A high-resolution pollen record of the past 13000 a from Huguangyan Maar Lake reveals the vegetation and environment changes in southern China during the Holocene. It shows that (i) pollen percentage of trees and shru...A high-resolution pollen record of the past 13000 a from Huguangyan Maar Lake reveals the vegetation and environment changes in southern China during the Holocene. It shows that (i) pollen percentage of trees and shrubs reached 56% during the early Holocene (11600―7800 cal a BP), of which the pollen percentage of tropical trees reached a maximum at 9500―8000 cal a BP, reflecting a hot and wet envi- ronment; (ii) during the mid-Holocene (7800―4200 cal a BP), the pollen percentage of montane conif- erous trees and herbs increased, while the percentage of tropical-subtropical trees decreased, indi- cating lower temperature and humidity; (iii) in the late Holocene spanning from 4200 to 350 cal a BP, the pollen percentage of herbs and montane conifer increased significantly, indicating a marked decrease of temperature and humidity. Our pollen data reveal that the time period 9500―8000 cal a BP in south- ern China represents a climatic optimum for the Holocene characterized by hot and wet conditions. This is consistent with the Holocene optimum found in lower latitude regions globally. We speculate that strong insolation might cause the northward migration of the ITCZ and subtropical summer mon- soon front, which resulted in an early Holocene optimum in the Huguangyan area. The dry tendency and climate fluctuations of the middle and late Holocene could be associated with a decrease in solar insolation and frequent ENSO event.展开更多
A new genus and species of basal neoceratopsian dinosaur, Auroraceratops rugosus, is reported based on material from the Early Cretaceous Xinminpu Group in the Gongpoquan Basin of Gansu Province, China. Auroraceratops...A new genus and species of basal neoceratopsian dinosaur, Auroraceratops rugosus, is reported based on material from the Early Cretaceous Xinminpu Group in the Gongpoquan Basin of Gansu Province, China. Auroraceratops is represented by a nearly complete skull and low jaws, and different greatly from all other neoceratopsians by its considerable breadth of the nasals, fungi form expansion of the dorsal end of the lacrimal, highly developed rugosity of the jugal, dentary and surangular, and inflated, striated premaxillary teeth. The finding of Auroraceratops adds diversity and helps elucidate the evolution of basal neoceratopsian dinosaurs.展开更多
The current paper presents landslide hazard analysis around the Cameron area, Malaysia, using advanced artificial neural networks with the help of Geographic Information System (GIS) and remote sensing techniques. Lan...The current paper presents landslide hazard analysis around the Cameron area, Malaysia, using advanced artificial neural networks with the help of Geographic Information System (GIS) and remote sensing techniques. Landslide locations were determined in the study area by interpretation of aerial photographs and from field investigations. Topographical and geological data as well as satellite images were collected, processed, and constructed into a spatial database using GIS and image processing. Ten factors were selected for landslide hazard including: 1) factors related to topography as slope, aspect, and curvature; 2) factors related to geology as lithology and distance from lineament; 3) factors related to drainage as distance from drainage; and 4) factors extracted from TM satellite images as land cover and the vegetation index value. An advanced artificial neural network model has been used to analyze these factors in order to establish the landslide hazard map. The back-propagation training method has been used for the selection of the five different random training sites in order to calculate the factor's weight and then the landslide hazard indices were computed for each of the five hazard maps. Finally, the landslide hazard maps (five cases) were prepared using GIS tools. Results of the landslides hazard maps have been verified using landslide test locations that were not used during the training phase of the neural network. Our findings of verification results show an accuracy of 69%, 75%, 70%, 83% and 86% for training sites 1, 2, 3, 4 and 5 respectively. GIS data was used to efficiently analyze the large volume of data, and the artificial neural network proved to be an effective tool for landslide hazard analysis. The verification results showed sufficient agreement between the presumptive hazard map and the existing data on landslide areas.展开更多
A massive rock and ice avalanche occurred on the western slope of the Ronti Gad valley in the northern part of Chamoli,Indian Himalaya,on 7 February 7,2021.The avalanche on the high mountain slope at an elevation of 5...A massive rock and ice avalanche occurred on the western slope of the Ronti Gad valley in the northern part of Chamoli,Indian Himalaya,on 7 February 7,2021.The avalanche on the high mountain slope at an elevation of 5600 m above sea level triggered a long runout disaster chain,including rock mass avalanche,debris avalanche,and flood.The disaster chain had a horizontal travel distance of larger than 17,600 m and an elevation difference of 4300 m.In this study,the disaster characteristics and dynamic process were analyzed by multitemporal satellite imagery.The results show that the massive rock and ice avalanche was caused by four large expanding discontinuity planes.The disaster chain was divided into five zones by satellite images and field observation,including source zone,transition zone,dynamic entrainment zone,flow deposition zone,and flood zone.The entrainment effect and melting water were recognized as the main causes of the long-runout distance.Based on the seismic wave records and field videos,the time progress of the disaster was analyzed and the velocity of frontal debris at different stages was calculated.The total analyzed disaster duration was 1247 s,and the frontal debris velocity colliding with the second hydropower station was approximately 23 m/s.This study also carried out the numerical simulation of the disaster by rapid mass movement simulation(RAMMS).The numerical results reproduced the dynamic process of the debris avalanche,and the mechanism of long-runout avalanche was further verified by parametric study.Furthermore,this study discussed the potential causes of disaster and flood and the roles of satellite images and seismic networks in the monitoring and early-warning.展开更多
We herein describe an associated partial postcranial skeleton of a theropod dinosaur discovered in the Lower Cretaceous Xinminpu Group of the Yujingzi Basin, in the Jiuquan area of Gausu Province, northwestern China. ...We herein describe an associated partial postcranial skeleton of a theropod dinosaur discovered in the Lower Cretaceous Xinminpu Group of the Yujingzi Basin, in the Jiuquan area of Gausu Province, northwestern China. Features of its humerus, such as strongly expanded proximal and distal ends, a well developed medial tuberosity, distal condyles expressed on the humeral cranial surface, and a hypertrophied entepicondyle, definitively establish the therizinosauroid affinities of the specimen. It differs from other therizinosauroids in having a shallow, poorly demarcated glenoid fossa with a prominent rounded and striated tumescence on the dorsomedial surface of its scapular portion, and a pubis with a strongly concave cranial margin. It represents a new taxon, Suzhousaurus megatherioides gen. et sp. nov. Cladistic analysis recovers Suzhousaurus as the sister taxon of Nothronychus mckinleyi from the mid-Cretaceous of western North America; together, they are basal members of the Therizinosauroidea, more derived than the Early Cretaceous Falcarius and Beipiaosaurus but less derived than Alxasaurus and the Therizinosauridae. Along with ＂Nanshiungosaurus＂ bohlini from possibly coeval beds in the Mazongshan area of northern-most Gansu, Suzhousaurus represents one of the largest-known Early Cretaceous therizinosauroids, demonstrating that this clade attained considerable body size early in its evolutionary history.展开更多
The Neoproterozoic Gaojiacun intrusive complex （GIC） is composed of one big intrusion （ca. 9 × 7.5 km） and numerous satellite intrusions, emplaced in the low-grade schists of the Neoproterozoic Yanbian Group....The Neoproterozoic Gaojiacun intrusive complex （GIC） is composed of one big intrusion （ca. 9 × 7.5 km） and numerous satellite intrusions, emplaced in the low-grade schists of the Neoproterozoic Yanbian Group. The main intrusion is concentrically zoned, with peridotite bodies ＋ leucogabbroids in its core （inner zone） and the sequence： olivine hornblende gabbronorite - porphyric pyroxene hornblende gabbronorite （transitional zone） - pyroxene hornblende gabbronorite ＋ hornblende gabbro ＋ diorite （outer zone）, towards the margins. The satellite intrusions are composed either of a single rock type （peridotite, gabbro, diorite or granite） or of different rock types （peridotite ＋ diorite ＋ granite）. Upper crustal contamination is evidenced by the occurrence of numerous metamorphic enclaves, migmatites and mixed rocks in the outer zone of the main intrusion and in the satellite intrusions. Hornblende （often oikocrystic） is present in all mafic and ultramafic rocks. Cu-Ni （-PGE） deposits occur in several satellite intrusions, hosted in peridotite. The geochemical and mineralogical features of GIC support the presence of a subduction zone at the western edge of the Yangtze Craton. A feederrelated genesis of the satellite intrusions is inferred.展开更多
An integrated approach was performed on the soil, plant-crops and groundwater system at the Thiva basin, to evaluate the extent and intensity of the heavy metal contamination, the percentage of metals transferred into...An integrated approach was performed on the soil, plant-crops and groundwater system at the Thiva basin, to evaluate the extent and intensity of the heavy metal contamination, the percentage of metals transferred into plants/crops （bio-accumulation） and the potential sources of contamination. Heavy metal contents （230--310 Cr, 1200--2200 Ni, 50--80 Co, 880--1150 Mn and 44,500--66,200 Fe all in ppm ） in the Thiva soils are higher than those in the Assopos basin. An increasing trend in the heavy metal contents, from the Assopos to the Thiva basin （Mouriki）, indicates that the metal source is probably the Ni-laterites and ophiolites, located towards north. On the other hand, groundwater samples from domestic and irrigation wells throughout the Thiva basin exhibit relatively low （8--37 ppb） concentrations in Cr compared to the Assopos （up to 150 ppb）. The plots of Cr versus Mg/Ca, Mg/Na versus Ca/Na, B versus Si/（Si ＋ Na） and Mg/Si versus Ca/Si ratios revealed a low degree of salinization in the Thiva compared to that in the Assopos （Avlida） basin. The low Cr concentration （average 23 ppb, during dry period） in the Thiva wells may be related with their depth （〉120 m）, in contrast to shallow wells in the central Euboea （hundreds ppb Cr） and points to a solution of a crucial environmental problem in Euboea and Assopos basin by using the deep karst-type aquifer instead the shallow-Neogene one. The average Cr contents （dry weight） ranges from 1.7 to 4.6 ppm （average 2.2） in carrots, potatoes and onions. The percentage of soil metals Crto^i, Cr（Vl）, Ni, Mn and Fe ranges between 0.06 and 3.2 （average （/.53 ~ 0.4）, whilst that for Cu and Zn ranges from 16 to 81 （average 36 ~ 24）. The Cr transfer to plants is low, due to the high resistance of chromite （main host of Cr）, but the determined Cr contents in plant- crops in the Thiva basin are higher than normal or sufficient vahles. Although mininml uptake for growth and production for Cr, Ni, Zn and Cn is s展开更多
The Dashuigou tellurium(Te) deposit in Shimian city, Sichuan Province is the only known independent Te ore deposit in China. Samples were collected by1/50,000 stream sediment survey and analyzed by inductively coupled...The Dashuigou tellurium(Te) deposit in Shimian city, Sichuan Province is the only known independent Te ore deposit in China. Samples were collected by1/50,000 stream sediment survey and analyzed by inductively coupled plasma–mass spectrometry, X-ray fluorescence spectrometry, emission spectrometry, and atomic absorption spectroscopy. An ore prospecting model for the Dashuigou Te deposit was then established. In the Dashuigou area, bismuth(Bi), Te, and gold(Au) concentrations in stream sediment samples displayed weak-positive anomalies, while silver(Ag) displayed a weaknegative anomaly. Bi, Te, Ag, and Au anomalies are regarded as indicators of Te deposits; the greater the ratio of Te+Bi/Au+Ag, the larger the possibility of an independent tellurobismuthite deposit. The ratio calculated from our samples is 7.288. Five locations were identified for prospecting for Te minerals by this model, including the northern part of the Dashuigou Te deposit, Majiagou,Tizigou, southeastern Miaoping, and northern Baishuihe.These five regions are within the Dashuigou dome anticline, the exposed strata of which are controlled by tracing the tensile shear fracture; the metallogenic geological conditions and geochemical characteristics are the same as those of the known Dashuigou Te deposit. Already, Te–Bi veins have been found in some of these areas.展开更多
Middle Triassic carbonate sequences of Shotori Formation have a thickness of 70 m and are deposited Robat-e-Kalmard region of Tabas city in Central Iran basin. Gradationally and conformably overlying Sorkh shale Forma...Middle Triassic carbonate sequences of Shotori Formation have a thickness of 70 m and are deposited Robat-e-Kalmard region of Tabas city in Central Iran basin. Gradationally and conformably overlying Sorkh shale Formation, Shotori Formation, mostly composed of medium to thick dolomites (50 m), interbeded with thin lime and sandstones, is disconformable by a laterite horizon at its upper boundary. This Formation mainly consists of fine-to-coarsely crystalline dolomites. According to petrographic (fabric and grain size) and geochemical (elemental analysis of Ca, Mg, Na, Sr, Fe, Mn) evidence, five various types of dolomites were recognized in Shotori Formation. This variety results from early and late diagenetic processes, triggering a change in dolomitizing fluids and thereby forming various dolomites. Geochemical studies have revealed that the dolomites of Shotori Formation have formed under meteoric diagenesis and reducing conditions. Various dolomitization mechanisms are proposed for various types of dolomites;that is to say, Sabkha model is considered for type 1 dolomite, mixing zone model for type 2 and 3 dolomites and burial model for type 4 and 5 dolomites.展开更多
This particular section represents a stratotype section for the Lower Cambrian Meishucunian Stage and is also a Chinese candidate for the global stratotype section and point for the Precambrian-Cambrian boundary. In J...This particular section represents a stratotype section for the Lower Cambrian Meishucunian Stage and is also a Chinese candidate for the global stratotype section and point for the Precambrian-Cambrian boundary. In January, 1984, having taken votes, the IUGS-IGCP Project 29 Working Group on Precambrian-Cambrian Boundary recommended the Meishucun section as a global展开更多
In this work we report a methodological procedure with an integrated physical-perceptual approach that allows units of landscape in protected natural areas to be differentiated. First, indirect methods were applied by...In this work we report a methodological procedure with an integrated physical-perceptual approach that allows units of landscape in protected natural areas to be differentiated. First, indirect methods were applied by means of a mapping procedure, which identified the physical components of major relevance. We then generated maps of natural units, anlyzing the “printed” landscape of a territory. Secondly, we developed direct methods to identify and describe the reresentative elements of the landscape, analyzing the “perceived” landscape. The identification and delimitation of these landscape units with geographical information systems provide detailed maps facilitate the tasks of planning and management. The procedure was validated by means of its application in two protected natural spaces. The treatment used here considers landscape not only as an aesthetic element but also as something “live” elaborating maps that should be of use in land planning and management of natural areas.展开更多
Sphagnum, a kind of moss, is a characteristic plant of raised bogs in temperate or cool climate. Modern sphagnum peat is distributed extensively over many districts of the whole world. It is very difficult to distingu...Sphagnum, a kind of moss, is a characteristic plant of raised bogs in temperate or cool climate. Modern sphagnum peat is distributed extensively over many districts of the whole world. It is very difficult to distinguish sphagnum remains from the coal after transformation owing to its limited distribution and minute body. It is well known so far that coal deposits mainly derived from sphagnum have not yet been reported in literature. Recently, a lot of unprecedented and bedded coal layers (named the 'white-light coal' by local people) were discovered in a section of thick coal seam located in Jinsuo brown coal basin in Yunnan Province. In a profile of 26-m thick coal seam, there are 19 layers of thick-展开更多
The Gelmandeh Massive is located in the Central part of Iranian Microcontinent. Amphibolitic rocks occupy the main portion of Gelmandeh complex, which consists of hornblendite, garnet amphibolites, and gneiss. Geochem...The Gelmandeh Massive is located in the Central part of Iranian Microcontinent. Amphibolitic rocks occupy the main portion of Gelmandeh complex, which consists of hornblendite, garnet amphibolites, and gneiss. Geochemical investigations indicate that the ratio of Eu/Eu* separates samples into two categories: first category with ratio of Eu/Eu* > 1 and the second with ratio of Eu/Eu* < 1, which the former indicates an enriched mantle origin while the latter points to crustal contamination. Generally, amphibolites can be differentiated into two separate series. First series is characterized with calc-alkaline to alkaline composition with enriched mantle origin, and the second one has calc-alkaline to tholeiitic nature and it is of continental type that underwent crustal contamination within subduction zone. The microprobe electron analysis shows that the amphiboles were a member of the calcic group and hastingsite-tschermakite series. Geo-barometric studied and mineral paragenesis show that the metamorphism is of Barovian type with PT condition upto 7 K bar and 580°C.展开更多
To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010, we present a short account of our present knowled...To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010, we present a short account of our present knowledge of the Eckfeld Maar after 20 years of continuous research. This paper does not attempt to include all of the detailed results on the geology of the Eckfeld site or its biota. To date, nearly 250 papers and books have been published since the start of our project. An up-to-date list of these publications can be found at www.eckfeldermaar.de.展开更多
Green’s function is well-known, among others, in the application of ambient noise tomography methodologies that may demonstrate the potential of hydrocarbon entrapment in the study area. Here it is also shown to be o...Green’s function is well-known, among others, in the application of ambient noise tomography methodologies that may demonstrate the potential of hydrocarbon entrapment in the study area. Here it is also shown to be of key importance in identifying the fractal dimension in the unified scaling law for earthquakes as well as in studying an explicit relationship of a future strong earthquake epicenter to the average earthquake potential score. Such studies are now in progress.展开更多
We have carried out systematic field investigations on calcareous concretions in the loess sections of Luochuan, Yulin and Weinan of Shaanxi, and Lishi and Wucheng of Shanxi as well as laboratory studies using methods...We have carried out systematic field investigations on calcareous concretions in the loess sections of Luochuan, Yulin and Weinan of Shaanxi, and Lishi and Wucheng of Shanxi as well as laboratory studies using methods of polarizing microscopy, SEM. etc.展开更多
members The sandstones of the Ridge and Athleta of Chari Formation （Callovian-Oxfordian） exposed at Jara have been analyzed for their petrographical and geochemical studies. Texturally, these sandstones are medium t...members The sandstones of the Ridge and Athleta of Chari Formation （Callovian-Oxfordian） exposed at Jara have been analyzed for their petrographical and geochemical studies. Texturally, these sandstones are medium to coarse grained, poorly to well sorted, sub-an- gular to sub-rounded, and show low to medium sphericity. These sandstones were derived from a mixed provenance including granites, granite-gneisses, low and high-grade metamorphic, and some basic rocks of Aravalli range and Nagarparkar massif. The petrofacies analysis reveals that these sandstones belong to the continental block and recycled orogen tectonic regime. The studied sandstones are modified by paleoclimate, distance of transport, and diagenesis. Mineralogically and geochemically, sandstones are classified as quartzarenite, subarkose, arkose, sublithic arenite, and wacke, respectively. The A-CN-K ternary plot and CIA, CIW, PIA, and ICV values suggest that the similar source rocks suffered moderate to high chemical weathering under a hot-humid climate in an acidic envi- ronment with higher Pco2. Generally good to strong cor- relations between AI2O3 and other oxides in these sediments indicate clay mineral control. The K2O/Na2O versus SiO2 diagram indicates that the studied samples occupy passive margin fields but the SiO2/A12O3 versus K2O/Na20 plot suggests that the Athleta Sandstone and Ridge Sandstone fall within the passive margin field, while Ridge Shale falls within the active continental margin field.展开更多
International agreement on the Silurian-Devonian boundary has been reached by selecting the section at Klonk of Barrandian area, Czechoslovakia, as the stratotype and the first simultaneous occurrence of Monograptus u...International agreement on the Silurian-Devonian boundary has been reached by selecting the section at Klonk of Barrandian area, Czechoslovakia, as the stratotype and the first simultaneous occurrence of Monograptus uniformis, Icriodus woschmidti and Warburgella rugulosa rugulosa as the marker of the lowermost Devonian. However, until now only isolated occurrences of these forms have been reported in China. For example, Monograptus of. uniformis was found in the Qinzhou-Fangcheng area, southern Guangxi Province, but unfortunately the geological structure in this area is展开更多
Multiple coal seams and interbedded rock assemblages formed in vertical progression due to the influence of multiple stages of sea level transgressions.Based on mercury injection experiment,low temperature liquid nitr...Multiple coal seams and interbedded rock assemblages formed in vertical progression due to the influence of multiple stages of sea level transgressions.Based on mercury injection experiment,low temperature liquid nitrogen experiment,porosity and permeability experiment and breakthrough pressure experiment,the vertical variation characteristics of coal-bearing strata in Gujiao block are explained in detail.The results of the mercury injection and low temperature liquid nitrogen experiments show that the pore structure characteristics fluctuate with increasing depth in the strata,with fewer micropores followed by transition pores.The BET specific surface area and average pore diameter of the Shanxi Formation are generally larger than those of the Taiyuan Formation.Due to the continuous cyclic sequence stratigraphy changes,the porosity,permeability,breakthrough pressure and breakthrough time of the samples show a certain cyclicity.Within the same sequence,the porosity is larger,and the permeability is smaller near the maximum flooding surface.Although the permeability of the sandstone samples is higher,the porosity is lower,and the breakthrough pressure and breakthrough times are greater.The strata in the study area formed in an oxidized environment that was affected by freshwater,and the pore structure of different lithologies is quite different.After the formation of sandstone,the intergranular pores generally underwent filling with secondary quartz,clay minerals and organic matter,resulting in low porosity and permeability.展开更多
The interest of this research: there is oil seepage at the contact between coal seam-A and sandstone facies of Warukin Formation, so it is necessary to study where is the source rock. The correlation between HI and Tm...The interest of this research: there is oil seepage at the contact between coal seam-A and sandstone facies of Warukin Formation, so it is necessary to study where is the source rock. The correlation between HI and Tmax as result from rock eval pyrolysis shows that the shale of the Warukin Formation is immature while the correlation between HI and OI shows oil prone. The vitrinite (Ro) reflectance of Central Wara coal is between 0.48% up to 0.5% (immature), the content of the vitrinite group is 68.0 - 84.8 (% Vol.), Liptinite 3.0 - 14.0 (% Vol.) and inertinite 0.48 - 25.0 (% Vol.). The high content of liptinite mineral groups (14% Vol.) and the presence of exsudatinite maceral are as an initial indication of bitumenization of oil formation when there is a change in reflectance and fluorescence. Therefore, Central Wara coal plays an important role as the source rock of the Warukin Formation, although the maturity level is immature, the presence of exsudatinite maceral is believed to be the source of origin for producing oil, where the organic material comes from terrestrial.展开更多
基金Supported by the National Natural Science Foundation of China for Distinguished Youth Scholar (Grant No. 40325002)the Key Research Project of the Knowledge Innovation Program of CAS (Grant Nos. KZCX3-SW-145 and KZCX2-YW-117)+1 种基金the National Basic Research Program of China (Grant No. 2005CB422002-2)the National Natural Science Foundation of China (Grant No. 40331011)
文摘A high-resolution pollen record of the past 13000 a from Huguangyan Maar Lake reveals the vegetation and environment changes in southern China during the Holocene. It shows that (i) pollen percentage of trees and shrubs reached 56% during the early Holocene (11600―7800 cal a BP), of which the pollen percentage of tropical trees reached a maximum at 9500―8000 cal a BP, reflecting a hot and wet envi- ronment; (ii) during the mid-Holocene (7800―4200 cal a BP), the pollen percentage of montane conif- erous trees and herbs increased, while the percentage of tropical-subtropical trees decreased, indi- cating lower temperature and humidity; (iii) in the late Holocene spanning from 4200 to 350 cal a BP, the pollen percentage of herbs and montane conifer increased significantly, indicating a marked decrease of temperature and humidity. Our pollen data reveal that the time period 9500―8000 cal a BP in south- ern China represents a climatic optimum for the Holocene characterized by hot and wet conditions. This is consistent with the Holocene optimum found in lower latitude regions globally. We speculate that strong insolation might cause the northward migration of the ITCZ and subtropical summer mon- soon front, which resulted in an early Holocene optimum in the Huguangyan area. The dry tendency and climate fluctuations of the middle and late Holocene could be associated with a decrease in solar insolation and frequent ENSO event.
文摘A new genus and species of basal neoceratopsian dinosaur, Auroraceratops rugosus, is reported based on material from the Early Cretaceous Xinminpu Group in the Gongpoquan Basin of Gansu Province, China. Auroraceratops is represented by a nearly complete skull and low jaws, and different greatly from all other neoceratopsians by its considerable breadth of the nasals, fungi form expansion of the dorsal end of the lacrimal, highly developed rugosity of the jugal, dentary and surangular, and inflated, striated premaxillary teeth. The finding of Auroraceratops adds diversity and helps elucidate the evolution of basal neoceratopsian dinosaurs.
文摘The current paper presents landslide hazard analysis around the Cameron area, Malaysia, using advanced artificial neural networks with the help of Geographic Information System (GIS) and remote sensing techniques. Landslide locations were determined in the study area by interpretation of aerial photographs and from field investigations. Topographical and geological data as well as satellite images were collected, processed, and constructed into a spatial database using GIS and image processing. Ten factors were selected for landslide hazard including: 1) factors related to topography as slope, aspect, and curvature; 2) factors related to geology as lithology and distance from lineament; 3) factors related to drainage as distance from drainage; and 4) factors extracted from TM satellite images as land cover and the vegetation index value. An advanced artificial neural network model has been used to analyze these factors in order to establish the landslide hazard map. The back-propagation training method has been used for the selection of the five different random training sites in order to calculate the factor's weight and then the landslide hazard indices were computed for each of the five hazard maps. Finally, the landslide hazard maps (five cases) were prepared using GIS tools. Results of the landslides hazard maps have been verified using landslide test locations that were not used during the training phase of the neural network. Our findings of verification results show an accuracy of 69%, 75%, 70%, 83% and 86% for training sites 1, 2, 3, 4 and 5 respectively. GIS data was used to efficiently analyze the large volume of data, and the artificial neural network proved to be an effective tool for landslide hazard analysis. The verification results showed sufficient agreement between the presumptive hazard map and the existing data on landslide areas.
文摘A massive rock and ice avalanche occurred on the western slope of the Ronti Gad valley in the northern part of Chamoli,Indian Himalaya,on 7 February 7,2021.The avalanche on the high mountain slope at an elevation of 5600 m above sea level triggered a long runout disaster chain,including rock mass avalanche,debris avalanche,and flood.The disaster chain had a horizontal travel distance of larger than 17,600 m and an elevation difference of 4300 m.In this study,the disaster characteristics and dynamic process were analyzed by multitemporal satellite imagery.The results show that the massive rock and ice avalanche was caused by four large expanding discontinuity planes.The disaster chain was divided into five zones by satellite images and field observation,including source zone,transition zone,dynamic entrainment zone,flow deposition zone,and flood zone.The entrainment effect and melting water were recognized as the main causes of the long-runout distance.Based on the seismic wave records and field videos,the time progress of the disaster was analyzed and the velocity of frontal debris at different stages was calculated.The total analyzed disaster duration was 1247 s,and the frontal debris velocity colliding with the second hydropower station was approximately 23 m/s.This study also carried out the numerical simulation of the disaster by rapid mass movement simulation(RAMMS).The numerical results reproduced the dynamic process of the debris avalanche,and the mechanism of long-runout avalanche was further verified by parametric study.Furthermore,this study discussed the potential causes of disaster and flood and the roles of satellite images and seismic networks in the monitoring and early-warning.
基金We are grateful to Ji Qiang, Tang Zhilu, and Peter Dodson for their generous help. We also thank Zhang Yuqing for the preparation of FRDC-GSJB-99 Equal thanks go to every member of the field team. Early drafts of this paper benefited from discussions with Lindsay Zanno and Bucky Gates. Funding was provided by the Ministry of Science and Technology of China （973 Project： 2006CB701405） to Ji Qiang, the National Natural Science Foundation of China （40672007） the Hundred Talents Project of Ministry of Land and Resources of China to You Hailu, and Bureau of Geology and Mineral Resources of Gansu Province to Li Daqing.
文摘We herein describe an associated partial postcranial skeleton of a theropod dinosaur discovered in the Lower Cretaceous Xinminpu Group of the Yujingzi Basin, in the Jiuquan area of Gausu Province, northwestern China. Features of its humerus, such as strongly expanded proximal and distal ends, a well developed medial tuberosity, distal condyles expressed on the humeral cranial surface, and a hypertrophied entepicondyle, definitively establish the therizinosauroid affinities of the specimen. It differs from other therizinosauroids in having a shallow, poorly demarcated glenoid fossa with a prominent rounded and striated tumescence on the dorsomedial surface of its scapular portion, and a pubis with a strongly concave cranial margin. It represents a new taxon, Suzhousaurus megatherioides gen. et sp. nov. Cladistic analysis recovers Suzhousaurus as the sister taxon of Nothronychus mckinleyi from the mid-Cretaceous of western North America; together, they are basal members of the Therizinosauroidea, more derived than the Early Cretaceous Falcarius and Beipiaosaurus but less derived than Alxasaurus and the Therizinosauridae. Along with ＂Nanshiungosaurus＂ bohlini from possibly coeval beds in the Mazongshan area of northern-most Gansu, Suzhousaurus represents one of the largest-known Early Cretaceous therizinosauroids, demonstrating that this clade attained considerable body size early in its evolutionary history.
文摘The Neoproterozoic Gaojiacun intrusive complex （GIC） is composed of one big intrusion （ca. 9 × 7.5 km） and numerous satellite intrusions, emplaced in the low-grade schists of the Neoproterozoic Yanbian Group. The main intrusion is concentrically zoned, with peridotite bodies ＋ leucogabbroids in its core （inner zone） and the sequence： olivine hornblende gabbronorite - porphyric pyroxene hornblende gabbronorite （transitional zone） - pyroxene hornblende gabbronorite ＋ hornblende gabbro ＋ diorite （outer zone）, towards the margins. The satellite intrusions are composed either of a single rock type （peridotite, gabbro, diorite or granite） or of different rock types （peridotite ＋ diorite ＋ granite）. Upper crustal contamination is evidenced by the occurrence of numerous metamorphic enclaves, migmatites and mixed rocks in the outer zone of the main intrusion and in the satellite intrusions. Hornblende （often oikocrystic） is present in all mafic and ultramafic rocks. Cu-Ni （-PGE） deposits occur in several satellite intrusions, hosted in peridotite. The geochemical and mineralogical features of GIC support the presence of a subduction zone at the western edge of the Yangtze Craton. A feederrelated genesis of the satellite intrusions is inferred.
基金The University of Athens is greatly aeknowledged for the financial support of this work
文摘An integrated approach was performed on the soil, plant-crops and groundwater system at the Thiva basin, to evaluate the extent and intensity of the heavy metal contamination, the percentage of metals transferred into plants/crops （bio-accumulation） and the potential sources of contamination. Heavy metal contents （230--310 Cr, 1200--2200 Ni, 50--80 Co, 880--1150 Mn and 44,500--66,200 Fe all in ppm ） in the Thiva soils are higher than those in the Assopos basin. An increasing trend in the heavy metal contents, from the Assopos to the Thiva basin （Mouriki）, indicates that the metal source is probably the Ni-laterites and ophiolites, located towards north. On the other hand, groundwater samples from domestic and irrigation wells throughout the Thiva basin exhibit relatively low （8--37 ppb） concentrations in Cr compared to the Assopos （up to 150 ppb）. The plots of Cr versus Mg/Ca, Mg/Na versus Ca/Na, B versus Si/（Si ＋ Na） and Mg/Si versus Ca/Si ratios revealed a low degree of salinization in the Thiva compared to that in the Assopos （Avlida） basin. The low Cr concentration （average 23 ppb, during dry period） in the Thiva wells may be related with their depth （〉120 m）, in contrast to shallow wells in the central Euboea （hundreds ppb Cr） and points to a solution of a crucial environmental problem in Euboea and Assopos basin by using the deep karst-type aquifer instead the shallow-Neogene one. The average Cr contents （dry weight） ranges from 1.7 to 4.6 ppm （average 2.2） in carrots, potatoes and onions. The percentage of soil metals Crto^i, Cr（Vl）, Ni, Mn and Fe ranges between 0.06 and 3.2 （average （/.53 ~ 0.4）, whilst that for Cu and Zn ranges from 16 to 81 （average 36 ~ 24）. The Cr transfer to plants is low, due to the high resistance of chromite （main host of Cr）, but the determined Cr contents in plant- crops in the Thiva basin are higher than normal or sufficient vahles. Although mininml uptake for growth and production for Cr, Ni, Zn and Cn is s
基金supported by the Institute of Geochemistry, Chinese Academy of Sciences (03JY029-027-1)Sichuan Geological Survey (12120113051400)the State Key Laboratory of Ore Deposit Geochemistry, Chinese Academy of Sciences for its open program funding
文摘The Dashuigou tellurium(Te) deposit in Shimian city, Sichuan Province is the only known independent Te ore deposit in China. Samples were collected by1/50,000 stream sediment survey and analyzed by inductively coupled plasma–mass spectrometry, X-ray fluorescence spectrometry, emission spectrometry, and atomic absorption spectroscopy. An ore prospecting model for the Dashuigou Te deposit was then established. In the Dashuigou area, bismuth(Bi), Te, and gold(Au) concentrations in stream sediment samples displayed weak-positive anomalies, while silver(Ag) displayed a weaknegative anomaly. Bi, Te, Ag, and Au anomalies are regarded as indicators of Te deposits; the greater the ratio of Te+Bi/Au+Ag, the larger the possibility of an independent tellurobismuthite deposit. The ratio calculated from our samples is 7.288. Five locations were identified for prospecting for Te minerals by this model, including the northern part of the Dashuigou Te deposit, Majiagou,Tizigou, southeastern Miaoping, and northern Baishuihe.These five regions are within the Dashuigou dome anticline, the exposed strata of which are controlled by tracing the tensile shear fracture; the metallogenic geological conditions and geochemical characteristics are the same as those of the known Dashuigou Te deposit. Already, Te–Bi veins have been found in some of these areas.
文摘Middle Triassic carbonate sequences of Shotori Formation have a thickness of 70 m and are deposited Robat-e-Kalmard region of Tabas city in Central Iran basin. Gradationally and conformably overlying Sorkh shale Formation, Shotori Formation, mostly composed of medium to thick dolomites (50 m), interbeded with thin lime and sandstones, is disconformable by a laterite horizon at its upper boundary. This Formation mainly consists of fine-to-coarsely crystalline dolomites. According to petrographic (fabric and grain size) and geochemical (elemental analysis of Ca, Mg, Na, Sr, Fe, Mn) evidence, five various types of dolomites were recognized in Shotori Formation. This variety results from early and late diagenetic processes, triggering a change in dolomitizing fluids and thereby forming various dolomites. Geochemical studies have revealed that the dolomites of Shotori Formation have formed under meteoric diagenesis and reducing conditions. Various dolomitization mechanisms are proposed for various types of dolomites;that is to say, Sabkha model is considered for type 1 dolomite, mixing zone model for type 2 and 3 dolomites and burial model for type 4 and 5 dolomites.
文摘This particular section represents a stratotype section for the Lower Cambrian Meishucunian Stage and is also a Chinese candidate for the global stratotype section and point for the Precambrian-Cambrian boundary. In January, 1984, having taken votes, the IUGS-IGCP Project 29 Working Group on Precambrian-Cambrian Boundary recommended the Meishucun section as a global
文摘In this work we report a methodological procedure with an integrated physical-perceptual approach that allows units of landscape in protected natural areas to be differentiated. First, indirect methods were applied by means of a mapping procedure, which identified the physical components of major relevance. We then generated maps of natural units, anlyzing the “printed” landscape of a territory. Secondly, we developed direct methods to identify and describe the reresentative elements of the landscape, analyzing the “perceived” landscape. The identification and delimitation of these landscape units with geographical information systems provide detailed maps facilitate the tasks of planning and management. The procedure was validated by means of its application in two protected natural spaces. The treatment used here considers landscape not only as an aesthetic element but also as something “live” elaborating maps that should be of use in land planning and management of natural areas.
文摘Sphagnum, a kind of moss, is a characteristic plant of raised bogs in temperate or cool climate. Modern sphagnum peat is distributed extensively over many districts of the whole world. It is very difficult to distinguish sphagnum remains from the coal after transformation owing to its limited distribution and minute body. It is well known so far that coal deposits mainly derived from sphagnum have not yet been reported in literature. Recently, a lot of unprecedented and bedded coal layers (named the 'white-light coal' by local people) were discovered in a section of thick coal seam located in Jinsuo brown coal basin in Yunnan Province. In a profile of 26-m thick coal seam, there are 19 layers of thick-
文摘The Gelmandeh Massive is located in the Central part of Iranian Microcontinent. Amphibolitic rocks occupy the main portion of Gelmandeh complex, which consists of hornblendite, garnet amphibolites, and gneiss. Geochemical investigations indicate that the ratio of Eu/Eu* separates samples into two categories: first category with ratio of Eu/Eu* > 1 and the second with ratio of Eu/Eu* < 1, which the former indicates an enriched mantle origin while the latter points to crustal contamination. Generally, amphibolites can be differentiated into two separate series. First series is characterized with calc-alkaline to alkaline composition with enriched mantle origin, and the second one has calc-alkaline to tholeiitic nature and it is of continental type that underwent crustal contamination within subduction zone. The microprobe electron analysis shows that the amphiboles were a member of the calcic group and hastingsite-tschermakite series. Geo-barometric studied and mineral paragenesis show that the metamorphism is of Barovian type with PT condition upto 7 K bar and 580°C.
基金supported by the Government of Rhineland-PalatinateThe German Science Foundation and the Stiftung Rheinland-Pfalz fur Innovation have financially supported several projects and for this we are grateful.
文摘To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010, we present a short account of our present knowledge of the Eckfeld Maar after 20 years of continuous research. This paper does not attempt to include all of the detailed results on the geology of the Eckfeld site or its biota. To date, nearly 250 papers and books have been published since the start of our project. An up-to-date list of these publications can be found at www.eckfeldermaar.de.
文摘Green’s function is well-known, among others, in the application of ambient noise tomography methodologies that may demonstrate the potential of hydrocarbon entrapment in the study area. Here it is also shown to be of key importance in identifying the fractal dimension in the unified scaling law for earthquakes as well as in studying an explicit relationship of a future strong earthquake epicenter to the average earthquake potential score. Such studies are now in progress.
基金Project supported by the Xi'an Research and Development Section of Loess and Quaternary Geology of Academia Sinica.
文摘We have carried out systematic field investigations on calcareous concretions in the loess sections of Luochuan, Yulin and Weinan of Shaanxi, and Lishi and Wucheng of Shanxi as well as laboratory studies using methods of polarizing microscopy, SEM. etc.
文摘members The sandstones of the Ridge and Athleta of Chari Formation （Callovian-Oxfordian） exposed at Jara have been analyzed for their petrographical and geochemical studies. Texturally, these sandstones are medium to coarse grained, poorly to well sorted, sub-an- gular to sub-rounded, and show low to medium sphericity. These sandstones were derived from a mixed provenance including granites, granite-gneisses, low and high-grade metamorphic, and some basic rocks of Aravalli range and Nagarparkar massif. The petrofacies analysis reveals that these sandstones belong to the continental block and recycled orogen tectonic regime. The studied sandstones are modified by paleoclimate, distance of transport, and diagenesis. Mineralogically and geochemically, sandstones are classified as quartzarenite, subarkose, arkose, sublithic arenite, and wacke, respectively. The A-CN-K ternary plot and CIA, CIW, PIA, and ICV values suggest that the similar source rocks suffered moderate to high chemical weathering under a hot-humid climate in an acidic envi- ronment with higher Pco2. Generally good to strong cor- relations between AI2O3 and other oxides in these sediments indicate clay mineral control. The K2O/Na2O versus SiO2 diagram indicates that the studied samples occupy passive margin fields but the SiO2/A12O3 versus K2O/Na20 plot suggests that the Athleta Sandstone and Ridge Sandstone fall within the passive margin field, while Ridge Shale falls within the active continental margin field.
文摘International agreement on the Silurian-Devonian boundary has been reached by selecting the section at Klonk of Barrandian area, Czechoslovakia, as the stratotype and the first simultaneous occurrence of Monograptus uniformis, Icriodus woschmidti and Warburgella rugulosa rugulosa as the marker of the lowermost Devonian. However, until now only isolated occurrences of these forms have been reported in China. For example, Monograptus of. uniformis was found in the Qinzhou-Fangcheng area, southern Guangxi Province, but unfortunately the geological structure in this area is
基金the National Natural Science Foundation of China(No.41672149 and No.41672146)the Key Project of the Natural Science Foundation of China(No.41530314)+3 种基金the Application Research Plan of Key Scientific Research Projects in Colleges and Universities of Henan Province(20B610006)Scientific Research Foundation of the Shandong Provincial Key Laboratory of Depositional Mineralization&Sedimentary Mineralsthe Shandong University of Science and Technology(DMSM2017012)the National Science and Technology Major Project(2016ZX05044-002).
文摘Multiple coal seams and interbedded rock assemblages formed in vertical progression due to the influence of multiple stages of sea level transgressions.Based on mercury injection experiment,low temperature liquid nitrogen experiment,porosity and permeability experiment and breakthrough pressure experiment,the vertical variation characteristics of coal-bearing strata in Gujiao block are explained in detail.The results of the mercury injection and low temperature liquid nitrogen experiments show that the pore structure characteristics fluctuate with increasing depth in the strata,with fewer micropores followed by transition pores.The BET specific surface area and average pore diameter of the Shanxi Formation are generally larger than those of the Taiyuan Formation.Due to the continuous cyclic sequence stratigraphy changes,the porosity,permeability,breakthrough pressure and breakthrough time of the samples show a certain cyclicity.Within the same sequence,the porosity is larger,and the permeability is smaller near the maximum flooding surface.Although the permeability of the sandstone samples is higher,the porosity is lower,and the breakthrough pressure and breakthrough times are greater.The strata in the study area formed in an oxidized environment that was affected by freshwater,and the pore structure of different lithologies is quite different.After the formation of sandstone,the intergranular pores generally underwent filling with secondary quartz,clay minerals and organic matter,resulting in low porosity and permeability.
文摘The interest of this research: there is oil seepage at the contact between coal seam-A and sandstone facies of Warukin Formation, so it is necessary to study where is the source rock. The correlation between HI and Tmax as result from rock eval pyrolysis shows that the shale of the Warukin Formation is immature while the correlation between HI and OI shows oil prone. The vitrinite (Ro) reflectance of Central Wara coal is between 0.48% up to 0.5% (immature), the content of the vitrinite group is 68.0 - 84.8 (% Vol.), Liptinite 3.0 - 14.0 (% Vol.) and inertinite 0.48 - 25.0 (% Vol.). The high content of liptinite mineral groups (14% Vol.) and the presence of exsudatinite maceral are as an initial indication of bitumenization of oil formation when there is a change in reflectance and fluorescence. Therefore, Central Wara coal plays an important role as the source rock of the Warukin Formation, although the maturity level is immature, the presence of exsudatinite maceral is believed to be the source of origin for producing oil, where the organic material comes from terrestrial.
