Tectonic generation is an important concept in geomechanics and tectonic geology.It refers to the sequence in which structural planes with different mechanical properties and orientations are formed during the same crustal movement.This occurs under the continuous action of the same period and dynamic action mode,or due to local changes in boundary conditions,which control the formation of structural features.Structural generation emphasizes the genetic relationship between structural features and serves as the basis for determining structural types and establishing structural systems.The structural generation relationship is common and distinct from the structural level.Different generation structures possess characteristics of time difference,derivation,absoluteness,and invisibility.Low-order structures are often distributed within the influence range of higher-order structures and are controlled by local stress fields.The study of ore-controlling structures should proceed from low order to high order.Starting with the investigation of ore-bearing structures,their mechanical properties and combination laws should be analyzed.This allows for the determination of ore-controlling structure types and the summarization of ore-controlling laws.Ore-prospecting predictions should follow a high-order to low-order approach.Based on the ore-controlling structure type and the control law of structure generation,the possible position and direction of low-order ore-bearing structures are analyzed,enabling ore-prospecting prediction.Through the structure generation analysis of ore-controlling structures,the Zoujiashan uranium deposit is considered to be controlled not by the NE-trending Zoujiashan-Shidong fault but by the NEE-trending hidden structural belt with a medium-low dip angle,dipping to NNW.The prospecting direction is along the SWW direction of the existing ore belt,and the deep part has a medium dip.In the Changjiang uranium ore field,uranium mineralization is not controlled by the Mianhuakeng fault and Youdongfault but by the NNW-trending structural belt with a steep dip angle.The shallow secondary fault is an ore-bearing(or ore-storing)structure,and the main structural belt,which merged from them and extended to the deep,plays the role of guiding mineralization and transporting ore-forming hydrothermal solutions(deposit distribution).The ore-prospecting direction is the extension and deepening part along the NNW-trending ore-bearing structure and the deep part of the surface mineral-free zone.When analyzing structural generation,it is essential to pay special attention to the genetic relationship of structural features along with structural periods.It is crucial to distinguish between structures formed before,during,and after mineralization.Within a specific ore field deposit or mineralization zone,the relationship between ore-guiding structures,ore-transporting(ore-matching)structures,and ore-storing(ore-bearing)structures(i.e.,the relationship between ore-controlling structures and ore-bearing structures)should be objectively analyzed.This analysis allows for the determination of an ore-controlling structural type,the construction of a structural ore-controlling model,and ultimatelyguides the practice of ore-prospecting and prediction.
Accurate evaluation of the distribution characteristics and physical properties of gas hydrate reservoirs is crucial for estimating gas hydrate resources,guiding development and utilization strategies,and understanding environmental impacts.Based on high-precision 3D seismic and well-logging data acquired in the Shenhu area,this paper presents a comprehensive method for discriminating between hydrate layers,free gas layers,and coexistence layers using integrated logging-seismic responses.Our results show that the gas hydrate layer and free gas layer at the W17 station can be accurately identified by combining post-stack seismic profiles with detailed analysis of logging curves.Above the BSR,a hydrate layer is characterized by relatively high seismic velocity,strong amplitude reflections,poor transverse continuity,and high resistivity and velocity values.In contrast,the underlying free gas layer exhibits low seismic velocity,low-frequency weak amplitude reflections,and low resistivity and velocity values.This study provides a robust basis and valuable reference for informed decision-making regarding gas hydrate reservoir identification,resource evaluation,exploration,and trial production activities.
The South-to-North Water Diversion Project Central Route (SNWDP-CR) is the largest water control project which has ever been built, and the aim of which is to optimize the reallocation of water resources from South China to North China. Since it was put into operation in December 2014, it has delivered more than 6 × 109 m3 of water to Beijing, which has changed the water supply pattern in Beijing and provided conditions for reducing groundwater extraction and controlling land subsidence. In this study, a variety of monitoring data are used to analyze the changes of the groundwater flow field, groundwater level, land subsidence, soil deformation, and hydrogeology parameters before and after the SNWDP-CR. The study showed that the groundwater level of the first to fourth aquifer groups rose on average by 2.72 m, 3.68 m, 3.31 m, and 1.91 m from 2015 to 2020. The average subsidence rate decreased from 18.8 mm/year in 2015 to 10.85 mm/year in 2020. The deformation characteristics of different lithological soil layers under different water level change modes can be summarized into 4 categories. The sand layer is mainly characteristic of elastic deformation. The cohesive soil layers of different depths have elastic, plastic, and creep deformation, and the viscoelastic-plastic characteristics are obvious. For different stages of soil deformation, the changes of elastic and inelastic skeletal specific storage rates are not constant. As the groundwater level decreases, the soil skeletal specific storage rate shows a decreasing trend.
There are relatively few sedimentological studies on the Cryogenian in the northwestern Yangtze Craton, especially in the Chengkou area of the Dabashan Mountain. Whether the Cryogenian Muzuo/Mingyue and Dai'anhe formations have glacial sedimentary characteristics is also uncertain due to lack of detailed sedimentological investigation, which limits the understanding of sedimentary evolution process of the Cryogenian in the Yangtze Craton. These lacunae are not conducive to the determination of the sedimentary stratigraphic framework and regional correlation of the Cryogenian. In this paper, four typical Cryogenian sections in the Chengkou area are selected for undertaking a detailed stratigraphic and sedimentological study, and the glacial sedimentary marks such as the gravels with glacial striae, dropstones, and subglacial soft sedimentary deformations are identified to prove the glacial genesis of the Dai'anhe and Muzuo/Mingyue formations. The facies of continental, periglacial and marine glacial are also discerned. On this basis, according to the rock assemblages, sedimentary characteristics, structure of stratigraphic succession, geochemical indices (such as chemical index of alteration) and detrital zircon UPb age, the Dai'anhe Formation is divided into two members. The ls' Member is correlated with the Gucheng Formation, the 2' Member is correlated with the Datangpo Formation, and the Muzuo/Mingyue Formation is correlated with the Nantuo Formation. Further, through regional correlation, the stratigraphic framework of the Cryogenian in the northwestern Yangtze Craton is re-evaluated, and correlated with that in the adjacent Shennongjia area and southeastern Yangtze Craton. The sedimentary co -evolution process of the Cryogenian in the Chengkou-Shennongjia areas is as follows: during the Stuartian glacial period, the glacial transgressive-regressive cycle from the glaciomarine to the land and then to the glaciomarine developed; subsequently extensive transgression of the interglacial period formed a lagoon environment represented by carbonaceous silty mudstone. With the global temperature falling again, the Marinoan glacial period was triggered, which was reflected in the multiple glacial dynamic evolution from the glaciomarine ice-proximal to the ice-distal environment, and accompanied by the opening of the ice sheet and finally to the end of the Cryogenian. This study has determined the correlation and subdivision of the Cryogenian in the northwestern Yangtze Craton, providing new basic data and important basis for the correlation of the Cryogenian in the Yangtze Craton.
Radon gas is the only radioactive inert gas, whose hazards for human have been confirmed by medical and health science. The WHO report revealed that the inhalation of radon and its decay products was carcinogenic for the human lungs among non-smokers. Approximate 3% similar to 15% human lung cancers are triggered by the radon gas among different countries all over the world. The synergistic effect of radon gas and smoke will significantly raise the possibility of lung cancer. In addition, excess radon inhalation will damage human nervous system, decrease the hemameba, and trigger the increasing of blood clotting and hyperglycemia. Radon is the decay product of 238U, whose one main source is the granite. Granite is the main constituent of continental crust of the Earth, occupying the 22% on volume. Lots of studies on granite origin have been implemented among geological community, however, the relationship of human lung cancer and the granite hasn't got enough attentions from geologists. In contrast, the medical and health community know much about the radon gas, but they don't understand the original source of radon gas and its closeness with granite. In the present study, we would like to address the linkage between granite and radon, shed light on the damage of radon gas for public.
