Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures

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PRELIMINARY DISCUSSION ON METALLOGENESIS OF LANCANGJIANG RIVER TRANSITIONAL FIELD TECTONIC ZONE IN WESTERN YUNNAN

Applying the crustobody geotectonic theory to geological prospecting at the Lancangjiang river metallogenic belt in western Yunnan province, and on the basis of the basic geological background of western Yunnan and the space-time evolution-movement historical-dynamic features of the Lancangjiang river tectonic belt, the author has discussed firstly the metallogenesis of the Lancangjiang river transitional field tectonic zone, which can provide a new theoretical foundation for exploring the space-time laws of mineralization in this region.

PROSPECTING FOR COPPER (GOLD)-POLYMETAL ORES FROM THE LANCANGJIANG TECTONIC ZONE IN WESTERN YUNNAN

The L ancangjiang tectonic zone in Western Yunnan is an important magmatic,meta- morphic and tectonic mobile zone of Southwestern China,whose geotectonic location is very unique. It is characterized by complex geological structures,perfectly developed strata,fre- quent magmatic activities,various degrees of metamorphism,rich ore resources and lots of metal deposits,thus formed a centralized zone of mineralization and also constituted one of the importantmetallogenicbelts of noble and nonferrousmetal deposits.Thatiswhy the re- searching on geology for this zone is of great

Soil Erosion and Its Relationship to the Spatial Distribution of Land Use Patterns in the Lancang River Watershed, Yunnan Province, China

The Lancang River Watershed is one of the most biologically diverse areas in the world. The river flows through Yunnan Province, China, which suffered serious deforestation since the 1980s;this in turn led to increased soil erosion in the region. To investigate the influence of the spatial distribution of land use and slope on soil erosion in the Lancang River Watershed, the Soil and Water Assessment Tool (SWAT) model was used to establish hydrological models using two-phase land use maps (1975 and 1985), a soil map, and meteorological data from 11 gauging stations. The satisfactory values of Nash-Sutcliffe efficiency Ens and correlation coefficient R2 during the calibration and validation period indicated that SWAT can be used in this area to simulate the average annual soil erosion under different land use scenarios change. By comparing soil erosion rate under different land use scenarios change, forests and grasslands had similar effects on preventing soil erosion. A parameter, soil erosion increment (Ei), was used to assess the effects of slope on soil erosion. The results revealed that variation in sediment yield was more sensitive to land use change for slopes exceeded 25° than for slopes being 0° - 15°. The spatial distribution of land use also had a relationship to soil erosion. Compared with the soil erosion rate in each sub-watershed using two-phase land use maps, the soil erosion rate increased when the percent cover of natural vegetation decreased. The results of this study provide baseline data for soil conservation and protection of the environment and ecology of the Lancang River Watershed in Yunnan Province.

CHARACTERISTICS OF TECTONIC MIXTITE ZONE IN THE LANCANG RIVER,WESTERN YUNNAN

Specialists think tectonic mixtite zone in Lancang River, which lies in southern and eastern fringe of Qingzang plateau, is the suture line (or contact strip) between Gondwana Land and Yangtz block (Fan Chengjun, 1982; Liu Zhengqian, etc, 1991; Fang Runsen,1993).By regional geological study (Legend:1∶50000) in Tu’e, western Yunnan, the author think major fracture zone about 6\|8km from western Lancang River is fragile\|ductile shear zone between batholithic granite of Biluo snow mountain and Jurassic\|Cretaceous slight curdle strata. The zone is a very complicated tectonic mixtite zone (width:0.7\|6km; strike: SN\|direction). Study based on geometric structure, constitution, metamorphism, deformation and kinematic characteristics, the author sum up the following features about the complex deformation zone.(1) Tectonic mixtite zone is a very complicate blocks made up of curdle blocks and residual blocks of granite. Its’ geometric structure is a net\|shape structure composed of matrixes and chaotic blocks in plane and have two kinds of structure types (obduction schists in early diagenesis and heteroploytypes in late diagenesis) in section.

Distribution and Influencing Factors of Residential Areas in Yunnan Section of the Lancang River Basin

Based on high-resolution Google Earth images,settlements in Yunnan section of the Lancang River basin were extracted.We use the kernal density and the optimized hot spot analysis methods to display spatial pattern of the settlements.Random forest model is used to explore the natural environmental impact factors of residential areas distribution.The results show that settlements in Yunnan section of the Lancang River basin are mainly distributed in the middle reaches and the upper reaches along the river.The random forest model contains 11 environmental factors,and the top three factors in importance are the nearest distance to forest,altitude and the nearest distance to glacier/snow.The partial dependence plots show the response trend of settlements to environmental factors.This research results could provide guidance for rational use of land resources,making regional development and construction plans,and coordinating the relationship between humans and the environment.

Geochemical discrimination of the geotectonic environment of basaltic-andesitic volcanic rocks associated with the Laochang polymetallic ore deposit at Lancang, Yunnan

The Laochang polymetallic ore deposit at Lancang is one of the well known ancient ore deposits associated with volcanic rocks in the Sanjiang (Tri-river) region of Southwest China. Volcanic rocks are dominated by alkali basalt and trachyte basalt. There has long been a controversy on the environment of formation of basalts. Some scholars hold that the basalts were formed in a continental environment, some thought they were formed in an oceanic environment and others considered that the basalts were emplaced in a back-arc basin. This study focuses on the geochemical characteristics of the basalts on the basis of their major elements, REEs and trace elements. At the same time, strongly incompatible elements such as Ta, Th and Hf and their ratios were used to differentiate the geotectonic settings of basalts. The results showed that the basalts in the region studied were formed in a continental rift environment.

Improved Geological Interpretation Using Landsat TM Data in Lancang-Jinghong Area, Yunnan Province, China

Landsat TM digital spectral data of Lancang Jinghong area (Yunnan P ro vince) has been used for the purpose of geological interpretation. To meet this object, different image processing techniques including selected band color comp osites, principal component analysis and IHS decorrelation stretching are used t o improve the discrimination of different lithological and structural features i n the area.It was found that IHS decorrelation stretching images obtained from t he transformation of false color composite 741 (in red, green and blue) prov ided the best results based on the original data.By combining the characteristic s of images produced by different approaches and other canonically transformed i mages with available geological data and surface observations, the geological in terpretation could be done with satisfactory degree of accuracy.

Geology and Geochemistry of K-feldspar Veins in Lamprophyre at the Zhenyuan Gold Deposit,Yunnan,Southwest China:Implications for Gold Mineralization

Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mineralization,whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids.K-feldspar veins,with ages between those of lamprophyres and gold deposits,appear in lamprophyres in Zhenyuan.Therefore,K-feldspar veins are ideal for investigating the relationship between lamprophyres and gold deposits.Phlogopite in K-feldspar veins has lower Mg#,Ni,and Cr contents and higher TiO2,Li,Ba,Sr,Sc,Zr,Nb,and Cs contents than phlogopite in lamprophyres.The in-situ Sr isotopic values of apatites(0.7063–0.7066)in K-feldspar veins are within the range for apatites(0.7064–0.7078)from lamprophyres.High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres,in addition to high(87Sr/86Sr)i values of apatite(0.7064–0.7078),indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle.Kfeldspar veins are genetically correlated with lamprophyres,whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to gold mineralization of the Zhenyuan deposit.

A Brief Discussion on the Development of the Silk-Weaving Industry Along the “Southern Silk Road” in Yunnan

Ancient Yunnan was one of the most significant regions along China’s ancient“Southern Silk Road.”During the Nanzhao period(738–902)of the late Tang Dynasty,Yunnan’s silk-weaving industry underwent a qualitative leap as skilled silk craftsmen from the Bashu area migrated to Yunnan and introduced mulberry planting,silkworm breeding,and advanced silk-weaving techniques from Sichuan to the region.Consequently,people in Yunnan gradually acquired expertise in brocade weaving and embroidery.Many even mastered complex silk-weaving techniques.The development and progress of the silk-weaving industry in the ancient Yunnan region were intricately linked to the economic function and value of silk as both a commodity and currency along the“Southern Silk Road.”The local government in ancient Yunnan was greatly motivated by the economic interests brought by the development of silk-related industries and recognized the significance of developing the local silk industry.They even initiated a campaign to capture skilled silk craftsmen from Sichuan,aiming to foster the growth of the silk-weaving industry in Yunnan.After years of dedicated efforts from the local government in ancient Yunnan,the region emerged as a significant hub for silk production along China’s ancient“Southern Silk Road.”Despite the devastation caused by the wars in other parts of the country,Yunnan’s silk industry continued to thrive and provide ample silk products to sustain trade along this renowned route.In the contemporary era,amidst the decline of the silk-weaving industry in eastern China,Yunnan has proposed an industrial development strategy known as“relocating the silk-weaving industry from east to west.”This involves introducing advanced silk production techniques from the eastern regions into Yunnan to enhance and enrich its local silk industry,thereby establishing it as a traditional national sector and securing a competitive position within the global silk market.The historical experience of Yunnan’s silk industry demonstrated that economic development opportunities can only be seized through proactive endeavors rather than passive anticipation.The modern Yunnan silk industry,which upholds its historical traditions,continues to actively engage in international high-end technical cooperation,thus ensuring the enduring vitality of the ancient“Southern Silk Road.”

Epidemiological survey of cystic echinococcosis in southwest China:From the Qinghai-Tibet plateau to the area of Yunnan

BACKGROUND Echinococcosis is prevalent in 9 provinces in Western and Northern China.An epidemiological survey of echinococcosis in 2012 and 2016 showed cases of echinococcosis in Yunnan Province.AIM To understand the spatial distribution and epidemiological characteristics of echinococcosis in Yunnan for the prevention and control of echinococcosis and to reduce the risk of infection in Yunnan Province.METHODS Based on the China Information System for Disease Control and Prevention(CISDCP),echinococcosis cases reported from 36 hospitals and 34 Centers for Disease Control were investigated and epidemiologically analyzed from 2021 to 2022.The exclusion criteria included suspected cases,same case only counted once and cases not from Yunnan.A total of 705 cases were investigated,of which 397 cases were suitable for statistical analysis.In these 397 cases,epidemiological investigation was tracked in 187 cases.All data were inputted using double entry in the Excel database,with error correction by double-entry comparison.The data on echinococcosis cases in Yunnan Province were analyzed by ArcGIS 10.1 software to generate a density map of echinococcosis distribution.All statistical analyses were conducted using SPSS 17.0,including the chi-square test,linear regression test and logistic univariate and multivariate regression analyses.RESULTS A total of 397 cases were found in 89 counties in Yunnan Province.The number of cases in the top three prefectures were Dali(38.1%),Diqing(10.1%),and Kunming(8.3%),and the top five counties were Jianchuan(9.1%),Shangri La(8.3%),Eryuan(7.6%),Heqing(6.9%),and Dali Districts(5.0%).There were significant differences between the different areas.The case reporting rate by CISDCP(33.8%)was low;the first case was reported by CISDCP in 2002,and the highest number of cases was 50(2017).Confirmed and clinical cases accounted for 62.5%and 37.5%,respectively.However,90.9%of the cases of hydatid disease were reported by the hospital system,and only 9.1%of the cases of hydatid disease were found in the community through active screening.The difference between the two methods of case detection was statistically significant.Most of the cases of echinococcosis were found in farmers/herdsmen(75.1%)and students(9.1%).In addition,Han(43.6%)and Bai(26.2%)had a higher incidence of infection than other nationalities,and the liver(87.7%)and lung(6.8%)were the most common sites of cyst formation.Among the analyzed cases,187 were epidemiologically analyzed and the clinical symptoms were not obvious in the early stage in 47.1%of cases.The results of logistic regression analysis showed that the age group,education level,presence of dogs in the family(either previously or currently),and handwashing(occasionally or not)were factors related to echinococcosis infection.55.6%of cases were in endemic areas,and 44.4%of cases were in non-endemic areas.Among 83 cases in non-endemic areas,only 4 cases had been to endemic areas and had a history of living,working,travelling,or hunting in echinococcosis epidemic areas.CONCLUSION Cases of echinococcosis were reported throughout the entire Yunnan province,with the majority distributed in Western Yunnan,suggesting that echinococcosis control should be strengthened in this area.We suggest that an epidemiological investigation should be carried out in the future,based on the clues from newly discovered cases in hospitals or from the CISDCP.The newly discovered cases in the hospital provided clues to comprehensively determine the location of cases and where epidemic spot investigation should be conducted.

Reanalysis on the Spectral Characteristics and Materials of Jade Jue Unearthed from Lijiashan Ancient Tomb in Yunnan Province, China

Jade ware Jue is one of the most fashionable ornament in ancient China from the Neolithic Age to the Han Dynasty.In this study,the remnants of jade ware Jue,from Lijiashan ancient tomb group have been tested and analyzed respectively.The samples through a light etch surface showing glass luster and those with a severe etch surface showing earthen luster.With the aid of X-ray fluorescence Spectrometer(X-ray Fluorescence)test and X-ray diffraction(XRD)detection,the results show that tremolite is not the main mineral of the sample.The main components of the tested samples with light erosion are antigorite and talc,although the main components of the samples with severe erosion are calcite containing calcium carbonate barium.Furthermore,the research on jade ware Jue in Yunnan culture has not only contributed to our further understanding of the jade objects from Yunnan culture and the variety of jade material located in the Yunnan Province.It also provides a basis for the trace of the history and culture through the distribution and evolution of burial hierarchy laws.At the same time,the microscopic observation of the tested samples manifested a residual trace of“string”at the perforation,which has played a critical role in restoring the wearing of jade ware Jue from the tombs of the ancient Yunnan State and the handicraft skills at that time.

Latest Neogene Paleoclimate Variation in Yunnan,Southwest China,Revealed by Fossil Leaf Physiognomy

Yunnan Province,located in the southeastern margin of the Tibetan Plateau,can provide important information on how climate change was influenced by global cooling.However,its variation patterns in temperature and precipitation during the latest Neogene are not well-understood.Based on the 357 specimens assigned to 31 morphotypes of plant fossils from the upper Pliocene Ciying Formation in Yiliang County,Yunnan Province,Southwest China,paleoclimate was estimated by Leaf Margin Analysis and Climate Leaf Analysis Multivariate Program.Compared to the present climate,the mean annual temperature and coldest month temperature have not changed significantly since the late Pliocene,whereas the warmest month temperature has decreased significantly.All precipitation-related parameters have decreased,particularly winter precipitation.Combined with the climatic data of the same period in other areas of Yunnan,the western and eastern Yunnan has shown a similar pattern in temperature variation since the late Pliocene except for central Yunnan;whereas the variation in precipitation does not follow a common law except for a consistent decrease in winter precipitation.Our study reinforced the fact that under the background of global cooling and intensified monsoon systems,different areas of Yunnan exhibit different climatic responses to these changes because of their topographic heterogeneities.

New and interesting diatoms from the Shimen Wetwalls,Yunnan Province,China.Ⅱ.The diatom genus Nupela Vyverman&Compère(Bacillariophyceae)

We detailed the valve morphology of five new species of diatom genus Nupela from wetwall communities in Yunnan Province,China,with light and scanning electron microscope.The five new species demonstrate great variability within the genus,as three of them are biraphid and two are monoraphid.In addition,variation was noted in the structure of internal proximal raphe ends,with some species having anchor-shaped ends and other species have hooked ends.The genus Nupela has grown considerably in 30years since it was first proposed,going from a monotypic genus to over 85 taxa.Diagnosis of the genus is based on the presence of an external covering over the areolae.We discussed the systematic placement of Nupela within the naviculoid diatoms.Yunnan Province appears to harbor many endemic diatom taxa,and many regions of the province have yet to be studied.

A New Species of the Genus Hebius Thompson,1913(Serpentes:Natricidae)from Yunnan,China

A new keelback snake of the genus Hebius,H.jingdongensis sp.nov.,is reported from Jingdong in Yunnan,China based on a combination of molecular and morphological evidence.Although closest to H.khasiensis and H.boulengeri phylogenetically,this new species is genetically distinct amongst congeners with the mitochondrial Cyt b uncorrected p-distance ranging from 9.5%(vs.H.octolineatus)to 14.8%(vs.H.andreae).In addition,this new species can be distinguished from its congeners by a combination of the following morphological characters:(1)body cylindrical,tail relatively short,TaL/TL 0.235–0.243;(2)dorsal scale rows 19-19-17;(3)ventrals 163–166,cloacal plate divided,subcaudals 71–74 pairs;(4)supralabials 8,the first two contact with the nasals;(5)infralabials 9 or 10,preocular 1,postoculars 3;(6)body dorsum sandy beige with the sides yellowish-brown decorated with two brick-red stripes on the dorsolateral scale rows in life;(7)sutures between the labials brick-red in life and taupe in preservative;(8)ventral light yellow with the outer part of each scale brick-red in life;(9)ventrolateral stripes present.

Inferring Human-elephant Coexistence Based on Characteristics of Human-elephant Interactions in Nangunhe of Yunnan,China

Human-wildlife conflict(HWC)negatively impacts both humans and wildlife.Attitudes of local residents have been critical in promoting wildlife conservation.It is therefore necessary to understand the characteristics of HWC and identify influential factors on attitudes towards conservation to implement conservation strategies efficiently.This research focused on features of human-elephant interactions,while attitudes and values regarding the small population of Asian elephants(Elephas maximus)in Nangunhe National Nature Reserve(NNR),Yunnan,China.The total of 327 valid questionnaires were gathered around the area where Asian elephants were distributed.Logistic regression models were employed to analyze the correlations among five predictor variables(‘Area’,‘Family size’,‘Annual income’,‘Quantity of family members in non-primary industries’and‘Experiencing loss or not’)and three response variables(‘Attitude towards elephants’,‘Perception of the values of elephants’and‘Attitude towards tourism development’).The study area was densely forested with tea plants,rubber trees,corns and sugarcane.There,25.99%of respondents reported the experience of human-elephant conflict(HEC),with crop raiding and cash crop damages being the major conflict types.To demonstrate respect for elephants and to mitigate HEC,a unique custom called‘Giving tribute to elephants’was developed long ago.Respondents’township with an official annual festival of‘Giving Tribute to Elephants’(odds ratio(OR)=2.75,P=1.73×10^(-6))and higher annual income(OR=2.09,P=5.45×10^(-5))significantly contributed to forming a more positive attitude towards elephants,whereas HEC itself have contributed to a more negative attitude(OR=0.50,P=3.29×10^(-3)).Therefore,we propose that:1)reducing human-elephant conflict by testing multiple mitigation measures and adopting the most effective one of them;2)enhancing local livelihoods through the development of ecological products and ecotourism;and 3)preserving and developing the Wa culture in this region.The study area deserves more attention and further research to explore and obtain endorsement from the public to achieve coexistence between human and wildlife.

Geological characterization and exploration potential of shale gas in the Carboniferous Jiusi Formation,northern Guizhou and Yunnan provinces,SW China

Dark mudstones and shales of the Carboniferous Jiusi Formation are widely developed in northern Guizhou and Yunnan provinces, SW China. However, the distribution, reservoir characterization, and exploration potential of organic-rich shales in this area are yet to be quantified, thus limiting the prospect of shale gas in this area. This study investigates the basic geological conditions of Jiusi shale gas, using core data, well-logs, and some other test data, obtaining the following results. The organic-rich shales are mainly composed of deltaic-to-shallow-shelf deposits, with thickness ranging from 0 to 450 m, and above 350 m around the subsidence center. The organic matter is mainly type Ⅱ kerogen with TOC content of mostly 1%–2%, indicating a moderate maturity. The argillaceous shale reservoirs are indicative of strong heterogeneity, high clay minerals content, low porosity, low permeability, high specific surface area, and relatively developed secondary porosity. The gas-log anomaly intervals obtained from the survey wells have a cumulative thickness that is apparently greater than 200 m, and a few shale intervals showing high desorbed and adsorbed gas contents. Due to complex structures in the study area, conditions responsible for shale gas occurrence and trapping are generally moderate. However, areas having wide and gentle folds with moderate depth of burial reveals relatively favorable conditions of hydrocarbon traps. In contrast with typical marine-continental transitional shales, the Jiusi shale have better geological conditions for shale gas preservation. The analysis of the geological framework and hydrocarbon potential of Carboniferous Jiusi Formation provide more insight for the exploration of Carboniferous shale gas in southern China.

DISTINGUISHING OF TWO VOLCANIC ROCK SERIES IN THE LANCANG GROUP, YUNNAN PROVINCE, SW CHINA AND ITS GEOLOGICAL IMPLICATION

The detailed study on petrochemistry and geochemistry shows that meta-volcanics from Huimin and meta-basalts from Suyi belong, respectively, to different volcanic series. The former is of non-alkalic volcanic series and the latter is of straddle A-type alkslic series. Based on their geochemical characteristics of REE, LIL, HFS and Nd, Sr isotope elements, we suggest that Huimin volcanics were formed in an island arc setting and Suyi basalts were formed in a back-continental arc extensive setting. These two volcanic series have not petrogenic relationship.

Tectonic Evolution of the Palaeo——Tethys in Changning——Menglian Belt and Adjacent Regions,Western Yunnan

The Changning-Menglian belt,located between theBaoshan-Gengma massif and the Simao-Lincangmassif in Western Yunnan,preserves the complete recordof a suture zone and the most continuous record of deepwater sedimentation,representing the main branch of thePalaeo-Tethys polyisland ocean in the Hercynian-Indo-sinian stage.This belt could be further subdivided into threetectono-lithofacies zones.In the east zone,terrigenouselastics,argillaceous,marl-argillaceous and silicate sediments lie on the metamorphosed Early Palaeozoic basement in concealed unconformity,representing deep watersediments on a passive continental margin.The centralzone,although the basement rocks are absent fromoutcropping here,includes a contemporary complexof various sedimentary types,among them one type is ofdeep ocean sediments represented by radiolarian beddedchert,appearing from at least early Early Devonian tothe Middle Triassic.Another type includes purecarbonates of the Early Carboniferous to the LatePermian,a type of shallow