The Sinian System in the District of Pangchiapu, Southern Chahar, North China, and Consideration of the Origin of its Contained Hsuanlung Type Iron Ore Deposits.

Abstract

In the district of Pangchiapu, southern Chahar, North China, the Sinian system overlies the PreSinian gneiss in a distinct angular unconformable relationship. The System is composed of two parts, the lower and the upper. The lower part can be further divided into five beds: (a) coarse sandstone, (b) slate, (c) quartzite, (d) siliceous slate and (e) phyllite. The upper part is composed of three beds: (f) lower siliceous limestone, (g) siliceous sandstone and (h) upper siliceous limestone. The beds (a) through (h) are in ascending order. The lower part corresponds to the Hoshan Sandstone of the Lower Sinian and the upper part to a comparatively lower part of the Nankou Limestone of the Middle Sinian. The stratigraphy and the succession of the Sinian rocks in this district are herein described briefly and correlated to those of other districts in North China.
Hsuanlung type hematite ores, with an oolitic or. stromatolitic texture form well-defined beds, alternating with siliceous slate and quartzitic sandstone with low-grade iron ore in the above mentioned siliceous slate (d). This paper presents a discussion of the formation of the oolitic and stromatolitic textures and the mechanism of the sedimentation of the ore deposits.