Abstract:

The lacustrine carbonates of the lower section of Es₁ Formation in Qibei slope was so thin that it was difficult to use seismic data to correlate the sublayer and understand the depositional model, evolution characteristics and the main control factors. We applyed the method of static and dynamic data matching with each other using of core, well logs, geochemistry, palaeontologic data, trace agent and entry profile to studied the lacustrine carbonates. The results show that overlap stratigraphic correlation method conform to the ture formation development. And five periods lakeshore line obviously to recognized. The lake transgression happened along the Gangxi fault trough and the central low area. Shallow lake is the mainly subfacies, include six kinds of microfacies for biological chip beach and mixed beach, et al. The organic bank accounts for 60% of the research area, at early times, the coastal sand dam was mainly developed. On the middle period, the area of shallow lake enlarged rapidly and the biological chip beach organic enlarged rapidly, too.  On the late period, both the area of shallow lake and the biological chip beach were largest. The salinization of water and the sediment of lacustrine carbonates are mainly caused by the transgression of sea and the condensation of the water in the shallow gentle slope tableland. The platformlike palaeogeomorphology and the great quantity of reproduction of the prehistoric life are also major control factors of the deposition types and evolution in Qibei slope.

Key words: Huanghua depression, Qibei slope, carbonates, stratigraphic overlap, depositional model, microfacies