The Tengchong geothermal area,an active tectonic region with frequent earthquakes,is located in Yunnan Province of southwestern China.This area contains abundant active hot springs, which often display high metal conc...The Tengchong geothermal area,an active tectonic region with frequent earthquakes,is located in Yunnan Province of southwestern China.This area contains abundant active hot springs, which often display high metal concentrations and obvious mineralization phenomena.At 19：19 on 9 July 2009,an earthquake occurred in Yao＇an,Chuxiong,Yunnan Province,which is 300 km to the northeast of the Tengchong geothermal area.We sampled water in the hot springs in the Tengchong area from 4 July to 9 July 2009 and from 10 July to 15 July 2009 to study the changes of elemental concentrations before and after the earthquake and discuss the influence of the earthquake on the mineralization of the hot springs.The concentrations of most trace elements increased slightly,but the concentration of REE（rare earth elements） decreased by 50%after the earthquake in the hot springs around a NS-trending fault.The elemental concentrations remained unchanged in Longtan and Suanshuigou,which are related to an inactive crater.The elemental concentrations in other springs controlled by superficial and small-scale faults decreased after the earthquake.The earthquake can stimulate the activity of deep faults and magma chambers,as is responsible for the increase of metal concentrations in the hot springs along the NS-trending deep fault;whereas it can decrease the porosity of permeable rocks,resulting in the decline of the flux of ore-bearing fluids and the corresponding mineralization in the hot springs related to superficial faults.展开更多
Carbon and noble gas isotope analyses are reported for bubbling gas samples from the Tengchong volcanic geothermal area near the Indo-Eurasian suture zone. All samples contain a resolvable component of mantle-derived ...Carbon and noble gas isotope analyses are reported for bubbling gas samples from the Tengchong volcanic geothermal area near the Indo-Eurasian suture zone. All samples contain a resolvable component of mantle-derived 3He. Occurrence of mantle-derived 3He coincides with surface volcanism. However, 3He occurs over a larger geographic areathan do surface volcanics. δ13C values for CO2 and CH4 vary from -33.4‰ to 1.6 ‰ and from -52.8‰ to -2.8‰, respectively. He and C isotope systematics indicate that CO2 and CH4 in the CO2-rich gases originated predominantly from magmatic component mixed with crustal CO2 produced from carbonate. However, breakdown of organic matter and near-surface processes accounts for the CH4 and CO2 in N2-rich gases. 3He/4He ratio distribution pattern suggests that mantle-derived He and heat sources of high-temperature system in central Tengchong originate from a hidden magma reservoir at subsurface. CO2-rich gases with the highest 3He/4He ratio (5.2 Ra) may be representative of the Tengchong magmatic component. Compared with MORB, this relative low 3He/4He ratio could be fully attributed to either deep crustal contamination, or radioactive aging, or past contamination of the local mantle by U- and Th-rich subducted crustal material. However, a combination of low 3He/4He, high radiogenic 4He/40Ar ratio and identical CO2/3He and δ13Cco2 relative to MORB may suggest addition of prior subductedd crsustal material (ca 1 %-2%) to the MORB reservoir around 1.3 Ga ago, which is essentially compatible with the LIL-elements, and Sr-Nd-Pb isotopes of volcanic rocks.展开更多
The Rehai Geothermal Field, located in Tengchong County, in central-western Yunnan Prov- ince, is the largest and most intensively studied geothermal field in China. A wide physicochemical diversity of springs （ambie...The Rehai Geothermal Field, located in Tengchong County, in central-western Yunnan Prov- ince, is the largest and most intensively studied geothermal field in China. A wide physicochemical diversity of springs （ambient to -97 ℃; pH from 〈1.8 to≥9.3） provides a multitude of niches for extremophilic microorganisms. A variety of studies have focused on the cultivation, identification, basic physiology, taxonomy, and biotechnological potential of thermophilic microorganisms from Rehai. Ther- mophilic bacteria isolated from Rehai belong to the phyla Firmicutes and Deinococcus-Thermus. Firmicutes include neutrophilic or alkaliphilic Anoxybacillus, Bacillus, Caldalkalibacillus, Caldanaerobacter, Laceyella, and Geobacillus, as well as thermoacidophilic Alicyclobacillus and Sulfobacillus. Isolates from the Deinococcus-Thermus phylum include several Meiothermus and Thermus species. Many of these bacteria synthesize thermostable polymer-degrading enzymes that may be useful for biotech- nology. The thermoacidophilic archaea Acidianus, Metallosphaera, and Sulfolobus have also been isolated and studied. A few studies have reported the isolation of thermophilic viruses belonging to Siphoviridae （TTSP4 and TTSP10） and Fuselloviridae （STSV1） infecting Thermus spp. and Sulfolobus spp., respectively. More recently, cultivation-independent studies using 16S rRNA gene sequences, shotgun metagenomics, or ＂＇functional gene＂ sequences have revealed a mtlch broader diversity of micro- organisms than represented in culture. Studies of the gene and mRNA encoding 113e large subunit of the ammonia monooxygenase （amoA） of ammonia-oxidizing Archaea （AOA） and the tetraether lipid cre- narchaeol, a potential hiomarker for AOA, suggest a wide diversity, but possibly low abundance, of ther- mophilic AOA in Rehai. Finally, we introduce the Tengchong Partnerships in International Research and Education （P1RE） project, an international collaboration between Chinese and U.S. scientists with the goal of promoting international and interdisciplinary cooperation to gain a more holistic and gh〉bal view of life in te^estrial geothermal springs.展开更多
Gas concentrations and isotopic compositions of He and CO2 were determined on free gas samples from ten hot springs of the Rehai geothermal field, Tengchong, China. The results showed that hot-spring CO2 gas, together...Gas concentrations and isotopic compositions of He and CO2 were determined on free gas samples from ten hot springs of the Rehai geothermal field, Tengchong, China. The results showed that hot-spring CO2 gas, together with He, was derived mainly from the mantle, indicating the accumulation of mantle-derived volatiles beneath the survey area. The δ 13C values of CO2, higher than those of the typical mantle-derived carbon and the isotopic composition of hot-spring-free CO2 in unequilibrium with dissolved CO2, are recognized only in the Rehai geothermal field, suggesting that there seems to be a still-degassing magmatic intrusion at depths, which provides mantle-derived volatiles to the hydrothermal system above. The accumulation of those volatiles has probably played an important role in triggering earthquakes in this region. In addition, the isotopic characteristics of He and C also indicate that the magmatic intrusion seems to have been derived from the MORB source, and could be contaminated by crustal materials during its upwelling through the continental crust.展开更多
Concentration of elements or element groups in a geological body is the result of multiple stages of rockforming and ore-forming geological processes.An ore-forming element group can be identified by PCA(principal com...Concentration of elements or element groups in a geological body is the result of multiple stages of rockforming and ore-forming geological processes.An ore-forming element group can be identified by PCA(principal component analysis)and be separated into two components using BEMD(bi-dimensional empirical mode decomposition):(1)a high background component which represents the ore-forming background developed in rocks through various geological processes favorable for mineralization(i.e.magmatism,sedimentation and/or metamorphism);(2)the anomaly component which reflects the oreforming anomaly that is overprinted on the high background component developed during mineralization.Anomaly components are used to identify ore-finding targets more effectively than ore-forming element groups.Three steps of data analytical procedures are described in this paper;firstly,the application of PCA to establish the ore-forming element group;secondly,using BEMD on the o re-forming element group to identify the anomaly components created by different types of mineralization processes;and finally,identifying ore-finding targets based on the anomaly components.This method is applied to the Tengchong tin-polymetallic belt to delineate ore-finding targets,where four targets for Sn(W)and three targets for Pb-Zn-Ag-Fe polymetallic mineralization are identified and defined as new areas for further prospecting.It is shown that BEMD combined with PCA can be applied not only in extracting the anomaly component for delineating the ore-finding target,but also in extracting the residual component for identifying its high background zone favorable for mineralization from its oreforming element group.展开更多
Tengchong Cenozoic volcanics that have record key information on the tectonic evolution and mantle features of the southeast margin of the Tibetan Plateau are of great importance because of its unique eruption history...Tengchong Cenozoic volcanics that have record key information on the tectonic evolution and mantle features of the southeast margin of the Tibetan Plateau are of great importance because of its unique eruption history spanning the entire Quaternary period. Magma origin and evolution of Tengchong Cenozoic volcanic rocks were studied on the basis of Nd-Sr-Pb isotope and major and trace element data from different eruptions in the Ma＇anshan area. Different samples within one eruption show relative identical lithologies, chemical and isotopic compositions. However, the geochemical features for the five eruptions are distinct from each other. These volcanic rocks show low Mg# values （〈45）, moderate to high fractionation of LREEs and HREEs, and enrichment of Pb and Ba and depletion of Nb. Tengchong Cenozoic volcanic rocks were derived from an enriched mantle based on Nd-Sr-Pb isotopic studies. And lines of evidence show that crustal contamination should be involved before the eruption of different periods of Tengchong Cenozoic volcanic rocks. Older subducted components may be responsible for adakite recycling at various stages of evolution, which results in the origin of the enriched mantle source magma accounting for the isotopic features of Tengchong Cenozoic volcanic rocks. Segregated primitive magma pulsating injected into magma chamber, fractional crystallized and contaminated with crust component. Finally, magmas with distinct chemical and isotopic compositions for each eruption formed. The extension of the northeast segment of the Yingjiang tectonic belt triggered the pulsating eruption of the Cenozoic volcanics in the Tengchong area.展开更多
Whole-rock major and trace element and Sr-Nd isotopic data, together with zircon LA ICP- MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand the...Whole-rock major and trace element and Sr-Nd isotopic data, together with zircon LA ICP- MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their petrogenesis and tectonic implications. Zircon U-Pb data gives the emplacement ages of ca. 115.3±0.9 Ma for syenites and 115.7±0.8 Ma for granites, respectively. The syenites are characterized by low SiO2 content （62.01-63.03 wt%） and notably high Na20 content （7.04- 7.24 wt%） and Na20/K20 ratios （2.02-2.10）, low MgO, Fe2OaT and TiO2, enrichment of LILEs（large-ion lithophile element） such as Rb, Th, U, K, and Pb） and obvious depletion HFSE（high field strength element; e.g. Nb, Ta, P, and Ti） with clearly negative Eu anomalies （dEu=0.53-0.56）. They also display significant negative whole-rock eNd（t） values of-6.8 and zircon eHf（t） values（-9.11 to -0.27, but one is ＋5.30） and high initial S7Sr/86Sr=0.713013. Based on the data obtained in this study, we suggest that the ca. l15.3Ma syenites were possibly derived from a sodium-rich continental crustal source, and the fractionation of some ferro-magnesian mineral and plagioclase might occur during the evolution of magma. The granites have high SiO2 content （71.35-74.47 wt%）, metaluminous to peraluminous, low Rb/Ba, Rb/Sr, and AI2Oa/（MgO＋FeOT＋TiO2） ratios and moderate （AI2Oa＋MgO＋FeOT＋TiO2） content. They show low initial a7Sr/86Sr （0.703408 to 0.704241） and eNd（t） values （-3.8 to -3.5）, plotted into the evolutionary trend between basalts and lower crust. Hence, we suggest that the granites were derived from the melting of mixing sources in the ancient continental crust involving some metabasaltic materials and predominated metasedimentary greywackes. Together with data in the literatures, we infer that the Early Cretaceous magmatism in the Tengchong block was dominated by magmas generated by the partial melting of ancient crustal material, which represent the products that associated to the closure of Bangong-Nujiang Meso-Tethys.展开更多
The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relativ...The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relatively low(^(87)Sr/^(86)Sr)iratios of 0.7090-0.7169 andε_(Nd)(t)values of-9.8 to-7.8 display metaluminous,calc-alkaline dominated by I-type granite affinity and hybrid mantle-crust geochemical signatures.They may have been derived from melting of the subducted Meso-Tethyan BangongNujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting.(b)The Late Cretaceous-Paleocene granitoids with relatively high(^(87)Sr/^(86)Sr)iratios of 0.7109-0.7627,andε_(Nd)(t)values of-12.1 to-7.9 exhibit metaluminous to peraluminous,calc-alkaline dominated by S-type granite affinity and hybrid Lower-Upper crust geochemical signatures,which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block.(c)The Early Eocene granitoids have metaluminous,calc-alkaline I-type and S-type granites dual affinity,with relatively high(^(87)Sr/^(86)Sr)iratios of 0.711-0.736,ε_(Nd)(t)values of-9.4 to-4.7,showing crust-mantle mixing geochemical signatures.They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao-Myitkyian oceanic crust,and collision between the Western Burma Block and the Tengchong Block.It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.展开更多
Based upon the deep seismic sounding profile conducted in the Tengchong volcanic-geothermal area, a two-dimensional crustal P velocity structure is obtained by use of the finite-difference inversion and the forward tr...Based upon the deep seismic sounding profile conducted in the Tengchong volcanic-geothermal area, a two-dimensional crustal P velocity structure is obtained by use of the finite-difference inversion and the forward travel-time fitting method. The crustal model shows that there is a low velocity zone in upper crust in the Tengchong area, which may be related to the volcanic-geothermal activities, and two intracrustal faults (the LonglingRuili fault and Tengchong fault) exist on the profile, where the Tengchong fault may extend to the Moho discontinuity. Meanwhile, based on teleseismic data recorded by a temporary seismic network, we obtained the S-wave velocity structures beneath the RehaiRetian region in the Tengchong area, which show the low S-wave velocity anomaly in upper crust. The authors discuss the causes of Tengchong volcanic eruption based on the deep crustal structure. The crustal structure in the Tengchong volcanic-geothermal area is characterized by low P-wave and S-wave velocity, low resistivity, high heat-flow value and low Q value. The P-wave velocity in the upper mantle is also low. For this information, it can be induced that the magma in the crust is derived from the upper mantle, and the low velocity anomaly in upper crust in the Tengchong area may be related to the differentiation of magma. The Tengchong volcanoes are close to an active plate boundary and belong to plate boundary volcanoes.展开更多
The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites;however, their geological background and petrogenesis have not been well constrained and elucidated. ...The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites;however, their geological background and petrogenesis have not been well constrained and elucidated. In this study, we present new zircon U-Pb dating, along with geochemical and Sr-Nd-Hf isotopic data for granites from the Tengchong–Lianghe granitoid belt(as abbreviated to Tengliang belt) and West Yingjiang batholiths from the Tengchong block. The mineralogical and geochemical features of the Tengliang granites and the West Yingjiang batholiths are ascribed to aluminous S-type granites and weak peraluminous I-type, respectively. Zircon U-Pb analyses yielded consistent ages ranging from 67.5 Ma, 68.4 Ma and 66.2 Ma from the Tengliang granitoid belt and 50.4 Ma to 60.8 Ma for three samples from the west Yingjiang batholiths. The Tengliang granites were emplaced during the Late Cretaceous(68-66 Ma) and demonstrate negative ε_(Hf)(t) values(-24 to-4) and initial ~(87)Sr/~(86)Sr ratios of 0.7101–0.7139 and significant negative ε_(Nd)(t) values from-8.91 to-13.2, indicating a Proterozoic sedimentary source or enriched components. The hornblende-bearing I-type granites from West Yingjiang are characterized by lower initial ~(87)Sr/~(86)Sr ratios of 0.7076–0.7106, compared to Tengliang granite and negative whole-rock ε_(Nd)(t) values from-4.0 to-11.9. The early Eocene west Yingjiang gneissic granites show wide ranges of ε_(Hf)(t) values from +7.4 to-8.5 and T_(2DM) of 1.30–0.65 Ga, indicating partial melting of ancient crust with contributions of depleted mantle materials. In combination with the regional background and previous studies, we propose that such a spatio-temporal distribution of the Tengchong granitoid belt might be related to the rollback or angleswitching of the Neo-Tethyan subducting slab. This study sheds new light on the evolutionary history of the Tengchong block.展开更多
The Early Cretaceous granitoids that are widespread in the Tengchong terrane of Southwest China play a critical role in understanding the tectonic framework associated with the Tethyan oceans. In this study, we presen...The Early Cretaceous granitoids that are widespread in the Tengchong terrane of Southwest China play a critical role in understanding the tectonic framework associated with the Tethyan oceans. In this study, we present a detailed description of zircon U-Pb ages, whole-rock geochemistry and Hf isotopes for the Laoxiangkeng pluton in the eastern Tengchong terrane and elucidate their petrogenesis and geodynamic implications. Zircon U-Pb dating of the Laoxiangkeng pluton yields ages of 114 ± 1 Ma and 115 ± 1 Ma,which imply an Early Cretaceous magmatic event. The Laoxiangkeng pluton enriched in Si and Na, is calcalkaline and metaluminous, and has the characteristics of highly fractionated I-type granites. Zircons from the pluton have calculated ε_(Hf)(t) values of-12.7 to-3.7 and two-stage model ages of 1327-1974 Ma,respectively, indicating a mixed source of partial melting of Paleo-Neoproterozoic crust-derived compositions with some inputs of mantle-derived magmas. By integrating all available data for the regional tectonic evolution of the eastern Tethys tectonic domain, we conclude that the Early Cretaceous magmatism in the Tengchong terrane was produced by the northeastward subduction of the Meso-Tethyan Bangong-Nujiang Ocean.展开更多
We calculated the crustal stress field using the composite focal mechanism method based on the P-wave initial motion polarity data of the Tengchong volcanic area from January 2011 to April 2019 obtained from the Bulle...We calculated the crustal stress field using the composite focal mechanism method based on the P-wave initial motion polarity data of the Tengchong volcanic area from January 2011 to April 2019 obtained from the Bulletin of Seismological Observations of Chinese stations.The magnitude range of earthquakes used in this study is 0–4,and their magnitudes are mainly approximately 1.0.To investigate the infl uence of the source location on the stress fi eld and obtain reliable stress fi elds of the study area,we applied the double-diff erence algorithm to relocate the seismic events,obtaining more accurate and reliable relative positions of seismic events with a clearer seismic belt.On the basis of relocation results,the study on the stress fi eld along the fault zone was conducted,and the infl uence of seismic event position on the stress fi eld was analyzed.Results show that,fi rst,the current stress regime in the shallow crust of the Tengchong volcanic area is strike-slip faulting,the orientation of the principal compressive stress axis is NE–SW,the orientation of the principal extension stress axis is SE–NW,the principal compressive and extension stress axes are nearly horizontal,and the dip angle of intermediate principal stress axis is relatively large.This reflects that the volcanic and seismic activities in the Tengchong volcanic area are mainly controlled by the collision and squeezing eff ect of the Indian–Eurasian plate.It also refl ects that the current tensile action caused by deep magma activity has little infl uence on the shallow crustal stress field.Second,the stress field along fault zones reveals that there exist local stress fi elds,such as the thrust stress regime at the strike-slip fault terminal area,which is consistent with the compressional area at the intersection of conjugate strike-slip faults indicated by previous study.Third,the stress fi eld results are consistent,regardless of using the original location in the bulletin or the relocated location,indicating that the infl uence of the event location error can be neglected when there are suffi cient data and refl ecting the stability of the composite focal mechanism method.The findings can serve as a reference for investigating geological structure movement,seismic activities,and volcanic activities in the Tengchong volcanic area.展开更多
Based on data collected by deep seismic sounding carried out in 1999, a three-dimensional P wave velocity structure is determined with tomographic inversion. The tomographic result shows that there is a P wave low vel...Based on data collected by deep seismic sounding carried out in 1999, a three-dimensional P wave velocity structure is determined with tomographic inversion. The tomographic result shows that there is a P wave low velocity zone (LVZ) in the upper crust beneath the Tengchong volcanic area. The LVZ is in the depth of 7~8 km and may be a smgma chamber or a partial melting body. The result also shows that the LVZ is in the northeastern side of the Rehai hydrothermal field, which is located in another LVZ near the surface. The shallow LVZ may represent a well-developed fracture zone. The strong hydrothermal activity in Rehai area can attribute to the existence of fractures between two LVZs. These fractures are the channels for going upwards of the deep hot fluid.展开更多
Tengchong volcanic area is located near the impinging and underthrust margin of India and Eurasia plates. The volcanic activity is closely related to the tectonic environment. The deep structure characteristics are in...Tengchong volcanic area is located near the impinging and underthrust margin of India and Eurasia plates. The volcanic activity is closely related to the tectonic environment. The deep structure characteristics are inferred from the receiver function inversion with the teleseismic records in the paper. The results show that the low velocity zone is influenced by the NE-trending Dayingjiang fault. The S-wave low velocity structure occurs obviously in the southern part of the fault, but unobviously in its northern part. There are low velocity zones in the shallow po-sition, which coincides with the seismicity. It also demonstrates that the low velocity zone is directly related to the thermal activity in the volcanic area. Therefore, we consider that the volcano may be alive again.展开更多
We present the first description of the acoustic characters of the endangered Tengchong leaf litter toad(Leptobrachella tengchongensis), aiming to inform future ecological studies of the species and taxonomic studies ...We present the first description of the acoustic characters of the endangered Tengchong leaf litter toad(Leptobrachella tengchongensis), aiming to inform future ecological studies of the species and taxonomic studies in the genus Leptobrachella. A total of 1179 calls, belonging to 6 adults male individuals, were recorded using TASCAM DR-40 digital sound recorder from its type locality in May 2015 and then analyzed using Raven Pro v.1.6.1 software. The advertisement call of male L. tengchongensis consists of primary advertisement call and secondary advertisement call. The primary advertisement call is invariably composed of two notes and has a call duration of 61 ± 5 ms(23–87 ms, n = 1142). The secondary advertisement call is composed of 3–10 notes(mean 5.25 ± 1.41 notes/call, n = 37) with a call duration of 90 ± 6 ms(37–127 ms, n = 37). The mean inter-call interval is 212 ± 121 ms(88–1121 ms, n = 1092). An introductory note is absent in advertisement calls and the dominant of calls is 4.1–4.8 kHz(at 20 ℃). We discuss the interspecific and intraspecific variations on advertisement calls in L. tengchongensis and among Leptobrachella species, and provide a summary on the major acoustic characters of all Leptobrachella species occurring north of the Isthmus of Kra.展开更多
This paper discusses the late Yanshanian-Himalayan igneous rock series and minerogenetic series (Cheng et al., 1979, 1982) related to tin polymetallic deposits in the Tengchong area. The multi-stage differentiation an...This paper discusses the late Yanshanian-Himalayan igneous rock series and minerogenetic series (Cheng et al., 1979, 1982) related to tin polymetallic deposits in the Tengchong area. The multi-stage differentiation and evolution of the igneous rock series led to the concentration of metal and ore-forming elements in a cupola of a granite body formed in the late stage. The minerogenetic series shows a zoning of Nb-Ta-W-Sn, Sn-Fe and Sn around the cupola in space and a multi-stage regularity in time. Finally a minerogenetic model and three key factors of tin minerogenesis are put forward for tin polymetallic deposits in the area.展开更多
The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to eval...The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to evaluate the reservoir temperature. The most likely temperature of the reservoir as representedby T_(Na-K-Ca) is about 230℃. The chemical and isotopic compositions of fluids before boiling within the reser-voir are estimated. The mixing and dilution of cold and warm waters are discussed. The Rehai geothermal fieldis a high-temperature (hot) water system with the subsurface boiling zone close to the surface. The reservoirpressure at different depths is calculated. And finally the water-rock equilibration is inferred.展开更多
A comprehensive study of zircon U-Pb geochronology,in situ Hf isotopes,whole-rock major and trace element geochemistry,and Nd isotopes was carried out for two Early Jurassic two-mica granites(Longtang and Menglong)in ...A comprehensive study of zircon U-Pb geochronology,in situ Hf isotopes,whole-rock major and trace element geochemistry,and Nd isotopes was carried out for two Early Jurassic two-mica granites(Longtang and Menglong)in the southern part of the Tengchong terrane,which is in the northern part of the larger Sibumasu terrane.We assess the origin of the granites and explore their possible genetic relationship to the Paleo-Tethyan regime.LA-ICP-MS zircon U-Pb dating shows that they were simultaneously emplaced in the Early Jurassic(ca.199 Ma).They have SiO2 contents of 69.7–75.1 wt%and are mainly strongly peraluminous with alumina saturation index(ASI)values ranging from 1.06 to 1.46.They show similar Mg#(0.29–0.42)to experimental partial melts of metasedimentary rocks under continental pressuretemperature(P-T)conditions.They are enriched in light rare earth elements(LREEs)relative to heavy rare earth elements(HREEs),with moderately negative Eu anomalies and flat HREEs patterns.They show negativeεNd(t)values(−9.0 to–12.4)andεHf(t)values(−8.0 to−9.1).Elemental and isotopic data suggest that they most likely to formed by muscovitedehydration melting of a metapelitic source at lower temperatures in the range of 700℃to 750℃.The granites might represent a post-collisional tectonic setting response to Paleo-Tethyan regime.展开更多
Due to its special observation principle, GPS remote sensing atmospheric precipitation has the advantages of high time resolution and no weather conditions, and has been widely used in the research field of atmospheri...Due to its special observation principle, GPS remote sensing atmospheric precipitation has the advantages of high time resolution and no weather conditions, and has been widely used in the research field of atmospheric precipitation. Using ground-based GPS precipitate water vapor data (GPS-PWV) and radiosonde-precipitate water vapor data (RS-PWV) that integrated by Radiosonde data, the error between GPS-PWV and RS-PWV in Tengchong is analyzed on its distribution of wet and dry seasons, also the difference between 00:00 UTC and 12:00 UTC. Results show that the RMSE of GPS-PWV and RS-PWV on both 00:00 UTC and 12:00 UTC are less than 5 mm, they correspond with each other well and their correlation coefficient is above 0.95, additionally, GPS-PWV value is stable than RS-PWV value. On the whole, the value of GPS-PWV is slightly larger than RS-PWV. And the mean absolute error between them has higher values, 4.5 mm in 2011 and 4.7 mm in 2012 from May to October (local rainy season) and lower values, 2.8 mm in 2011 and 3.1 mm in 2012 in November to April (local dry season). Besides, the mean absolute error in the morning seems has a difference with its component in the evening. Specifically, it is bigger on 12:00 UTC than on 00:00 UTC and the mean absolute errors on 12:00 UTC of two years are 27% and 11% larger than errors on 00:00 UTC respectively. The correlation of mean absolute error and surface vapor pressure, surface air temperature is examined in this study as well. We achieved that the correlation coefficient between mean absolute error and surface vapor pressure, surface air temperature equals 0.32, 0.37 separately. Diverse characters of mean absolute error under different precipitation conditions are also discussed. The outcome is that the mean absolute error has a higher value on rainy days and a lower value on clear days. However, during the precipitation periods, it appears that the mean absolute error and the rainfall situation don’t agree with each other well, it is likely to change randomly.展开更多
Objective The Tengchong volcanic field is located at the eastern edge of the convergence zone between India and Eurasia.New tomographic results show that the subducting Indian Plate is imaged clearly as high-V anomali...Objective The Tengchong volcanic field is located at the eastern edge of the convergence zone between India and Eurasia.New tomographic results show that the subducting Indian Plate is imaged clearly as high-V anomalies beneath Burma and dips eastward with a high angle in the uppermantle, and then it flattens in the mantle transition zone.展开更多
基金supported by the Major State Basic Research Development Program of the People's Republic of China(973 project)(No.2009CB421008)the 111 Project(No.B07011)+2 种基金the National Natural Science Foundation of China(No.40234051)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0755)the Special Plans of Science and Technology of Land Resource Department(No. 20010103)
文摘The Tengchong geothermal area,an active tectonic region with frequent earthquakes,is located in Yunnan Province of southwestern China.This area contains abundant active hot springs, which often display high metal concentrations and obvious mineralization phenomena.At 19：19 on 9 July 2009,an earthquake occurred in Yao＇an,Chuxiong,Yunnan Province,which is 300 km to the northeast of the Tengchong geothermal area.We sampled water in the hot springs in the Tengchong area from 4 July to 9 July 2009 and from 10 July to 15 July 2009 to study the changes of elemental concentrations before and after the earthquake and discuss the influence of the earthquake on the mineralization of the hot springs.The concentrations of most trace elements increased slightly,but the concentration of REE（rare earth elements） decreased by 50%after the earthquake in the hot springs around a NS-trending fault.The elemental concentrations remained unchanged in Longtan and Suanshuigou,which are related to an inactive crater.The elemental concentrations in other springs controlled by superficial and small-scale faults decreased after the earthquake.The earthquake can stimulate the activity of deep faults and magma chambers,as is responsible for the increase of metal concentrations in the hot springs along the NS-trending deep fault;whereas it can decrease the porosity of permeable rocks,resulting in the decline of the flux of ore-bearing fluids and the corresponding mineralization in the hot springs related to superficial faults.
文摘Carbon and noble gas isotope analyses are reported for bubbling gas samples from the Tengchong volcanic geothermal area near the Indo-Eurasian suture zone. All samples contain a resolvable component of mantle-derived 3He. Occurrence of mantle-derived 3He coincides with surface volcanism. However, 3He occurs over a larger geographic areathan do surface volcanics. δ13C values for CO2 and CH4 vary from -33.4‰ to 1.6 ‰ and from -52.8‰ to -2.8‰, respectively. He and C isotope systematics indicate that CO2 and CH4 in the CO2-rich gases originated predominantly from magmatic component mixed with crustal CO2 produced from carbonate. However, breakdown of organic matter and near-surface processes accounts for the CH4 and CO2 in N2-rich gases. 3He/4He ratio distribution pattern suggests that mantle-derived He and heat sources of high-temperature system in central Tengchong originate from a hidden magma reservoir at subsurface. CO2-rich gases with the highest 3He/4He ratio (5.2 Ra) may be representative of the Tengchong magmatic component. Compared with MORB, this relative low 3He/4He ratio could be fully attributed to either deep crustal contamination, or radioactive aging, or past contamination of the local mantle by U- and Th-rich subducted crustal material. However, a combination of low 3He/4He, high radiogenic 4He/40Ar ratio and identical CO2/3He and δ13Cco2 relative to MORB may suggest addition of prior subductedd crsustal material (ca 1 %-2%) to the MORB reservoir around 1.3 Ga ago, which is essentially compatible with the LIL-elements, and Sr-Nd-Pb isotopes of volcanic rocks.
基金supported generously by the U.S.National Science Foundation(Grant Nos.MCB-0546865 and OISE- 0968421 & OISE-0836450)National Natural Science Foundation of China(Grant No.31070007)
文摘The Rehai Geothermal Field, located in Tengchong County, in central-western Yunnan Prov- ince, is the largest and most intensively studied geothermal field in China. A wide physicochemical diversity of springs （ambient to -97 ℃; pH from 〈1.8 to≥9.3） provides a multitude of niches for extremophilic microorganisms. A variety of studies have focused on the cultivation, identification, basic physiology, taxonomy, and biotechnological potential of thermophilic microorganisms from Rehai. Ther- mophilic bacteria isolated from Rehai belong to the phyla Firmicutes and Deinococcus-Thermus. Firmicutes include neutrophilic or alkaliphilic Anoxybacillus, Bacillus, Caldalkalibacillus, Caldanaerobacter, Laceyella, and Geobacillus, as well as thermoacidophilic Alicyclobacillus and Sulfobacillus. Isolates from the Deinococcus-Thermus phylum include several Meiothermus and Thermus species. Many of these bacteria synthesize thermostable polymer-degrading enzymes that may be useful for biotech- nology. The thermoacidophilic archaea Acidianus, Metallosphaera, and Sulfolobus have also been isolated and studied. A few studies have reported the isolation of thermophilic viruses belonging to Siphoviridae （TTSP4 and TTSP10） and Fuselloviridae （STSV1） infecting Thermus spp. and Sulfolobus spp., respectively. More recently, cultivation-independent studies using 16S rRNA gene sequences, shotgun metagenomics, or ＂＇functional gene＂ sequences have revealed a mtlch broader diversity of micro- organisms than represented in culture. Studies of the gene and mRNA encoding 113e large subunit of the ammonia monooxygenase （amoA） of ammonia-oxidizing Archaea （AOA） and the tetraether lipid cre- narchaeol, a potential hiomarker for AOA, suggest a wide diversity, but possibly low abundance, of ther- mophilic AOA in Rehai. Finally, we introduce the Tengchong Partnerships in International Research and Education （P1RE） project, an international collaboration between Chinese and U.S. scientists with the goal of promoting international and interdisciplinary cooperation to gain a more holistic and gh〉bal view of life in te^estrial geothermal springs.
基金jointly by the National Natural Science Foundation of China(Grant Nos.40173006 and 49133009)the Key Project of the Ministry of Education(No.03106)
文摘Gas concentrations and isotopic compositions of He and CO2 were determined on free gas samples from ten hot springs of the Rehai geothermal field, Tengchong, China. The results showed that hot-spring CO2 gas, together with He, was derived mainly from the mantle, indicating the accumulation of mantle-derived volatiles beneath the survey area. The δ 13C values of CO2, higher than those of the typical mantle-derived carbon and the isotopic composition of hot-spring-free CO2 in unequilibrium with dissolved CO2, are recognized only in the Rehai geothermal field, suggesting that there seems to be a still-degassing magmatic intrusion at depths, which provides mantle-derived volatiles to the hydrothermal system above. The accumulation of those volatiles has probably played an important role in triggering earthquakes in this region. In addition, the isotopic characteristics of He and C also indicate that the magmatic intrusion seems to have been derived from the MORB source, and could be contaminated by crustal materials during its upwelling through the continental crust.
基金funded by the Na-tional Natural Science Foundation of China(Grant Nos.41672329,41272365)the National Key Research and Development Project of China(Grant No.2016YFC0600509)the Project of China Geological Survey(Grant No.1212011120341)
文摘Concentration of elements or element groups in a geological body is the result of multiple stages of rockforming and ore-forming geological processes.An ore-forming element group can be identified by PCA(principal component analysis)and be separated into two components using BEMD(bi-dimensional empirical mode decomposition):(1)a high background component which represents the ore-forming background developed in rocks through various geological processes favorable for mineralization(i.e.magmatism,sedimentation and/or metamorphism);(2)the anomaly component which reflects the oreforming anomaly that is overprinted on the high background component developed during mineralization.Anomaly components are used to identify ore-finding targets more effectively than ore-forming element groups.Three steps of data analytical procedures are described in this paper;firstly,the application of PCA to establish the ore-forming element group;secondly,using BEMD on the o re-forming element group to identify the anomaly components created by different types of mineralization processes;and finally,identifying ore-finding targets based on the anomaly components.This method is applied to the Tengchong tin-polymetallic belt to delineate ore-finding targets,where four targets for Sn(W)and three targets for Pb-Zn-Ag-Fe polymetallic mineralization are identified and defined as new areas for further prospecting.It is shown that BEMD combined with PCA can be applied not only in extracting the anomaly component for delineating the ore-finding target,but also in extracting the residual component for identifying its high background zone favorable for mineralization from its oreforming element group.
基金supported by the Chinese Ministry of Science and Technology(Sinoprobe-05-03)Doctoral Fund of Ministry of Education of China(20110022120003)+1 种基金the Fundamental Research Funds for the Central UniversitiesOpen Fund of State Key Laboratory of Geological Processes and Mineral Resources(GPMR2011)
文摘Tengchong Cenozoic volcanics that have record key information on the tectonic evolution and mantle features of the southeast margin of the Tibetan Plateau are of great importance because of its unique eruption history spanning the entire Quaternary period. Magma origin and evolution of Tengchong Cenozoic volcanic rocks were studied on the basis of Nd-Sr-Pb isotope and major and trace element data from different eruptions in the Ma＇anshan area. Different samples within one eruption show relative identical lithologies, chemical and isotopic compositions. However, the geochemical features for the five eruptions are distinct from each other. These volcanic rocks show low Mg# values （〈45）, moderate to high fractionation of LREEs and HREEs, and enrichment of Pb and Ba and depletion of Nb. Tengchong Cenozoic volcanic rocks were derived from an enriched mantle based on Nd-Sr-Pb isotopic studies. And lines of evidence show that crustal contamination should be involved before the eruption of different periods of Tengchong Cenozoic volcanic rocks. Older subducted components may be responsible for adakite recycling at various stages of evolution, which results in the origin of the enriched mantle source magma accounting for the isotopic features of Tengchong Cenozoic volcanic rocks. Segregated primitive magma pulsating injected into magma chamber, fractional crystallized and contaminated with crust component. Finally, magmas with distinct chemical and isotopic compositions for each eruption formed. The extension of the northeast segment of the Yingjiang tectonic belt triggered the pulsating eruption of the Cenozoic volcanics in the Tengchong area.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41421002, 41190072, 41372067 and 41102037)the program for Changjiang Scholars and Innovative Research Team in University (Grant IRT1281)+2 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of PR China (201324)the MOST Special Fund from the State Key Laboratory of Continental Dynamics, Northwest UniversityProvince Key Laboratory Construction Item (08JZ62)
文摘Whole-rock major and trace element and Sr-Nd isotopic data, together with zircon LA ICP- MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their petrogenesis and tectonic implications. Zircon U-Pb data gives the emplacement ages of ca. 115.3±0.9 Ma for syenites and 115.7±0.8 Ma for granites, respectively. The syenites are characterized by low SiO2 content （62.01-63.03 wt%） and notably high Na20 content （7.04- 7.24 wt%） and Na20/K20 ratios （2.02-2.10）, low MgO, Fe2OaT and TiO2, enrichment of LILEs（large-ion lithophile element） such as Rb, Th, U, K, and Pb） and obvious depletion HFSE（high field strength element; e.g. Nb, Ta, P, and Ti） with clearly negative Eu anomalies （dEu=0.53-0.56）. They also display significant negative whole-rock eNd（t） values of-6.8 and zircon eHf（t） values（-9.11 to -0.27, but one is ＋5.30） and high initial S7Sr/86Sr=0.713013. Based on the data obtained in this study, we suggest that the ca. l15.3Ma syenites were possibly derived from a sodium-rich continental crustal source, and the fractionation of some ferro-magnesian mineral and plagioclase might occur during the evolution of magma. The granites have high SiO2 content （71.35-74.47 wt%）, metaluminous to peraluminous, low Rb/Ba, Rb/Sr, and AI2Oa/（MgO＋FeOT＋TiO2） ratios and moderate （AI2Oa＋MgO＋FeOT＋TiO2） content. They show low initial a7Sr/86Sr （0.703408 to 0.704241） and eNd（t） values （-3.8 to -3.5）, plotted into the evolutionary trend between basalts and lower crust. Hence, we suggest that the granites were derived from the melting of mixing sources in the ancient continental crust involving some metabasaltic materials and predominated metasedimentary greywackes. Together with data in the literatures, we infer that the Early Cretaceous magmatism in the Tengchong block was dominated by magmas generated by the partial melting of ancient crustal material, which represent the products that associated to the closure of Bangong-Nujiang Meso-Tethys.
基金funded by the National Natural Science Foundation of China(Grant Nos.41972312,41672329,41272365)the National Key Research and Development Project of China(Grant No.2016YFC0600509)。
文摘The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relatively low(^(87)Sr/^(86)Sr)iratios of 0.7090-0.7169 andε_(Nd)(t)values of-9.8 to-7.8 display metaluminous,calc-alkaline dominated by I-type granite affinity and hybrid mantle-crust geochemical signatures.They may have been derived from melting of the subducted Meso-Tethyan BangongNujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting.(b)The Late Cretaceous-Paleocene granitoids with relatively high(^(87)Sr/^(86)Sr)iratios of 0.7109-0.7627,andε_(Nd)(t)values of-12.1 to-7.9 exhibit metaluminous to peraluminous,calc-alkaline dominated by S-type granite affinity and hybrid Lower-Upper crust geochemical signatures,which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block.(c)The Early Eocene granitoids have metaluminous,calc-alkaline I-type and S-type granites dual affinity,with relatively high(^(87)Sr/^(86)Sr)iratios of 0.711-0.736,ε_(Nd)(t)values of-9.4 to-4.7,showing crust-mantle mixing geochemical signatures.They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao-Myitkyian oceanic crust,and collision between the Western Burma Block and the Tengchong Block.It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.
基金The Climb Program (95-S-05-01) of National Scientific and Technological Ministry of China, the Key Project (95-11-02) from China Seismological Bureau, the State Natural Sciences Foundation of China (49974020) and the Joint Earthquake S
文摘Based upon the deep seismic sounding profile conducted in the Tengchong volcanic-geothermal area, a two-dimensional crustal P velocity structure is obtained by use of the finite-difference inversion and the forward travel-time fitting method. The crustal model shows that there is a low velocity zone in upper crust in the Tengchong area, which may be related to the volcanic-geothermal activities, and two intracrustal faults (the LonglingRuili fault and Tengchong fault) exist on the profile, where the Tengchong fault may extend to the Moho discontinuity. Meanwhile, based on teleseismic data recorded by a temporary seismic network, we obtained the S-wave velocity structures beneath the RehaiRetian region in the Tengchong area, which show the low S-wave velocity anomaly in upper crust. The authors discuss the causes of Tengchong volcanic eruption based on the deep crustal structure. The crustal structure in the Tengchong volcanic-geothermal area is characterized by low P-wave and S-wave velocity, low resistivity, high heat-flow value and low Q value. The P-wave velocity in the upper mantle is also low. For this information, it can be induced that the magma in the crust is derived from the upper mantle, and the low velocity anomaly in upper crust in the Tengchong area may be related to the differentiation of magma. The Tengchong volcanoes are close to an active plate boundary and belong to plate boundary volcanoes.
基金the financial support provided by the open fund from the Key Laboratory of Deep-Earth Dynamics of the Ministry of Natural Resources, Institute of Geology, as well as Chinese Academy of Geological Sciences (Grant No. J1901-16)the State Key Laboratory for Mineral Deposits Research, Nanjing University (Grant No. 2020-LAMD-K04)+1 种基金the National Natural Science Foundation of China (Grant No. 41403029)The support provided by the China Scholarship Council (CSC) during a visit to the University of Arizona (201709110012)。
文摘The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites;however, their geological background and petrogenesis have not been well constrained and elucidated. In this study, we present new zircon U-Pb dating, along with geochemical and Sr-Nd-Hf isotopic data for granites from the Tengchong–Lianghe granitoid belt(as abbreviated to Tengliang belt) and West Yingjiang batholiths from the Tengchong block. The mineralogical and geochemical features of the Tengliang granites and the West Yingjiang batholiths are ascribed to aluminous S-type granites and weak peraluminous I-type, respectively. Zircon U-Pb analyses yielded consistent ages ranging from 67.5 Ma, 68.4 Ma and 66.2 Ma from the Tengliang granitoid belt and 50.4 Ma to 60.8 Ma for three samples from the west Yingjiang batholiths. The Tengliang granites were emplaced during the Late Cretaceous(68-66 Ma) and demonstrate negative ε_(Hf)(t) values(-24 to-4) and initial ~(87)Sr/~(86)Sr ratios of 0.7101–0.7139 and significant negative ε_(Nd)(t) values from-8.91 to-13.2, indicating a Proterozoic sedimentary source or enriched components. The hornblende-bearing I-type granites from West Yingjiang are characterized by lower initial ~(87)Sr/~(86)Sr ratios of 0.7076–0.7106, compared to Tengliang granite and negative whole-rock ε_(Nd)(t) values from-4.0 to-11.9. The early Eocene west Yingjiang gneissic granites show wide ranges of ε_(Hf)(t) values from +7.4 to-8.5 and T_(2DM) of 1.30–0.65 Ga, indicating partial melting of ancient crust with contributions of depleted mantle materials. In combination with the regional background and previous studies, we propose that such a spatio-temporal distribution of the Tengchong granitoid belt might be related to the rollback or angleswitching of the Neo-Tethyan subducting slab. This study sheds new light on the evolutionary history of the Tengchong block.
基金supported jointly by the National Natural Science Foundation of China(Grant No.41502347)the Young Scholars development fund of SWPU(Grant No.201499010028)+2 种基金the Research Program for the Education Department of Sichuan Province(Grant No.16ZB0087)the Research Program for the Education Department of Sichuan Province(Grant No.15ZB0073)the"Innovative Research Teams at the Local University of Sichuan Province"(Grant No.13TD0008)
文摘The Early Cretaceous granitoids that are widespread in the Tengchong terrane of Southwest China play a critical role in understanding the tectonic framework associated with the Tethyan oceans. In this study, we present a detailed description of zircon U-Pb ages, whole-rock geochemistry and Hf isotopes for the Laoxiangkeng pluton in the eastern Tengchong terrane and elucidate their petrogenesis and geodynamic implications. Zircon U-Pb dating of the Laoxiangkeng pluton yields ages of 114 ± 1 Ma and 115 ± 1 Ma,which imply an Early Cretaceous magmatic event. The Laoxiangkeng pluton enriched in Si and Na, is calcalkaline and metaluminous, and has the characteristics of highly fractionated I-type granites. Zircons from the pluton have calculated ε_(Hf)(t) values of-12.7 to-3.7 and two-stage model ages of 1327-1974 Ma,respectively, indicating a mixed source of partial melting of Paleo-Neoproterozoic crust-derived compositions with some inputs of mantle-derived magmas. By integrating all available data for the regional tectonic evolution of the eastern Tethys tectonic domain, we conclude that the Early Cretaceous magmatism in the Tengchong terrane was produced by the northeastward subduction of the Meso-Tethyan Bangong-Nujiang Ocean.
基金the National Scholarship Fundthe National Natural Science Foundation of China(Nos.41704053,42174074,41674055)the East China University of Technology Research Foundation for Advanced Talents(ECUT)(DHBK2019084)for financial support。
文摘We calculated the crustal stress field using the composite focal mechanism method based on the P-wave initial motion polarity data of the Tengchong volcanic area from January 2011 to April 2019 obtained from the Bulletin of Seismological Observations of Chinese stations.The magnitude range of earthquakes used in this study is 0–4,and their magnitudes are mainly approximately 1.0.To investigate the infl uence of the source location on the stress fi eld and obtain reliable stress fi elds of the study area,we applied the double-diff erence algorithm to relocate the seismic events,obtaining more accurate and reliable relative positions of seismic events with a clearer seismic belt.On the basis of relocation results,the study on the stress fi eld along the fault zone was conducted,and the infl uence of seismic event position on the stress fi eld was analyzed.Results show that,fi rst,the current stress regime in the shallow crust of the Tengchong volcanic area is strike-slip faulting,the orientation of the principal compressive stress axis is NE–SW,the orientation of the principal extension stress axis is SE–NW,the principal compressive and extension stress axes are nearly horizontal,and the dip angle of intermediate principal stress axis is relatively large.This reflects that the volcanic and seismic activities in the Tengchong volcanic area are mainly controlled by the collision and squeezing eff ect of the Indian–Eurasian plate.It also refl ects that the current tensile action caused by deep magma activity has little infl uence on the shallow crustal stress field.Second,the stress field along fault zones reveals that there exist local stress fi elds,such as the thrust stress regime at the strike-slip fault terminal area,which is consistent with the compressional area at the intersection of conjugate strike-slip faults indicated by previous study.Third,the stress fi eld results are consistent,regardless of using the original location in the bulletin or the relocated location,indicating that the infl uence of the event location error can be neglected when there are suffi cient data and refl ecting the stability of the composite focal mechanism method.The findings can serve as a reference for investigating geological structure movement,seismic activities,and volcanic activities in the Tengchong volcanic area.
基金State Natural Science Foundation of China (D49974020), Joint Seismological Science Foundation of China (199110) and Project (95-11-01-06) during Ninth Five-Year Plan from China Seismological Bureau.
文摘Based on data collected by deep seismic sounding carried out in 1999, a three-dimensional P wave velocity structure is determined with tomographic inversion. The tomographic result shows that there is a P wave low velocity zone (LVZ) in the upper crust beneath the Tengchong volcanic area. The LVZ is in the depth of 7~8 km and may be a smgma chamber or a partial melting body. The result also shows that the LVZ is in the northeastern side of the Rehai hydrothermal field, which is located in another LVZ near the surface. The shallow LVZ may represent a well-developed fracture zone. The strong hydrothermal activity in Rehai area can attribute to the existence of fractures between two LVZs. These fractures are the channels for going upwards of the deep hot fluid.
文摘Tengchong volcanic area is located near the impinging and underthrust margin of India and Eurasia plates. The volcanic activity is closely related to the tectonic environment. The deep structure characteristics are inferred from the receiver function inversion with the teleseismic records in the paper. The results show that the low velocity zone is influenced by the NE-trending Dayingjiang fault. The S-wave low velocity structure occurs obviously in the southern part of the fault, but unobviously in its northern part. There are low velocity zones in the shallow po-sition, which coincides with the seismicity. It also demonstrates that the low velocity zone is directly related to the thermal activity in the volcanic area. Therefore, we consider that the volcano may be alive again.
基金supported by Kadoorie Farm and Botanic Garden, Hong Kong。
文摘We present the first description of the acoustic characters of the endangered Tengchong leaf litter toad(Leptobrachella tengchongensis), aiming to inform future ecological studies of the species and taxonomic studies in the genus Leptobrachella. A total of 1179 calls, belonging to 6 adults male individuals, were recorded using TASCAM DR-40 digital sound recorder from its type locality in May 2015 and then analyzed using Raven Pro v.1.6.1 software. The advertisement call of male L. tengchongensis consists of primary advertisement call and secondary advertisement call. The primary advertisement call is invariably composed of two notes and has a call duration of 61 ± 5 ms(23–87 ms, n = 1142). The secondary advertisement call is composed of 3–10 notes(mean 5.25 ± 1.41 notes/call, n = 37) with a call duration of 90 ± 6 ms(37–127 ms, n = 37). The mean inter-call interval is 212 ± 121 ms(88–1121 ms, n = 1092). An introductory note is absent in advertisement calls and the dominant of calls is 4.1–4.8 kHz(at 20 ℃). We discuss the interspecific and intraspecific variations on advertisement calls in L. tengchongensis and among Leptobrachella species, and provide a summary on the major acoustic characters of all Leptobrachella species occurring north of the Isthmus of Kra.
文摘This paper discusses the late Yanshanian-Himalayan igneous rock series and minerogenetic series (Cheng et al., 1979, 1982) related to tin polymetallic deposits in the Tengchong area. The multi-stage differentiation and evolution of the igneous rock series led to the concentration of metal and ore-forming elements in a cupola of a granite body formed in the late stage. The minerogenetic series shows a zoning of Nb-Ta-W-Sn, Sn-Fe and Sn around the cupola in space and a multi-stage regularity in time. Finally a minerogenetic model and three key factors of tin minerogenesis are put forward for tin polymetallic deposits in the area.
基金This paper is one or the results of Project D14021 sponsored by the National Natural Science Foundation.
文摘The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to evaluate the reservoir temperature. The most likely temperature of the reservoir as representedby T_(Na-K-Ca) is about 230℃. The chemical and isotopic compositions of fluids before boiling within the reser-voir are estimated. The mixing and dilution of cold and warm waters are discussed. The Rehai geothermal fieldis a high-temperature (hot) water system with the subsurface boiling zone close to the surface. The reservoirpressure at different depths is calculated. And finally the water-rock equilibration is inferred.
基金supported by the National Natural Science Foundation of China(Grant No.41903032)Science(Engineering)Research Project of Yunnan University(Grant No.2017YDQN08)Applied Basic Research Programs of Science and Technology Department of Yunnan Province(Grant No.2018FD009).
文摘A comprehensive study of zircon U-Pb geochronology,in situ Hf isotopes,whole-rock major and trace element geochemistry,and Nd isotopes was carried out for two Early Jurassic two-mica granites(Longtang and Menglong)in the southern part of the Tengchong terrane,which is in the northern part of the larger Sibumasu terrane.We assess the origin of the granites and explore their possible genetic relationship to the Paleo-Tethyan regime.LA-ICP-MS zircon U-Pb dating shows that they were simultaneously emplaced in the Early Jurassic(ca.199 Ma).They have SiO2 contents of 69.7–75.1 wt%and are mainly strongly peraluminous with alumina saturation index(ASI)values ranging from 1.06 to 1.46.They show similar Mg#(0.29–0.42)to experimental partial melts of metasedimentary rocks under continental pressuretemperature(P-T)conditions.They are enriched in light rare earth elements(LREEs)relative to heavy rare earth elements(HREEs),with moderately negative Eu anomalies and flat HREEs patterns.They show negativeεNd(t)values(−9.0 to–12.4)andεHf(t)values(−8.0 to−9.1).Elemental and isotopic data suggest that they most likely to formed by muscovitedehydration melting of a metapelitic source at lower temperatures in the range of 700℃to 750℃.The granites might represent a post-collisional tectonic setting response to Paleo-Tethyan regime.
文摘Due to its special observation principle, GPS remote sensing atmospheric precipitation has the advantages of high time resolution and no weather conditions, and has been widely used in the research field of atmospheric precipitation. Using ground-based GPS precipitate water vapor data (GPS-PWV) and radiosonde-precipitate water vapor data (RS-PWV) that integrated by Radiosonde data, the error between GPS-PWV and RS-PWV in Tengchong is analyzed on its distribution of wet and dry seasons, also the difference between 00:00 UTC and 12:00 UTC. Results show that the RMSE of GPS-PWV and RS-PWV on both 00:00 UTC and 12:00 UTC are less than 5 mm, they correspond with each other well and their correlation coefficient is above 0.95, additionally, GPS-PWV value is stable than RS-PWV value. On the whole, the value of GPS-PWV is slightly larger than RS-PWV. And the mean absolute error between them has higher values, 4.5 mm in 2011 and 4.7 mm in 2012 from May to October (local rainy season) and lower values, 2.8 mm in 2011 and 3.1 mm in 2012 in November to April (local dry season). Besides, the mean absolute error in the morning seems has a difference with its component in the evening. Specifically, it is bigger on 12:00 UTC than on 00:00 UTC and the mean absolute errors on 12:00 UTC of two years are 27% and 11% larger than errors on 00:00 UTC respectively. The correlation of mean absolute error and surface vapor pressure, surface air temperature is examined in this study as well. We achieved that the correlation coefficient between mean absolute error and surface vapor pressure, surface air temperature equals 0.32, 0.37 separately. Diverse characters of mean absolute error under different precipitation conditions are also discussed. The outcome is that the mean absolute error has a higher value on rainy days and a lower value on clear days. However, during the precipitation periods, it appears that the mean absolute error and the rainfall situation don’t agree with each other well, it is likely to change randomly.
基金financially supported by the National Science Foundation of China(grant No.41472305)Special Project of China Earthquake Administration(grant No.201108001)
文摘Objective The Tengchong volcanic field is located at the eastern edge of the convergence zone between India and Eurasia.New tomographic results show that the subducting Indian Plate is imaged clearly as high-V anomalies beneath Burma and dips eastward with a high angle in the uppermantle, and then it flattens in the mantle transition zone.
