Numerical investigation of the hydrodynamic response of an impermeable sea-wall subjected to artificial submarine landslide-induced tsunamis

Landslides - Landslide-induced tsunamis are common natural hazards that potentially affect the safety and stability of waterfront structures. A numerical tank was constructed using FLOW-3D to...     

Duobaoshan Porphyry Copper Deposit and Its Associated Components

Duobaoshan porphyry copper deposit,situated in Nen-jiang County of Heilongjiang Province,Northeast China,liestectonically in the Mongolian-Okhotsk geosyncline.Duobaoshan porphyry copper ore field consisting ofDuobaoshan copper deposit and Tongshan copper deposit con-tains rich copper associated with molybdenum,gold,silverand osmium (Os1 87) . In this sense,this porphyry copper orefield will turn into a large industrial base of copper,gold,sil-ver and osmium.At present,in Duobaoshan porphy…     

西藏高原大地电磁深探测———亚东—巴木错沿线地区壳幔电性结构

摘 要　 展示了超宽频带大地电磁深探测所获得的西藏亚东—巴木错沿线地区电性结构图像; 阐述了西藏中、南部特殊的壳幔电性特征。     

岩溶沉积堆积建造类型及其特征

岩溶沉积— 堆积建造是岩溶作用形成的产物,是认识岩溶发育史、发育规律的物质依据,是岩溶作用时间和空间的记录。本文根据岩溶沉积— 堆积建造的成因以及赋存空间的相互关系,将岩溶沉积—堆积建造划分为岩溶外(地表)沉积和岩溶内(洞穴)沉积两大类;而依据沉积建造的成岩物质及其形成作用,又可分为不含矿的岩溶外沉积、含矿的岩溶外沉积、不含矿的岩溶内沉积和含矿的岩溶内沉积等四大亚类。此外,还根据大地构造运动与岩溶的发育关系,将中国岩溶发育史划分为五大岩溶建造期: ( 1)元古代古岩溶期; ( 2)早古生代加里东古岩溶期; ( 3)晚古生代海西古岩溶期; ( 4)中生代印支和燕山古岩溶期;( 5)新生代喜山岩溶期。      

Water source partitioning among trees growing on carbonate rock in a subtropical region of Guangxi, China

It is not clear how the water sources are used by trees in typical karst areas of Guangxi, China. Trees growing on rigid carbonate rock can primarily use spring water, precipitation-recharged soil water or a mixture of the two. In this study, the Nongla karst dynamic monitoring station in the southwest of Guangxi, China, was observed. To determine the water sources accessed by trees growing on rigid carbonate rock, seasonal change of isotope ratios (δ¹⁸O and δ D) in twig sap, soil water, rainfall and spring water were measured. Stem water samples plotted to the right of the meteoric water line indicates utilization of water sources subject to evaporative isotopic enrichment. Trees growing on rigid carbonate rock in the southwest of China used rainfall directly in the rainy season. Adult trees tended to use deeper water stored in the epikarst zone, while the young ones used soil water when precipitation decreased. In the dry season, all trees sampled depend mostly on water stored in the epikarst zone. Spring water was the major water source for all of the tree species investigated in the dry season. In conclusion, these data indicate that trees growing on rigid carbonate rock in southwest China depend mostly on water stored in the epikarst zone. Therefore, water storage in the epikarst zone is the essential water source for trees growing on carbonate rock in southwest China.     

Hydrogeochemical effects of secondary forest in Guangxi Nongla karst areas in China

Rainfall, throughfall, stemflow and spring were studied in a secondary forest during a wet season from April to August in 2006. Some of the chemicals in throughfall, stemflow and spring were increased in contrast with incident rainfall. Specifically, Cl⁻, HCO₃ ⁻, Na⁺ and Ca²⁺ were leached negatively in throughfall, but K⁺ and Mg²⁺ were leached positively. In stemflow, Cl⁻ and Na⁺ were leached negatively, the others were leached positively and their concentrations were higher than those in throughfall. Total carbon, organic carbon and inorganic carbon in throughfall and stemflow were increased as rainfall went through the secondary forest. The concentration of free CO₂ in rainfall was lower than both, throughfall and stemflow; the relationship between total acidity and free CO₂ was linear. pH of throughfall and stemflow , such as maximum, minimum and mean, were lower than that of rainfall and the extent of pH in spring was changed minimally. We came to a conclusion that rainfall via the secondary forest can lead to further erosion, accelerate the biogeochemical cycle in epikarst zone, enhance the effective state of alkali elements in the soil, supply vegetation with more nutrients and advance vegetation’s growth and succession, which are reasonably sufficient to form a stable karst ecosystem.     

Microstructure characteristics and forming environment of late Quaternary Period loess in the Loess Plateau of China

Since the late Quaternary Period, the rapid rising of the northeastern Qinghai-Tibetan Plateau has greatly changed the East Asian climate and formed different regional monsoon climates. Various microstructures of the loess in northern China have formed under a variety of climatic conditions. The scanning electron microscope (SEM) and energy spectrum analysis are used in this paper to study the relationship between the indexes of loess microstructures and the forming climates, and the indexes include the diameter of sand grains, Ca/Fe value and the characteristic shapes of the loess from SEM microstructures pictures. In terms of their respective climatic circumstances, the major microstructures of regional loess may be classified into nine categories according to their forms and particle sizes, such as loess formed in near-sand source, loess of granule sand dropping, and loess formed in hot and rainy places, i.e. with the loess SEM pictures, climates of about 15 ka b.p. in different places may be evaluated. In conclusion, the clear and distinguishable loess microstructures and their indexes in the Loess Plateau of China can also deduce the evolution of climate, such as warm or cold and wet or dry, and even sandstorm activities when the loess is deposited.