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1.
INTRODUCTIONThe Changbaishan volcano is located in Jilin Province , along the border of China and NorthKorea .It isthelargest nature reservein China .Changbaishan belongstothe northeastern Asian activebelt in the eastern margin of the Euro-Asia plate . The Changbaishan volcano is a gigantic ,polygenetic ,central volcano,and has been active since Holocene .The early eruption started in thePliocene andformedthe basaltic shield. Duringthe middle and late Pleistocene ,the volcanic cone …  相似文献   

2.
Located in Xilin Gol League of Inner Mongolia Autonomous Region,the Xilinhot-Abaga volcanic cluster is in the centre of the Daxing’anling-Datong volcanic eruption belt.More than 300 Quaternary basaltic volcanoes of different types are developed in the volcanic eruption belt.Maars are found for the first time in the study area,with those in Haotewula in the southeast of Abagaqi,and Chelewula and Esigewula in the northwest of Abagaqi to be the most representative.They all are large in scale,with cone diameters generally 3~4km,with the largest up to 6.5km.The maars show intact structure,a similar two-ringed mountain landscape and obviously phased eruption which contained a vigorous phreatomagmatic explosion at the earlier stage,and weak magmatic explosion at the later stage,and basaltic lava effusion in the last stage.The eruption sequence reflects the interaction between magma and water,the change of intrusive speed and outflow rate of magma.The Middle Pleistocene deposits of sand and gravel in the valley are covered by basal surge deposits.The TL age of sandstone-shale "xenolith"which was found in the spatter deposits close to the crater is( 0.112 ± 0.0096) Ma,indicating that the eruption time of the Maars was the early Late Pleistocene.  相似文献   

3.
One of largest eruptions in the Tianchi volcano during the Holocene occurred in about 1000 years ago[1―3]. The volcanic ash erupted had been found in Japan, which is more than 1000 km from the Tianchi volcanic vent[4,5]. Moreover, this eruption has been recognized in the study of Greenland ice core (GISP2)[6,7]. There have been many studies about eruption products of the Tianchi volcano, which dominantly focused on petrological, geochemical and volcanic eruptive dynamic aspects[8―10]. On…  相似文献   

4.
Introduction Changbaishan Tianchi volcano, a dormant volcano in southeastern Jilin Province, northeast- ern China, is the most completely preserved Cenozoic polygenetic compound volcano (LIU, 2000). Study shows that the volcano has erupted many times from mid-late Pleistocene to Holocene and up to modern times (LIU et al, 1992, 1995; SHANGGUAN et al, 1997; SHANGGUAN and SUN, 1996). The latest eruption in A.D. (1215±15) was regarded as one of the largest explosive volcanic erupti…  相似文献   

5.
IntroductionThe Changbaishan-Tianchi volcano, located in Jilin Province, northeast of China, is one of the well-known active volcanoes in China. In the year 1 215(15, the volcano underwent an eruption that is believed to be one of the greatest explosive eruptions on earth in the past 2000 years with regard to its scale and violence. The eruption amounted to over 100 km3, and the eruption cylinder reached a height of more than 30 km, the volcanic ashes floated and fell south of Hokkaido, Jap…  相似文献   

6.
Cosmogenic nuclide burial age of the Sanying Formation and its implications   总被引:1,自引:0,他引:1  
The Pliocene fluvial/lacustrine sediments of the Sanying Formation lie along the Red River fault and its northwest extension;their majority outcrops appear around Eryuan.The Sanying Formation is characterized by multiple intercalated coal layers and its unconformities contact with the underlying Triassic limestone and the overlying Quaternary coarse sediments.Cosmogenic nuclide burial dating confirms the Pliocene age of the Sanying Formation.The burial ages of the overlying Quaternary sediments provide the lower age limit of the Sanying Formation:2 Ma.Detrital zircon U-Pb age distribution suggests provenance of the Sanying Formation traced to the Songpan-Ganzi flysch belt.From the spatial distribution as well as sedimentary and fault ages,we found a strong connection of the Sanying Formation with the Red River and the Jianchuan faults.We therefore propose that activation of the Red River and the Jianchuan faults during the Late Miocene resulted in subsidence of basins in the extensional areas around Eryuan and in the middle to south segments of the Red River fault.The basins were filled with water carried by the Jinsha River and overflow-lakes formed within the basins where the Sanying Formation was deposited.Most of the lakes were dried and sedimentation of the Sanying Formation ceased due to the uplift of the Yunling Mountains,which forced rerouting of the Jinsha River at the beginning of Quaternary.  相似文献   

7.
The Wudalianchi volcano is a modern volcano erupted since the Holocene.Its frequent occurrence of the small earthquake is considered to be indicator of active dormancy volcano.The S wave velocity structure is inferred from the receiver function for the crust and upper mantle of the Wudalianchi volcano area.The results show that the low velocity structure of Swave is widely distributed undemeath the volcano area and part of the low-velocity-zone located at shallow depth in the Wudalianchi volcano area.The low velocity structure is related to the seismicity.The Moho interface is not clear undemeath the volcano area,which may be regard to be an nec-essary condition for the lava upwelling.Therefore,we infer that the Wudalianchi volcano has the deep structural condition for the volcano activity and may be alive again.  相似文献   

8.
There occurred several eruptions from Changbaishan Tianchi volcano in Holocene, and at least three of them were believed to be true according to the formal studies. The products of three eruptions were yellow comenditic pumice of - 5000a B.P. (Eruption Ⅰ ), gray comenditic pumice and pyroclastic flow of - 1000a B.P. ( Eruption II, i.e. the millennium explosive eruption), black trachy pumice and welded tuff of - 300a B.P. ( Eruption Ⅲ ) respectively. There were a large number of melt inclusions found in phenocrysts, which differ in size and color. The Leitz 1350 heating stage experiments for melt inclusions in host feldspars from three Holocene eruptions of Changbaishan Tianchi volcano imply that there were little differences between the homogenization temperatures of melt inclusions from Eruptions Ⅰ and Ⅲ, whereas it was rather complicated for Eruption H, i.e. there might be two kinds of melt with different homogenization temperature periods, which gave the evidence for the assumption that the explosive millennium eruption of Tianchi volcano was triggered by injection and mixing of two different magmas. The experimental results also indicate that ( 1 ) small melt inclusion is easy to be homogenized, while the large one, especially the one with lots of daughter crystals, is rather difficult to be homogenized; (2) homogenization temperature closely correlates with the size of melt inclusion within host crystal, with the temperature point switching from high heating rate to low heating rate, and correlates with whether it is the first time to obtain homogenization as well; and (3) a melt inclusion can get different homogenization temperatures when it is repeatedly heated. Even more, the next homogenization temperature is usually higher than the former one, which testifies the phenomenon that hydrogen migration occurs during repeated heating.  相似文献   

9.
Introduction From the records of Wudalianchi volcanic group eruption in 1720~1721 obtained from the Man ethnic group files of Heilongjiang General Yamen in Qing Dynasty (WU, 1998; CHEN, WU, 2003), we have discovered the eruption time, state, material and scale of Laoheishan and Hu-oshaoshan volcanoes, as well as numerous seismic records. These historical materials are discov-ered for the first time although the study on Wudalianchi volcanic group has a long history. These earthquakes co…  相似文献   

10.
Through detailed field mapping, the tectonic deformation in the front area of the Tianjingshan fault zone is discussed in this paper. The result shows that there are two Quaternary thrust (oblique) fault-fold belts, namely: the Miaoshan and Hongjianshan fault-fold belts, in the front area of the south wall's strike-slip movement of the Tianjingshan fault zone. The Hejiakouzi Quaternary anticline, which is a part of the Miaoshan fault-fold belt, is mainly discussed. It is pointed out that the fold began to grow in the middle part near Hejiakouzi in the mid-late stage of middle Pleistocene epoch and then gradually developed towards the ends in late Quaternary. Based on the Cenozoic structural features, the genesis of the Miaoshan and Hongjianshan fault-fold belts and the kinematic relation they bear with the Tianjingshan fault zone are analyzed.  相似文献   

11.
陈德亮  高歌 《湖泊科学》2003,15(Z1):105-114
近几年来,国家气候中心己经建立了中国主要四大流域气候对水资源影响评估的模式框架.本文拟进一步证明其中之一的两参数分布式月水量平衡水文模式对长江之上汉江和赣江两子流域径流的模拟能力,结果表明该水文模式对目前气候条件下径流模拟效果较好,运行稳定,可用于实时业务运行.在此基础上,利用ECHAM4和HadCM2两GCM(General Circulation Model)未来气候情景模拟结果及目前实测气候情况,对汉江和赣江两子流域的径流对未来气候变化的敏感性进行评估.经检验,两GCM对未来气候,特别是降水情景模拟存在一定差异,因此,造成径流对气候变化的响应不同,这充分反映了全球模式模拟结果不确定性在气候变化影响研究中的重要性.  相似文献   

12.
王昊  冉祥滨  臧家业  刘军  曹磊  刘森  马永星 《湖泊科学》2018,30(5):1246-1259
根据长江与黄河各一个完整水文年的调查数据,并结合历史资料分析了我国这两条大型河流活性硅((RSi,RSi=溶解硅(DSi)+生物硅(BSi))的入海通量及长时间序列的变化规律与影响因素.结果表明,长江与黄河RSi的组成存在显著的差异,二者水体中BSi/RSi的平均比值分别为0.22和0.49;黄河DSi的年平均浓度为长江的74%,而BSi年平均浓度却是长江的3倍.黄河水体中相对较高的BSi浓度反映了黄河流域水体浑浊度与土壤侵蚀程度较高,源自黄土高原高的泥沙输送量是导致黄河水体中BSi浓度较长江高的主要原因.长江与黄河下游RSi通量在丰水期、平水期与枯水期的比值分别为5.3∶3.1∶1.6与3.8∶3.4∶2.8,长江半数以上的RSi入海通量是在丰水期输出的,而黄河在3个时期的差异不明显.相比于径流的变化,1958-2014年间长江DSi通量变化主要是由DSi浓度的变化引起的,流域气候变化(如温度变化)是其浓度及其通量年代际变化的重要原因;而黄河1985-2001年间DSi通量下降是由于径流量与DSi浓度降低的双重原因引起的.气候变化,特别是温度的变化会对流域硅的风化速率与硅的产出产生重要影响,但其具体的影响有待进一步揭示.  相似文献   

13.
Hydrocarbon distribution in sediments from three lakes are related to the level of human activity in the respective drainage basins. Petroleum hydrocarbon contamination is found in surface sediments of a lake surrounded by a major city, compared to no detectable contamination in a lake located in a National Park.  相似文献   

14.
Glaciers on the Tibetan Plateau play an important role in the local hydrological cycle. However, there are only few studies on groundwater in the alpine basins in the Tibetan Plateau which considered the effects of glaciers. Glaciers are extensively distributed in the Dongkemadi River Basin, which is a representative alpine basin in the Yangtze River source region. This study focuses on building a numerical groundwater flow model with glaciations using HydroGeoSphere (HGS) to simulate subglacial meltwater recharge to groundwater in the Dongkemadi River Basin in response to future climate changes. Effects of hydraulic conductivity, precipitation, and temperature on subglacial meltwater recharge to groundwater were discussed. Glacier changes in the future 50 years were predicted under different climate change scenarios. Results show that: (1) the average thickness of the glacier will change significantly; (2) the simulated rate of annual mean subglacial meltwater recharge to groundwater is 4.58 mm, which accounts for 6.33% of total groundwater recharge; and (3) hydraulic conductivity has the largest influence on subglacial meltwater recharge to groundwater, followed by temperature and precipitation. Results of this study are also important to sustainable water resource usage in the Yangtze River source region.  相似文献   

15.
16.
Flooding on the German Rhine during the 20th century was tested for trends and assessed to identify causal mechanisms driving worsening of flooding. A review of previous research outlines the range of impacts due to climate change, land‐use shifts, and river regulation. Analysis of hydrologic data, especially of the long record at Cologne, documents statistically significant increases in both flood magnitudes and frequencies. Specific‐gauge analysis, which isolates the effects of channel modification, documents that 20th century river engineering has caused little of the observed increase in flooding on the German Rhine. Precipitation records from the Rhine basin confirm that flood magnification has been driven by upstream factors, including an increase in flood‐producing precipitation of roughly 25% during the past 100 years and increases in runoff yields. In addition, agricultural land‐use records suggest that flood magnification can be partially explained by 20th century trends documenting intensification and industrialization of German agriculture. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

17.
Based on daily meteorological data at 43 gauging stations in the Pearl River basin and 65 gauging stations in the Yellow River basin, we analyze changing properties of actual evapotranspiration (ETa), reference evapotranspiration (ETref) and precipitation in these two river basins. In our study, Pearl River basin is taken as the ‘energy-limited’ system and the Yellow River basin as the ‘water-limited’ system. The results indicate decreasing ETa in the Pearl River and Yellow River basin. However, different changing properties are detected for ETref when compared to ETa. The middle and upper Yellow River basin are characterized by increasing ETref values, whereas the Pearl River basin is dominated by decreasing ETref values. This result demonstrates enhancing drying force in the Yellow River basin. ETa depends mainly on the changes of precipitation amount in the Yellow River basin. In the Pearl River basin, however, ETa changes are similar to those of ETref, i.e. both are in decreasing trend and which may imply weakening hydrological cycle in the Pearl River basin. Different influencing factors are identified behind the ETa and ETref in the Pearl River and Yellow River basin: In the Pearl River basin, intensifying urbanization and increasing aerosol may contribute much to the evapotranspiration changes. Variations of precipitation amount may largely impact the spatial and temporal patterns of ETa in the Yellow River basin. The current study is practically and scientifically significant for regional assessment of water resource in the arid and humid regions of China under the changing climate.  相似文献   

18.
The East River in the Pearl River basin, China, plays a vital role in the water supply for mega‐cities within and in the vicinity of the Pearl River Delta. Knowledge of statistical variability of streamflow is therefore important for water resources management in the basin. This study analyzed streamflow from four hydrological stations on the East River for a period of 1951–2009, using ensemble empirical mode decomposition (EEMD), continuous wavelet transform (CWT) technique, scanning t and F tests. Results indicated increasing/decreasing streamflow in the East River basin before/after the 1980s. After the early 1970s, the high/low flow components were decreasing/increasing. CWT‐based analysis demonstrates a significant impact of water reservoirs on the periodicity of streamflow. Scanning t and F test indicates that significantly abrupt changes in streamflow are largely influenced by both water reservoirs construction and precipitation changes. Thus, changes of streamflow, which are reflected by variations of trend, periodicity and abrupt change, are due to both water reservoir construction and precipitation changes. Further, the changes of volume of streamflow in the East River are in good agreement with precipitation changes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

19.
20.
1 Origin, process and method of the research Silt deposition created the fertile Dongting and Jianghan Plains of the middle Yangtze drainage, but has become a main cause of the deteriorating flooding along the middle Yangtze. The history of flood and waterlog of the Yangtze River in last century, esp. the disastrous 1998 flood, has proved that the key to the Yangtze flood control is its middle reach, especially the Jingjiang Segment. To study the silt deposition of the middle Yangtze and …  相似文献   

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