藏东缘昌都大型复合盆地喜马拉雅期陆内造山与成矿作用

研究藏东缘大型复合盆地喜山期陆内造山与成矿作用的目的,在于建立横断山型陆内碰撞造山构造模式、成岩成矿模式。根据地层接触关系、构造变形特征、矿床分布规律的研究,证实盖层褶皱推覆运动发生在早喜马拉雅期;盆地内的推覆(滑覆)构造圈闭、走滑断裂构造圈闭、走滑推覆脆-韧性剪切带圈闭、与造山带走向近直交的横向构造圈闭是主要的成岩、成矿空间。通过横断山型陆内造山动力学和喜山期成矿作用研究,分别建立了“横断山型”陆内碰撞造山模式和藏东缘大型复合盆地的成岩成矿模式。

Spatial and temporal variation of drought index in a typical steep alpine terrain in Hengduan Mountains

This study describes the spatial and temporal variation of a drought index and makes inferences regarding the environmental factors that influence this variability in the Hengduan Mountains. A drought index is typically used to determine the moisture conditions and the magnitude of water deficiency in a given area. Based on data from 26 meteorological stations over the period 1960-2012, the spatial and temporal variations of the drought index were analyzed using a thin plate smoothing splines method that considered elevation as a covariate. The drought index was estimated based on the potential evapotranspiration(E0) as defined by the Penman Monteith model modified by FAO(1998). The results of the reported analysis showed that the drought index in the Hengduan Mountains has been decreasing since 1960 at a rate of-0.008/a. This represented a progressive shift from the "sub-humid" class, which typified the wider area in the Hengduan Mountains, toward the "humid" class, which appeared in the Hengduan Mountains areas. The drought index was relatively high in the north and low in the south and the variation of the drought index varied with seasons. The drought index showed increasing trends in summer and autumn and it is greater in autumn than in summer, while it showed a decreasing trend in spring and winter. Drought index is inversely proportional to the soil relative humidity and Normalized Difference Vegetation Index(NDVI).

Effects of environment and genotype-by-environment interaction on phenotype of Rorippa elata(Brassicaceae),an endemic alpine plant in the Hengduan mountains

Global climate change poses a severe threat to mountain biodiversity.Phenotypic plasticity and local adaptation are two common strategies for alpine plant to cope with such change.They may facilitate organismal adaptation to contrasting environments,depending on the influences of the environment or genotype or their interacted effects.In this study,we use an endemic alpine plant(Rorippa elata)in the Hengduan mountains(HDM)to unravel its phenotypic basis of adaptation strategy and evaluate the relative contributions of environment and genotype to its phenotype.We transplanted 37 genotypes of R.elata into two common gardens across low and high elevations(2800 vs.3800 m)during 2021-2022.Nine fitness-related traits were measured,including flowering probability and glucosinolates(GS)content.We estimated the environmental or genotypic contributions to the phenotype and identified the main environmental components.Our results revealed that both environment and genotype-by-environment interactions contributed to the phenotypes of R.elata.Latitudinal heterogeneity was identified as a key factor that explained 24%of the total phenotypic variation.In particular,genotypes of the northern HDM showed significantly higher plasticity in flowering probability than those of the southern HDM.Furthermore,within the southern HDM,GS content indicated local adaptation to herbivory stresses for R.elata genotypes along elevations.In conclusion,our results suggest that R.elata may have adapted to the alpine environment through species-level plasticity or regional-level local adaptation.These processes were shaped by either complex topography or interactions between genotype and mountain environments.Our study provides empirical evidence on the adaptation of alpine plants.