthone) of the fracture F_2 are confirmed the Late Triassic Epoch to Jurassic Period.
关键词
矿区地层
早古生代
非地层划分单位
蛇屋山
Gufeng Formation
Qixia Formation
Maokou Formation
Argillization
Formal petrostratigraphical unit
Informal petrostratigraphical unit
Autochthone
