Tectonic Characteristics and Emplacement Mechanism of Dayishan Granite in Hunan Province, China

Dayishan granite, a significant metallogenic-rock body located in Shaoyang-Chenxian tectonomagmatic belt of Hunan Province, was controlled by 'Dayishan-type' fault pattern. Based on the study of tectonic setting and geological features of the grantie, it is concluded that the tectonic system controlling magmatic emplacement is a shear folded-fauted zone which resulted from NW-trending convergent strike-slip faulting. The close relationship between the temporal-spatial distribution, emplacement mechanism of Dayishan granite and the strike-slip faulting is detailed.

Characteristics of strike-slip inversion structures of the Karatau fault and their petroleum geological significances in the South Turgay Basin,Kazakhstan

The Karatau fault is one of the important strike-slip faults in central Asia,and the South Turgay Basin is located towards its northern end.Detailed seismic interpretation indicated that the strikeslip tectonism of the Karatau fault weakened gradually from west to east in the South Turgay Basin.Typical flower structures developed on the section,and strike-slip faults showed an echelon pattern on planar view.The Karatau strike-slip fault affected the South Turgay Basin in two periods：（1） The South Turgay strike-slip pull-apart rift basin formed as a result of regional extensive stress in the Early-Middle Jurassic,characterized by the juxtaposition of horsts and grabens.The formation of horsts provided favorable reservoir spaces for later hydrocarbon accumulation,and different filling stages of grabens controlled different reservoir-forming factors in grabens.（2） Two stages of tectonic inversion occurred in the Late Jurassic and Late Cretaceous and played a crucial role in the final shape of the structure in the South Turgay Basin.The oil and gas migrated to form reservoirs and mainly concentrated in the horsts,graben slopes and in both sides of the strike-slip fault zone.In the case of the degree of accumulation of petroleum,the factor explaining why horsts are better than grabens is the strike-slip pull-apart of the South Turgay Basin,and the structure inversion of the South Turgay Basin explains why the west graben is better than the east one.Overall,the Karatau strike-slip fault played a very important role in the formation of the South Turgay Basin and its hydrocarbon accumulations.

Multi-Directional and Multiphase Tectonic Modification,and Hydrocarbon Differential Enrichment in the Middle-Upper Yangtze Region

Based on the analysis of the deformation styles in different tectonic belts of the MiddleUpper Yangtze region,as well as the dissection of typical hydrocarbon reservoirs,this study determined the controlling effects of deformations on the hydrocarbon accumulations,obtaining the following results.The Middle-Upper Yangtze region experienced significant deformations during the Late Indosinian(T_(2)–T_(3)),the Middle Yanshanian(J_(3)–K_(1)),and the Himalayan,and five styles of tectonic deformations mainly occurred,namely superimposed deep burial,uplift,compressional thrusting,multi-layer decollement,and secondary deep burial.The distribution of hydrocarbon reservoirs in the piedmont thrust belts is controlled by the concealed structures on the footwall of the deep nappe.The gentle deformation area in central Sichuan experienced differential uplift,structural-lithologic hydrocarbon reservoirs were formed over a wide area.The eastern Sichuan-western Hunan and Hubei deformation area experienced Jura Mountains-type multi-layer detachment,compressional thrusting,and uplift.In relatively weakly folded and uplifted areas,conventional structural-lithologic hydrocarbon reservoirs have undergone adjustment and re-accumulation,and the shale gas resources are well preserved.In the strongly deformed areas,conventional hydrocarbon reservoirs were destroyed,while unconventional hydrocarbon reservoirs have been partially preserved.The marine strata in the Jianghan Basin experienced compression,thrusting,and denudation in the early stage and secondary deep burial in the late stage.Consequently,the unconventional gas resources have been partially preserved in these strata.Secondary hydrocarbon generation become favorable for conventional hydrocarbon accumulations in the marine strata.