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2019 Vol. 38, No. 2

Display Method:
Research progress of sulfuric acid rain participating in the dissolution of carbonate rocks
HUANG Qibo, QIN Xiaoqun, CHENG Ruirui, LI Tengfang, LIU Pengyu
2019, 38(2): 149-156. doi: 10.11932/karst20190201
Abstract:
Carbonate rocks dissolved by carbonic acid plays an important role in contributing to the atmospheric and pedospheric CO2 uptake, which accounts for 94% of the globe carbon sinks of rock weathering. Nowadays, the sulfuric acid rain in karst area of southwest China is serious, and acid rain is widely involved in the dissolution of carbonate rocks. On one hand, the weathering of carbonate rocks with sulfuric acid participation is a net release process of atmospheric CO2, which has a great effect on reducing the sink; on the other hand, the soil formed by the weathering of carbonate rocks and the karst groundwater have higher pH and salt base saturation, which would have a great buffer effect on H+. Thus, atmospheric acid deposition in carbonate rock area will not cause the decrease of HCO3- and pH of groundwater. On the contrary, the salt load produced by relatively high concentrations of SO42- and the ion pairs formed by SO42- with various cations will increase the solubility of calcite and dolomite, which could enhance the carbonate dissolution by H2CO3 and produce more CO2 uptake in karst processes. Therefore, the deficit of CO2 uptake involved in carbonate weathering by sulfuric acid rain may be overvalued, the acid rain can also enhance the dissolution of carbonate rocks, and increase the CO2 consumption by carbonate weathering. We Should combine with the soil buffer capacity and the threshold value to the atmospheric acid deposition and exchange capacity of the soil base ion with the H+ from atmospheric acid deposition, and consider the salt effect, ion pairs and common ion, to objectively evaluate the effect of sulfuric acid rain, after flowing through the limestone soil layer, on the absorption of atmospheric/soil CO2 by carbonate rocks dissolution.
Diurnal variation characteristics of soil respiration and influencing factors in the Maocun karst area, Guilin
WU Xia, PAN Moucheng, CAO Jianhua, ZHU Xiaoyan, ZHANG Meiliang, YANG Hui, TANG Wei, LAN Gaoyong
2019, 38(2): 157-163. doi: 10.11932/karst20190202
Abstract:
This work aimed to reveal the circadian variation of soil respiration in the karst surface zone during summer in the Maocun karst area, Guilin. Using the static camera obscura/gas chromatography, soil respiration diurnal change in the study area was monitored in the background without precipitation. Meanwhile oil temperature, atmospheric temperature, pressure and other the environmental parameters were measured. By virtue of these data, main controlling factors of soil respiration were analyzed statistically. Results show that diurnal variation of soil surface temperature has a single peak which is affected by the change of atmospheric temperature. Soil respiration also displays obvious diurnal change in the study area. The maximum soil respiration appears at 12:40 to 14:40, and the minimum value appears 4:40 to 6:40. The intensity and amplitude of soil respiration in the day are greater than the night. The diurnal variation of soil respiration is mainly influenced by atmospheric temperature in the condition without precipitation. Therefore, atmospheric temperature is the primary controlling factor of soil respiration on a short- term scale. These results can help accurately estimate the carbon budget of the whole ecosystem.
Comparison of soil bacterial community structures from three soil land-use between karst and non-karst areas under three kinds of land use
ZHANG Shuangshuang, JIN Zhenjiang, JIA Yuanhang, LI Qiang
2019, 38(2): 164-172. doi: 10.11932/karst20190203
Abstract:
The purpose of this study is to reveal the effect of microbe on the cycle of soil organic carbon (SOC) in karst areas. Soil samples of paddy fields,maize fields and citrus orchards were collected from a karst area, mixed area and non-karst area at the Maocun karst experimental site in Guilin. The abundance, composition and diversity of microbe were compared based the results from high-throughput sequencing technology. The results show that there are 48,159 sequences with 2,602 OTUs. The dominant phylum of soil bacteria (relative abundance >10%) are Proteobacteria, Acidobacteria and Actinobacteria. The dominant classes (relative abundance >10%) are Acidobacteria and β-proteobateria. The OTUs abundances of both Proteobacteria and Latescibacteria subgroup 6 in the karst area are higher than those in the other two areas. The relative abundances of both subgroup1 and subgroup 2 in the karst area are lower than those in the other areas. Redundancy analysis indicates that SOC, pH and total nitrogen are the key factors to cause microbial changes.
Study on the boundaries and properties of the underground river system in Nandong, Yunnan Province
MO Meixian, WANG Yu, LI Feng, YU Hui
2019, 38(2): 173-185. doi: 10.11932/karst2018y12
Abstract:
With a fixed source of recharge and resource elements, underground river system forms an independent unit in karst groundwater circulation, controlling karst water movement and enrichment, hydrochemical evolution, composition of water resources and environmental geological problems. In order to carry out karst groundwater system research, the primary task is to determine the location of the system boundaries and its hydrogeological properties. In this paper, taking Nandong underground river system as the research object, based on field investigation, exploration, test data, a multi-disciplinary method including modern karstology, geology and hydrogeology are applied. It is conclude that the Nandong underground river system is composed of two subsystems, namely No.1 and No.2 underground river subsystems, and the No.2 underground river system has two full-row type underground subsystems of Pingshiban and Heilongtan.The aquifer is mainly limestone, calcite dolomite and dolomitic limestone of Triassic system. According to the hydrogeological properties of the boundaries, it can be divided into surface watershed boundary, underground watershed boundary, confining boundaries, karst aquifers deep stagnant boundary and other types.
Effect of Ms 7.0 earthquake on travertine landscapes and hydrochmistry of Jiuzhaigou core scenic spots
DANG Zheng, REN Jinhai, AN Chao, DAI Qunwei, DONG Faqin, DENG Yuanming, YANG Qingxia, ZHUO Manta
2019, 38(2): 186-192. doi: 10.11932/karst20190204
Abstract:
There was an earthquake with magnitude of 7.0 occurred in 8th August, 2017. The Jiuzhaigou scenic spot is located in the vicinity of epicenter area which was seriously damaged. After the earthquake, the research group carried out surveys of the scenic spot and collected samples in the surface water of Pearl Shoal, Mirror Lake, Nuorilang Waterfull and Sparking Lake. Through the analysis of the spatial-temporal distribution characteristics and correlation of main ions in the surface water, the damage of the scenic spot landscape and the change of hydrochemical characteristics were preliminarily assessed. Results demonstrated that this earthquake caused the damage including cracking and collapse to some core landscapes in Jiuzhaigou valley, among which the Sparking Lake was the worst damaged. Hydrochemistry of surface water after earthquakes was related to the change of Ca2+ and HCO3- concentrations, both ions were higher than historical data with increasing mineral dissolution caused by earthquake and precipitation. The concentration of Ca2+ and HCO3- decreased with decreasing altitude due to the influence of travertine depositions.The concentration of Ca2+ decreased with time which were related to the precipitation decreases, and the concentration of HCO3- decreased first and then increased with time, it was deduced that CO2 dissolution in water has rose. After the earthquake,the SIc value in surface runoff of 4 landscapes was more than 0,which was easy to travertine deposition. The hydrochemical results show that the earthquake increased the concentration of Ca2+ and HCO3- in the water , if the artificial intervention is implemented in time, the damaged landscape could be restored.
Analysis of cyclic evolution condition of a karst water system in central Huaying mountain
SU Guifen, XU Mo
2019, 38(2): 193-201. doi: 10.11932/karst2019y01
Abstract:
This paper aims to find out the causes and take preventive measures towards karst spring water depletion, water quality degradation and other problems in HuaYing mountains. Based on existing data and site investigations, this paper analyzed the change in the karst groundwater circulation condition under both natural and human activity environments in the central of HuaYing mountain, with main focuses in the changes of water-bearing media, karst water recharge, runoff discharge, hydrochemical characteristics and the resources quantity, etc.The influencing factors causing the change of cycling conditions of karst water system are also analyzed and reasonable suggestions are put forward. The research results have a good guidance for the rational utilization of regional karst water resources and the benign circulation of water environment.
Study on characteristics of chromium pollution in a typical chromium slag contaminated site
XIE Hao, ZOU Shengzhang, ZHOU Changsong, ZHU Danni, CAO Jianwen, LU Haiping
2019, 38(2): 202-207. doi: 10.11932/karst2017y25
Abstract:
In this paper, a chromium slag site near a river in a karst area in southwestern China was selected as the research object. The soil and groundwater samples were collected at different locations and depths of the site. The spatial distribution characteristics of chromium (as Cr) in the site and its influence on groundwater were analyzed by means of mathematical statistics. The results show that the horizontal distribution of total Cr concentration in soil is different, and the concentration of Cr in surface soil decreased significantly from upstream to downstream with a change rate of 3.59 .The distribution of total Cr in deep soil at saturated zone is affected by the flow field of groundwater, and the Cr concentration in downstream is subsequently higher than that in the upstream. The concentration of chromium in vertical profile of miscellaneous backfill soil is different from that of diluvial-residual red clay in the slopes, the Cr concentration in miscellaneous backfill soil increases with the increase of depth, and the relationship between it concentration and soil depth can be represented by . In the red clay section, most of the Cr is gathered on the surface, and then its concentration decreases with the increase of depth, which tends to increase near the bedrock surface. The concentration of Cr (VI) in groundwater samples is affected by total Cr concentration in the deep soil, and the two are positively correlated.
Spatial distribution and evolution characteristics of settlement in Maolan nature reserve of karst area, Guizhou Province
LI Yangbing, LUO Guangjie, XU Qian, XIE Jing
2019, 38(2): 208-216. doi: 10.11932/karst20190205
Abstract:
To explore the characteristics of spatial distribution and evolution of settlement is of great significance to understand the man-environment dynamic in the Nature Reserve Area. In this paper, we studied the spatial distribution and dynamic evolution of settlements in the Maolan Reserve Area with data derived from the interpretation of high resolution imagery and topographic maps from the period of 1963 to 2015. The results showed that, (1) The settlement of the study area are mainly concentrated in 4 experimentation areas. Moreover, from 1963 to 2015, the size of settlement in the experimentation area had been increasing, and in 2005, the settlement agglomeration degree experienced a turning point from which it began to increase from the weakened process. (2) At the same time, the function of the settlement is changing with the increasing of settlement scale, and a new type of ecological tourism settlement is formed. (3) There is a significant positive correlation between the settlement area and the cultivated land area in the peak-cluster depression area of Maolan Reserve Area. The low density of settlements and the low ratio of settlement area to cultivated land area are the basic reasons for the existence of intact vegetation in the study area. The study results are useful to understand the dynamic relationship between human and the environment of Maolan Reserve Area, and provide a reference for the optimal regulation of man-land relationship in the contiguous peak-cluster depression area.
Spatial differences and evolution of economic development of county-level mature resource cities in karst mountainous region:A case study of Xingwen county, Sichuan Province
LUO Huailiang
2019, 38(2): 217-226. doi: 10.11932/karst20190206
Abstract:
Xingwen county is located in the transition zone between Sichuan basin and Yunnan-Guizhou plateau. It covers an area of 1,373 km2 and has jurisdiction over 15 townships with a population of 484,000 and an urbanization rate of 33.19%. The terrain in the county gradually rises from north to south, and large areas of karst landforms occur in the middle and south. There are typical Xingwen-type karsts in Xingwen Stone Field World Geopark. Xingwen county belongs to matured resource-based city at county-level in karst mountainous area, which is dominated by coal, pyrite and limestone mines. Taking the villages and towns of the county as the basic unit, and the last 10 years (2006-2015) as the research period, 15 townships of Xingwen county which is a mountainous and matured resource-based city in karst region at a county level are divided into 4 township groups, namely mining group, tourism and mining group, agriculture group and industry group. The spatial differences and evolution of economic development during the last 10 years (2006-2015) in the county were discussed through analyzing per capita GDP, Theil Index, and separation coefficient. Results show that difference of per capita GDP, Theil Index (increased from 0.1088 to 0.1697, up to 55.97%), and the separation coefficient among villages and towns (the separation factor increased from 2.4041 to 2.8414) have been rising, with an economic spatial difference increasing in the county over the last 10 years. Economic differences in 4 township groups are larger than that among township groups (mean contribution rates for total difference are respectively 70.43% and 29.51%), but rising extent of economic difference among 4 township groups (76.21%) is higher than that in township groups (47.94%). Average Theil index sequence of township groups is as follows, mining group (0.2370)>industrial group (0.0624)> tourism and mining group (0.0581) > agricultural group (0.0108). The Theil Indices of industrial group, mining group and agricultural group increased by 193.13%, 27.69% and 20.18%, respectively, while that of tourism and mining group decreased by 30.95%. The main reasons for spatial difference and evolution of economic development in the county include, economic development being over reliance on resources, development of industrial townships being accelerated by establishment of industrial park, macro-economic effect on mining townships being obvious, double restrictions for tourism and mining townships concluding single exploitation of tourism resources and macro-economic effect on mining, economic development of agricultural township being overall lag and imbalance and so on. In order to promote industrial restructuring and regional coordinated development, these measures should be taken, such as implementing comprehensive development of diversified industries, carrying out differentiated development according to local conditions for the 4 township groups, and paying attention to coordination between economic development and environmental protection, and so on.
Reasons of vegetation degradation in the Southwest China Guizhou Province base on MODIS NDVI data
MA Shibin, YANG Guangbin, AN Yulun, ZHANG Yongrong
2019, 38(2): 227-232. doi: 10.11932/karst20190207
Abstract:
Guizhou Province is located in southwest China, a typical subtropical karst landscape area bordering on Sichuan, Yunnan, Guangxi, Hunan and Chongqing, and is an important ecological barrier in the upper reaches of Pearl River and Yangtze River. Its ecological functions such as water, soil and biodiversity conservations are closely related to the forest ecosystem of the province. The recent years, the forest coverage in Guizhou Province has increased significantly, but in some regions such as Chishui-Xishui area it has decreased drastically. The aim of this study is to examine the major factors that has been driving the forest degradation (expressed in vegetation cover) in the province. In this study, the Mann-kendall change detection method was employed to calculate statistical trends in the Normalized Difference Vegetation Index (NDVI-a spectral index representing vegetation cover), using a 16-year MODIS time series between 2000 and 2015, to identify areas where vegetation cover has significantly decreased (z>2.36,P<0.01). For this purpose, 197 land areas with significant NDVI decrease were selected in the conditions of unchanged forestland type from 2000 to 2015 and each piece of the land size was greater than 10 km2. Pearson correlation coefficients of climate and forest NDVI values for the 197 land areas of interest were calculated to reflect the response of vegetation NDVI to climate change,which include the mean annual and seasonal values, respectively. The 197 Region Of Interest (ROI) are mainly distributed in Chishui-Xishui in the northwest, Mountain Fanjingshan in the northeast and non-karst areas in the southeast of Guizhou Province.The results showed that the NDVI annual mean decrease rate in the ROI is -0.006 per year and the variation rate of NDVI between grids in the all ROI is small. The trend of NDVI change in spring and summer is consistent with the annual NDVI at a rate of -0.01 per year from 2000 to 2015. However, the trend of NDVI change in winter is not significantly increasing. The temperature increases significantly in spring and summer, whereas the precipitation and sunshine time do not change significantly, and the overall climate change has shown a warm and dry trend in the study area during the last 16 years. The core-density analysis of the correlation coefficient shows that the increase of summer temperature is the main driving factor for the decrease of NDVI, which may be due to the increase in temperature that promotes soil evaporation, resulting in the decrease of soil moisture and thus inhibiting the growth of vegetation.
Effects of light rainfall events on spatial variation of soil moisture and leaf water potential of apple tree (Malus pumila Mill.) in a karst graben basin, Yunnan Province
LI Jianhong, PU Junbing, ZHANG Tao, WANG Sainan, XIONG Xiaofeng, HUO Weijie
2019, 38(2): 233-242. doi: 10.11932/karst20190208
Abstract:
Karst graben basins are special type of karst landforms, which are widely distributed in southwestern Sichuan and Eastern Yunnan Province. In mountainous areas of karst graben basins, light rainfall takes a big proportion of annual precipitation with short occurrence. with short occurrence intervals. The purpose of this work is to study the spatial variations and the response processes of soil moisture and leaf water potential of apple tree (Malus pumila Mill.) to such light rainfall events. The results showed that,(1) the light rainfall events in the mountainous area can only supply the soil water to the maximum depth of 10 cm, so in the dry season (before heavy rainfall events), soil moisture declines with the depth in the vertical section. Due to the topography of the depression, soil moisture (0-80 cm) and leaf water potential of apple tree gradually increase along the slope direction from the top to the bottom of the depression. Because of geological background differences, the soil moisture in the west slope (soil-rocky slope) is 2.67% higher than that in the east slope (rocky slope), thus, the drought degree of apple trees on west slopes are less than that east slopes. (2) There were 12 times light rainfall events in 8 days which can make the surface soil moisture (0~10 cm) rise slightly, but failed to completely change the characteristics that the soil moisture in the bottom of the depression was higher than that on both slopes and the soil moisture of west slop was higher than that of east slope. (3) Although light rainfall events can only supply the soil moisture of 0-10 cm, some shallow apple roots can absorb water because of the shallow distribution (5-30 cm) of apple roots in sloping areas. On the other hand, light rainfall events could decrease air temperature, increase humidity and reduce the solar radiation, which could reduce the transpiration of apple tree and the water potential of apple leaves. It is indicated that the light rainfall events can significantly reduce the drought degree of apple trees.
Study on ecological distribution of Arthrodontae mosses and their environmental factors in karst peak-cluster area
LI Fang, WANG Zhihui
2019, 38(2): 243-251. doi: 10.11932/karst20190209
Abstract:
In order to explore the ecological distribution of Arthrodontae mosses in karst peak-cluster area and their environmental influencing factors, three typical karst peak-clusters with different vegetation coverage in Siya river basin of Guiyang were selected for the research, where each peak-cluster was divided into lower slope, middle slope and upper slope according to relative height difference. The mosses were collected by the S-shape sampling method, and they were classified by the peristome teeth types of mosses. The Summed Dominance Ratio(SDR), Sorenson similarity index and RDA were used to analyse the ecological distribution on Arthrodontae and the effect of environmental factors. The results show that 74 species from 26 genera in 11 families were identified in the three karst peak-clusters, including 26 species of acrocarpi-haplolepideae mosses (SDR:97.73%), 21 species of acrocarpi-diplolepideae mosses (SDR:53.35%) and 27 species of pleurocarpi-diplolepideae mosses (SDR:93.01%). The No.1 peak-cluster is dominated by the pleurocarpi-diplolepideae mosses with their SDR value of 100%, while the No.2 and No.3 peak-clusters are dominated by acrocarpi-haplolepideae mosses, and their SDR are 81.80% and 69.75%, respectively. The pleurocarpi-diplolepideae mosses mainly distribute at the bottom of the karst peak-cluster, with SDR of 97.06%, and the middle and top of the peak-cluster is dominated by theacrocarpi-haplolepideae mosses, with SDR of 86.23% and 90.76%, respectively. Furthermore, Sorenson similarity analysis shows that the similarity coefficient of the species of the acrocarpi-haplolepideae mosses is the highest in the middle and top of the peak-cluster, of which the Sorenson similarity is 27.91%; and that of pleurocarpi-diplolepideae mosses in the middle and top of the peak-cluster is the lowest, which is 11.63%. The RDA analysis shows that the distribution of the acrocarpi-haplolepideae mosses is mainly influenced by light intensity and environmental temperature. The extension of the pleurocarpi-diplolepideae mosses is mainly influenced by the relative humidity; while the distribution of the acrocarpi-diplolepideae mosses is mainly affected by the altitude.
Study on the improvement of experimental methods for carbonate mineral bionic synthesis:A case of gas diffusion method
SUN Yuting, QIN Wen, LI Fuchun, ZHANG Chonghong, LYU Jiejie, LI Xuelin
2019, 38(2): 252-257. doi: 10.11932/karst2018y14
Abstract:
In preparing calcium carbonate solution samples by gas diffusion method, the stacking of samples will lead to asynchronous precipitation of dissolved constituents at different layers that in turn cause the increase of experimental error. In this paper, the effect of sample placement height on experimental results was studied, and the method of collecting sediment was optimized. The results showed that the pH, the electrical conductivity and the precipitate weight decreased with the increase of the placement height of the solution. When the Petri dishes are placed in super position, it will affect the mineralization process of the calcium carbonate to a certain extent. In the sediment collection process, the small amount of sediments residue on Petri dishes and/or solution is the main cause of incompletion of sediment collection (or inaccuracy of weight data). The experimental results of this paper have some reference for bionic synthesis of calcium carbonate using gas diffusion method.
Response relationship between chemical composition and dissolution rate of carbonate rocks in the Three Gorges Area
CHEN Rubing, LUO Mingming, LUO Zhaohui, CHEN Zhihua, ZHOU Hong
2019, 38(2): 258-264. doi: 10.11932/karst20190210
Abstract:
In this paper, the chemical dissolution rate of carbonate rocks, aging from the Sinan to Triassic sampled from the Xiangxi river basin, Three Gorges Area, was determined by indoor static water dissolution experiments. The response relationship between the chemical dissolution rate of carbonate rocks and the chemical composition of rocks was discussed, which provides a scientific basis for the quantitative studies of regional karst and aquosity evaluation of karst aquifers. The results show that the dissolution rates of relatively pure carbonate rocks are controlled by the promotion of CaO, SrO and the inhibitory effect of MgO, but these three factors have little influence on the dissolution rate of pure limestone. The acid insoluble substance in carbonate rocks presents an inhibiting tendency on chemical dissolution process. As a result, the dissolution rate of carbonate rocks is influenced by the multi-chemical composition, which comprehensively determines the solubility of carbonate rocks.
Preliminary experimental study on time-temperature effects of gypsum rock corrosion in static water
ZHANG Lingling
2019, 38(2): 265-268. doi: 10.11932/karst20190211
Abstract:
This work studies the time-temperature effects of gypsum rock corrosion in static water in laboratory. The mechanism of gypsum rock corrosion is observed by the Scanning Electron Microscope (SEM) method. The results indicate that gypsum rock would be corroded more seriously with temperature rising and time prolonging. The weight loss rate of gypsum rock increases with temperature rising and time prolonging. The corrosion rate of gypsum rock also increases with the rise of temperature. So does the concentration of Ca2+ in water. The main reasons for gypsum rock corrosion are Fick diffusion and water swelling stress resulted from water absorption. The main corrosion ways of gypsum rock in static water are fracturing caused by water swelling, columnar splitting and flake exfoliation.
Causes of formation and geo-scientific significance of karst gorge group in Xiangxi geopark
JIANG Zhongcheng, ZHANG Jing, HUANG Chao, RONG Yuebing, WU Liangjun
2019, 38(2): 268-275.
Abstract:
Xiangxi geopark has the most densely distributed area of karst gorges in the world with more than 200 karst gorges in an area of about 1,162 km2,which distribute like a spider network.The karst gorges appear in a manner of linear, V-shaped and U-shaped distributions, with a lot of caves, waterfalls and stone pillars along the rock cliffs. Between gorges there are karst table landform and peak cluster mountain,showing a peculiar and spectacular landscape. The alternating extension of silicate carbonate rock and mud carbonate rock, dense tectonic features, high degree joints, inclined uplift earth blocks and strong karst hydrodynamics together provide a favorable condition for the development of karst gorge groups.The formation of the karst gorge group can be divided into three stages: geological tectonic uplift , river gorge formation and karst gorge development. Based on the correlation with other gorges of karst areas in the world, the karst gorge group in Xiangxi is the most typical karst with the largest distribution scale, the densest gorges and the most karst development in the world. Meanwhile, the karst gorge group in Xiangxi has not only important research and geological historic value, but also great significance of geological landscape and mankind cultures.
Evaluation of geological relics tourism resources based on AHP:An example of the Hanzhong Tiankeng group
HONG Zenglin, XU Tong, XUE Xuping
2019, 38(2): 276-280. doi: 10.11932/karst20190213
Abstract:
The Hanzhong Tiankeng group is the first geologic relics discovered in the northern boundary of karst landforms in China. This work made an evaluation to tourism resources of this area to provide scientific basis for its tourism planning and development. Considering ecotourism resource conditions, ecological environment conditions, and ecological tourism development conditions, the evaluation index system include landforms, culture, quality of ecological environment, safety, location, transportation, and social economy. A multiple-layer model was established to conduct a comprehensive evaluation by using the analytic hierarchy process (AHP) method. Results show that this area obtains a score 90.67, implying a feature of fifth class and fairly high value of development in tourism resources.
Geologic conditions and distribution features of Tiankeng groups in Hanzhong, Shaanxi Province
LUO Qianzhou, ZHANG Junliang, LI Yichao, YIN Zongyi, TANG Li, WANG Peng, WANG Yan, ZHANG Shuanhou
2019, 38(2): 281-291. doi: 10.11932/karst20190214
Abstract:
An extensive investigation determines the Tiankeng groups in Hanzhong, Shaanxi Province which are concentrated at four places, Chanjiayan of Ningqiang, Chanjiayan Group, Nanzheng Xiaonanhai of Nanzheng, Luojiaba of Xixiang and Sanyuan of Zhenba. Their geological conditions and genesis are analyzed from stratum lithology, geomorphology and structure. It is considered that the very thick carbonate strata of Permian-Triassic was the material basis for development of these big karst caves. Faults and folds controlled their generation, especially the secondary structure determined their locations. New tectonic uplift and hot and humid climate provide karst dynamic power for the formation of Tiankeng.These Tiankeng groups are clustered in a belt-like pattern in plane with large differences in vertical direction. Most of the caves are located at altitudes of 1,000-2,000 m. These results allow us to understand that the formation of Tiankeng groups has undergone four stage evolution.
Two newly recorded plants from the Hanzhong Tiankeng group
LIU Peiliang, GUO Yaoxin, LI Zhonghu, WANG Mali1, YUE Ming, HONG Zenglin
2019, 38(2): 292-294. doi: 10.11932/karst20190215
Abstract:
The unique geological features of Tiankeng create unique biological groups, and the investigation of these biological groups is important to further reveal the evolution of Tiankeng organisms and the formatting process of Tiankeng. In this paper, two plant species found in the Hanzhong Tiankeng group are recorded to Shaanxi Province for the first time. They are Strobilanthes flexa Benoist of the Family Acanthaceae, and Mahonia bodinieri Gagnep. of the Family Berberidaceae.
2019, 38(2): 295-299.
Abstract: