A New Vetulicolian from the Early Cambrian Chengjiang Fauna in Yunnan of China

The genus and species Yuyuanozoon magnificissimi gen. et sp. nov., a new fossil vetulicolian, is reported from the Early Cambrian Chengjiang Fauna in Yunnan of China. It has a bipartite body plan and five pairs of chain-formed gill sacs, showing the general characteristics of Ventulicolia. However, the exclusive 'atrial cavity' and external gill observed indicate that the new form is different from those previously described as vetulicolians, probably representing a lineage developed within deuterostomes and more primitive than urochordates.

New Occurrence of the Early Cambrian Chengjiang Fauna in Haikou, Kunming, Yunnan Province,and Study on Trilobitoidea

This paper gives a brief report on the new occurrence of the Early CambrianQiongzhusi' an Chengjiang fauna in the Haikou area, Kunming and its assemblage feature andthe stratigraphic section of the horizon yielding these fossils. Eight genera and 8 species ofTrilobitoidea are described here, embracing Leanchoilia asiatica Luo et Hu (sp. nov.), Yohoiasinensis Luo et Hu (sp. nov.), Zhongxinia speciosa Luo et Hu (gen. et sp. nov.), Xandarellaspectuculum Hou et al., Dianchia mirabilis Luo et Hu (gen. et sp. nov.), Kuamaia lata Hou,Retifacies longispinus Luo et Hu (sp. nov.) and Sinoburius lunaris Hou et al.

Dimorphism of Bivalved Arthropod Branchiocaris？ Yunnanensis from the Early Cambrian Chengjiang Biota, South China

The bivalved arthropod Branchiocaris？ yunnanensis Hou, 1987 is redescribed on the basis of new fossil material from the early Cambrian Chengjiang biota, South China. In total, 81 specimens have been examined. The carapace comprises two identical valves, each valve are sub-circular in outline, ranging from 24 mm to 58 mm in length, and from 15 mm to 46 mm in height. The dorsal margin is straight and bears two short cardinal spines. The valve surface is either smooth or ornamented with polygonal reticular structures, which may result from different preservation conditions. Two morphotypes have been recognized based on the presence or absence of a subdorsal swelling of the valve, which is convex dorsolaterally and extends beyond the dorsal margin when it appears. Statistic and ontogenetic analyses show both morphotypes grow isometrically and have the same growth trajectory. Therefore, the two morphotypes are interpreted as dimorphism within the same species. Our results are helpful for investigating the taxonomy and ontogeny of arthropod fossils and suggest that dimorphism might be fairly common in these early arthropods.

Isotopic dating of the Chengjiang Fauna-bearing horizon in Central Yunnan Province, China

Twenty black shale samples, which are free from the influence of weathering, were collected from the Chengjiang Fauna-bearing horizon, central Yunnan Province, yielding a Pb-Pb isochron age of 534±60 Ma. Although this age is younger than both the Rb-Sr isochron age and 40Ar-39Ar age, it should represent the lower isotopic age limit of the Chengjiang Fauna.

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.

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.”

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.

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.

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.

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.

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.

A New Platy-armored Worm from the Early Cambrian Chengjiang Lagerstatte,South China

The Lower Cambrian Chengjiang Lagerstatte provides a good window to explorethe origin and radiation of early bilaterians. Here we describe a netted sclerite-bearing wormTabelliscolex hexagonus gen. et sp. nov., and tentatively assign it to palaeoscolecidans ofpriapulids. The cuticle of the animal is covered with two kinds of platy sclerites which areconstructed by hexagonally arranged tubercles Similar structures of the sclerites can be seen onsome Cambrian palaeoscolecidans and lobopods, so, this new species is critical for understanding therelationships between lobopods and palaeoscolecidans.

Geochronology and Petrogenesis for the Protolith of Biotite Plagioclase Gneiss at Lianghe,Western Yunnan

In this paper,we report an integrated study of U-Pb age and Hf isotope compositions of zircons from biotite plagioclase gneiss at Lianghe in western Yunnan.The zircons preserved inherited core and rim texture.Igneous zircon grains and rims yielded a weighted mean ^（206）Pb/^（238）U age of 120.4±1.7 Ma,theirε_（Hf）（120 Ma）values were mainly negative ranging from-13.9 to-10.7,with Hf model ages between 1.9 Ga and 2.0 Ga,some zircons had positiveε_（Hf）（120 Ma）values ranging from 0.2 to 2.1.The inherited cores showed the wide variations in the U-Pb age of 375-1315 Ma.One of them showed theε_（Hf）（506 Ma）value of-4.2,it was similar to the gray gneiss of old crust,whichε_（Hf）（500 Ma） values were negative ranging from-4.5 to-3.3.Combining geological feature and geochemical data,we concluded that the protolith of biotite plagioclase gneiss was old crust-derived tonalitic magma during the early Cretaceous.

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

The Changning - Menglian belt , located between the Baoshan - Gengma massif and the Simao - Lincang massif in Western Yunnan , preserves the complete record of a suture zone and the most continuous record of deep water sedimentation , representing the main branch of the Palaeo - Tethys polyisland ocean in the Hercynian - Indo-sinian stage .This belt could be further subdivided into three tectono - lithofacies zones . In the east zone , terrigenous elastics , argillaceous ,marl-argillaceous and silicate sedi-ments lie on the metamorphosed Early Palaeozoic base ment in concealed unconformity , representing deep water sediments on a passive continental margin . The central zone , although the basement rocks are absent from outcropping here , includes a contemporary complex of various sedimentary types , among them one type is of deep ocean sediments represented by radiolarian bedded chert , appearing from at least early Early Devonian to the Middle Triassic . Another type includes pure carbonates of the Early Carboniferous to the Late Permian , a type of shallow water carbonate platform on seamount or oceanic plateau within an ocean basin . In the west zone , the Permo - Carboniferous terrigenous elastics , argillaceous and silicate sediments appear again -representing the passive continental slope sedimentation in the east of the Baoshan - Gengma massif .As the Permo-Carboniferous rock types,sedimentary environments and palaeontological characters of the east and west zones are quite similar , we hold that these two zones were originally formed all on the eastern continental slope of the Baoshan - Gengma massif , and were separated due to eastward thrust later in the Indosinian orogeny . Intense thrust compacting also resulted in tectonic melange in the central zone , which is displayed by shallow water carbonates overlapping on or embedded in deep water volcanics . In the Lancangjiang belt , the Permo - Carboniferous are very complicated in sedimentary types which include island arc volcanics , deep water turbidites, silicolites and shallow water carbonates , representing the active continental margin in the west of the Simao massif. Whether there existed by Early Permi an, a Lincang magma tic arc still awaits further evidence . From the Late Permian,both the Changning-Meng-lian belt and the Lancangjiang belt experienced important sedimentary and volanic events which took place contemporaneously or penecontemporaneously but with different characters . Evidence for the Lincang magmatic arc began to be apparent , and the turbidite deep water basin in the Lancangjiang belt closed . Nevertheless , the Palaeo - Tethys oceanic basin , represented by the Changning - Menglian suture zone , existed until the Mid-dle Triassic . In the Late Triassic . massifs of Baoshan -Gengma ,Simao - Lincang ,collided and aggregated ,resulting in the disappearance of the Palaeo - Tethys ocean .

Devonian to Triassic Successions of the Changning-Menglian Belt,Western Yunnan,China

Phanerozoic strata are distributed in several north-south trending zones in the central part of the Changning-Menglian Belt. Four types of Devonian to Triassic stratigraphic successions can be identified: (1) elastics with limestone lenses in the mid-section, changing up-section into alternations of fine elastics and cherts; (2) elastics with chert intercalations and limestone lenses, and topped by Permian basic volcanics; (3) elastics-basic volcanics-carbonates-clastics; and (4) limestones, dolomitic limestones-dark gray thin-bedded limestones, argillaceous limestones, mudstones and siliceous mudstones. Devonian to Triassic cherts occur in different horizons and different zones from east to west. These cherts are usually transitional to their neighboring elastics. There is no continuous Devonian to Middle Triassic chert sequence in the central zone of the Changning-Menglian Belt as Liu et al. (1991,1993) reported. Volcanics and the overlying carbonates described by some workers as 'seamount' sequences are more likely to have formed in a marine environment on continental crust. Succession (4) is newly recognized in the area from Menglai to Yong'an in Cangyuan County and further north to Padi of Gengma County. Basalts, cherts and elastics also appear in this area. Mid-Triassic (very probably Ladinian) radiolarians extracted from bedded cherts in the Ganzhejidi section indicate that they are in higher stratigraphic positions. The change from bedded cherts via siltstones to thick-bedded sandstones with thin-bedded fine intercalations in the Ganzhejidi section and (some other outcrops along the road from Cangyuan to Gengma) suggests a fundamental change of sedimentary environment caused by a rapid increase of a large quantity of detritus supply. These siliciclastic sediments are possibly syn-orogenic deposits.

Lead Isotopic Composition and Lead Source in the Bainiuchang Ag-polymetallic Deposit, Yunnan Province, China

The Bainiuchang deposit in Yunnan Province, China, is located geographically between the Gejiu ore field and the Dulong ore field. In addition to the 〉7000 t Ag reserves, the deposit also boasts of large-scale Pb, Zn and Sn reserves with a lot of dispersed elements （In, Cd, Ge, Ga, etc.）. We have determined systematically the Pb isotope composition of the deposit. The Pb isotope ratios of the ores that are of sea-floor exhalative sedimentary origin in the northwest of the mining district, are 206pb/204pb = 17.758-18.537, 207pb/204pb = 15.175-15.862 and 206pb/204pb = 37.289-39.424, while those of ores that are of magmatic hydrothermal superimposition origin in the southeast of the mining district, are 206pb/204pb = 17.264-18.359, 207pb/204pb = 14.843-15.683 and 208pb/204pb = 36.481-38.838, respectively. In terms of the Pb isotope composition of feldspar in magmatic rocks or magmatic whole- rock samples from the mining district, we have determined the Pb isotope composition and acquired the Pb isotope ratios as： 206pb/204pb -- 18.224-18.700, 207pb/204pb -- 15.595-15.797 and 208pb/204pb -- 38.193-39.608. Then, in the light of the Pb isotope composition of metamorphic rock samples from the Proterozoic basement exposed in the Dulong ore field, we have determined the Pb isotope composition and obtained the isotope ratios as： 206pb/204pb -- 18.434-19.119, 207pb/204pb -- 15.644-15.693, and 208pb/204pb = 38.514-38.832. And the Pb isotope ratios of Cambrian sedimentary rocks, which are exposed in the Bainiuchang mining district, are 206pb/204pb = 18.307-19.206, 207pb/204pb = 15.622-15.809, and 208pb/204pb = 38.436-39.932. By comparing the two types of ores with respect to their Pb isotope compositions, it is indicated that lead in the Bainiuchang deposit was derived largely from the lower-crust granulite which is earlier than Neoproterozoic in age, but the Yanshanian magmatic hydrothermal fluids probably provided a part of ore-forming elements such as Sn for the ore blocks in the south of the mining district.

First Discovery and Zircon U-Pb Dating of Early Ordovician Granitoids in Lincang Batholith, Western Yunnan： Implications for the Presence of Proto-Tethyan Orogeny in the Sanjiang Region, SW China

Objective The Lincang granitic batholith, extending over 370 km from north to south with an area of more than 10000 km2, is the major part of the Sanjiang region in western Yunnan, SW China, and is one key area to study the evolution of the Tethys. Previous studies all agreed that the Lincang batholith was formed in the Triassic, and widely considered its formation to be the result of Paleo- Tethyan orogeny （Dong et al., 2013）. However, the early Ordovician syenogranite has been discovered recently for the first tirne in the Lincang batholith, and its petrologic and geochronological results are presented here to provide evidence in support of its association with Proto-Tethyan orogeny. This new discovery has important significance lbr understanding the geodynamic history of the Lincang batholith and tectonic evolution of the Sanjiang region.

Researches on Plants from the Lower Devonian Xujiachong Formation in the Qujing District, Eastern Yunnan

Fossil plants Hedeia sinica Hao et Gensel 1998, Huia gracilis Wang Ct Hao2001 and Guangnania cuneata Wang et Hao are described from the Lower Devonian Xujiachong Formation,the Qujing district, eastern Yunnan, China. They contribute to our knowledge of the flora in thisdistrict. Based on the occurrence of common plants (Hedeia, Huia, Guangnania and Zosterophyllumaustralianum) and their horizons, it is proved for the first time that the mid-lower assemblage ofthe Xujiachong flora is comparable with the Early Devonian ((late) Pragian) Posongchong flora ofsoutheastern Yunnan and the upper Baragwanathia flora of Australia. In view of this fact and thestratigraphic sequence, the mid-lower part of the Xujiachong Formation is considered to be of (late)Pragian age. Through comprehensive analyses of plant, bivalve and fish assemblages and thelithology, the upper part of the Xujiachong Formation is dated to he of early Emsian age. TheXujiachong flora belonged to the northeastern Gondwana palaeophytogeographic unit during the EarlyDevonian. The early Emsian assemblage of this flora inherited the characters of the Posongchongflora and also exhibited the endemic elements. Belonging to different phytogeographic units, theXujiachong and Posongchong floras differ from the coeval flora of the Laurussian palaeocontinent.The Xujiachong flora is comparatively simple in composition, while the Posongchong flora hasabundant and highly diversified endemics. The disparity between them has resulted from the differentenvironments.

Regional Metallogenesis of the Chang'an Gold Ore Deposit in Western Yunnan:Evidences from Fluid Inclusions and Stable Isotopes

The Chang＇an gold ore deposit in western Yunnan is located at the southern segment of the Ailaoshan metallogenic belt.The ore bodies are preserved in fractured Ordovician sedimentary clastic rocks.The gold-bearing minerals occur dominantly in sulfide-quartz veins.Fluid inclusion analysis shows that the Chang＇an gold ore deposit is characterized by epithermal gold mineralization at temperatures between 200℃and 280℃at a shallow crustal level.The mineralizing fluids have intermediate to low salinity（6%-18%） and low densities（0.72-1.27 g/cm^3）.The ore minerals haveδ^（34）S in a range from -13‰to 3.57‰,concentrated from -2.06‰to 3.57‰with an average of 1.55‰.The ^（206）Pb/^（204）Pb,^（207）Pb/^（204）Pb and ^（208）Pb/^（204）Pb values are 18.9977-19.5748,15.7093-15.784,39.3814-40.2004 respectively.These isotope data suggest that the ore-forming elements were mainly derived from mixed crustal and mantle sources.The Chang＇an gold ore deposit and Tongchang Cu-Mo deposit are closely related to each other in their spatial distribution and age of formation.They have similar sources of mineralizing elements and identical ore-forming metal elements,and show a close relationship in physical and chemical conditions of mineralization.The two deposits constitute an epithermal-porphyry -skarn type Cu-Mo-Au mineralization system in the Tongchang-Chang＇an area,which is related to the Cenozoic high-K alkaline magmatism.

Seismic Evidence for Plume and Subducting Slab in West Yunnan,Southwestern China

Western Yunnan is located within a gigantic Tethys orogenic zone between Gondwana and Laurasia.Magmatic activity records of the associated Wilson orogenic cycle show that the causes of plate spreading in the region might have been related to sub-mantle plume.Tectonics,geophysics, sedimentary strata,tectonic evolution of the lithosphere and other research results indicate that there is geological evidence for mantle plume magmatic activities in West Yunnan.Tomography also supports the idea that there is a subducting slab near the Red River fault and an upwelling mantle plume in West Yunnan.Here our research presents seismic evidence for upwelling mantle plume,which is a main cause leading to subducting slab in West Yunnan.The analysis is based on compressional-to-shear（P-to -S）converted seismic phases,recorded on seismograph stations in the Sichuan-Yunnan seismic network,and made a study on 410-km and 660-km discontinuities,as well as on three sections of CCP stacking.