It has researched geological and geochemical characteristics of the barite rocks in Guangxi hydrothermal sedimentary deposit based on lithology and geochemistry.In Al/(Al+Fe+Mn) and Al-Fe-Mn diagrams,the barite rocks' coordinates lie in the area of hydrothermal sediment,which means the rocks were formed by hydrothermal deposition.The As,Sb content of this area is close to that of hydrothermal sediment which presents the characteristics of hydrothermal deposition.The REE pattern of the barite rocks is a typical hydrothermal sedimentary distribution pattern with LREE enriched,weak negative Ce anomalies and stong positive Eu anomalies.
The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong ’an New Area, North China, which caused the enhanced mixing of groundwater in different aquifers and significant changes in regional groundwater chemistry characteristics. In this study, groundwater and sediment pore-water in drilling cores obtained from a 600 m borehole were investigated to evaluate hydrogeochemical processes in shallow and deep aquifers and paleo-environmental evolution in the past ca. 3.10 Ma. Results showed that there was no obvious change overall in chemical composition along the direction of groundwater runoff, but different hydrochemical processes occurred in shallow and deep groundwater in the vertical direction. Shallow groundwater (< 150 m) in the Xiong ’an New Area was characterized by high salinity (TDS > 1000 mg/L) and high concentrations of Mn and Fe, while deep groundwater had better water quality with lower salinity. The high TDS values mostly occurred in aquifers with depth < 70 m and >500 m below land surface. Water isotopes showed that aquifer pore-water mostly originated from meteoric water under the influence of evaporation, and aquitard pore-water belonged to Paleo meteoric water. In addition, the evolution of the paleoclimate since 3.10 Ma BP was reconstructed, and four climate periods were determined by the δ18O profiles of pore-water and sporopollen records from sediments at different depths. It can be inferred that the Quaternary Pleistocene (0.78‒2.58 Ma BP) was dominated by the cold and dry climate of the glacial period, with three interglacial intervals of warm and humid climate. What’s more, this study demonstrates the possibilities of the applications of pore-water on the hydrogeochemical study and further supports the finding that pore-water could retain the feature of paleo-sedimentary water.
The Minshan Mountain region is a habitat of A population of giant pandas,which is the biggest one of the wild giant pandas.This region is also one of the main seismic areas of the catastrophic Wenchuan Earthquake in the year 2008.It was faced with diversified artificial interferences before the earthquake,but now is met with some more severe threats brought by the Earthquake.Basing on A population giant panda's habitat in the Minshan Mountain,this paper deals with all kinds of threats before and after the Wenchuan Earthquake and aims to provide reference for the restoration and rehabitation of the habitat of giant pandas after the tragedy.
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