Qinshui Basin, Shanxi, Chinai

Regional Level Types
Qinshui Basin	Basin
Shanxi	Province
China	Country

The Qinshui Basin, located on the eastern margin of Shanxi, north China, preserved strata from the Cambrian, Ordovician, Carboniferous, Permian, Triassic, and Quaternary. The principal coal-bearing sequences in the northeastern part of the basin include the Upper Carboniferous Benxi Formation (C2b), Upper Carboniferous Taiyuan Formation (C2t), and Lower Permian Shanxi Formations (P1s).
The Benxi Formation, which is unconformably overlain by the Ordovician Fengfeng Formation, primarily comprises bauxite-rich mudstone, interbedded with argillaceous siltstone and sporadic thin coal layers, and the uppermost section of the sequence is punctuated by localized limestone deposits. The “Si–Al–Fe” strata examined in this study are situated at the foundation of the Benxi Formation and host numerous karst-type bauxite deposits. The stratum is stratigraphically subdivided into three distinct layers from bottom to top, namely ferruginous, aluminous, and siliceous layers, respectively. The lower ferruginous layer, which contains clays intermixed with iron-rich minerals such as hematite and goethite, is known as a “Shanxi-type” iron deposit in North China. The middle aluminous layer consists of bauxitic clay and clayey bauxite, while the upper siliceous layer is a clay-rich stratum.
The Taiyuan and Shanxi Formations are composed of a variety of sediments, including fine- to medium-grained sandstone, siltstone, mudstone, limestone, and coal layers. In the study area, the Taiyuan Formation was deposited in environments associated with tidal deltas, tidal flats, and lagoons, whereas the Shanxi Formation developed in a fluvial-lacustrine setting. The primary mineable coal seams within these formations, listed from top to bottom, are the Nos. 3, 9, and 15 seams.

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