Origin of the Yueguang gold deposit in Xinhua, Hunan Province, South China: insights from fl uid inclusion and hydrogen–oxygen stable isotope analysis

The Yueguang gold deposit is located in Fengjia,Xinhua County,Hunan Province,South China.It represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt,west of the Baimashan granitic batholith.In order to discern the characteristics of the ore-formingfluids,the underlying mineralization processes,and establish a foundation for the origin of the Yueguang gold depositfluid inclusion micro-thermometry,as well as quartz hydrogen and oxygen isotope analysis,have been carried out on samples obtained from various stages of mineralization.The hydrothermal miner-alization stages within the Yueguang gold deposit can be categorized into three stages:(i)the barren,pre-ore quartz-pyrite stage(Stage Ⅰ),the quartz-pyrite-gold stage(Stage Ⅱ),and the post-ore quartz-carbonate stage(Stage Ⅲ),with the second stage being the main mineralization stage.Thefluid inclusions identified in samples from the main min-eralization stage can predominantly be described with the NaCl–H_(2)O and CO_(2)–NaCl–H_(2)O systems.These inclusions display homogenization temperatures ranging from 158.8 to 334.9℃,and thefluid salinity ranges from 0.3%to 4.0%(wt.%NaCl equiv.).Laser Raman spectroscopy analysis of individual inclusions further reveals the presence of gas-phases such as CO_(2),CH_(4),and N_(2).Isotopic analysis indicatesδ^(18)Ofluid values ranging from 3.95 to 6.7‰ and δDH_(2)O values ranging from-71.9 to-55.7‰.These results indi-cate that the ore-formingfluid of the Yueguang gold deposit belongs to metamorphic hydrothermalfluids of middle-low temperature and low salinity.In the process of ore formation,gold is transported in the form of Au(HS)2-complexes,with gold deposition being driven byfluid immiscibility.Therefore,the Yueguang gold deposit is categorized as an orogenic gold deposit dominated by metamorphic hydrother-malfluid.It may become a new target for gold exploration in the Baimashan region,central Hunan Province.

Winter Wheat Yield Estimation Based on Sparrow Search Algorithm Combined with Random Forest:A Case Study in Henan Province,China

Precise and timely prediction of crop yields is crucial for food security and the development of agricultural policies.However,crop yield is influenced by multiple factors within complex growth environments.Previous research has paid relatively little attention to the interference of environmental factors and drought on the growth of winter wheat.Therefore,there is an urgent need for more effective methods to explore the inherent relationship between these factors and crop yield,making precise yield prediction increasingly important.This study was based on four type of indicators including meteorological,crop growth status,environmental,and drought index,from October 2003 to June 2019 in Henan Province as the basic data for predicting winter wheat yield.Using the sparrow search al-gorithm combined with random forest(SSA-RF)under different input indicators,accuracy of winter wheat yield estimation was calcu-lated.The estimation accuracy of SSA-RF was compared with partial least squares regression(PLSR),extreme gradient boosting(XG-Boost),and random forest(RF)models.Finally,the determined optimal yield estimation method was used to predict winter wheat yield in three typical years.Following are the findings:1)the SSA-RF demonstrates superior performance in estimating winter wheat yield compared to other algorithms.The best yield estimation method is achieved by four types indicators’composition with SSA-RF)(R^(2)=0.805,RRMSE=9.9%.2)Crops growth status and environmental indicators play significant roles in wheat yield estimation,accounting for 46%and 22%of the yield importance among all indicators,respectively.3)Selecting indicators from October to April of the follow-ing year yielded the highest accuracy in winter wheat yield estimation,with an R^(2)of 0.826 and an RMSE of 9.0%.Yield estimates can be completed two months before the winter wheat harvest in June.4)The predicted performance will be slightly affected by severe drought.Compared with severe drought year(2011)(R^(2)=0.680)and normal year(2017)(R^(2)=0.790),the SSA-RF model has higher prediction accuracy for wet year(2018)(R^(2)=0.820).This study could provide an innovative approach for remote sensing estimation of winter wheat yield.yield.

The Spatial Distribution Characteristics of Resident Population Growth Rate in Henan Province, China

Population is an important strategic resource for national development, a fundamental element of socio-economic development. The coordinated development of population and economy is an effective way to achieve rapid economic growth. Based on the population statistics data of counties (districts) in Henan Province, China, from 2006 to 2021. The paper firstly uses the logistic population growth mathematical model to calculate the resident population growth rate of counties (districts), then utilizes the hotspot analysis and spatial semi-variogram analysis, to research the spatial distribution characteristics of the resident population growth rate in Henan Province. The research results show that the evolution of the regional resident population in the province basically conforms to the logistic natural growth model. The resident population growth rate shows the characteristics of high in the north and low in the south, high in the center and low in the surrounding regions. The resident population growth rate is positively correlated with the level of economic development;the urban built-up areas, especially the new regions in urban planning, have a fast growth rate of resident population, which has a significant siphon effect on the population of surrounding regions. The hotspots of resident population growth rate in the province are mainly distributed in the urban built-up areas and surrounding regions of Zhengzhou, Luoyang, and Xinxiang, accounting for about 3.51% of the total area of the province. The cold spots are mainly distributed in the eastern part of the province, forming zonal distribution, which spans across Shangqiu City, Zhoukou City, and Zhumadian City, accounting for about 8.61% of the total area of the province. The area with negative growth of resident population accounts for approximately 53.47% of the total province. The spatial distribution of the growth rate of the resident population in the whole province basically conforms to the spherical model, with a small dispersion degree and a short range. In the range, there is a high degree of variability in resident population growth rate.

Analysis of the Impact of Off-farm Employment of Agricultural Labor on Grain Production in Shandong Province and Henan Province

[Objective] This study aimed to investigate the impact of off-farm employment of agricultural labor on grain production. [Method] Impact of off-farm employment of agricultural labor on grain production was investigated based on path analysis by using data from 200 counties and cities in Shandong Province and Henan Province in 2000 and 2008. [Result] Off-farm employment of agricultural labor affects grain production through agricultural land use patterns, off-farm employment of agricultural labor has negative impacts on grain production through multiple cropping index and positive impacts through the proportion of grain planting area. The positive impacts were greater in 2008. [Conclusion] Prerequisite of the positive impacts of off-farm employment on grain production is the substitution of agricultural mechanization development and agricultural technology advancement for agricultural labor. Orderly land circulation and scale land use should be promoted to avoid the lack of agricultural labor due to off-farm employment.

Study on the Change Character of Double Rice Cold Damage in Hunan and Hubei Province during the Past 50 Years

Based on the meteorological data of representative meteorological stations in Hunan and Hubei from 1961 to 2008 years,the change character of double rice cold damage under the background of climate change were analyzed adopting 30 years glide accumulation method.The analysis showed that the 30 years sliding cumulative days of mild low-temperature during spring sowing in Hunan and Hubei were decreased in the recent 50 years,as well as the 30 years sliding cumulative days of moderate low-temperature in central south Hubei,northern and western Hunan.However,there was an increase in southern Hunan,so was the 30 years sliding cumulative days of severe low-temperature.The 30 years sliding cumulative days of mild low-temperature in May reduced in Hunan and Hubei.Instead,that of moderate low-temperature in May in central south Hubei was on the rise,and it was opposite in northern and southern Hunan,but there was no obvious change in western Hunan.The 30 years sliding cumulative days of severe low-temperature showed a decreasing tendency in May in central south Hubei,northern and western Hunan,and southern Hunan showed a contrary tendency.The 30 years sliding cumulative days of mild cold dew wind in Hunan and Hubei were decreased,that of moderate cold dew wind in central south Hubei,northern and western Hunan had the same tendency,but there was a contrary tendency in southern Hunan.The 30 years sliding cumulative days of severe cold dew wind was decreased in central south Hubei and increased in western Hunan,without cold dew wind in northern and southern Hunan.

Difference Analysis on Contents of Gallic Acid and Catechins of Tea Resources from Yunnan Province

[Objective] This study aimed to analyze the difference in the contents of gallic acid and catechins of tea resources from Yunnan Province. [Method] By using high performance liquid chromatography （HPLC）, the contents of gallic acid （GA）, catechins （C）, epicatechin （EC）, epigallocatechin （EGC）, epicatechin gallate （ECG） and epigallocatechin gallate （EGCG） of 121 tea germplasms from the China National Germplasm Tea Repositories （CNGTR） at the Tea Research Institute of Yunnan Academy of Agricultural Sciences （TRIYAAS） were measured. [Result] The content of GA ranged from 0.210% to 1.902%, with an average of 0.834%, explaining rela- tively low GA content among tea germplasms. The content of C ranged from 0.069% to 8.865%, with an average of 1.916%. The content of EC ranged from 0.126% to 2.865%, with an average of 1.112%. The content of EGC ranged from 0.00% to 3.709%, with an average of 0.954%. The content of ECG ranged from 0.739% to 8.957%, with an average of 4.063%. The content of EGCG ranged from 0.819% to 11.77%, with an average of 5.939%. The content of total C ranged from 6.354% to 22.654%, with an average of 14.042%. [Conclusion] There was relatively big difference of catechin contents among different tea resources, indicating that there was plentiful biodiversity of Yunnan tea germplasms. At the same time, three tea germplasms with high epigallocatechin gallate content （≥10%） was selected preliminarily, which would provide important materials for breeding tea cultivars with high EGCG content in the future.

A Preliminary Survey on Pest of Bamboo in Yunnan Province

In order to improve the development step of bamboo industry, the pest investigation was done in Yunnan Province from 2000, and 1 500 specimens were collected. Basing on the investigation and the date of recordation, there had 224 species pests, belonging to 7 orders and 49 families. Among the pest, most done harm to the bamboo slightly, except Omphisa sp., Pantana phyllostachysae and Cyrtotrachelus buqueti. The disease and pest of bamboo should be investigated in whole province systematically.

Analysis on the Necessity and Feasibility of Implementing the Strategy of "Protecting Farmland in Flatland Areas and Constructing Mountainous Cities" in Yunnan Province

Yunnan is one of the most typical mountalnous provinces in western Chi-na. For the geographical features of mountalnous areas accounting for most parts and fIatIand areas accounting for smal parts, the contradiction between farmIand protection and construction guarantee is very prominent. In the first half of 2011, Yunnan Province estabIished creativeIy the strategy of ＆quot;protecting farmIand in fIat-Iand areas and constructing mountalnous cities＆quot; （hereinafter referred to as the strat-egy of ＆quot;constructing mountalnous cities＆quot;）, which was almed at protecting effectiveIy the Iimited and high quality arabIe Iand resources in fIatIand area and providing new construction area for new type of urbanization and industrialization, so as to achieve win-win situation between arabIe Iand protection and urbanization deveIopment. Im-pIementing this strategy in Yunnan Province is feasibIe, malnIy in the Iarge deveIop-ment potentials in the gentIe gradient between 8° to 25°. The gentIe sIope area be-tween 8° to 25° occupies 51% of the total Iand area in Yunnan Province, which is almost 140 times of the area of urban construction Iand in Yunnan in 2009. The surrounding areas of fIatIand or maln town in most counties （cities, regions） dis-tribute with different sizes of Iow hiI s and gentIe sIopes, thus mountalnous construc-tion Iand reserves are abundant, which benefits for impeI ing the strategy of ＆quot;con-structing mountalnous cities＆quot; in the Iight of Iocal conditions.

Wild Ornamental Plant Resources and Their Application to City Gardening in Hainan Province

This paper deals with the wild ornamental plant resources which are suitable for the application to gardening in Hainan Province and with the significance and the influencing factors in the application and extension of these resources to gardening. The strategies for the application of the wild ornamental plant resources have been established as the result of this research.

Variations of Frost-free Period and Its Impact on Grain Yields in Henan Province during 1961-2013

The aim of this study was to investigate the responses of frost dates to global warming and its influences on grain yields. In this study, based on the frost date series defined by daily minimum ground temperature, the spatial and temporal characteristics of first frost date （FFD）, last frost date （LFD） and frost-free period （FFP） were analyzed. The impact of extending FFP on major crop yields was also studied. The results were as follows： FFD showed a significantly delaying trend of 2.2 d/10 y, and LFD presented an advancing trend of 2.4 d/10 y. FFP extended at a rate of 4.5 d/10 y due to the later FFD and earlier LFD. The most obvious trend of FFD was in westem Henan, while the most significant trend of LFD and FFP oc- curred in south central parts of the study area. However, in eestem region, the trends of FFD, LFD and FFP were not so obvious. Major crop yield showed a sig- nificant correlation with frost-free period for Henan during 1961-2013. The yields of grain, rice, wheat, and maize increased by 79.5, 90.0, 79.5 and 70.5 kg/hm2 with FFP extending by one day.

Study on Urban Construction Land Suitability Evaluation in Southwestern Mountainous Areas of Yunnan Province Based on the Strategy of "Protecting Farmland in Flatland Areas and Constructing Mountainous Cities" : A Case in Lianghe County

According to the particularity of towns＇ construction in the southwestern mountainous areas of Yunnan Province, this study has built constructive land suit- ability evaluation index system which is different to flat area. Then this study deter- mined single evaluation factors index and comprehensive suitability index using ＂ex- treme conditions method＂ and ＂suitability index method＂, and analyzed and assessed the constructive land suitability on each evaluation unit polygons and its suitability level by using GIS software. Taking Lianghe County of Dehong Dai-Jingpo Au- tonomous Prefecture as an example to evaluate land suitability in Lianghe County＇s main towns around the gentle slope, the results show, in the evaluation area, the area of land suitable for construction and unsuitable for construction respectively ac- count 73.58% and 26.42%. And first-class, second and third-class of land suitable for construction should be composited at the ratio of about 11：49：40. The suitability evaluation index system and method developed in this paper is applicable for evalu- ating the construction land suitability in mountainous areas of southwest Yunnan Province, and will provide theoretical and technical support for land policy measures which strengthen the protection of farmland and promote the scientific development of urbanization in Yunnan Province and even similar mountainous areas of the whole China.

Spatial Characteristic Analysis of the Comparative Advantage of Watermelon and Melon Production in Hainan Province

[Objective] This study investigated the spatial characteristics of counties （cities） with comparative advantages in watermelon and melon production to provide reference bases in formulating strategies for the development of watermelon and melon industries in Hainan Province. [Method] By using the sowing area, total yield, and yield per unit area of watermelon and melon in Hainan Province as research u- nits, the yield comparative advantage （YCA）, efficiency comparative advantage （E- CA）, scale comparative advantage （SCA）, concentration ratio comparative advantage （CRCA）, comprehensive comparative advantage （CCA）, ratio of yield per unit area （RYPA）, sowing area ratio （SAR）, and distribution characteristics of watermelon and melon were systematically analyzed. By referring to the agricultural statistic data of 18 counties （cities） in Hainan Province, indexes for each research unit （i.e., the YCA index, ECA index, SCA index, CRCA index, CCA index, RYPA index, and SAR index） were established and calculated to determine the comparative advantage of watermelon and melon production in Hainan Province. A spatial expression of the research result on a map was conducted by using GIS software. [Result] Seven counties （cities） exhibited comparative advantages in watermelon production, namely, Lingshui, Wanning, Wenchang, Dongfang, Sanya, Ledong, and Changjiang. The Eastern and Southern Hainan Provinces had CCAs, and the Western and Northern Hainan Provinces could be reserved for future development. For melon production, four counties （cities） exhibited comparative advantages, namely, Ledong, Lingshui, Sanya, and Dongfang. The Southern Hainan Province had CCA, whereas the West- ern Hainan Province could be reserved for later development. [Conclusion] The result has showed that establishing watermelon and melon as dominant agricultural prod- ucts is necessary for the future development of the industry and for the formulation of a layout of regions with advantages, where key support and construction should be provided preferentially with the aim to raise the yield, quality, and market com- petitiveness of products.

Analysis of Change of Cultivated Land and Grain Production in Hunan Province

[Objective] This paper aimed at exploring the countermeasures for cultivated land protection and food security assurance and providing references for the formulation of policies related to cultivated land and grain production of the whole province.[Methods] Data of population,cultivated land,grain and others in Hunan Province during 1989 to 2008 were collected by county（district）.The changes of cultivated land and grain production of the whole province were analyzed using Geographical Information System（GIS）.[Results] The population was increasing continuously,the total area of cultivated land was reducing as a whole in spite of increasing in one or two year in one or two county,the total grain production and per capita grain yield was fluctuated within a certain range in recent 20 years of the whole province.The reducing of cultivated land was mainly due to the industrialization and urbanization development.The unbalanced quantity and quality of cultivated land,various natural disasters,readjustment of industry structure and inner readjustment in the agriculture,variety improvement and improvement of cultivated technology mainly affected of the grain production.[Conclusions] The protection of the quantity and quality of cultivated land has to be strengthened to ensure food security.It is important to enhance the ability of resisting drought and flood disasters by improving the construction of agriculture establishment in order to insure the productivity of cultivated land,to increase farmer’s enthusiasm for growing grain with favourable food policy,to improve the per unit area yield of grain by variety improvement and to increase grain sown area by enlarging the double-cropping rice sown area.

Relation between Economic Development Level and Resource and Environment Carrying Capacity of Central Area of Yunnan Province Based on Decoupling Analysis

Based on the decoupiing theory and method, an indicator system was built for the relation between economic development level and resource and environment carrying capacity. And the study was carried out on decoupling degree and temporal changes of economic development level and resource and environment carrying ca- pacity in the central area of Yunnan Province. Results indicated that （i） the economic development level and resource and environment carrying capacity in the central area of Yunnan Province mainly experienced strong decoupling, weak decoupling, and ex- pansive negative coupling, and in general it was strong decoupling, and it took on re- verse ＂N＂ in temporal changes. （ii） Change rate of economic development level in the central area of Yunnan Province was greater than zero, but the amplitude of change was not large, while the change rate of resource and environment carrying capacity was negative in 2007-2008, and it was positive in the rest years; from 2007, it took on gradual expansion trend, and scissors difference gradually increased after experi- encing reverse ＂V＂ change. （iii） The strong decoupling was the main situation and it reached the peak value in T5 period and T6 pedod.

Analysis of Emergy Structure,Function and Efficiency of Agro-ecosystem in Hunan Province

[Objective] The aim was to explore function and efficiency of emergy input/ output of Hunan agricultural ecosystem to reveal relationship of human being with natural resources and environment. [Method] Emergy structure, function and efficien- cy of Hunan agricultural ecosystem were analyzed based on input/output data in Hunan Province in 2009 as per emergy theory. [Result] The structure characters of agricultural ecosystem were as follows： Hunan is characterized with traditional agri- culture, depending greatly on both human and animal labor. For industrial accessory emergy, chemical fertilizers make most contribution to the system, and agricultural mechanization is not satisfied. Furthermore, renewable ratio of industrial accessory emergy is lower, and development and potential of green energy is promising. In addition, prices of the products are lower, without consideration of contribution made by natural resources and environment. It also suggested that Hunan agricultural chain is short and added value of products is not high. In general, emergy output of farming and animal husbandry dominates and the prices are lower than those of forestry and fishery. The function of the system was as follows： With lower environ- mental load ratio, the system is overloaded by population and the index of sustain- able development was 5.96, suggesting that the system enjoys vitality and potential, but the economy is undeveloped and the pressure from natural resources and envi- ronment is not high. The emergy output ratio was a little lower than national level in 2009, suggesting Hunan agricultural production is extensive. [Conclusion] The re- search indicated that rapid increase of population should be controlled; surplus labor should be transferred; agricultural structure and products structure should be further adjusted; agricultural technology should be further developed; agdcultural mechaniza- tion and modernization should be improved.

A Study on Vertical Spatial Transfer of Cultivated Land in Yunnan Province from 1986 to 2008

Based upon ArCGIS,the vertical spatial transfer law of cultivated land in Yunnan was studied through referring to three periods of remote sensing data of Land-Use and Land-Cover Change（LUCC） in Yunnan in 1986,1995 and 2000,Digital Elevation Model（DEM） of Yunnan Province and LUCC data in Yunnan from 2000 to 2008.The main factors that promote vertical spatial transfer law of cultivated land were analyzed by using SPSS,and the influence of policies and government acts upon the change of cultivated land was clarified.The findings indicated that for Yunnan cultivated land there is a trend that in the vertical direction steep slope areas and gentle slope areas divert into mid-slope areas.The primary factor influencing the vertical spatial transfer of cultivated land was policies and government acts.Also,the gradient of ground,total population and number of agriculture employed persons were also main factors in influencing the change of cultivated land,whose influence was obviously below policies and government acts.

Technological Paths for Improving Grain Comprehensive Productivity ——Taking Henan Province for Instance

[Objective] This paper aimed at exploring technological paths for improving grain productivity based on the conditions and production practice in Henan Province.[Method] The status and dynamics of grain production in Henan Province were analyzed as a whole.[Result] The total production of grain in Henan Province had generally shown a tendency of ascent.Total grain production in Henan Province was 54 370 thousand t,which was 2.5 times of the total grain production in 1978,as 20 974 thousand t.The growth of grain production was more and more relying on the improvement of grain yield per unit area.[Conclusion] This research had provided theoretical basis for the improvement of grain production in Henan Province as well as for the grain production of the whole country.

Research on Coconut Germplasm Resource in Hainan Province

The researches on coconut germplasm resource of Hainan Province and its importance were reviewed in this study.The classification and characters of coconut germplasm resource in Hainan Province,as well as its development and utilization of were summarized.In addition,some of the problems in researches on coconut germplasm resource and the potential research directions were discussed.

On the Employment Structure and Transfer Characteristics of Rural Laborers in He'nan Province

He’nan is a populous province in China, in which a large number of rural laborers are one of the important factors affecting social and economic development of He’nan Province. However, the employment structure and transfer characteristics of rural laborers have important effect on regional industrial structure. Applying shiftshare method（ SSM） which is often used in analyzing the characteristics of industrial structure to the structure analysis of the labour force can better show the characteristics of labor employment and transfer, thereby providing some reference for the development of regional social economy. The results showed that the transfer of rural laborers in He’nan Province still showed the typical characteristics of traditional agricultural province; the basic advantages of agricultural employment of rural laborers have gradually weakened, while the competitive advantages of the industry, the building industry, and the wholesale ＆ retail trade and catering service industry gradually became obvious, at the same time, there were differences in the deviation of departments among different regions of He’nan Province.

Analysis of Driving Factors of Grain Output in Henan Province Based on Grey Correlation Model

Henan Province is an important grain production base, whose stable production is related to the economic development and social stability significantly. To summarize the primary factors of grain producing, we used grey correlation analysis method to analyze 10 correlative factors such as grain yield, grain yield per unit area, effective irrigated area, rural employed persons, grain planting area, consumption of chemical fertilizer in 25 years. The results showed order of synthetic degree of incidence: effective irrigated area>rural electricity consumption>consumption of chemical fertilizer>disaster crop area>grain yield per unit of area>total power of agricultural machinery>afflicted crop area>grain planting area>number of the rural employed persons. Finally, according to synthetic degree of incidence between influential factors and total grain output respectively, a series of measures and the suggestions was proposed for grain production in Henan Province, which will also provide the scientific basis and help for the government correct decision-making.