Global snowmelt flood disasters and their impact from 1900 to 2020北大核心CSCD

Under the background of climate warming, the occurrence time, frequency, intensity, and impact of snowmelt flood disasters have changed significantly. Thus, establishing a global snowmelt flood disaster database is particularly important for disaster risk management. With the help of a web crawler, and based on multiple data sources such as natural disaster databases, documents, books, government agency websites, and news media, this study collected relevant information of snowmelt floods and mixed floods and established standards for identifying snowmelt flood events and their disaster impacts based on data from the different sources. Following the screening, sorting, fusion, and integration of snowmelt flood events, a global snowmelt flood disaster dataset containing 579 pieces of data with strong pertinence and reliability was constructed. The temporal and spatial distribution characteristics of global snowmelt flood disasters from 1900 to 2020 were preliminarily analyzed. The results showed that the snowmelt floods were mainly distributed between 30° N and 60° N, with more mixed floods south of 50° N and more snowmelt floods north of 50° N. Spring was the period of highest incidence of snowmelt flood disasters, followed by winter, summer, and autumn, respectively. The snowmelt floods that occurred in spring, autumn, and winter were mainly at 40°~50° N, and the snowmelt floods that occurred in summer were mainly at 30°~40° N. Compared with the snowmelt floods, the mixed floods were more frequent and more destructive, and their frequency increased with climate warming. The results provide a scientific basis for risk prevention and loss assessment of global snowmelt flood disasters. © 2022 Science Press (China).     

Outline of Uranium Resources Characteristics and Metallogenetic Regularity in China

Uranium,as one of twenty-six kinds of important minerals in China,is strategic resource and energy mineral,which has been thoroughly investigated in the project of National Potential Evaluation of Uranium Resource.During the implementation of this project,the authors summarized the metallogenic regularity of uranium resource in China systematically,through the researches of geological characteristics of uranium resource,uranium deposits type(genetic and prediction type),temporal and spatial distribution,and metallogenic series.Based on the investigation of present situation and progress in uranium exploration,this paper proposes the uranium deposits in China should be divided into 4 classes,9 types,21 subtypes in genetic,and 50 types in prediction;suggests to divide China into 29 uranium metallogenic belts and 20 uranium prospective area,and constructs 20uranium-polymetallic metallogenic series,through summarizing temporal and spatial distribution characteristics and metallogenic regularity of uranium deposits in China.The above research is beneficial to the comprehensive understanding of regional uranium metallogenic regularity,and will direct the uranium exploration in the future.     

Spatiotemporal distribution of snow cover and its variation in the upper reaches of the Taolai River basin，Qilian Mountains北大核心CSCD

Snow is an important part of the cryosphere and plays an important role in the hydrological cycle and energy balance. Study of the spatiotemporal characteristics of snow cover and its change is the prerequisite for analyzing the formation,distribution and variation of runoff from mountains in inland river basins. In this study,we selected the upper reaches of the Taolai River basin of Qilian Mountains as the study area,used down⁃ scaling methods to obtain high-resolution snow depth data,and adopted methods of spatial statistics,sensitivity analysis and contribution separations to quantify snow cover distribution and variation influenced by terrain and the regional climate during the time period from 2002 to 2018. Results showed that basin early average snow depth ranged from 0 cm to 2. 5 cm,with variation from -0. 19 cm·a-1 to 0. 06 cm·a-1. The area of snow depth re⁃ duction during the study period accounted for 68. 30% of the total area. It was found that the snow depth increase more with altitude and less with the increase of slope. Variation of snow depth increased below 2 500 m a. s. l. and decreased above 2 500 m a. s. l. As the slope increases,it first increases and then decreases;the snow depth of each aspect decreases,especially in the northwest orientation. The sensitivity of snow depth to air tempera⁃ ture and solar radiation were found negative in general,while that of the precipitation was found positive. The precipitation in high-altitude areas has a relatively large contribution to the snow depth variation,while in the val⁃ ley areas,the contribution of temperature to snow cover is more significant. This work provides an example for the study of snow dynamics in the upper reaches of inland river watersheds,and benefits model simulation and prediction of mountain runoff and regional water management. © 2023 The Author(s).     

Simulation and assessment of soil temperature and moisture in seasonally frozen soil regions of the Tibetan Plateau based on SHAW model北大核心CSCD

In recent years,more and more attention has been paid to the problem of the cryosphere changes on the Tibetan Plateau,and it has gradually become a hot issue for scholars. Known as the“water tower of Asia”,the Tibetan Plateau is the source of many major rivers in Asia. Under the combined influence of climate change and human activities,water resources on the Tibetan Plateau have undergone profound changes,especially soil water,as an important component of water resources,which plays an important role in regulating vegetation and crop growth,rainfall and runoff. However,global warming leads to the degradation of permafrost and seasonal⁃ ly frozen soil,which affects the original water cycle process and the spatial and temporal pattern of water re⁃ sources by changing the properties of soil water storage and water transport. In the Tibetan Plateau,where there are few data,it is difficult to directly study the soil water cycle process under freezing-thawing by using original data. Therefore,it is an important means to simulate the variation characteristics of soil water and temperature under freezing-thawing in seasonally frozen soil regions of the Tibetan Plateau by using coupling model of soil water and heat. Aiming at the key problem of the difference of soil temperature and moisture characteristics in typical seasonally frozen soil regions under different meteorological conditions,this paper simulated the charac⁃ teristics of soil moisture and temperature change in Maqu,Naqu（Nagqu）and Shiquanhe from 2017 to 2018 by using SHAW（Simultaneous Heat and Water）model and three soil moisture characteristic curve models. The simulation effect and variation characteristics of soil moisture and temperature under different meteorological conditions were analyzed,and the influence of soil moisture characteristic curve model on the simulation effect was studied. The results show that SHAW model can well simulate the temporal variation and vertical distribu⁃ tion of soil temperature and moisture under different meteorological conditions. The simulation effect of soil tem⁃ perature is better than that of soil moisture. The average NSE,R2 and RMSE of soil temperature are 0. 88,0. 96 and 2. 20 ℃,respectively. The mean NSE,R2 and RMSE of soil moisture are 0. 60,0. 72 and 0. 03 m3·m-3,respec⁃ tively. In terms of different meteorological conditions,the simulation effect of soil temperature in relatively dry region was significantly better than that in humid region,while the simulation effect of soil water in relatively hu⁃ mid region was significantly better than that in arid region. From different depths in soil,the simulation effect of soil temperature decreases gradually with the increase of depth,while the simulation effect of soil moisture in the middle and lower layers is better than that in the surface layer. From the view of different soil moisture character⁃ istic curve models,different soil water characteristic curve models have no significant effect on soil temperature simulation effect,but there are significant differences in soil moisture simulation effect. In addition,there are great differences and uncertainties in simulating soil temperature and moisture in different freezing-thawing stag⁃ es. With the increasing trend of climate warming,permafrost and seasonally frozen soil on the Tibetan Plateau may continue to degrade,may change the current water resources pattern,resulting in frequent extreme weather events. Therefore,from the perspective of numerical simulation,this paper verified the applicability of soil moisture and heat coupling model in soil temperature and moisture simulation under different meteorological con⁃ ditions,revealed the influence of precipitation and temperature on soil temperature and moisture simulation at different depths in seasonally frozen soil regions,and analyzed the differences in simulation effects of different soil moisture characteristic curve models. The results provide reference for the study of soil water resources vari⁃ ation under freezing-thawing conditions. © 2023 Chinese Journal of General Practitioners. All rights reserved.     

A Framework of Massively Parallel Analysis of Regional Earthquake Activities

Abstract: Recent rapid progress in cyberinfrastructure in geosciences is providing seismologists an enormous boost for addressing multi-physical phenomena of regional seismic activities. The inherent nature of their multi-scale properties, from temporal to spatial spaces, makes it inevitably to be solved using large-scale computations and distributed parallel data processing schemes. Under such circumstance, using the advanced numerical algorithms and unstructured mesh generation technologies become the obstacles for modern seismologists. The main objective of this paper is to present a framework, which includes a parallel finite element simulation and distributed data infrastructure, to address the novel algorithms, state-of-the-art modeling and their implementation in regional seismicgenic systems. We also discuss and implement this framework to analyze the strong earthquake evolution processes in the Sichuan-Yunnan region. This study is the key to long-term seismic risk by estimates, providing a platform for predictive large-scale numerical simulation modeling of regional earthquake activities.     

Exploration of Water Resource and Multiple Model for Water Resource Development in Karst Areas with the Preferred Plane Theory

According to the theory of preferred plane, preferred planes (faults) always control the distribution of bedrock fissure water and hold abundant groundwater. Thus, the exploration of fissure or karst water can be converted into searching for the watery preferred plane (WPP). In the paper, the characteristic of watery preferred planes is analyzed and a series of superior indices has been set up. It is introduced that WPPs are determined by the methods of geological analysis, superior index and complex geophysical analysis. Meanwhile, new multiple model for water resource development in the water-scarce areas of karst mountainous regions are advanced.     

A Framework of Massively Parallel Analysis of Regional Earthquake Activities

Recent rapid progress in cyberinfrastructure in geosciences is providing seismologists an enormous boost for addressing multi-physical phenomena of regional seismic activities.The inherent nature of their multi-scale properties,from temporal to spatial spaces,makes it inevitably to be solved using large-scale computations and distributed parallel data processing schemes.Under such circumstance,using the advanced numerical algorithms and unstructured mesh generation technologies become the obstacles for m...     

Study on rain-runoff process in the peripheral mountainous area of the Sichuan Basin

Studies on rain-runoff process in the peripheral mountainous area of the Sichuan Basin, which is regarded as a key ecological shelter, will contribute to flood control and environmental protection for the Upper Yangtze River Basin. In two typical catchments--the Fujiang River Catchment and the Wujiang River Catchment, rainfall simulations have been conducted to study the rain-runoff processes of yellow soil and limestone soil in three types of land use--forestland, farmland and grassland. Results showed that （1） within the same rainfall process, overland flow occurs first on farmland, then on grassland, and finally on forestland; （2） soil surface coverage has a great impact on the occurrence and amount of overland flow. The runoff amount can increase 2-4 times after the coverage is removed; （3） the infiltration before the occurrence of overland flow will decrease because of higher gravel contents of soil, but it takes no effect on infiltration once overland flow becomes stable; （4） the runoff coefficient of the limestone soil forestland is greater than that of the yellow soil forest land, but less than that of the farmland; （5） three empirical infiltration models, including Horton＇ model, Kostiakov＇ model, and modified Kostiakov＇ model, were compared by using the observed results under rainfall simulation. The results showed that the Kostiakov＇ model performed better than both the Horton＇ model and modified Kostiakov model. According to the results of this research, the Kostiakov＇s model can be used to simulate rainfall infiltration when water erosion is modeled in the peripheral mountainous area of the Sichuan Basin.     

A Preliminary Review of Metallogenic Regularity of Gold Deposits in China

Gold is one of the most important mineral resources in China with its rich mineral resources. In recent years,significant progress has been made on the process of gold resource exploration. Some large and giant gold deposits were newly found and some important expansions in the main mining regions were also been completed. Studies on metallogenic regularity of gold deposits in China also have made achievements with a long–term work. This review aims to conclude the achievements of research on gold metallogenic regularity in China. Based on the data of about 2000 gold deposits and other ore(mineralized) occurrences,gold deposits in China were classified into five prediction types: gold deposits genetically related to granite–greenstone formation,gold deposits related to sedimentary formation(including the Carlin type and the metamorphosed clastic rock related vein gold deposit),gold deposits genetically related to volcanic rocks(including the continental and marine types),gold deposits genetically related to intrusions(including the porphyry type and the inner intrusion and contact zone related gold deposit),gold deposits of supergenesis(including fracture zone–altered rock gold deposit,placer gold deposit,gossan type gold deposit and soil type gold deposit). Statistics on precise chronology data of gold deposits indicate that there occurred 5 main periods of gold–mineralization in geological history of China. They were Neoarchean to Paleoproterozoic,Meso–Neoproterozoic,Paleozoic,Mesozoic,and Cenozoic. Gold deposits in China mainly formed in the Mesozoic and the Cenozoic. On the studies of the spatial–temporal distribution characteristics of gold deposits,53 gold–forming belts were delineated in China. The metallogenic regularity of gold deposits was preliminarily summarized and 71 gold metallogenic series were proposed in China. This suggests that it is necceary to deepen the study on metallogenic regularity of gold deposits and to provide the theory guide for the ore–prospecting for gold resources in China.     

Analysis on the sources of mercury in soils in the Chengdu Basin, China

Mercury is a pollutant of concern due to its toxic and bioaccumulative properties. Studies on the distribution and hazard of mercury in the environment are mainly focused on its forms, toxicity and the environment standard, and progresses and results have been achieved. But these studies in the past were concentrated on the scales of laboratory or smaller districts merely, such as a small unit of mineral area, vegetable base, paddy field, lake, etc. Multi-target regional geochemical survey carried out by China Geological Survey from the 1990s to now is a fundamental and commonweal geological survey, large-scale and systematical inquisition and research were conducted in 19 provinces （or municipalities directly under the Central Government） in the eastern overlay region of China, and the purpose is to provide the basic geochemical data for national economic construction, adjustment of industrial and agricultural structures and sustainable social development. Geochemical studies aim at investigating soils in these regions and 52 elements have been tested, producing a great amount of data at the same time. Methods： based on the data from 3061 samples of surface soil and 832 samples of deep soil from the project of multi-purpose geochemical survey in the Chengdu Basin, Sichuan, China, this paper describes the correlation relationship between Hg and other 48 elements and their spatial distribution in surface and deep soils of these areas by applying the method of linear regression and factor analysis.     

Rainfall-runoff modeling for storm events in a coastal forest catchment using neural networks

The process of transformation of rainfall into runoff over a catchment is very complex and highly nonlinear and exhibits both temporal and spatial ＂variabilities, In this article, a rainfall-runoff model using the artificial neural networks （ANN） is proposed for simulating the runoff in storm events. The study uses the data from a coastal forest catchment, located in Seto Inland Sea, Japan, This article studies the accuracy of the short-term rainfall forecast obtained by ANN time-series analysis techniques and using antecedent rainfall depths and stream flow as the input information. The verification results from the proposed model indicate that the approach of ANN rainfall-runoff model presented in this paper shows a reasonable agreement in rainfall-runoff modeling with high accuracy,     

Simulation of surface runoff in theWujiang River watershed based on GIS

Surface runoff in the Wujiang River watershed was simulated by a GIS-based method using precipitation, hydrology data, and land-use data. The volume of surface runoff is chiefly controlled by climates, topographical characteristics and types of land use at the watershed. Five subwatersheds that can represent the whole watershed were chosen and their average annual precipitation, average annual surface runoff and current land use were calculated respectively in the grid model of the Wujiang River watershed based on the climate and hydrology data from 1965 to 2000 and the land-use data acquired in the year of 2000. Surface runoff is assumed to be a function of precipitation and land use and the multiple regression tool is used to determine the relationship between surface runoff, precipitation and present land use. Thus, the rainfall-runoff model for each land-use type has been established. When calibrating these models, the results show that the percent errors are all below 7%, which indicates that the accuracy of this simulation is high.     

Sedimentary Microfacies and Porosity Modeling of Deep-Water Sandy Debris Flows by Combining Sedimentary Patterns with Seismic Data: An Example from Unit I of Gas Field A, South China Sea

Sandy debris flow deposits are present in Unit I during Miocene of Gas Field A in the Baiyun Depression of the South China Sea. The paucity of well data and the great variability of the sedimentary microfacies make it difficult to identify and predict the distribution patterns of the main gas reservoir, and have seriously hindered further exploration and development of the gas field. Therefore, making full use of the available seismic data is extremely important for predicting the spatial distribution of sedimentary microfacies when constructing three-dimensional reservoir models. A suitable reservoir modeling strategy or workflow controlled by sedimentary microfacies and seismic data has been developed. Five types of seismic attributes were selected to correlate with the sand percentage, and the root mean square (RMS) amplitude performed the best. The relation between the RMS amplitude and the sand percentage was used to construct a reservoir sand distribution map. Three types of main sedimentary microfacies were identified: debris channels, fan lobes, and natural levees. Using constraints from the sedimentary microfacies boundaries, a sedimentary microfacies model was constructed using the sequential indicator and assigned value simulation methods. Finally, reservoir models of physical properties for sandy debris flow deposits controlled by sedimentary microfacies and seismic inversion data were established. Property cutoff values were adopted because the sedimentary microfacies and the reservoir properties from well-logging interpretation are intrinsically different. Selection of appropriate reservoir property cutoffs is a key step in reservoir modeling when using simulation methods based on sedimentary microfacies control. When the abnormal data are truncated and the reservoir properties probability distribution fits a normal distribution, microfacies-controlled reservoir property models are more reliable than those obtained from the sequence Gauss simulation method. The cutoffs for effective porosity of the debris channel, fan lobe, and natural levee facies were 0.2, 0.09, and 0.12, respectively; the corresponding average effective porosities were 0.24, 0.13, and 0.15. The proposed modeling method makes full use of seismic attributes and seismic inversion data, and also makes the property data of single-well depositional microfacies more conformable to a normal distribution with geological significance. Thus, the method allows use of more reliable input data when we construct a model of a sandy debris flow.     

Research advances in passive microwave remote sensing of surface freeze-thaw state北大核心CSCD

Soil freeze-thaw cycles have important effects on surface water and energy balance,and then affect vegetation growth,soil water content,carbon cycle and terrestrial ecosystem. Passive microwave plays an important role in monitoring global and regional surface freeze-thaw processes due to its high temporal resolution,abundant data and sensitivity to soil moisture. With the launch of passive microwave sensors at home and abroad,it provides conditions for the study of permafrost interannual variation,seasonal variation,diurnal variation and long time series of near-surface soil freeze-thaw cycle. In recent years,the study of surface freeze-thaw cycle using passive microwave data has gradually increased. Based on previous studies,this paper summarizes the types of passive microwave remote sensing data and the characteristics of the bands contained in them. Expounded the principle of passive microwave monitoring data used for freezing and thawing,focus on passive microwave data in five categories in the study of freezing and thawing monitoring algorithms,including double index algorithm,the decision tree algorithm,freeze-thaw discriminant algorithm,seasonal threshold algorithm and based on the freezing L-band relative factors discriminant algorithm threshold,and analysis of 5 kinds of algorithms are compared;The freeze-thaw products based on different algorithms and passive microwave data were combed. Finally,the problems and future research directions of passive microwave remote sensing in surface freeze-thaw applications are summarized. In the acquisition of passive microwave data,it is found that the passive microwave data is missing due to the physical characteristics of the sensor,the shape and orbit of the earth,and the low resolution of passive microwave data leads to the low precision of freeze-thaw discrimination. For the problem of missing passive microwave data,it is proposed to use the average value of passive microwave data before and after two days to fill the missing brightness temperature data,or establish statistical function to complement the missing data. For the problem of low passive microwave resolution,the current development trend is to scale down based on passive microwave data and combine with multiple data products,such as ground temperature and active microwave data,or perform probability discrimination on surface freezing-thawing state in pixels,so as to better describe surface freeze-thaw state. In terms of the algorithm for discriminating surface freezing-thawing,based on the problem that dual-index algorithm,decision tree algorithm,freezing-thawing discriminant algorithm and seasonal threshold algorithm cannot accurately distinguish snow and frozen soil,this paper proposes to adopt the method of data assimilation or start from the snow radiation and frozen soil dielectric model. Optimization of the algorithm for the snow covered surface can further improve the accuracy of freeze-thaw classification. Based on existing freeze-thaw products,Although SMAP freeze-thaw products continue to be updated,SAMP satellite was launched late,and SAMP freeze-thaw products have a short time series. In the future,the time span of this algorithm for freezing-thawing products can be extended by combining L-band data provided by SMOS satellite. The problems mentioned above and the direction of further research are of great significance for improving the accuracy of freezing and thawing discrimination and improving the understanding of the variation law of freezing and thawing cycles,and also have certain research space. © 2022 Science Press (China).     

http://www.sciencedirect.com/science/article/pii/S1674987113000510

In this paper,we analyze lithospheric density distribution of China and surrounding regions on the basis of 300300gravity data and 1 1 P-wave velocity data.Firstly,we used the empirical equation between the density and the P-wave velocity difference as the base of the initial model of the Asian lithospheric density.Secondly,we calculated the gravity anomaly,caused by the Moho discontinuity and the sedimentary layer discontinuity,by the Parker formula.Thirdly,the gravity anomaly of the spherical harmonics with 2e40 order for the anomalous body below the lithosphere is calculated based on the model of EGM96.Finally,by using Algebra Reconstruction Techniques(ART),the inversion of 300300residual lithospheric Bouguer gravity anomaly caused by the lithosphere yields a rather detailed structural model.The results show that the lithospheric density distribution of China and surrounding regions has a certain connection with the tectonic structure.The density is relatively high in the Philippine Sea plate,Japan Sea,the Indian plate,the Kazakhstan shield and the Western Siberia plain,whereas the Tibetan Plateau has low-density characteristics.The minimum value of density lies in the north of Philippines,in the Taiwan province and in the Ryukyu island arc.     

Advances, Problems and Prospects of Modern Geodesy Applied in Tibetan Geodynamic Changes

Modern geodetic techniques have developed rapidly in recent years, providing reliable observation data and new effective approaches, and greatly enhancing studies of the Tibetan geodynamics. For instance, the well-known GPS technique has been employed to measure seismic slips for many faults in the Tibetan Plateau. GPS data agree well with the hypothesis of a thickening crust and eastward mass flow. Moreover, absolute gravimetric data have been applied to interpret geophysical phenomena such as crust movement, co-seismic gravity change, GIA, and ground water change. The satellite gravity mission GRACE launched in 2002 provided global gravity models with unprecedentedly high precision and high spatial resolution. It has been used in implementing temporal gravity changes and improving our knowledge of the Earth’s interior, including lithosphere dynamics, mantle viscosity and rheology, plateau uplift, and subduction processing. It is noteworthy that gravity presents unique advantages for the study of Tibetan geodynamics because of its sensitivity to mass migration and dynamic redistribution. To date, great advances have been made in applying modern geodetic data in studying dynamic changes of Tibetan plateau. For instance, the horizontal displacement field from GPS data revealed dynamical characteristics of the present-day Tibetan plateau. The combination of gravity anomalies and topographic data describe the tectonic characteristics of Tibetan plateau. The combination of gravity data and GPS data show present properties of the Tibetan plateau such as crust thickening, Moho’s subsidence, and plateau uplift. GRACE data were used to estimate the distribution of ice/snow melting.     

Current Status of the Research on Coal Geology in China

Coal is the main energy in China, which has already played and will continue to play an important role in the national economy. Coal geology, as a practical science, has an access to gradual development with the growth and prosperity of China. From the meaning of the coalfield geology, this paper introduces the research progress and status of coalfield geology, including the research on coal basin, stratigraphy of coal-bearing stratigraphic sequences, coal-forming process, structural geology of coalfields, and exploration and development status of coal resources. The paper specially focuses on coal-forming process, including coal formation in terrestrial facies and transgressive / regression events, and introduces new technology which has been applied to research progress in structural geology of coalfield. This paper puts forward a new comprehensive exploration system for coal exploration and reviews regional coal geological exploration results in recent years, such as coal-poor regions of seven provinces in southern China and the coal resources area in northwest China, which will be an important coal-producing area in the future.     

Runoff Variation Law and Its Response to Climate Change in the Headstream Area of the Keriya River Basin,Xinjiang

Based on the runoff and meteorological data of Langan(兰干) Hydrological Station from 1957 to 2009 in Keriya(克里雅) River,the periodicities,abrupt changes,and trends of climate factors and runoff were investigated by wavelet analysis and nonparametric test;then,the future change of the annual runoff was predicted by a periodic trend superposition model.In succession,the influencing volumes of climate change on the annual runoff were separated from the observation values of the an-nual runoff in Keriya River.The...     

Comparative analysis of the cold surge characteristics over China before and after 2000北大核心CSCD

Based on the daily minimum temperature data in China from 1961 to 2018, using n-order polynomial fitting, sliding t-test, empirical Orthogonal Function analysis, Morlet wavelet transform and other methods, this paper reveals the temporal and spatial distribution characteristics of the number of cold surge (CS) day, CS frequency and CS intensity by time and region. The results are as follows. On a national level, the number of CS day, CS frequency, and CS intensity decreased from 1962 to 2000. Specifically, the trend of every element of CS has changed from a previous decrease trend to an increase trend, and the inflection point was around 2000. The CS activity occurred more frequently, became more strengthen, and last for longer time after 2000. There are obvious spatial differences in the number of CS days, CS frequency, CS intensity and their changing trends in China. The number of CS days and CS frequency reach the maximum value in northeast China and northern Inner Mongolia. Meanwhile, the CS intensity value is low in the southeast China and high in the northwest China, with the exception of southern Xinjiang. The changes in the number of CS day and the CS frequency are mainly manifested as the “Northeast, Southwest Reverse Pattern”, the CS intensity is mainly manifested as the “Uniform Change Pattern”. The number of CS day, CS frequency, and CS intensity did not change significantly after, but a significant transition point was detected in 1980. On a regional scale, from 1962 to 2018, the number of CS day, frequency and intensity of cold surge in all regions showed a decreasing trend, while they increased after 2000. In the northern and northeastern of China, mean of three elements of cold surge increased after 2000. The transition year was different in different regions. The transition year of three elements of cold surge in Northeast China were the earliest. Mean value of the number of CS day, CS frequency, and CS intensity have an oscillation period of 3~5 years in total China and all regions. In addition, the periodic oscillations of the number of CS day and CS frequency in all regions are basically the consistent. © 2022 Science Press (China).     

Hydrocarbon Generation Evolution of Permo-Carboniferous Rocks of the Bohai Bay Basin in China

<正>The Bohai Bay Basin is a Mesozoic subsidence and Cenozoic rift basin in the North China Craton.Since the deposition of the Permo-Carboniferous hydrocarbon source rock,the basin has undergone many tectonic events.The source rocks have undergone non-uniform uplift,twisting,deep burying,and magmatism and that led to an interrupted or stepwise during the evolution of hydrocarbon source rocks.We have investigated the Permo-Carboniferous hydrocarbon source rocks history of burying,heating,and hydrocarbon generation,not only on the basis of tectonic disturbance and deeply buried but also with new studies on apatite fission track analysis,fluid inclusion measurements,and the application of the numerical simulation of EASY%R_o.The heating temperature of the source rocks continued to rise from the Indosinian to Himalayan stage and reached a maximum at the Late Himalayan.This led to the stepwise increases during organic maturation and multiple stages of hydrocarbon generation.The study delineated the tectonic stages, the intensity of hydrocarbon generation and spatial and temporal distribution of hydrocarbon generations.The hydrocarbon generation occurred during the Indosinian,Yanshanian,and particularly Late Himalayan.The hydrocarbon generation during the late Himalayan stage is the most important one for the Permo-Carboniferous source rocks of the Bohai Bay Basin in China.