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Mounded seismic units in the modern canyon system in the Shenhu area,northern South China Sea:Sediment deformation,depositional structures or the mixed system?
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作者 Xishuang Li Chengyi Zhang +1 位作者 Baohua Liu Lejun Liu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2022年第9期107-116,共10页
The canyon system,including 17 small slope-confined canyons in the Shenhu area,northern South China Sea,is significantly characterized by mounded or undulating features on the canyon flanks and canyon heads.However,th... The canyon system,including 17 small slope-confined canyons in the Shenhu area,northern South China Sea,is significantly characterized by mounded or undulating features on the canyon flanks and canyon heads.However,the mechanism underlying the formation of these features has yet to be elucidated.In previous studies,most of them were interpreted as sediment deformation on the exploration seismic profiles.In this paper,we collected high-resolution bathymetric data,chirp profiles and geotechnical test data to investigate their detailed morphology,internal structures,and origin.The bathymetric data indicated that most mounded seismic units have smooth seafloors and are separated by grooves or depressions.The distance between two adjacent mounded units is only hundreds of meters.On chirp profiles,mounded seismic units usually exhibit chaotic reflections and wavy reflections,of which the crests migrate upslope.The slope stability analysis results revealed that the critical angle of the soil layers in the study area tends to be 9°,indicating that most mounded seismic units on the canyon flanks and heads are stable at present.The terrain characteristics and seismic configurations combined with the slope stability analysis results indicated that most mounded seismic units are not sediment deformation but depositional structures or mixed systems composed of deformation and depositional structures. 展开更多
关键词 northern South China Sea submarine canyons mounded seismic units chirp profile slope stability
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Effects of site preparation methods on soil physical properties and outplanting success of coniferous seedlings in boreal forests
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作者 Aleksey S.Ilintsev Elena N.Nakvasina Alexander P.Bogdanov 《Journal of Forestry Research》 SCIE EI CAS CSCD 2024年第2期70-80,共11页
This study assessed the effect of patch scarification and mounding on the physical properties of the root layer and the success of tree planting in various types of forests.This study was conducted on 12 forest sites ... This study assessed the effect of patch scarification and mounding on the physical properties of the root layer and the success of tree planting in various types of forests.This study was conducted on 12 forest sites in taiga forests of the European part of Russia.A total of 54 plots were set up to assess seedling survival;root collar diameter,height,and heigh increment were measured for 240 seedlings to assess growth.In the rooting layer,240 soil samples were taken to determine physical properties.The study showed that soil treatment methods had no effect on bulk density and total porosity in Cladina sites.However,reduced soil moisture was noted,particularly in mounds,resulting in increased aeration.In Myrtillus sites,there were increased bulk density,reduced soil moisture,and total porosity in the mounds.Mounding treatment in Polytrichum sites resulted in reduced soil moisture and increased aeration porosity.In the Myrtillus and Polytrichum sites,patch scarification had no effects on physical properties.In Polytrichum sites,survival rates,heights,and heigh increments of bareroot Norway spruce seedlings in mounds were higher than in patches;however,the same did not apply to diameter.In Cladina and Myrtillus sites,there was no difference in growth for bareroot and containerised seedlings with different soil treatments.Growing conditions and soil types should be considered when applying different soil treatment methods to ensure high survival rates and successful seedling growth. 展开更多
关键词 Boreal forests Mechanical site preparation Patch scarification MOUNDING Soil properties Containerised seedlings Bareroot seedlings
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Wave Force on the Crown Wall of Rubble Mound Breakwaters at Intermediate Depths
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作者 HAN Xinyu DONG Sheng 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第1期53-64,共12页
Rubble mound breakwaters with a crown wall are a common coastal engineering structure.The wave force on crown walls is an important parameter for the practice engineering design.Particularly,the wave force on crown wa... Rubble mound breakwaters with a crown wall are a common coastal engineering structure.The wave force on crown walls is an important parameter for the practice engineering design.Particularly,the wave force on crown walls under intermediate depths has been studied through physical model tests and numerical simulations.In this study,a three-dimensional numerical wave flume was developed to investigate monochromatic wave interactions in a rubble mound breakwater with a crown wall.Armor blocks were modeled in detail.The Navier-Stokes equations for two-phase incompressible flows,combined with shear stress transport k-ωturbulence model and volume of fluid method for tracking the free surface,were solved.A set of laboratory experiments were performed to validate the adopted model.Subsequently,a series of numerical simulations were implemented to examine the impacts of different hydrodynamic parameters(including wave height,incident wave period,and water depth)and the berm width on the wave force of the crown wall.Finally,a comparison of the experimental results and Martin method shows that the latter method is not suitable for this experimental scope.New empirical formulas are proposed to predict the wave force on crown walls under intermediate depth.The results can provide a basis for the design of crown wall of rubble mound breakwaters at intermediate depths. 展开更多
关键词 wave force crown wall rubble mound breakwater intermediate depth experimental test numerical simulation
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Composite Stratigraphy of the Sailinhudong Group and Ore-bearing Micrite Mounds in the Bayan Obo Deposits,Inner Mongolia,China 被引量:5
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作者 Qiao Xiufu, Gao Linzhi, Peng Yang,Institute of Geology, Chinese Academy of Geological Sciences,26 Baiwanzhuang Rd., Fuchengmenwai, Beijing 100037and Zhang Yuxu Chinese Academy of Geological Sciences, Beijing 100037 Gao Linzhi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1997年第4期357-369,506-507,共15页
Based on studies of sequence stratigraphy, event stratigraphy, biostratigraphy and lithostratigraphy, it is concluded that the Sailinhudong Group is a part of the Bayan Obo Group. Some trilobite fragments are first fo... Based on studies of sequence stratigraphy, event stratigraphy, biostratigraphy and lithostratigraphy, it is concluded that the Sailinhudong Group is a part of the Bayan Obo Group. Some trilobite fragments are first found in thin sections of the rock from the lower part of the Sailinhudong Group and some Ordovician acritarchs and chitinozoans are also found in this group. A formationa unit of carbonate seismites is first recognized in the upper part and a huge micrite mound is first identified at the top. Dolomite, the host rock of the super giant Bayan Obo Fe-Nb-REE deposits, is neither an igneous carbonatite nor a common bedded sedimentary carbonate, but a huge micrite mound. It has the same macroscopic characters as the micrite mounds at the top of the Sailinhudong Group, which suggests that they should be of the same horizon. According to the fossils, the Sailinhudong and Bayan Obo Groups should be of the Early Palaeozoic rather than the Middle Proterozoic. The new discovery and new idea will throw light on the explanation of the genesis of the supergiant Bayan Obo Fe-Nb-REE deposits. 展开更多
关键词 Sailinhudong Group Bayan Obo Group SEISMITE micrite mound
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Formation mechanisms,potentials and exploration practices of large lithologic gas reservoirs in and around an intracratonic rift:Taking the Sinian-Cambrian of Sichuan Basin as an example 被引量:4
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作者 WEI Guoqi YANG Wei +9 位作者 XIE Wuren SU NanX IE Zengye ZENG Fuying MA Shiyu JIN Hui WANG Zhihong ZHU Qiuying HAO Cuiguo WANG Xiaodan 《Petroleum Exploration and Development》 CSCD 2022年第3期530-545,共16页
By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,... By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift. 展开更多
关键词 intracratonic rift large lithologic gas reservoir accumulation mechanism Sichuan Basin Sinian-Cambrian Deying-Anyue rift mound and shoal belt
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Spatial correlation of pit and mound topography with canopy gaps in a virgin mixed beech forest, northern Iran 被引量:2
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作者 Hashem Habashi 《Journal of Forestry Research》 SCIE CAS CSCD 2019年第1期295-303,共9页
In a reserved forest parcel in a virgin eastern Hyrcanian mixed beech forest,80 ha was surveyed to determine the pit and mound topography,canopy gaps and dead trees.The aim was to investigate the spatial patterns and ... In a reserved forest parcel in a virgin eastern Hyrcanian mixed beech forest,80 ha was surveyed to determine the pit and mound topography,canopy gaps and dead trees.The aim was to investigate the spatial patterns and correlation of pit and mound features with canopy gaps.Seventy-five canopy gaps and 61 pit and mound features were identified.The univariate first order nearest neighbor(R_(CE))and bivariate second order test(Ripley’s K)statistic were applied.R_(CE) statistics highlighted a general aggregation pattern for canopy gaps and pits and mounds,while pits and mounds alone were more clumped.Distances between canopy gaps were 130 m average,whereas distances between pit and mound features and dead trees were 60 and 78 m,respectively.Spatial positive correlation of canopy gaps with pits and mounds were observed with all distances.The result of spatial correlations between canopy gaps with pits and mounds confirmed that windthrows cause micro successions in fallen tree ecosystem-scale correlated with gap phase dynamics in the forest community-scale. 展开更多
关键词 PIT and mound CANOPY gap MIXED BEECH SPATIAL pattern SPATIAL correlation
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A Study on Some Causes of Rubble Mound Breakwater Failure 被引量:3
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作者 Zhang Fugui Ge Zhijin Senior Engineer, River and Harbour Department, Nanjing Hydraulic Research Institute, Nanjing 210024 《China Ocean Engineering》 SCIE EI 1996年第4期473-481,共9页
Rubble mound breakwater, one of the protection structures, has been widely used in coastal and port engineering. Block stones were first used as its armor layer, and its use was limited to shallow sea areas where ther... Rubble mound breakwater, one of the protection structures, has been widely used in coastal and port engineering. Block stones were first used as its armor layer, and its use was limited to shallow sea areas where there is no large waves. Since the specially-shaped armor unit was developed, the rubble mound breakwater has become the main sort of the protection structures, which can be used in deep water zones where storm sometimes occurs. Owing to severe and complex surrounding conditions, the rubble mound breakwater failure sometimes occurs, thus the study on the causes of failure is of great importance. In the present study some breakwater failures at home and abroad are illustrated and the causes of failure are investigated from the point of view of design, test, construction and maintenance. 展开更多
关键词 rubble mound breakwater protection structure breakwater failure
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Trace and Rare Earth Element Geochemistry of Micrite Mound Carbonates and Other Related REE Mineralized Carbonates from Bayan Obo Area in Inner Mongolia 被引量:2
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作者 杨晓勇 郑永飞 +3 位作者 杨学明 章雨旭 彭阳 裘丽雯 《Journal of Rare Earths》 SCIE EI CAS CSCD 2005年第2期129-137,共9页
Geochemical study on trace and rare earth element geochemistry was carried out for different carbonates including the very REE-rich ones in the main ore bodies, a carbonatite dyke and two micrite mounds from Heilaobao... Geochemical study on trace and rare earth element geochemistry was carried out for different carbonates including the very REE-rich ones in the main ore bodies, a carbonatite dyke and two micrite mounds from Heilaobao far away from the Bayan Obo ore deposit, and Xishan in west Beijing. The results show that both carbonatite dyke and REE mineralized carbonates (dolomite and marble) in the main ore bodies and outside ore bodies have similarities to each other, with very extreme positive anomaly of Ba, Th, Nb, La, Ce, Nd, Sm, Pb, medium positive anomaly of Y, Ho, Tb, Er, Yb and negative anomaly of Sc, Ti and Cu. The REE concentration in the mineralized carbonates changes greatly, the total REE content changes from 262×10^(-6) in both east and west ore deposits to 104562 ×10^(-6) (10.46%), which is relatively lower than those samples of carbonatite dyke, whose REE contents vary greatly, from 1% up to 20 % of mass fraction. Light REE in the carbonatites are enriched and highly fractionated relative to heavy REE and there is no Eu anomaly. The REE distribution patterns of both mineralized carbonate and carbonatite dyke are of some similarities. However, the sedimentary carbonate micrite of Salinhudong Group in Heilaobao far outside the ore bodies and the pure carbonates from Xishan in Beijing, central part of North China plate, have the similarities in REE distributions with much lower REE contents, which are significantly different from those of carbonatite dyke and REE mineralized carbonate. In Bayan Obo district, both carbonates in the ore deposit and micrite mound outside the ore deposit underwent widespread metasomatism by fluids that resulted in formation of the superlager Fe-Nb-REE mineralization. It appears that the carbonates represent the evolution products of different geological stages. 展开更多
关键词 GEOCHEMISTRY CARBONATE micrite mound trace element rare earth element Bayan Obo
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New high-resolution 2D seismic imaging of fluid escape structures in the Makran subduction zone,Arabian Sea 被引量:4
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作者 Bin Liu Jiang-xin Chen +3 位作者 Syed Waseem Haider Xi-guang Deng Li Yang Min-liang Duan 《China Geology》 2020年第2期269-282,共14页
Seabed fluid escape is active in the Makran subduction zone,Arabian Sea.Based on the new highresolution 2D seismic data,acoustic blanking zones and seafloor mounds are identified.Acoustic blanking zones include three ... Seabed fluid escape is active in the Makran subduction zone,Arabian Sea.Based on the new highresolution 2D seismic data,acoustic blanking zones and seafloor mounds are identified.Acoustic blanking zones include three kinds of geometries:Bell-shaped,vertically columnar and tilted zones.The bellshaped blanking zone is characterized by weak and discontinuous reflections in the interior and upbending reflections on the top,interpreted as gas chimneys.Vertically columnar blanking zone is interpreted as side-imaged gas chimneys associated with focused fluid flow and topped by a seafloor anomaly expressed as a localized reflection discontinuity,which may together serve as a vent structure.Tilted acoustic blanking zone could be induced by accretionary thrust activity and rapid sedimentation surrounding slope.Seafloor mounds occur at the sites of bell-shaped acoustic blanking zone and may be associated with the material intrusion.Bottom simulating refectors(BSRs)are widely distributed and exhibit a series of characteristics including diminished amplitude,low continuity as well as local shoaling overlapping with these acoustic blanking zones.The large amount of gases dissociated from the gas hydrates migrated upwards and then arrived at the near-seafloor sediments,followed by the formation of the gas hydrates and hence the seafloor mound. 展开更多
关键词 MAKRAN Fluid escape structure Gas hydrate Gas chimney Seafloor mound Marine geological survey engineering Pakistan Arabian Sea
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Effects of salt-alkali stress on active oxygen metabolism in roots of Spiraea × bumalda 'Gold Mound' and Spiraea × bumalda 'Gold Flame' 被引量:2
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作者 YAN Yong-qing CHE Dai-di SHI Xi-chan LIU Xing-liang 《Journal of Forestry Research》 SCIE CAS CSCD 2011年第1期59-64,共6页
Under artificially-simulated complex salt-alkali stress, the levels of active oxygen metabolism in roots were studied using three-year-old cutting seedlings of Spiraea × bumalda ‘Gold Mound' and Spiraea × ... Under artificially-simulated complex salt-alkali stress, the levels of active oxygen metabolism in roots were studied using three-year-old cutting seedlings of Spiraea × bumalda ‘Gold Mound' and Spiraea × bumalda ‘Gold Flame'. The present study aimed at exploring the antioxidant capacity in roots of spiraeas and revealing their adaptability to salt-alkali stress. Results indicate that the oxygen free radicals contents, electrolyte leakage rates and MDA contents in roots of Spiraea × bumalda 'Gold Mound' and Spiraea × bumalda 'Gold Flame' show an increasing tendency with the increases of the salinity and pH value, whereas the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) all increased firstly and then decreased. With the increase in intensity of salt-alkali stress, the CAT activity in roots of Spiraea × bumalda ‘Gold Flame' is higher and the increasing extents in the oxygen free radicals contents, electrolyte leakage rates as well as MDA contents are lower compared with Spiraea × bumalda ‘Gold Mound', indicating that Spiraea × bumalda ‘Gold Flame' has a stronger antioxidant capacity. 展开更多
关键词 active oxygen metabolism ROOTS salt-alkali stress Spiraea× bumalda ‘Gold Mound' Spiraea × bumalda ‘Gold Flame'
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具有经济性前景的粗岩屑堆天然冷能集聚分析 (英文) 被引量:1
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作者 Aldar P.Gorbunov Edward V.Severskiy 《冰川冻土》 CSCD 北大核心 2004年第S1期197-200,共4页
The coarse-detrital deposits have the properties of cold accumulation and maintenance of cold for a long time. Now, at some place where the mean annual temperature of air is positive, one even can get the permafrost b... The coarse-detrital deposits have the properties of cold accumulation and maintenance of cold for a long time. Now, at some place where the mean annual temperature of air is positive, one even can get the permafrost by artificial formation of the burial mound. According to these properties, some low-energy storehouses are built for various purposes. 展开更多
关键词 coarse-detrital DEPOSIT PERMAFROST STONE BURIAL mound storehouse
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Segmented evolution of Deyang-Anyue erosion rift trough in Sichuan Basin and its significance for oil and gas exploration, SW China 被引量:1
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作者 MA Kui WEN Long +8 位作者 ZHANG Benjian LI Yong ZHONG Jiayi WANG Yunlong PENG Hanlin ZHANG Xihua YAN Wei DING Yi CHEN Xiao 《Petroleum Exploration and Development》 CSCD 2022年第2期313-326,共14页
Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluate... Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluated. The results show that:(1) Dengying Formation in and around Deyang-Anyue erosion rift trough varies widely in sedimentary characteristics. The Dengying Formation in the northern part of the erosion rift trough developed deep-water sediments, the Dengying Formation in the northern part of the basin varied gradually from basin to slope, platform margin, and restricted platform, and the Dengying Formation in the middle and southern parts of the trough developed carbonate platform facies.(2) Deyang-Anyue erosion rift trough is formed by extensional rift and karst erosion jointly, the north section of the erosion rift trough is mainly the product of tensile rift, while the middle and south sections are formed by erosion in multi-episodes of Tongwan period.(3) Based on the segmented origins of the erosion rift trough, Dengying Formation in and around it is divided into three exploration fields: lithologic mound and beach bodies at the northern platform margin of the basin, karst mound and beach bodies in the central platform, and karst residual mounds in the central southern trough of the basin, among them, the karst residual mounds in the central southern trough of the basin are a new frontier for natural gas exploration in the basin, and the lithologic mound and beach bodies at the northern platform margin are a new position for increasing the reserves of trillions of cubic meters of natural gas resources in the basin. 展开更多
关键词 Sichuan Basin Sinian Dengying Formation deep water deposits erosion rift trough segmented origin karst mounds platform marginal lithologic mounds and shoals
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Deformation monitoring and analysis at two frost mounds during freeze–thaw cycles along the Qinghai–Tibet Engineering Corridor 被引量:1
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作者 LiHui Luo Wei Ma +1 位作者 YanLi Zhuang ZhongQiong Zhang 《Research in Cold and Arid Regions》 CSCD 2017年第4期378-383,共6页
This paper presents various deformation-monitoring technologies employed to monitor the frost heave and thaw settlement of two mounds along the Qinghai–Tibet Engineering Corridor(QTEC), China. The QTEC is known as a ... This paper presents various deformation-monitoring technologies employed to monitor the frost heave and thaw settlement of two mounds along the Qinghai–Tibet Engineering Corridor(QTEC), China. The QTEC is known as a critical infrastructure and passage connecting inland China and the Qinghai–Tibet Plateau(QTP). Three technologies—global navigation satellite system(GNSS), terrestrial laser scanning(TLS), and unmanned aerial vehicle(UAV)—were used to estimate the freeze/thaw–induced 3D surface deformation of two frost mounds. Our results showed that (1) the two frost mounds exhibited mainly thaw settlement in thawing periods and frost heave in the freezing period, but frost heave dominated after repeated freeze–thaw cycles;(2) different zones of the mounds showed different deformation characteristics;(3) active-layer thickness(ALT) and elevation changes were highly correlated during thaw periods;(4) integrated 3D-measurement technologies can achieve a better understanding and assessment of hazards in the permafrost area. 展开更多
关键词 FROST mound thaw SETTLEMENT FROST HEAVE freeze–thaw cycles surface DEFORMATION
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Characteristics and origins of middle Miocene mounds and channels in the northern South China Sea 被引量:1
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作者 Yufeng Li Gongcheng Zhang +3 位作者 Renhai Pu Hongjun Qu Huailei Shen Xueqin Zhao 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第2期65-80,共16页
Numerous elongated mounds and channels were found at the top of the middle Miocene strata using 2D/3D seismic data in the Liwan Sag of Zhujiang River Mouth Basin(ZRMB)and the Beijiao Sag of Qiongdongnan Basin(QDNB).Th... Numerous elongated mounds and channels were found at the top of the middle Miocene strata using 2D/3D seismic data in the Liwan Sag of Zhujiang River Mouth Basin(ZRMB)and the Beijiao Sag of Qiongdongnan Basin(QDNB).They occur at intervals and are rarely revealed by drilling wells in the deepwater areas.Origins of the mounds and channels are controversial and poorly understood.Based on an integrated analysis of the seismic attribute,palaeotectonics and palaeogeography,and drilling well encountering a mound,research results show that these mounds are dominantly distributed on the depression centres and/or slopes of the Liwan and Beijiao sags and developed in a bathyal sedimentary environment.In the Liwan and Beijiao sags,the mounds between channels(sub)parallel to one another are 1.0–1.5 km and 1.5–2.0 km wide,150–300 m and 150–200 m high,and extend straightly from west to east for 5–15 km and 8–20 km,respectively.Mounds and channels in the Liwan Sag are parallel with the regional slope.Mounds and channels in the Beijiao Sag,however,are at a small angle to the regional slope.According to internal geometry,texture and external morphology of mounds,the mounds in Beijiao Sag are divided into weak amplitude parallel reflections(mound type I),blank or chaotic reflections(mound type II),and internal mounded reflections(mound typeⅢ).The mounds in Liwan Sag,however,have the sole type,i.e.,mound type I.Mound type I originates from the incision of bottom currents and/or gravity flows.Mound type II results from gravity-driven sediments such as turbidite.Mound typeⅢis a result of deposition and incision of bottom currents simultaneously.The channels with high amplitude between mounds in the Beijiao and Liwan sags are a result of gravity-flow sediments and it is suggested they are filled by sandstone.Whereas channels with low-mediate amplitudes are filled by bottom-current sediments only in the Beijiao Sag,where they are dominantly composed of mudstone.This study provides new insights into the origins of the mounds and channels worldwide. 展开更多
关键词 South China Sea middle Miocene channels and mounds contour currents
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Characteristics of termite mounds and associated Acrisols in the coastal savanna zone of Ghana and impact on hydraulic conductivity 被引量:1
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作者 Gabriel N. N. Dowuona Pearl Atwere +4 位作者 W. Dubbin Prosper M. Nude Baba E. Mutala Eric K. Nartey Richard J. Heck 《Natural Science》 2012年第7期423-437,共15页
Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy cla... Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy clay in contrast to the sandy clay loam of the surface soils. Translocation of fine to medium sized soil materials influenced the relatively higher bulk density (>1.60 Mg/m3) and contents of organic carbon, nitrogen and exchangeable bases in the mounds. Kaolinite was the dominant clay mineral with pH values generally below 5.3 in all the soils reflecting the weathered tropical soil environment. Dispersion ratio values, which were 0.5 for the surface soils, indicated greater stability of the mound due to aggregate cementing action by the termites. Estimated mound density was about 120 mounds per ha, which tied in with known groundwater reserves at the study sites. Majority of the mounds exhibited a cone-shaped morphology with heights varying between 3.05-4.00 m in the Rhodic Acrisol and 2.05-4.20 m in the Haplic Acrisol with corresponding estimated total mass of 96,361 kg and 54,910 kg per 1000 m2 land area. These estimates represented a large amount of material relative to the 25,000-26,000 kg of surface soil material within the same unit area. The K in the surface soils ranged from 3.3 x 10-5 to 5.0 x 10-5 m/s while the value for the mound was ≤0.5 x 10-5 m/s. Lower porosity, θ;the effect was more pronounced when the mound was applied on the soil surface. Improvement in water retention and nutrient availability to plants and prevention of leaching to avoid groundwater contamination are some of the positive attributes of this study. 展开更多
关键词 AGGREGATE Stability Clay MINERALOGY Dispersion Ratio Hydraulic Conductivity Mound Morphology TERMITE MOUNDS
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Improvement of the Geotechnical Properties of the Soil of Lime-Treated Cubitermes Mound Soil 被引量:2
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作者 Séverin Jean Maixent Loubouth Louis Ahouet +2 位作者 Raymond Gentil Elenga Sylvain Ndinga Okina Paul Louzolo Kimbembe 《Open Journal of Civil Engineering》 2020年第1期22-31,共10页
This work consisted in determining the geotechnical properties of the soil of the Cubitermes termite mound soil treated with lime for use in road construction in accordance with the relevant standards. The raw soil is... This work consisted in determining the geotechnical properties of the soil of the Cubitermes termite mound soil treated with lime for use in road construction in accordance with the relevant standards. The raw soil is composed of 29.45% clay, 45.12% silt and 25.43% sand, and its granulometric curve is above the relevant standard curve. The addition of lime up to 9% decreases the fine fraction content from 75% to 60%, and the maximum dry density from 1.62 t/m3 to 1.36 t/m3. The reduction of the fine fraction should reduce the soil sensitivity to water, and the emission of dust from the road. The compressive strength of the raw soil (3.89 MPa) is higher than that of most cohesive soil, and is probably one the causes of the longevity of the rural road paved with this soil. Treated soil with 6% in lime content has the highest compressive strength (5.95 MPa), and the lowest deformation at failure. Until 28 days, the improvement of the compressive upon the curing time is almost the same for untreated and treated termite mound soils. Thus, this improvement could be mostly attributed to the drying of the samples instead to the pozzolanic reactions. Besides, adding lime also enhances the shear strength of soil. Therefore, adding lime up to 6% in content to the termite mound soil should improve its behavior as surface roads. 展开更多
关键词 Cubitermes Mound SOIL CEBTP 1980 Unpaved ROADS GEOTECHNICAL Properties
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Tectonic paleogeography of Late Sinian and its significances for petroleum exploration in the middle-upper Yangtze region, South China 被引量:2
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作者 WANG Zecheng JIANG Hua +8 位作者 CHEN Zhiyong LIU Jingjiang MA Kui LI Wenzheng XIE Wuren JIANG Qingchun ZHAI Xiufen SHI Shuyuan LI Qi 《Petroleum Exploration and Development》 2020年第5期946-961,共16页
The paleotectonic pattern,lithofacies paleogeographic features,sedimentary evolution and its controlling effects on hydrocarbon accumulation assemblages during the depositional period of the Sinian Dengying Formation ... The paleotectonic pattern,lithofacies paleogeographic features,sedimentary evolution and its controlling effects on hydrocarbon accumulation assemblages during the depositional period of the Sinian Dengying Formation in middle-upper Yangtze region were investigated based on outcrops,drilling,log and seismic data.The study shows that,(1)Affected by the breakup of the Rodinia supercontinent,the middle and upper Yangtze areas were in extensional tectonic environment during the depositional period of Dengying Formation.The carbonate platform was structurally differentiated.Intra-platform depressions controlled by syndepositional faults developed,forming a tectonic-paleogeographic pattern of"three platforms with two depressions".(2)During the depositional period of the first and second members of the Dengying Formation,rimmed platforms and intra-platform fault depressions developed in upper Yangtze area and isolated platform developed in middle Yangtze area,and there was the Xuanhan-Kaijiang ancient land block in eastern Sichuan.The depositional period of the third member of the Dengying Formation is the transformation period of tectonic-paleogeographic pattern,when a set of shallow water shelf sediment rich in mud was deposited due to transgression on the background of the eroded terrain formed in EpisodeⅠof Tongwan Movement.The sediment of the fourth member of the Dengying Formation inherited the paleogeographic pattern of the first and second members of the Dengying Formation in general,but the Deyang-Anyue intra-platform fault depression further expanded,and the middle Yangtze platform evolved into two separated platforms.(3)Tectonic-sedimentary differentiation and evolution of carbonate platform in the Sinian gave rise to two types of accumulation assemblages with wide distribution and great exploration potential,which are platform margin and intra-platform. 展开更多
关键词 tectonic paleogeography structural differentiation intra-platform fault depression rimmed platform microbial mounds and shoals Sinian Dengying Formation Sichuan Basin the middle-upper Yangtze region
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宁夏中卫姚滩段长城四方墩的病害调查 被引量:3
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作者 唐智亮 《岩土工程技术》 2016年第6期282-285,共4页
四方墩长城属于宁夏西长城中卫段。宁夏西长城始筑于汉武帝时代,属汉代万里长城的一部分,由于受风蚀、冻融、雨水冲蚀、洪水冲涮、风沙掩埋等自然作用的破坏,以及蜂、鼠类动物在墙体上打洞、植被根劈等生物作用的破坏,为查清遗址区内敌... 四方墩长城属于宁夏西长城中卫段。宁夏西长城始筑于汉武帝时代,属汉代万里长城的一部分,由于受风蚀、冻融、雨水冲蚀、洪水冲涮、风沙掩埋等自然作用的破坏,以及蜂、鼠类动物在墙体上打洞、植被根劈等生物作用的破坏,为查清遗址区内敌台、城堡、长城的病害的种类及其潜在危险性,并对其进行定性分析,提出预防和治理措施;查明夯土墙体的物理力学与化学性质,为修复保护工程的设计提出详细的工程地质资料和设计所需的相关技术参数的病害调查研究。 展开更多
关键词 夯土体 三维扫描技术 四方墩(敌台) 明长城 土遗址 文物保护 SQUARE mound (enemy station)
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Toxicity and Efficacy of Two Emulsifiable Concentrates of 2-Tridecanone against Red Imported Fire Ants 被引量:2
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作者 Jian Chen 《Advances in Entomology》 2016年第1期37-46,共10页
2-tridecanone is a major constitute of defensive secretion in tawny crazy ants, Nylanderia fulva that is an ant species reported to be able to displace red imported fire ants, Solenopsis invicta in the field. 2-tridec... 2-tridecanone is a major constitute of defensive secretion in tawny crazy ants, Nylanderia fulva that is an ant species reported to be able to displace red imported fire ants, Solenopsis invicta in the field. 2-tridecanone was proven to be toxic to S. invicta. Although 2-tridecanone is commercially available, utilization of this naturally occurring compound in fire ant management has received little attention. In this study, toxicity and efficacy of two 2-tridecanone formulations were assessed against S. invicta. Two emulsifiable concentrates were prepared using 2-tridecanone as an active ingredient, vegetable oil as a solvent and polyoxyethylene tridecyl ether as a surfactant. Piperonyl butoxide (PBO) was used as a synergist in one formulation. Both formulations showed significant toxicity in laboratory bioassays. In a field trial, at application rate of 5.28 mL/L and 14 days after mound drench treatment, 100% control was achieved for formulation with PBO and 90% control for the formulation without PBO. In conclusion, both formulations had significant efficacy against S. invicta. Due to the low mammalian toxicity of 2-tridecanone, no involvement of hazardous synthetic organic solvents, no phytotoxicity at applied concentrations, and relatively low cost, both formulations are promising alternatives to commercial insecticide products for fire ant mound drench. The outstanding efficacy of both formulations observed in this study warrants further research on their efficacy against other pest insects. 展开更多
关键词 Defensive Chemical Fire Ant Control Mound Drench
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Geotechnical Characterization of Termite Mound Soils of Congo 被引量:1
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作者 Louis Ahouet Mondésire Odilon Ngoulou +1 位作者 Sylvain Ndinga Okina Sorel Dzaba 《Open Journal of Civil Engineering》 CAS 2022年第3期370-389,共20页
This study is to determine the activities and correlations in the fundamental properties of the termite mounds soils Cubitermes spp and Macrotermes sp. The Intrinsic properties depend on the mineralogy, organic compos... This study is to determine the activities and correlations in the fundamental properties of the termite mounds soils Cubitermes spp and Macrotermes sp. The Intrinsic properties depend on the mineralogy, organic composition and texture of soil. Grain size, Atterberg limits and soil blue values are geotechnical properties that were used to characterize the two soils. On the basis of the geotechnical properties, specific surface area, cation exchange capacity, relative activity, surface activity and soil activity were determined. The correlations obtained in the intrinsic soil properties are linear and polynomial fits. Indeed, the relationship between the plasticity index and the blue value of a soil on the one hand and between the specific surface area and the cation exchange capacity on the other hand, is a linear fit for all soils in general. The relationship between plasticity index and specific surface area is a linear fit for the soils (C, M). Correlations in intrinsic soil properties that have a coefficient of determination close to 1 can be used in geotechnical engineering to predict one of the two desired parameters. 展开更多
关键词 ACTIVITY Relative Activity Surface Activity Cation Exchange Capacity Specific Surface Termite Mound Soil
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