Within the seven coal forming periods restricted to from Late Carboniferous to early Late Permian,there are seven coal groups and more than 20 seams defined in the whole area,of which seams B 3,D 2and G 7 1 are economically important.

• 全区自晚石炭世至晚二叠世早期所限定的7个成煤期内，共圈出煤组7个，煤层20层以上，以B3，D2，G71煤层最具工业价值。