Late Cenozoic uplift of the Liupan Mountains:Evidence from the Neogene loess deposits

The Liupan Mountains,one of the important mountain ranges in western China,are located on the boundary between the northeastern Tibetan Plateau and the Ordos Block.The uplift history of the Liupan Mountains remains controversial.Loess deposits are good tracers of regional tectonic and geomorphic changes,because loess is sensitive to erosion and the formation and preservation of loess requires relatively flat highlands and relatively stable tectonic environments.We investigated the distribution of Neogene loess deposits on the western piedmont of the Liupan Mountains and examined a near-continuous loess section(Nanping section)on the piedmont alluvial highlands.Correlation of magnetic susceptibility stratigraphy with the QA-ⅠMiocene loess sequence dates this 56-m section covering the interval from~8.1 to 6.2 Ma.The lower boundary age of this section,together with previously reported Zhuanglang red clay(sand-gravel layers with intercalated loess during~9–8 Ma and near-continuous loess during~8–4.8 Ma)and Chaona red clay(~8.1–2.58 Ma),indicates that the Liupan Mountains were uplifted in the late Miocene(~9–8 Ma)and basically formed by~8 Ma,attesting to no intense mountain building since that time.In addition,based on the information from the Zhuanglang core and the QA-Ⅰsection,we infer that sizable parts of the Liupan Mountains were uplifted during the late Oligocene–early Miocene and did not experience intense uplift during~22–9 Ma.

Influencing Factors and Prediction of Risk of Returning to Ecological Poverty in Liupan Mountain Region,China

China has resolved its overall regional poverty in 2020 by attaining moderate societal prosperity.The country has entered a new development stage designed to achieve its second centenary goal.However,ecological fragility and risk susceptibility have increased the risk of returning to ecological poverty.In this paper,the Liupan Mountain Region of China was used as a case study,and the counties were used as the scale to reveal the spatiotempora differentiation and influcing factors of the risk of returning to poverty in study area.The indicator data for returning to ecological poverty from 2011-2020 were collected and summarized in three dimensions:ecological,economic and social.The autoregressive integrated moving average model(ARIMA)time series and exponential smoothing method(ES)were used to predict the multidimensional indicators of returning to ecological poverty for 61 counties(districts)in the Liupan Mountain Region for 2021-2030.The back propagation neural network(BPNN)and geographic information system(GIS)were used to generate the spatial distribution and time variation for the index of the risk of returning to ecological poverty(RREP index).The results show that 1)ecological factors were the main factors in the risk of returning to ecological poverty in Liupan Mountain Region.2)The RREP index for the 61 counties(districts)exhibited a downward trend from 2021-2030.The RREP index declined more in medium-and high-risk areas than in low-risk areas.From 2021 to 2025,the RREP index exhibited a slight downward trend.From 2026 to2030,the RREP index was expected to decline faster,especially from 2029-2030.3)Based on the RREP index,it can be roughly divided into three types,namely,the high-risk areas,the medium-risk areas,and the low-risk areas.The natural resource conditions in lowrisk areas of returning to ecological poverty,were better than those in medium-and high-risk areas.

Liupan Mountain

The State Postal Bureau has issued a set of four special stamps bearing images of Liupan Mountain.

Effect of land use and land cover change on soil erosion and the spatio-temporal variation in Liupan Mountain Region,southern Ningxia,China

The Liupan Mountains are located in the southern Ningxia Hui Autonomous Region of China,that forms an important divide between landforms and biogeographic regions.The populated part of the Liupan Mountain Region has suffered tremendous ecological damage over time due to population pressure,excessive demand and inappropriate use of agricultural land resources.To present the relationship between land use/cover change and spatio-temporal variation of soil erosion,data sets of land use between the late 1980s and 2000 were obtained from Landsat Thematic Mapper(TM)imagery,and spatial models were used to characterize landscape and soil erosion conditions.Also,soil erosion in response to land use and land cover change were quantified and analyzed using data from geographical information systems and remote sensing.Soil erosion by water was the dominant mode of soil loss,while soil erosion by wind was only present on a relatively small area.The degree of soil erosion was classified into five severity classes:slight,light,moderate,severe,and very severe.Soil erosion in the Liupan Mountain Region increased between the late 1980s and 2000,both in terms of acreage and severity.Moderate,severe,and very severe eroded areas accounted for 54.86%of the total land area.The lightly eroded area decreased,while the moderately eroded area increased by 368817 ha(22%)followed by severe erosion with 146552 ha(8.8%),and very severe erosion by 97067.6 ha(5.8%).Soil loss on sloping cropland increased with slope gradients.About 90%of the cropland was located on slopes less than 15°.Most of the increase in soil erosion on cropland was due to conversion of steep slopes to cropland and degradation of grassland and increased activities.Soil erosion was severe on grassland with a moderate or low grass cover and on dry land.Human activities,cultivation on steep slopes,and overgrazing of pastures were the main reasons for the increase in erosion severity.