Abstract:

Sanshandao gold mine is divided into two mining areas.One is the Xishan mining area，whose orebody is buried on land,the other is the Xinli mine area.It is the only undersea metal mines in China，its mining technology demand is higher，and also have serious security problems.Among them，the clay aquifer of the Quaternary bottom and F1 fault mud are the key parts of water blocking，and the two aquifers will cause seawater to break into.Therefore，it is necessary to ascertain the geological conditions of the overlying strata in the mining area，especially the distribution of the clay aquifer.After exploration，high precision three-dimensional seismic exploration technology including flexible acquisition geometry，low noise receiver conditions and quantitative control has been formed.The foundation of 3D seismic exploration technology is 2D seismic exploration technology.3D seismic exploration is more accurate and spatially stereoscopic than the data obtained by 2D seismic exploration，but it also has higher requirements for the exploration environment.This paper briefly discusses the difficulties and countermeasures of exploration，the layout and data collection of exploration lines，the fine interpretation of the overlying layer and the hydraulic connection between the overlying strata and seawater.In the submarine seismic exploration in the Xinli mining area，good results have been achieved，as follows：In the geological exploration of mining areas，the 3D seismic exploration method can accurately detect the geological structure of shallow and deep in a large depth range，which is an effective and practical technical method.In this submarine seismic exploration in the Xinli mining area，good results have been achieved.The specific understanding is as follows：The Quaternary is stably distributed in the detection area，buried in depth of 8～39 m，which is mainly characterized by the thinness of the stratum in the west and the north and the deepening of the stratum in the southeast.Among them，the thickness of clay aquifer at the bottom of Quaternary varies in the range of 1～11 m，and the distribution trend is basically the same as Quaternary.But it thins obviously near the F1 fault，the thickness is 2.5～5.0 m，and thins gradually to the north-west direction，and the stability of aquifer becomes worse，which has a certain risk to the mining of the deposit.The total thickness of the weathering zone of the underlying bedrock in strong，medium and weak layers varies in the range of 3～35 m.The weathering zone near the F1 fault is obviously thicker，with a thickness of 20～35 m，which is the main permeable structure in the mining area.High-precision three-dimensional seismic technology was first applied in the geological structure exploration of the Xinli mining area，which provided data support for the safe mining design of the submarine mining area of the Sanshandao gold mine.

Key words: Sanshandao gold deposit, seabed mining area, seawater inrush, three-dimensional seismic exploration, geological structure analysis