关键词: 叠加褶皱, 沙箱模拟, 构造样式, 岩层能干性

Abstract: The Nanpanjiang Basin develops a series of tectonic domes which control the distribution of lowtemperature mineralization. An example is the typical Laizishan Dome, it controls the Lannigou giant gold deposit in the southwest Guizhou Province. Based on the statistics of strata attitude around the Laizishan Dome, the studied area was subdivided into NW and NE subregions through π circle projection analysis, and the fold type in the subregion was confirmed to be upright horizontal anticline by cross section and geometric projection analysis. Selection of axial plane cleavages was made based on statistics of all cleavages and parallel relationship between cleavage and axial plane of fold in the subdistrict. According to crosscutting relationships of axial plane cleavages, and age of strata and related intrusion involved in the deformation, the sequence offold development in the subdistrict and age of deformation were constrained, consequently inferring that the NWSE and NNESSWtrending anticlines were developed in the early and late Yanshanian, respectively.In the structural analysis based on the stratigraphic strength, strata shortening and deformation boundary conditions, four groups of sandbox simulation experiments with two sandbox models were designed to study the process and types of tectonic compounding and conjunction; and factors affecting the superposed deformation are discussed. The simulation results suggest that the Laizishan Dome is the result of superposition the NNEand NWtrending buckling folds,and the type of superposition is a migration of fold superimposition. Furthermore, the two folds correspond to the lateral extrusion to the Nanpanjiang Basin by the Xuefengshan uplift during the early Yanshanian, and the largescale thrusting from NW to SE in southwest Guizhou during the late Yanshanian, respectively. The results also show that difference in rock strengths and deformation intensities are the main factors affecting the styles and types of superimposition:when strength difference is large, the weak layer affects the structural styles of the upper and lower hard layers;when later stage deformation is weak, limited or migrating superimposed fold is formed,otherwise it forms the oblique crossing or crossing superimposed fold; and phased deformation leads to tectonic compound superposition,whilecoinstantaneous deformation or lesser difference in deformation velocity results in curved tectonic conjunction superposition.

Key words: superimposed anticline, sandbox modelling, structural style, stratigraphic strength