Structural model of the Bố Hạ coal mine on the bases of new deformation study
Vũ Xuân Lực, Nguyễn Công Thuận
The Bố Hạ coal mine area is structurally complicated. The area had been studied by many geological works with different results, which have caused many difficulties for the orientation of coal mining activities. New research results show that Bố Hạ coal mine area was heavily affected by at least 3 deformational events, in which the First deformational phase was taken place in ductile to brittle-ductile environment, forming large scale shear systems with significant displacement and flexural tight to isoclinal folds. The second deformational phase includes the reverse shear zones, truncated, displaced and refolded the 1st phase’s structures. The third deformational phase produced sinitral strike-slip shear zones that modified the previously formed structures. As such, the geometry and orientation of the coal seams in the area were strictly controlled by the development and interference of the aforementioned generations of structure and therefore are very complicated, which are different from previous geological interpretation. The results of this study show that in order to properly construct a structural model of the coal seams, both on the surface and at depth to guide in exploiting the deep coal seams, it is necessary to have detailed and qualitative studies on the regional structure and coal seams.
Keywords: Bố Hạ coal mine, structure of coal seams, shear zone, deformation phase.