The large-scale Yalujing fault zone,lying in Eastern Liaoning Pr ov ince,is the secondary fault zone of the Tan-Lu fault zone on its east side, wi th multiple activities. The movements underwent four stages, namely, left-late ral shearing in Late Indosinian-Early Yanshanian epoch (T3 - J1) ; low ang le expanding-slipping and compressive reverse thrust in Middle Yanshanian epoc h (J2-3); left-lateral normal strike-slip faulting from Late Yanshanian (K 1) to the end of Yanshanian (K2); and right-lateral strike-lateral strike- slip faulting from the end of Yanshanian (K2) to Early Himalayan epoch (N). The fault zone controls the distribution of the magmatic rocks, sedimentary basins and minerals. It also controls the intermediate-basic and acidic-intermediat e volcanic rocks of Cretaceous. It is a deep fault that cut the sima. The lift- lateral transposition is up to 20 km, with the greatest vertical displacement o f 4 km. The geological and structural characteristics on both sides of the fault zone are comparable, which is significantly important for the research in the r egion.
Tongling is one of the most significant ore cluster area in the Middle-Lower Yangtze River Cu-Au-Fe-Mo metallogenic belt. The Fenghuangshan Cu deposit is a typical skarn type Cu deposit in the Tongling ore cluster area. In this study we yield molybdenite Re-Os model ages ranging from 139.1±2.4 to 142.0±2.2Ma and the isochronal age 141.1±1.4Ma. The results show that Cu mineralization of the Fenghuangshan Cu deposit occurred at the Early Cretaceous,which are slightly younger than quartz monzodiorite and granodiorite(144.2Ma,zircon U-Pb age). The ages indicate close temporal relations between Cu mineralization and magmatism. Our study is consistent to previous studies that Cu mineralization occurred at the Mesozoic second mineralization stage,responding to the Mesozoic lithosphere delamination event in south of China.
In order to increase the exploration level of hidden oil gas pools in the area around Puwei sag, Dongpu depression, sequence stratigraphy theory and the Walther's law are taken as a guide to research Sha 3 member. On the basis of the analyses of cores, logs and seismic data, combined with the analyses of basin structure and stratigraphy, 5 depositional systems are recognized in Sha 3 member, i. e. lake turbidite fan system, coast shallow lake system with sand dam and tempestite, low stand salt lake system, delta system and deep hemi deep lake system. The characteristics of lithoface assemblages of each system are studied one by one. The distribution patterns of the depositional systems in space are analysed in each main reservoir body member, while the sedimentary models and reservoir distribution regulations of the Sha 3 member are also discussed. It is pointed out that the junctions of the under water channels and the slope break belt in the east and north of Puwei sag are the places where the main reservoir bodies develop very well, and where lake turbidite fan system and delta system develop.
The Luanping basin is a well-preserved extensional basin in the Yanshan structural belt.There exist various depositional sedimentary lithofacies that show obvious spatial variations.Alluvial fan and fan delta dominated proximal areas of the northern and western basin margins,while fine-grained lacustrine sediments were prevalent in the basin centre.In southeast basin is mostly fluvial sandstone and conglomerate facies associations.Sediments were demonstrated to have mainly come from metamorphic basements on the north and west,only small proportion from southeastern margin,as indicated by restored paleo-current directions and provenance. Tectonic subsidence and deposition sedimentation were primarily controlled by the northern and western basin border faults.Uplift of basement rocks of the footwall was due to the tilting of border faults and became main provenance areas.Sedimentary evolution of Luanping basin can be divided into three stages.The first stage is featured by vigorous volcanic eruptions,the second is characterized by extensional subsidence and the third by sedimentary infilling.Luanping basin is a proxy of other similar basins in the Yanshan structural belt in the Early Cretaceous,indicating that late Mesozoic basins are characterised by development of small and isolated basins.
During the Late Mesozoic,extensive magmatism and associated ore deposits were developed in the Middle-Lower Yangtze River metallogenic belt,East China.As the Tieshan and Jinshandian quartz diorite in the southeastern Hubei Province examples,we performed in situ zircon U-Pb dating and Hf isotopic analyses on 5 samples.Twenty-six zircons in the quartz diorite from the Tieshan sample jls1-110 yield excellent concordant results with a weighted mean 206 Pb/ 238 U age of 138.9±0.96Ma(n=26,MSWD=0.82). Zircons from Tieshan sample jls3 yield excellent concordant results with a weighted mean 206 Pb/ 238 U age of 138.2±0.94Ma(n=24, MSWD=0.85).Zircons from Tieshan sample jls4 yield excellent concordant results with a weighted mean 206 Pb/238 U age of 131.0± 1.2Ma(n=11,MSWD=0.94).Zircons from Tieshan sample jls5 yield excellent concordant results with a weighted mean 206 Pb/238 U age of 118.9±1.2Ma(n=14,MSWD=1.20).Zircons from Jinshandian sample jsd yield excellent concordant results with a weighted mean2 06Pb/ 238 U age of 128.6±0.88Ma(n=22,MSWD=0.98).e Hf (0)ande Hf (t)values of the Tieshan quartz diorite are minus.Hf model age of the first stage(t DM1 )is 1.33Ga and the age of the second stage(t DM2 )is 2.03Ga.e Hf (0)ande Hf (t) values of the Jinshandina quartz diorite are minus.Hf model age of the first stage(t DM1 )is 1.03Ga and the age of the second stage (t DM2 )is 1.56Ga.Hf isotopic compositions from the Tieshan and Jinshandian quartz diorites show that maybe the curst-derived materials joined in the rock body forming supplement for the crust-derived magma of the Middle-Lower Yangtze River.Based on the datum of petrology,geochemistry and ore isotope ages,we can infer that the skarn type iron deposits of the Early Cretaceous in the southeastern Hubei Province formed on the environment of lithospheric extending and thinning.
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