Abstract:

This thesis studies the evolution of normal faults and the relationship between the Western Shandong Rise (WSR) and Jiyang Depression (JD), and discusses their possible formation deep background or mechanism. The study reveals the existence of steep key faults and décollement structures in both shallow and deep levels in western Shandong, China. The steep faults controlled the formation of halfgraben and detachment at a depth of 1222 km and up to 30 km distance to the south, while the most outstanding shallow décollement structures occurred along the regional unconformity surface between the Cambrian and Archean, and the disconformity surface between the Carboniferous and Ordovician with main direction to the NNW and NNE. The décollement structure surface manifests as a fault zone with cataclastic rocks, asymmetrical folds and cleavages and occurred most obviously in north of the WSR and south of the JD. They occurred in opposite dip, faulted from south to north with approximately the same time in the Late JurassicCretaceous 176103 Ma, the PaleoceneEarly Eocene 6749 Ma, and the Middle EoceneOligocene 4225 Ma according to KAr and FT dating. Physical simulation indicated that the steep fault developed from south to north on piggyback propagation. Seismic tomography reveals that the extension fault system probably initiated by mantle upwelling derived from subduction and collision of the Yangtze Plate with the North China Plate along the TanchengLujiang Fault in the Late TriassicEarly Jurassic. This circumstance implies a multidirection subduction and collision of these two plates in the Mesozoic. In the Cenozoic, Vshaped mantle heading north caused by PacificEurasian Plate subduction and IndoEurasin Plate collision resulted in the extension order from south to north. Meanwhile, the older age magmatic rocks occurred in south while the younger ones existed in north in the Late Mesozoic, which shows that the magmatism migration pole is from south to north. The extension order controls the formation of the fault, half graben, sedimentary characteristics and oilgas distribution.

Key words: extension order, normal fault, décollement fault, Late MesozoicCenozoic, West Shandong Province