Yunnan Region Research Articles

Novel insights into the dissemination route of Japanese apricot (Prunus mume Sieb. et Zucc.) based on genomics

SUMMARYJapanese apricot (Prunus mume) is an attractive fruit tree originating from China, and its cultivation history dates back 7000 years. In this study, we investigated the genetic diversity, population structure, and genetic relationship of Japanese apricots in different regions of China and Japan. The analyses of the genetic variation between wild and cultivated populations improved our understanding of the general mechanisms of domestication and improvement. A total of 146 accessions of Japanese apricot from different geographic locations were sequenced. The genetic diversity of wild and domesticated accessions (3.60 × 10−3 and 3.51 × 10−3, respectively) from China was high, and the effect of artificial selection pressure on domesticated accessions was small; however, the genetic diversity of artificially bred accessions decreased significantly (2.68 × 10−3) compared to domesticated accessions, which had an obvious improvement bottleneck effect. The chloroplast genome results showed that 41 haplotypes were detected, and Japanese apricots from the Yunnan region had the most haplotypes and the highest genetic diversity. The results revealed the dissemination route of Japanese apricot, not only along the Yangtze River basin system (from southwest China to Hunan, Jiangxi, and Anhui, and finally to the Jiangsu, Zhejiang, and Shanghai areas). Additionally, we discovered a second route for Japanese apricot dispersion, which was mostly in the Pearl River basin system, from southwest China to Libo of Guizhou and then to the Guangdong, Fujian, and Taiwan areas. This also showed that Japanese‐bred accessions originated from Zhejiang, China. In addition, selective sweep analysis showed that most of the high‐impact single nucleotide polymorphisms were identified in genes related to glucose metabolism, aromatic compound metabolism, flowering time, dormancy, and resistance to abiotic stress during the domestication and improvement of Japanese apricot.

Diversity of transcription activator-like effectors and pathogenicity in strains of Xanthomonas oryzae pv. oryzicola from Yunnan.

The present study aimed to evaluate transcriptional activator-like effector (TALE) genes in 86 Xanthomonas oryzae pv. oryzicola strains collected from 8 rice-growing regions in Yunnan, and to examine the relationship between TALE genotypes and virulence in 6 differential rice lines. Besides, the geographical areas, distribution of these genotypes were studied in detail. Genetic diversity was analyzed through the number and size of putative TALE genes based on TALE gene avrXa3 as a probe. We found that X. oryzae pv. oryzicola strains consist of variable number (13-27) of avrXa3-hybridizing fragments (putative TALE genes). Test strains were classified into 8 genotypes (G1-G8) with major genotypes G3 and G7 widely distributed in Yunnan. Pathogenicity of X. oryzae pv. oryzicola was evaluated by inoculating 6 differential rice lines with a single resistance gene into 9 pathotypes clusters (I-IX), the dominant Genotypes G3 and G7 consist of pathotypes I, II, and IV. Furthermore, we also detected the known TALE target genes expression in susceptible rice cultivar (cv. nipponbare) after inoculating 8 genotypes-representative X. oryzae pv. oryzicola strain. Correlation between the numbers of putative TALE genes of X. oryzae pv. oryzicola and relevant target genes in nipponbare confirmed up-regulation. Altogether, this study has given insights into the population structure of X. oryzae pv. oryzicola that may inform strategies tocontrol BLS in rice.

The Current Crustal Vertical Deformation Features of the Sichuan–Yunnan Region Constrained by Fusing the Leveling Data with the GNSS Data

This study uses the least squares collocation method to fuse the leveling vertical deformation velocity in the Sichuan–Yunnan region with the GNSS observations of this region from 320 stations in the China Crustal Movement Observation Network (CMONOC) and the China Continental Tectonic Environment Monitoring Network (CMTEMN) from 1999 to 2017. Such fusion is to improve the accuracy of the vertical deformation rates in large spatial scales. The fused vertical deformation results show that: (1) the fused deformation field has a uniform spatial distribution, and shows detailed change characteristics of key regions; (2) the current vertical crustal motion in this region is featured by the contemporaneous occurrence of crustal compression, shortening and uplift and basin extensional subsidence; (3) most areas in this region experience uplifts, as the lateral push of the Qinghai–Tibet Plateau was blocked by the Sichuan Basin. The areas on the northwest side of the Longmenshan fault and the Lijiang-Xiaojinhe fault are dominated by uplifts, with the velocity of 1.5 mm/a–5.5 mm/a, and the region on the southeast side has slight uplifts, with the velocity of 1.0 mm/a–1.5 mm/a; (4) many areas have high gradient vertical deformation, especially the region close to the Wenshan fault and on the two sides of the Yarlung Zangbo fault that has the value of 3.0–4.0 × 10−8/a, deserving further attention to be paid to the long-term earthquake hazards.

Association of Sedentary Behavior and Physical Activity With Hyperuricemia and Sex Differences: Results From the China Multi-Ethnic Cohort Study.

To determine the association of physical activity (PA) and sedentary time (ST; leisure and total ST), commuting mode with hyperuricemia in a multiethnic Chinese population, and to analyze the difference between sexes. Baseline data were analyzed from 22,094 participants from the China Multi-Ethnic Cohort study in the Yunnan region, China. PA and sedentary behavior were assessed through questionnaires. Hyperuricemia was defined as serum urate > 7.0 mg/dL among men and > 6.0 mg/dL among women. A restricted cubic spline (RCS) was created to model the possible nonlinear relationship of PA and ST with hyperuricemia. Logistic regression was used to estimate the odds ratio (OR) and 95% CI. Hyperuricemia prevalence in the observed population was 15.5% (men 25.5%, women 10.7%). Compared to those with light PA, participants with moderate-to-vigorous PA had lower odds of hyperuricemia (adjusted ORs were 0.85 [95% CI 0.77-0.94] and 0.88 [95% CI 0.79-0.97]). However, RCS showed a U-shaped nonlinear relationship between PA and hyperuricemia, and a linear relationship between hyperuricemia prevalence and increasing ST. Total ST ≥ 4 hours/day increased the risk of hyperuricemia in women but not in men. Mode of transportation revealed that sedentary behavior increased the risk of hyperuricemia, but there were inconsistent results based on sex. Moderate PA may be more beneficial in reducing the risk of hyperuricemia. Reducing ST may have a greater effect on preventing hyperuricemia in females than in males.

Identification of Groundwater Radon Precursory Anomalies by Critical Slowing down Theory: A Case Study in Yunnan Region, Southwest China

In this study, we use the critical slowing down (CSD) theory to identify the precursory anomalies of groundwater radon based on the 1000-day continuous data from 8 monitoring stations in Yunnan Province, China during the seismically active period of 1993–1996. The low-frequency and high-frequency information were extracted from raw groundwater radon data to calculate their one-step lag autocorrelation (AR-1) and variance, respectively, in order to identify the precursory anomalies. The results show that the anomaly characteristics can be divided into three categories: sudden jump anomalies, persistent anomalies, and fluctuation anomalies. The highest average seismic recognition rate is 72.78%, based on the high-frequency information’s autocorrelation, while the lowest is 45.08%, based on the low-frequency information’s variance. The crustal activity and the change in hydrogeological conditions are possibly the main factors influencing groundwater radon anomalies in the selected period in the study area. There is a positive correlation between the anomaly occurrence time and epicentral distance when epicentral distance is less than 300 km, which may be related to the seismogenic modes and hydrogeological conditions. This study provides a reference for identifying groundwater radon anomalies before earthquakes by mathematical methods.

Support Vector Machine-Based Rapid Magnitude Estimation Using Transfer Learning for the Sichuan–Yunnan Region, China

ABSTRACTThe Sichuan–Yunnan region is a seismically active area. To explore the feasibility of using the support vector machine (SVM) method for magnitude estimation in the area and to improve the rapid magnitude estimation accuracy, we construct an SVM magnitude estimation model using transfer learning (TLSVM-M model) based on a single-station record in this study. We find that the magnitude estimation of a single station shows that for the test dataset, within the 3 s time window after the P-wave arrival, the average absolute error (which reflects the size of the estimated magnitude error as a whole) and standard deviation (which reflects the scatter of magnitude estimation error) of the magnitudes estimated by the TLSVM-M model are 0.31 and 0.41, respectively, which are less than those of the SVM magnitude estimation model without transfer learning (0.44 and 0.55, respectively), the τc method (1.35 and 1.74, respectively) and the Pd method (0.44 and 0.56, respectively). In addition, in test involving five earthquake events via the TLSVM-M model, at 1 s after the first station is triggered, the magnitudes of three events (Ms 4.2, 5.2, and 6.3) are estimated within an error range of ±0.3 magnitude units. For the other two earthquakes (Ms 6.6 and 7.0), there is an obvious magnitude underestimation problem at 1 s after the first station is triggered, with less underestimation by increasing time after the first station is triggered. Meanwhile, for these two events (Ms 6.6 and 7.0), within 13 s after the first station was triggered, the magnitude estimation errors are both within ±0.3 magnitude units. The TLSVM-M model has the capability of rapid magnitude estimation for small-to-moderate events in the Sichuan–Yunnan region. Meanwhile, we infer that the proposed model may have potential in earthquake early warning.

137Cs and 40K activity concentrations in edible wild mushrooms from China regions during the 2014–2016 period

Introduction. Contamination by radiocaesium of edible wild mushrooms after major nuclear accidents is a long-lasting process in some regions of the world. Following greater awareness of radioactive pollution in Asia, particularly after the Fukushima accident, this study investigated the radioactivity of 137Cs and 40K contamination in edible wild mushrooms in China.
 Study objects and methods. The objects of the research were edible wild mushrooms collected during 2014 to 2016, from the Inner Mongolian and Yunnan regions of China. To obtain an insight into any environmental impacts to distant regions of mainland Asia, the mushrooms were analyzed for 137Cs activity. In parallel, the natural activity of 40K was also determined and used to estimate the content of total K. The topsoil underneath the mushrooms was also investigated from a few sites in Bayanhushu in Inner Mongolia in 2015.
 Results and discussion. The results showed that in 4 to 6 mushrooming seasons after the accident, mushrooms from both regions were only slightly contaminated with 137Cs, which implied negligible consequences. The activity concentrations of 137Cs in dried caps and whole mushrooms in 63 of 70 lots from 26 locations were well below 20 Bq kg–1 dry weight. Two species (Lactarius hygrophoroides L. and Lactarius volemus L.), from Jiulongchi in Yuxi prefecture showed higher 137Cs activities, from 130 ± 5 to 210 ± 13 Bq kg–1 dw in the caps. 40K activities of mushrooms were around two- to three-fold higher. A composite sample of topsoil (0–10 cm layer) from the Bayanhushu site (altitude 920 m a.s.l.) in Inner Mongolia showed 137Cs activity concentration at a low level of 6.8 ± 0.7 Bq kg–1 dw, but it was relatively rich in potassium (40K of 595 ± 41 Bq kg–1 and total K of 17000 ± 1000 mg kg–1 dw).
 Conclusion. Wild mushrooms from the Yunnan and Inner Mongolia lands only slightly affected with radioactivity from artificial 137Cs. Lack of 134Cs showed negligible impact from Fukushima fallout. Ionizing radiation dose from 137Cs in potential meals was a fraction of 40K radioactivity. The associated dietary exposure to ionizing irradiation from 137Cs and 40K contained in mushrooms from the regions studied was considered negligible and low, respectively. Mushroom species examined in this study are a potentially good source of dietary potassium.

A review of the non-lyctine powder-post beetles of Yunnan (China) with a new genus and new species (Coleoptera: Bostrichidae).

The powder post beetles (Coleoptera: Bostrichidae) (except Lyctinae) of Yunnan Province in Southwest China are reviewed for the first time. Keys to twenty-six genera and fifty-two species from the Yunnan region are provided. One new genus and seven new species are described: Dinoderus (Dinoderastes) hongheensis sp. nov., Dinoderus (Dinoderastes) nanxiheensis sp. nov., Gracilenta yingjiangensis gen. nov., sp. nov., Calonistes vittatus sp. nov., Calophagus colombiana sp. nov., Xylodrypta guochuanii sp. nov. and Xylodrypta zhenghei sp. nov.. Fourteen species are recorded in China for the first time. The bostrichid fauna of Yunnan is compared with those of the neighbouring bio-geographically related Southeast Asian and Himalayan regions. The fauna has a close affinity with that of tropical Southeast Asia and a much weaker relationship with the Palearctic region. The differences with the Himalayas may reflect the separate evolutionary and complex geological history of the two areas.

Predicting potential suitable habitat for Ensete glaucum (Roxb.) Cheesman using MaxEnt modelling

Ecological niche models (ENMs) and species distribution models (SDMs) are widely used to predict suitable habitat for plants and animals. In the present study, we used MaxEnt ecological niche modelling to identify the potential suitable habitat for Ensete glaucum—a pseudo banana species found in Northeast India, Yunnan region of China, Southeast Asia, and Papua New Guinea. Fifty-one occurrence records along with 19 bioclimatic and three topographic variables were used for the modelling. The model accuracy was tested using the area under the receiver operating curve (AUC) metric, and each variable's contribution was estimated using a Jackknife test. Highly suitable regions were observed in the Indo-Burma region with an area of 58,371 km2, while less suitable regions were observed in most of the countries of Southeast Asia. The potential habitat suitability of E. glaucum was mainly influenced by three bioclimatic variables (precipitation of warmest quarter, temperature annual range, and mean diurnal range) and one topographic variable (slope). The predicted suitable habitat regions (high, medium, and low) can be used for future explorations to study the morphological and genetic diversity in E. glaucum and to conserve the genetically diverse and vulnerable populations of this banana crop relative.

Splendor in the Frass

FOR HUNDREDS OF YEARS, THE MOST CONSPICUOUS EXAMPLE OF CULTURAL USE OF FRASS HAS BEEN “INSECT TEA,” A TRADITIONAL BEVERAGE THAT IS CONSUMED BY LOCAL POPULATIONS IN THE MOUNTAINOUS REGIONS OF SOUTHERN CHINA, INCLUDING GUANGXI, YUNNAN, AND GUIXHOU. Because insects have long been part of the human experience, insect excrement has also long been part of the human experience, but for most of the time people have walked the planet, they really haven’t paid that much attention to it. Consequently, insect excrement, or frass, hasn’t had as much of a tangible impact on human culture as have other materials produced by insects. For hundreds of years, the most conspicuous example of cultural use of frass has been “insect tea,” a traditional beverage that is consumed by local populations in the mountainous regions of southern China, including Guangxi, Yunnan, and Guixhou. With historical records dating back to The Compendium of Materia...

Knockdown CYP2S1 inhibits lung cancer cells proliferation and migration.

The incidence of lung cancer in Yunnan area ranks firstly in the world and underlying molecular mechanisms of lung cancer in Yunnan region are still unclear. We screened a novel potential oncogene CYP2S1 used mRNA microassay and bioinformation database. The function of CYP2S1 in lung cancer has not been reported. To investigate the functions of CYP2S1 in lung cancer. Immunohistochemistry and Real-time PCR were used to verify the expression of CYP2S1. Colony formation and Transwell assays were used to determine cell proliferation, invasion and migration. Xenograft assays were used to detected cell growth in vivo. CYP2S1 is significantly up-regulated in lung cancer tissues and cells. Knockdown CYP2S1 in lung cancer cells resulted in decrease cell proliferation, invasion and migration in vitro. Animal experiments showed downregulation of CYP2S1 inhibited lung cancer cell growth in vivo. GSEA analysis suggested that CYP2S1 played functions by regulating E2F targets and G2M checkpoint pathway which involved in cell cycle. Kaplan-Meier analysis indicated that patients with high CYP2S1 had markedly shorter event overall survival (OS) time. Our data demonstrate that CYP2S1 exerts tumor suppressor function in lung cancer. The high expression of CYP2S1 is an unfavorable prognostic marker for patient survival.

Different facets of dry–wet patterns in south-western China over the past 27 000 years

Abstract. Frequently occurring mega-droughts under current global climate change have attracted broad social attention. A paleoclimatic perspective is needed to increase our understanding of the causes and effects of droughts. South-western (SW) China has been threatened by severe seasonal droughts. Our current knowledge of millennial-scale dry and wet phases in this region is primarily based on the variability of the Indian summer monsoon. However, water availability over land does not always follow patterns of monsoonal precipitation but also depends on water loss from evaporation and transpiration. Here, we reconstructed precipitation intensity, lake hydrological balance and the soil water stress index (SWSI) for the last 27 000 years. Grain size, geochemical and pollen records from Yilong Lake reveal the long-term relationships and inconsistencies of dry–wet patterns in meteorological, hydrological and soil systems in the central Yunnan region, SW China. Our results show that the long-term trends among precipitation, hydrological balance and soil moisture varied through time. The hydrological balance and soil moisture were primarily controlled by temperature-induced evaporation change during periods of low precipitation such as the Last Glacial Maximum and Younger Dryas. During periods of high precipitation (the early to late Holocene), intensified evaporation from the lake surface offset the effects of increased precipitation on the hydrological balance. However, abundant rainfall and the dense vegetation canopy circumvented a soil moisture deficit that might have resulted from rising temperature. In conclusion, the hydrological balance in the central Yunnan region was more sensitive to temperature change while soil moisture could be further regulated by vegetation changes over millennial timescales. Therefore, under future climate warming, the surface water shortage in the central Yunnan region may become even more serious. Our study suggests that reforestation efforts may provide some relief to soil moisture deficits in this region.

Species diversity, morphometrics, and nesting biology of Chinese stingless bees (Hymenoptera, Apidae, Meliponini)

Stingless bees (Meliponini) form a large monophyletic group with a pantropical distribution. Southern China is on the northern border of this distribution in Asia, and previous studies have recorded a single species in Taiwan and twelve species in Yunnan. In this study, by extensive sampling from both natural nests and the nests of bee keepers in Yunnan, we identified seven stingless bee species from four genera. Species with distinctive characters that were recorded in Xishuangbanna previously but not found during this study may be rare in this region, including Homotrigona lutea and Geniotrigona thoracica. A new key, information on nesting biology, and a snapshot of the current status of meliponiculture in Yunnan are provided. Morphological characters of males of Tetragonula laeviceps, Tetragonilla collina, and Lisotrigona carpenteri are shown, including their genitalia characters. Results of multivariate morphometrics based on twelve characters support the taxonomic classification. For further studies, wider sampling, including tropical and subtropical regions of Fujian, Guangxi, Guangdong, Yunnan, Tibet, Hainan, and Taiwan, is needed to assess the full diversity of Chinese stingless bees.

Spatial differentiation of traditional villages using ArcGIS and GeoDa: A case study of Southwest China

In order to explore the role of environmental factors of traditional villages in the large-scale space category and promote the integral protection of traditional village culture, 1767 traditional villages in Sichuan, Guizhou and Yunnan Province in Southwest China were selected as the objects. With the support of spatial analysis tools such as ArcGIS and GeoDa, the spatial differentiation characteristics of traditional villages and their related factors were analyzed. It was found that the distribution of traditional villages in Southwest China is uneven, and in the overall distribution pattern, there are six spatial agglomeration areas in the east of Guizhou and the central and western regions of Yunnan, as well as large discrete distribution areas in other traditional villages. Traditional villages are influenced by natural factors such as topography, elevation, etc. in terms of spatial differentiation, as well as human, economic and social development environment factors such as population, ethnic composition, regional economic development level, central town, road traffic, etc., and show certain regular characteristics. From the perspective of integrity protection of large-scale traditional village culture, we should make the protection plan for traditional village cultural ecological areas, implement flexible and differentiated traditional village protection strategies, enhance the connectivity level of various development elements of traditional villages in regional scope, and promote the development of global tourism based on traditional villages.

Genome-level diversification of eight ancient tea populations in the Guizhou and Yunnan regions identifies candidate genes for core agronomic traits

The ancient tea plant, as a precious natural resource and source of tea plant genetic diversity, is of great value for studying the evolutionary mechanism, diversification, and domestication of plants. The overall genetic diversity among ancient tea plants and the genetic changes that occurred during natural selection remain poorly understood. Here, we report the genome resequencing of eight different groups consisting of 120 ancient tea plants: six groups from Guizhou Province and two groups from Yunnan Province. Based on the 8,082,370 identified high-quality SNPs, we constructed phylogenetic relationships, assessed population structure, and performed genome-wide association studies (GWAS). Our phylogenetic analysis showed that the 120 ancient tea plants were mainly clustered into three groups and five single branches, which is consistent with the results of principal component analysis (PCA). Ancient tea plants were further divided into seven subpopulations based on genetic structure analysis. Moreover, it was found that the variation in ancient tea plants was not reduced by pressure from the external natural environment or artificial breeding (nonsynonymous/synonymous = 1.05). By integrating GWAS, selection signals, and gene function prediction, four candidate genes were significantly associated with three leaf traits, and two candidate genes were significantly associated with plant type. These candidate genes can be used for further functional characterization and genetic improvement of tea plants.

Seismic Reflection Analysis of AETA Electromagnetic Signals

Acoustic and electromagnetics to artificial intelligence (AETA) is a system used to predict seismic events through monitoring of electromagnetic and geoacoustic signals. It is widely deployed in the Sichuan–Yunnan region (22° N–34° N, 98° E–107° E) of China. Generally, the electromagnetic signals of AETA stations near the epicenter have abnormal disturbances before an earthquake. When a significant decrease or increase in the signal is observed, it is difficult to quantify this change using only visual observation and confirm that it is related to an upcoming large earthquake. Considering that the AETA data comprise a typical time series, current work has analyzed the anomalism of AETA electromagnetic signals using the long short-term memory (LSTM) autoencoder method to prove that the electromagnetic anomaly of the AETA station can be regarded as an earthquake precursor. The results show that there are 2–4% anomalous points and some outliers exceeding 0.7 (after normalization) in the AETA stations within 200 km of the epicenter of the Jiuzaigou earthquake (M. 7.0) and the Yibin earthquake (M. 6.0) half a month before the earthquakes. Therefore, the AETA electromagnetic disturbance signal can be used as an earthquake precursor and for further earthquake prediction.

Conservation planning on China's borders with Myanmar, Laos, and Vietnam.

Transboundary conservation is playing an increasingly important role in maintaining ecosystem integrity and halting biodiversity loss caused by anthropogenic activities. However, lack of information on species distributions in transboundary regions and understanding of the threats in these areas impairs conservation. We developed a spatial conservation plan for the transboundary areas between Yunnan province, southwestern China, and neighboring Myanmar, Laos, and Vietnam in the Indo‐Burma biodiversity hotspot. To identify priority areas for conservation and restoration, we determined species distribution patterns and recent land‐use changes and examined the spatiotemporal dynamics of the connected natural forest, which supports most species. We assessed connectivity with equivalent connected area (ECA), which is the amount of reachable habitat for a species. An ECA incorporates the presence of habitat in a patch and the amount of habitat in other patches within dispersal distance. We analyzed 197,845 locality records from specimen collections and monographs for 21,004 plant and vertebrate species. The region of Yunnan immediately adjacent to the international borders had the highest species richness, with 61% of recorded species and 56% of threatened vertebrates, which suggests high conservation value. Satellite imagery showed the area of natural forest in the border zone declined by 5.2% (13,255 km2) from 1995 to 2018 and monoculture plantations increased 92.4%, shrubland 10.1%, and other cropland 6.2%. The resulting decline in connected natural forest reduced the amount of habitat, especially for forest specialists with limited dispersal abilities. The most severe decline in connectivity was along the Sino‐Vietnamese border. Many priority areas straddle international boundaries, indicating demand and potential for establishing transboundary protected areas. Our results illustrate the importance of bi‐ and multilateral cooperation to protect biodiversity in this region and provide guidance for future conservation planning and practice.

Utricularia lihengiae (Lentibulariaceae), a new species from Northwest Yunnan, China.

Utricularia lihengiae, a new species from the Dulongjiang region of northwest Yunnan, China, is here described and illustrated. The new species belongs to the section Oligocista and is similar to U. bifida L. and U. scandens Benj., from which it can be easily distinguished by the dark purple stripe on the corolla. The new species also differs in its shorter inflorescence and the shape of the calyx lobes.

A newly discovered Late Cretaceous metamorphic belt along the active continental margin of the Neo-Tethys ocean

Abstract High-grade metamorphic rocks and crustal melts provide crucial evidence for growth and differentiation of the continental crust, and are widespread in collisional orogens. However, their importance in the evolution of continental arcs remains poorly understood. Metamorphism and related anatexis in the preserved continental margin of the Neo-Tethys ocean serves as a key natural laboratory to investigate this process. Along the Neo-Tethyan arc margin, the Gaoligong shear zone, Yunnan region of China, is an important locality for linking Lhasa in the north with Sibumasu and Burma in the south. Here, Late Cretaceous granulite-facies metamorphism and crustal anatexis have been identified for the first time in the Gaoligong area. Zircon and monazite U-Pb dating indicates that S-type granites formed at 87–73 Ma, granites and buried pelitic sediments were simultaneously metamorphosed at 75–70 Ma during Neo-Tethyan subduction, and all lithologies were overprinted by a younger 40–30 Ma magmatic and strike-slip event related to India-Asia collision. Phase equilibria modeling of high-grade anatectic gneiss in the MnO-Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2 system indicates peak pressure-temperature (P–T) conditions of 780–800 °C and 6.5–7.5 kbar and defines a cooling and decompressional P–T path for the metapelites. This demonstrates that sediments within the Neo-Tethyan active continental arc were buried to >20 km depth at 75–70 Ma. In combination with the metamorphic record of the Lhasa, Burma, and Sibumasu blocks, an extensive Late Cretaceous metamorphic belt must have formed along the Neo-Tethyan subduction zone. This spatially correlates with coeval gabbro-diorite suites exposed in the Gangdese, Sibumasu and Burma terranes that were triggered by thinning of the lithospheric mantle. This prolonged Late Cretaceous mantle-derived magmatism and lithospheric thinning may have provided a regional-scale heat source for high-grade metamorphism and crustal anatexis along the active continental margin of the Neo-Tethys ocean.

Strain characteristics distribution and potential information analysis in Yunnan based on GNSS data

Based on the observation data of 211 Global Navigation Satellite System (GNSS) regional stations from 2011 to 2016, and 59 continuously operating GNSS stations in the Yunnan region of China since 2013, we analyzed the strain characteristics of Yunnan from the following two perspectives. On the one hand, we analyzed the strain characteristics and tried to determine the potentially abnormal areas of Yunnan based on a multi-scale spherical wavelet method, from an overall strain background view. On the other hand, we investigated the relationship between the strain time series and the potentially abnormal areas of Tonghai County through an earthquake case study, and we attempted to extract the potentially information before the earthquake from the strain time series based on Hilbert-Huang transform (HHT), from a local strain time-series view. The results showed that: (1) in the integrated solution processing of the regional strain patterns, the spherical wavelet method can adapt to the spatial variability in station density and estimate the strain patterns at multiple scales; and (2) by combining the long-term characteristics of the strain time series, the grid division, the two times standard deviation constraint, and the HHT dynamic analysis, it gives the some potential information details on the eve of an earthquake such as the Tonghai earthquake.