Abstract:

A classical concept of foreland basin can be defined as follows: Formed between the contracted orogen and its neighboring craton,an asymmetrical thrust flexure basin parallels to the orogen and extends in a long and narrow type. This definition includes the main characteristics of distribution location,crustal feature, dynamic mechanism developing stage, planar distribution and profile structures along with corresponding sedimentary formation. However, the basic structures and the location of main units of the foreland basin are variable in various stages of its evolution and also with difference both in its pattern and oil and gas bearing features. The foreland basin, on the basis of its geodynamic environment, can be subdivided into three types of peripheral foreland basin, retro-arc foreland basin and broken foreland basin. The former two types are the fundamental subdivisions. Many compressive basins around orogens in mid-west China generally have the structural features, deformation and deposition of foreland basins. According to dynamic sources, developing stages, and main characters during the development of the foreland basin, the basin could be named in a new type of foreland basin namely, intra-continent foreland basin that can be discriminated from the peripheral foreland basin and retro-arc foreland basin. Therefore they are corresponding to the three different featured convergent stages of ocean subduction, continental collision and intra-continent contraction in the structural evolution of plates. The basis for the definition and the contents for the research of the foreland basin are as follows:(1) tectonic attribute in which kinds the foreland basin belongs to;(2)developing states;(3) basin and orogen coupling;(4) regional bacground;(5) prototype basin topography;(6)evolutional process;(7) sedimentary reaction;(8) vertical distribution. Attention should be paid to the generality of the foreland basin while defining it; Importance should be attached to the individuality of the foreland basin when studying it.

Key words: foreland basin, intra-continent foreland basin, mid-west basin in China, definition base, research content, relations between basin and orogen, oil and gas exploration