a framework for karst ecohydrology ecohydrology can be defined as the science of integrating hydrological and biological processes over varied spatial and temporal scales there exists in karst a strong and direct interaction between the circulation and storage of groundwater and surface water these fluxes in turn affect the spatial distribution of organisms in these habitats because of the fact that the appearance storage and circulation of water in karstified areas is significantly different from other more homogenous and isotropic terrains karst ecohydrology should develop original methods and approaches at the same time traditional approaches are also very useful large karst underground geomorphological patterns occur in many sizes and varieties ranging from a few meters long or deep to very large the deepest being deeper than 1km and longer than hundreds of kilometres in this article special attention is paid to ecohydrological functions of karst underground features caves pits conduits etc which play a crucial dual role in 1 hydrology and hydrogeology of water circulation and storage and 2 ecology of many rare and endangered species differences in morphology hydrology hydrogeology and climate have resulted in a range of different environments which provide the opportunity for the coexistence of different species the role of the epikarst and vadose zones as well as caves in ecohydrological processes is discussed the importance of the flood factor in karst ecology is analysed the aim of this article is to move forward the discussion among different disciplines to promote and develop a conceptual framework for karst ecohydrology

provenance of neoproterozoic and early paleozoic siliciclastic rocks of the tepla barrandian unit bohemian massif evidence from u pb detrital zircon ages abstract new la icp ms u pb detrital zircon ages from ediacaran and paleozoic siliciclastic rocks are used to constrain provenance and paleogeographic affinities of the tepla barrandian unit tbu in the centre of the bohemian massif central europe czech republic the samples taken span the period from 635 ma to 385 ma and permit recognition of provenance changes that reflect changes in geotectonic regime detrital zircon age spectra of two ediacaran one lower cambrian and three upper ordovician samples resemble the ages known from the nw african proportion of gondwana particularly the trans saharan belt while three rocks from higher lower cambrian to lowermost ordovician strata contain detritus that may have been derived exclusively from local sources the age spectrum of the devonian rock is a combination of the nw gondwanan and local features these new findings in combination with a wide range of published data are in agreement with a neoproterozoic subduction related setting at the margin of gondwana followed by a cambrian early ordovician rifting stage and an ordovician passive margin setting furthermore the data are in favour of a position of the tbu at the gondwanan margin throughout pre variscan times

three dimensional modeling of near field ground motion with relation to fault geometry and driving force abstract the initial baseline stress is first calculated quasi statically under various loading conditions by using a three dimensional finite element scheme with double nodes to simulate stress on a locked fault once the shear stress at the end of the fault reaches the rupture criterion the accumulated stress is suddenly released simultaneously causing a frictional slip along the fault plane the new state of stress is recalculated by reducing the shear resistance of the faulted plane with the same boundary conditions then the difference between the baseline stress before faulting and the new stress state during faulting is regarded as the driving force to estimate the near field ground motion numerical results show that both the fault geometry and the loading system play an important role in the distribution of the intensity of the ground motion for instance a reactivated pre existing fault in a sedimentary basin would cause greater damage and more subsidence on one side of the fault than on the other side for this to occur a certain dip angle and the gravitational potential must overtake the horizontal driving force to avoid thrust faulting as is evident from the 1976 tangshan earthquake

subsurface flow in a soil mantled subtropical dolomite karst slope a field rainfall simulation study abstract soil and epikarst co evolve resulting in complex structures but their coupled structural effects on hydrological processes are poorly understood in karst regions this study examined the plot scale subsurface flow characteristics from an integrated soil epikarst system perspective in a humid subtropical cockpit karst region of southwest china a trench was excavated to the epikarst lower boundary for collecting individual subsurface flows in five sections with different soil thicknesses four field rainfall simulation experiments were carried out under different initial moisture conditions dry and wet and rainfall intensities 114 mm h 1 high and 46 mm h 1 low on average the soil epikarst system was characterized by shallow soil overlaying a highly irregular epikarst surface with a near steady infiltration rate of about 35 mm h 1 the subsurface flows occurred mainly along the soil epikarst interface and were dominated by preferential flow the subsurface flow hydrographs showed strong spatial variability and had high steady state coefficients 0 52 and 0 36 for high and low rainfall intensity events irregular epikarst surface combining with high vertical drainage capacity resulted in high threshold rainfall depths for subsurface flows 67 mm and 263 mm for initial wet and dry conditions respectively the above results evidenced that the irregular and permeable soil epikarst interface was a crucial component of soil epikarst architecture and consequently should be taken into account in the hydrological modeling for karst regions

tracking paleozoic evolution of the south korean peninsula from detrital zircon records implications for the tectonic history of east asia abstract the southern part of the korean peninsula preserves important records of the paleozoic evolutionary history of east asia here we present shrimp u pb ages of detrital zircon grains from paleozoic metasedimentary successions okcheon and joseon supergroups yeoncheon group taean formation and pyeongan supergroup that are incorporated into the major phanerozoic mountain belts okcheon and hongseong imjingang belts in south korea providing new insights for provenances and paleotectonic evolution of the south korean peninsula during paleozoic time the zircon ages from our samples display two distinct spectra patterns in their presence absence of neoproterozoic and or paleozoic populations our results together with the available data from the korean peninsula suggest that 1 the early to middle paleozoic successions in the okcheon belt were deposited in continental margin setting s formed by neoproterozoic intracratonic rifting 2 the middle paleozoic metasedimentary rocks in the imjingang belt can be interpreted as molasse and flysch sediments along an active continental margin 3 the late paleozoic to early triassic taean formation along the western gyeonggi massif represents a syn to post collision deltaic complex of a remnant oceanic basin and 4 the late paleozoic to possibly early triassic pyeongan supergroup in the okcheon belt might represent a wedge top and or foreland basin the spatial and temporal discrepancy between the south korean peninsula and the central china orogenic belt during paleozoic might reflect lateral variations in crustal evolution history along the east asian continental margin during the paleo tethyan ocean closure

early middle paleozoic intraplate orogeny in the ogcheon belt south korea a new insight on the paleozoic buildup of east asia the polycyclic ogcheon belt of south korea represents the boundary between two precambrian blocks investigation on the timing and kinematics of the block agglomeration is of considerable bearing on the understanding of the constitution of the asian continent we report here structural evidence showing that the earlier tectonic event dates back to early middle paleozoic the ogcheon tectonism or orogeny the ductile piling up of nappes of the ogcheon belt corresponds to an intracontinental orogeny involving the opening and the subsequent closure of an aborted rift and not of a wide oceanic area the nappes contain unequivocal evidence for ductile shearing with a northwest over southeast sense of movement field evidence includes the presence of s1 and s1 2 foliations bearing an extensive stretching lineation perpendicular to the belt associated with a strongly noncoaxial deformation regime the f1 isoclinal folds are commonly a type and sheath folds whose axes are parallel to the stretching lineation whereas the southeast facing f2 recumbent folds have subhorizontal axes parallel to the belt all lines of evidence unconformity superposed deformations age of the metamorphism etc imply that the d1 2 ogcheon tectonism is pre middle carboniferous late silurian early devonian the subsequent indosinian middle triassic f3 upright synfolial folds that trend nne ssw and later structures clearly overprint the middle paleozoic ductile thrusts and isoclinal folds the early paleozoic ogcheon supergroup is formed of a thick volcanosedimentary pile deposited above an early platform sequence in a rift basin on the basis of the geochemical characteristics of the metavolcanics it appears that oceanization did not occur and ogcheon rift aborted soon after it was formed we suggest that middle paleozoic ductile nappe structures have been formed by the structural inversion of the rift extensional features during the ductile stacking episode the early formed foliation and isoclinal folds have been folded in a continuum during the same tectonic event middle carboniferous terrigenous formations have been deposited unconformably upon folded and thrust older rocks a tentative correlation with early paleozoic imjingang qinling and cathaysian belts within the asian continent reveals that ogcheon rift was emplaced within the south china plate and that imjingang belt should represent the limit between north and south china blocks in the korean peninsula

geodynamics of the ogcheon belt south korea abstract the ogcheon belt is a stack of synmetamorphic southeastward verging nappes resulting from the deformation of a volcanosedimentary sequence deposited in an early palaeozoic rift which was affected by polyphase tectonics its pre cretaceous structure results from three main orogenic events the ogcheon late silurian devonian indosinian late permian triassic and yenshanian middle jurassic early cretaceous tectonic phases the external autochthonous or para autochthonous units represent platform zones with shallow water deposits whereas rift facies characterize the internal domain the yeongweol sequence forming an outer shelf on the southeastern margin of the rift displays affinities with the jiangnan basin of south china it is in wrench fault contact with the easternmost duwibong sequence correlated with the north china north korea platform in the internal metamorphic units post cambrian early ordovician pelitic and turbiditic rift metasediments overlie a thin cambrian or cambrian ordovician early platform sequence two subdomains are distinguished the upper units chung ju and pibaryeong units representing the deep axial part of the basin contain distal flyshoids and large olistoliths derived from the northwestern narrow margin the lower units turung san poeun and iwharyeong are related to the wide margin located between the deep rift domain and the stable southeastern platform the latter transitional domain is characterized by thick submarine debris flows and volcanics of alkali or transitional tholeiitic affinity the volcanic activity and mass gravity flow sedimentation are closely related to the crustal thinning and subsequent rifting and tilting lithostratigraphic evidence allows the correlation of the unfossiliferous rift metasediments with the cambrian ordovician platform sequence in one single basin the post middle silurian pre mid carboniferous ogcheon ensialic orogeny resulted in the closure of the rift with relatively minor effects in the platform area it gave rise to an intracontinental fold thrust belt without ophiolites this tectonic event may have been contemporaneous with early palaeozoic tectonism in the quinling belt in central china and in the southeast china fold belt the definitive constitution of the sino korean craton took place before the mid carboniferous and molasse sedimentation was initiated on a single platform located on the western edge of the yakuno oceanic basin of southwest japan in late permian and early triassic times the closure of the oceanic area and the subsequent westward collision of the honshu block are marked in korea by the intracratonic indosinian tectonism since late triassic times predominantly transcurrent movements have occurred along nne ssw faults associated with syntectonic intermontane troughs and important granitization

measurement of field saturated hydraulic conductivity on fractured rock outcrops near altamura southern italy with an adjustable large ring infiltrometer up to now field studies set up to measure field saturated hydraulic conductivity to evaluate contamination risks have employed small cylinders that may not be representative of the scale of measurements in heterogeneous media in this study a large adjustable ring infiltrometer was designed to be installed on site directly on rock to measure its field saturated hydraulic conductivity the proposed device is inexpensive and simple to implement yet also very versatile due to its large adjustable diameter that can be fixed on site it thus allows an improved representation of the natural system s heterogeneity while also taking into consideration irregularities in the soil rock surface the new apparatus was tested on an outcrop of karstic fractured limestone overlying the deep murge aquifer in the south of italy which has recently been affected by untreated sludge disposal derived from municipal and industrial wastewater treatment plants the quasi steady vertical flow into the unsaturated fractures was investigated by measuring water levels during infiltrometer tests simultaneously subsurface electrical resistivity measurements were used to visualize the infiltration of water in the subsoil due to unsaturated water flow in the fractures the proposed experimental apparatus works well on rock outcrops and allows the repetition of infiltration tests at many locations in order to reduce model uncertainties in heterogeneous media

where was south china in the rodinia supercontinent evidence from u pb geochronology and hf isotopes of detrital zircons abstract u pb geochronology and lu hf isotopic studies on detrital zircons from late neoproterozoic sediments of the cathaysia block south china show abundant grenville age 1 0 ga and neoarchaean populations and minor eoarchaean 3 8 ga paleo to mesoarchaean 3 3 3 0 ga mesoproterozoic 1 7 1 4 ga and pan african 0 70 0 54 ga populations this is the first report of 3 8 ga material in the crust of the cathaysia block the presence of euhedral 1 0 ga zircons indicates that a grenville orogenic belt was within or very close to the southern cathaysia block however the provenance containing the 3 8 ga 3 3 3 0 ga 2 5 ga 1 0 ga and 0 70 0 54 ga zircon populations cannot be found in the south china block the combination of zircon age distributions and the rounded strongly abraded shapes of the archean zircons suggesting long transport is consistent with derivation from other continental terranes previously linked with the southern part of the south china block comparison with the tectono magmatic history and compositions of rocks in western laurentia eastern australia and eastern india east antarctica western australia we suggest that these late neoproterozoic sediments may have originated mainly from eastern india east antarctica this indicates that the south china block was linked with the eastern india east antarctica continents in the late neoproterozoic rather than being located between the western laurentia and eastern australia continental blocks u pb and hf isotope studies on detrital zircons provide an important independent constraint on the palaeogeography of the south china block in the context of the breakup of rodinia and the subsequent assembly of gondwana in late neoproterozoic time and insights into the relationship between the cathaysia and yangtze blocks

spatial analysis of soil hydraulic conductivity in a tropical rain forest catchment the topography of first order catchments in a region of western amazonia was found to exhibit distinctive recurrent features a steep straight lower side slope a flat or nearly flat terrace at an intermediate elevation between valley floor and interfluve and an upper side slope connecting interfluve and intermediate terrace a detailed survey of soil saturated hydraulic conductivity ksat depth relationships involving 740 undisturbed soil cores was conducted in a 0 75 ha first order catchment the sampling approach was stratified with respect to the above slope units exploratory data analysis suggested fourth root transformation of batches from the 0 0 1 m depth interval log transformation of batches from the subsequent 0 1 m depth increments and the use of robust estimators of location and scale the ksat of the steep lower side slope decreased from 46 to 0 1 mm h over the overall sampling depth of 0 4 m the corresponding decrease was from 46 to 0 1 mm h on the intermediate terrace from 335 to 0 01 mm h on the upper side slope and from 550 to 0 015 mm h on the interfluve a depthwise comparison of these slope units led to the formulation of several hypotheses concerning the link between ksat and topography

shrimp zircon geochronology and geochemical characteristics of metaplutonic rocks from the south western gyeonggi block korea implications for paleoproterozoic to mesozoic tectonic links between the korean peninsula and eastern china abstract the hongseong area in the south western gyeonggi block of the korean peninsula consists of several precambrian complexes that were regionally metamorphosed during the triassic collision between the north and south china blocks paleoproterozoic and neoproterozoic magmatism and triassic regional metamorphism in the hongseong area suggest a possible tectonic link with the yangtze craton in the south china block the early magmatism in the western hongseong area was neoproterozoic while that in the eastern hongseong area was paleoproterozoic sensitive high resolution ion microprobe shrimp u pb dating of zircon indicates that the neoproterozoic igneous activity occurred at ca 850 830 ma u pb ages of zircon cores and first metamorphic overgrowths in the paleoproterozoic gneisses are indistinguishable 1 88 1 86 ga indicating that the igneous activity and early metamorphism occurred in relatively rapid succession the geochemical signatures indicate an arc tectonic setting for both the paleoproterozoic and neoproterozoic rocks the age and geochemical signatures of the neoproterozoic magmatism can be matched with the neoproterozoic magmatism at the margin of the yangtze craton before amalgamation of the rodinian supercontitnent the paleoproterozoic igneous and metamorphic events may be related to the assembly of the columbian supercontinent both the neoproterozoic igneous rocks and the paleoproterozoic orthogneisses in the hongseong area were regionally metamorphosed in the triassic at ca 235 ma this regional metamorphism is well correlated with metamorphism at the northern margin of the yangtze craton where the qinling dabie sulu uhp metamorphic belt formed due to the triassic collision between the yangtze craton and north china blocks similarities in the overall age distribution and the geographic resemblance between the hongseong area and the northern margin of the yangtze craton show that the hongseong area in the south western gyeonggi block was tectonically linked with the yangtze craton at least since the time of rodinia

mineralogy and geochemistry of metalliferous black slates in the okcheon metamorphic belt korea a metamorphic analogue of black shales in the south china block metalliferous black slates which were locally exploited for their low quality coal are distributed in the late proterozoic to paleozoic okcheon metamorphic belt omb of the korean peninsula the mineralogy of the fine matrix is dominated by either quartz ba v mica graphite or quartz ba feldspar graphite polycrystalline submillimeter ellipsoids and elongate lenses aligned along foliations and veinlets are scattered through the fine matrix both ellipsoids and veinlets include many minor minerals containing rare elements titanite apatite allanite rutile polycrase barite uraninite xenotime armenite zircon molybdenite and sphalerite large graphite apatite ellipsoids nodules with widths of several centimeters also occur in the highly carbonaceous black slates goldmanite occurs locally as porphyroblasts the maximum rare element contents are ba 9 7 v 2 04 mo 0 13 u 0 11 cr 0 33 cu 254 ppm ni 479 ppm zn 607 ppm y 255 ppm platinum group element pge au 309 ppb and carbon 57 the occurrence of the black slates and their elemental abundances suggests that most of the rare elements were accumulated from seawater in an oxygen poor environment however the high ba content of the omb black slates indicates some hydrothermal input into an organic rich basin although metamorphism and multiple deformations prevent a direct temporal and spatial correlation metal abundances and a close association with graphite apatite nodules and low quality coal suggest that the omb black slates are metamorphosed analogues of the early cambrian ba v deposits hosted by the black shales in the south china block

when interflow also percolates downslope travel distances and hillslope process zones copyright 2014 john wiley sons ltd introduction in hillslopes with soils characterized by deep regoliths such as ultisols oxisols and alfisols interflow occurs episodically over impeding layers near and parallel to the soil surface such as low conductivity b horizons e g newman et al 1998 buttle andmcdonald 2002 du et al in review till layers mcglynn et al 1999 bishop et al 2004 hardpans mcdaniel et al 2008 c horizons detty and mcguire 2010 and permeable bedrock tromp van meerveld et al 2007 as perched saturation develops within and above these impeding but permeable horizons flow moves laterally downslope but the perched water also continues to percolate through the impeding horizon to the unsaturated soils and saprolite below perched water and solutes will eventually traverse the zone of perched saturation above the impeding horizon and then enter and percolate through the impeding horizon in such flow situations only lower hillslope segments with sufficient downslope travel distance will deliver water to the riparian zone within the time scale of a storm farther up the slope lateral flow within the zone of perched saturation will act mainly to shift the point of percolation location where a water packet leaves the downslope flow zone in the upper soil layer and enters the impeding layer down the hillslope from the point of infiltration in flatter parts of the hillslope or in areas with little contrast between the conductivities of the upper and impeding soil layers lateral flow distances will be negligible from darcy s law we can estimate the downslope travel distance for quasi steady state conditions within the saturated layer assuming boussinesq slope parallel flow above the restrictive layer and normal flow perpendicular to the slope through the restrictive layer to unsaturated soils below figure 1 using a downslope flow vector we must employ an orthogonal normal vector and avoid harr s 1977 mistake of adding non orthogonal and non independent gradient vectors in calculating flow directions weassume that each layer is isotropic and the impeding layer is saturated or nearly so and drains freely to an unsaturated layer below pressure head equals zero at the base of the impeding layer we assume diffuse porosity within the impeding layer so percolation is not restricted to randomly spaced discontinuities with these assumptions generally applicable to hillslopes with deep regoliths and a low conductivity layer paralleling the soil surface we will calculate downslope travel distances for reasonable combinations of slopes conductivities and impeding layer thicknesses evaluate these distances with respect to typical slope lengths map the downslope travel distances on watersheds with soil and slope conditions matching these assumptions and discuss how couplingboussinesq downslope flow and percolation affect our understanding of the potential zonation of lateral flow processes

neoproterozoic bimodal volcanism in the central ogcheon belt korea age and tectonic implication abstract u pb zircon ages were determined for a metavolcanic rock from the munjuri formation in the central ogcheon belt korea four zircon fractions were analyzed of which three are nearly concordant the data define a discordia with an upper intercept at 755 8 1 3 ma and a lower intercept at 160 19 ma mswd 0 72 the upper intercept age is interpreted to indicate the timing of bimodal volcanism and the lower intercept age is interpreted to reflect jurassic thermal metamorphism this is the first definite evidence supporting the existence of a formation in the ogcheon belt that is at least in part late precambrian nd isotope and trace element geochemistry of the amphibolites and felsic metavolcanics suggests that they originated from a mantle source in a continental rift environment the rift does not appear to have matured enough to develop oceanic crust since rocks indicating deep sea environments are absent the possibility that the ogcheon belt is an extension of the east chinese collision belt as suggested by several authors is not supported by the available evidence

multiple generations of mafic ultramafic rocks from the hongseong suture zone western south korea implications for the geodynamic evolution of ne asia abstract dismembered mafic and serpentinized ultramafic bodies within the hongseong suture zone of the gyeonggi massif southwestern korean peninsula are tectonically correlated with those from the chinese qinling dabie sulu collisional belt we report sensitive high resolution ion microprobe shrimp u pb zircon ages detailed mineral compositions and whole rock geochemical data from the mafic rocks including eclogite and garnetite from the hongseong suture zone the zircon u pb data show multiple protolith ages corresponding to neoproterozoic ca 815 770 ma paleozoic ca 310 ma and middle triassic ca 240 ma the peak high pressure and retrograde regional intermediate pressure metamorphic events of middle triassic ca 240 230 ma are also recorded in zircons from the mafic rocks in the hongseong suture zone the ages and p t estimates presented in this study match well with those of the peak ultra high pressure metamorphism in the sulu area of china our results from the hongseong suture zone provide important insights into the geodynamic history of the ne asian region with evidence for both neoproterozoic subduction and a paleozoic to triassic subduction accretion event

the role of the subcutaneous zone in karst hydrology abstract the subcutaneous zone is the upper weathered layer of rock beneath the soil but above the permanently saturated phreatic zone it is of particular hydrological importance in karst because of its high secondary permeability arising from the considerable chemical solution in this zone however corrosional enlargement of fissures diminishes with depth thus permeability decreases in the same direction with the result that percolation is inhibited except down widened master joints and faults storage of water consequently occurs in this zone particularly after storms the upper surface of this suspended saturated layer in the subcutaneous zone is defined by a perched water table which slopes towards points of rapid vertical percolation the potential induces lateral water movement converging on the most permeable areas such as beneath dolines leakage from the subcutaneous store sustains slow percolation in the vadose zone cross correlation of rainfall with percolation rates in caves in new mexico u s a and new zealand reveal response lags of 2 14 weeks with no apparent relationship to depth below the surface other percolation sites show no correlation with rainfall interpreted as being a consequence of considerable friction in tight fissure networks the recognition of storage and rapid as well as very slow percolation from the subcutaneous zone requires re interpretation of the components of hydrographs from karst springs and of some conceptual models of karst aquifers the importance of subcutaneous storage in sustaining baseflow discharge at some sites must be recognised as must the contribution of subcutaneous water to flood hydrographs methods of estimating the volumes of subcutaneous and phreatic components of karst spring flood hydrographs are presented the paper concludes with a discussion of the significance of subcutaneous hydrologic processes for an understanding of karst geomorphology the desirability of explaining karst landform evolution in terms of hydrologic processes is stressed

soil hydraulic properties on the steep karst hillslopes in northwest guangxi china soil hydraulic properties such as soil infiltration rate and hydraulic conductivity are closely linked to runoff generation and infiltration processes but little is known about them on karst hillslopes the objectives of this paper were to investigate the change in soil stable infiltration rate q s and near saturated hydraulic conductivity k ns in different slope positions and to understand their relationship with rock fragment content and soil texture within the topsoil in subtropical karst regions of southwest china tension infiltrometers 20 cm in diameter were used to measure q s and k ns at pressure head of 20 mm on hillslopes 1 a disintegrated landslide failure and 2 an avalanche slope the change of q s and k ns was great and they mostly had a moderate variability with coefficient of variations cv between 0 1 and 1 0 in the different slope positions on average q s ranged from 0 43 to 4 25 mm min and k ns varied from 0 75 to 11 00 mm min these rates exceed those of most natural rainfall events confirming that overland flow is rare on karst hillslopes from bottom to top q s and k ns had a decrease increase decrease trend due to the presence of large rock outcrops 2 m in height on hillslope 1 but had an increasing trend on hillslope 2 with less complex landform they tended to increase with increase in total rock fragment content 5 250 mm within the topsoil as well as slope gradient on both hillslopes pearson correlation analysis suggested that higher coarse pebble 20 75 mm cobble 75 250 mm and sand 2 0 05 mm contents as well as total rock fragment content could significantly facilitate water infiltration into soils but higher clay 0 002 mm content could restrict water movement this result indicated that rock fragment sand and clay contents may remarkably affect water flow in the topsoil layers and should be considered in hydrological modeling on karst hillslopes in subtropical regions

pretectonic and posttectonic emplacements of the granitoids in the south central okchon belt south korea implications for the timing of strike slip shearing and thrusting structural analyses of three granitic plutons in the south central okchon belt of the korean peninsula reveal that the baegnok and cheongsan plutons are pretectonic with respect to right lateral strike slip ductile shearing along the cheongsan shear zone and later top to the ese thrusting whereas the boeun pluton is posttectonic with respect to these two deformation events u pb sphene age data from the three plutons indicate that the intrusion ages of the baegnok cheongsan and boeun plutons are 222 7 2 1 ma 216 9 2 2 ma and 171 7 1 4 ma respectively microstructural evidence preserved in deformed rocks from the ne striking cheongsan shear zone and adjacent nne striking thrusts suggests that the right lateral ductile shearing event along the shear zone occurred before the ese directed thrusting since these thrusts crosscut the late triassic early jurassic taedong group we estimate that the thrusts developed at 180 ma during the daebo tectonic event just prior to the intrusion of the boeun pluton we also constrain the age of the cheongsan shear zone at middle late triassic time corresponding to the songrim orogeny so that the shear zone is not related to deformation along the middle jurassic honam shear zone 176 ma the honam shear zone is not a simple tectonic boundary between the okchon belt and the yongnam massif but an anastomosing ductile shear zone not only affecting the okchon belt and the yongnam massif but also crosscutting the boundary between them at a low angle we suggest that the right lateral cheongsan shear zone is a major boundary between the okchon zone and the yongnam massif with paleozoic cover rocks the kyonggi massif and the okchon zone south china block were juxtaposed against the yongnam massif and taebaeksan basin north china block along the cheongsan shear zone during a late stage of the middle triassic songrim orogeny probably related to the late paleozoic early mesozoic collision between the north and south china blocks

neoproterozoic bimodal volcanism in the okcheon belt south korea and its comparison with the nanhua rift south china implications for rifting in rodinia abstract a systematic geochemical examination and zircon u pb dating of neoproterozoic bimodal volcanic rocks from the chungju area in the northeast segment of the okcheon metamorphic belt omb south korea allow a comparison with similar rocks from the nanhua rift south china the bimodal metavolcanics of the chungju area comprise the subalkaline to alkaline basalts hereafter mafic metavolcanic rocks and trachytes hereafter felsic metavolcanic rocks the mafic metavolcanic rocks are characterized by light rare earth element lree enriched and humped trace element patterns with moderate depletions in sr and ti and variable but reasonably low end t values between 0 83 and 2 99 these geochemical features are consistent with the area s origin in an ocean island basalt oib mantle source with minor crustal contamination the felsic metavolcanic rocks are characterized by lree enriched patterns with a remarkable negative eu anomaly they display an overall enriched trace element pattern with

hydraulic properties of karst fractures filled with soils and regolith materials implication for their ecohydrological functions abstract in regions with shallow soils underlain by fractured bedrock hydrological processes of substrate are no longer only limited to soil layers however ecohydrological functions of bedrock fractures especially those filled with different soil and regolith materials have not been fully understood in this study we aimed to evaluate water transport and supplying capacities of the filled fractures through investigating hydraulic properties and explore their dominant influencing factors three typical fractures a vertical one filled with fine textured soil vsf a vertical one filled with soil and regolith materials vsrf and a non vertical one filled with coarse textured soil nsf were selected from a large newly excavated trench on a karst hillslope of southwest china stratified samples of fracture fillings were collected to measure saturated hydraulic conductivity k s water retention curves and basic physicochemical properties additionally twenty soil profiles in different topographic locations in the same study area were also analyzed in order to support the results derived from the filled fractures all fractures exhibited extremely high k s 87 149 mm h 1 in surface soil 0 10 cm which allowed rapid infiltration of rainwater into subsurface subsurface water transport was smooth when underlying fracture fillings were loamy with relatively high k s about 10 mm h 1 like in nsf but was blocked when they were clayey with low k s 1 like in vsf and vsrf all fracture fillings had abilities to hold water and available water was the most in nsf which provided an extra water source for plant growth in shallow soil regions the ecohydrological functions of the filled fractures often depend on the properties and layering of fracture fillings which was supported by those obtained from the twenty soil profiles these results are helpful for better understanding of the ecohydrological processes and functions of fractures filled with different materials in karst regions

early to middle paleozoic arc magmatism in the korean peninsula constraints from zircon geochronology and geochemistry abstract the hongseong area of the central southwestern korean peninsula has been tectonically correlated to the qinling dabie sulu collisional belt of the central china orogenic belt here we have presented geochemical and sensitive high resolution ion microprobe shrimp u pb zircon data on the metaigneous rocks from the early to middle paleozoic gwangcheon gneiss located in the middle of the hongseong area our data show u pb ages of ca 450 ma for quartz dioritic gneiss 442 ma for metagabbro 409 407 and 402 ma for tonalitic gneiss 440 ma for intermediate dyke and 401 ma for mafic intrusive the rocks display geochemical features suggesting magma generation within late ordovician ca 450 ma to early devonian ca 401 ma subduction related volcanic arc and subsequent collapsing environment the ages and geochemical characteristics presented in this study correlate well with those of the early to middle paleozoic orogenic belts in the qinling orogenic belt our study provides further insights into the tectonic linkage among paleozoic to triassic east asian continents with evidence for a paleozoic pacific type subduction prior to the triassic alpine type collision

threshold relations in subsurface stormflow 2 the fill and spill hypothesis analysis of subsurface stormflow from 147 storms at the 20 m long trench in the panola mountain research watershed by tromp van meerveld and mcdonnell 2006a showed that there was a distinct 55 mm precipitation threshold for significant subsurface stormflow production this second paper in the series investigates the processes responsible for this threshold response we installed a dense spatial array of maximum rise crest stage gauges and recording wells on the hillslope and studied the temporal and spatial patterns of transient saturation at the soil bedrock interface and its relation to subsurface stormflow measured at the trench face results show that while transient groundwater developed on parts of the hillslope during events smaller than 55 mm it was not until more than 55 mm of rain fell before bedrock depressions on the hillslope were filled water spilled over microtopographic relief in the bedrock surface and the subsurface saturated areas became connected to the trench when connectivity was achieved the instantaneous subsurface stormflow rate increased more than fivefold compared to before the subsurface saturated areas were connected to the trench face total subsurface stormflow was more than 75 times larger when connectivity was achieved compared to when connectivity was not achieved the fill and spill hypothesis presented in this paper is a process explanation for the observed threshold behavior of tromp van meerveld and mcdonnell 2006a thereby linking patterns and processes

constructing a saturated hydraulic conductivity map of spain using pedotransfer functions and spatial prediction abstract currently most of the research focused on general pedotransfer functions ptfs has been generated under humid climatic conditions nevertheless this article proposes an estimation of pedotransfer functions for a great variety of climatic and physiographic conditions with a predominance of soils developed under semi arid conditions such as those occurring in spain the results obtained in spite of the variety of measuring methods of the variables used show that it is possible to estimate saturated hydraulic conductivity values for soils from sand content data these are compared with results obtained from the application of other authors ptfs this is an important support to the present attempts at establishing soil inference systems the ptfs obtained have increased the number of profile points in networks with saturated hydraulic conductivity data allowing the transformation of point data to a continuous saturated hydraulic conductivity surface to reach this goal three methods have been applied that of batjes inverse distance weight and kriging interpolation with the latter giving the best results finally a saturated hydraulic conductivity map with a spatial resolution of 1 1 km for the spanish part of the iberian peninsula has been generated the resulting map showed a good spatial fit after being compared with lithological distribution which confirms the applicability of the method for future hydrological applications

significance of preferential flow at the rock soil interface in a semi arid karst environment abstract in many semi arid environments the surface materials are frequently characterized by thin soils and large proportions of bare rock both of which are expected to considerably influence infiltration and groundwater recharge processes in this study small plot scale irrigation experiments in combination with dye tracer application as well as real time and subsequent soil moisture measurements and soil particle size analysis were conducted to investigate the significance of preferential flow at the rock soil interface large scale assessments of soil depth and surface type distribution were used to upscale the findings of the irrigation experiments to the scale of a complete hillslope and further to estimate percolation properties of a hypothetical rainfall event the two experimental plots were each located in the west bank mountains close to ramallah each irrigation experiment was designed with 50 mm of precipitation applied on an area of 1 m 2 during the course of ca 2 5 h each irrigation plot had a surface share of approximately 50 rock outcrop and 50 soil surface percolation properties were investigated by subsequent soil moisture measurements at high spatial resolution on vertical soil profiles on the irrigated plot dye tracer application on the rock outcrop during the sprinkling allowed for tracking of resulting outcrop runoff in the subsurface the soil depth survey included 2100 measurement points on 7 transects which allowed the estimation of local soil depth distribution results of the irrigation experiments showed that precipitation induced runoff from rock outcrops continued below ground as preferential flow along the rock soil interface while water from the soil surface percolated mainly vertically and much more homogeneously this was evident from the high density soil moisture measurements as well as from the dye tracer patterns outcrop runoff percolated faster and to greater depths than water infiltrating directly from the soil surface thus possessing a greater potential for groundwater recharge

tectonometamorphic evolution of the permo triassic songrim indosinian orogeny evidence from the late paleozoic pyeongan supergroup in the northeastern taebaeksan basin south korea the deformed and metamorphosed middle pennsylvanian to early triassic rocks of the pyeongan supergroup occurring in northeastern flank of the paleozoic taebaeksan basin east central south korea record the impact of the late permian triassic songrim indosinian collisional orogeny in the eastern eurasia margin analysis of meso and microstructures and their relationship with porphyroblast growth has revealed that these metasedimentary rocks were affected by four deformation events d1 d4 during the polyphase deformations successive foliations with alternately steep s1 and s3 and flat lying s2 and s4 orientations were produced with growth of chloritoid andalusite and kyanite porphyroblasts during d1 and d2 and growth of garnet staurolite and andalusite porphyroblasts during d3 and d4 shrimp u pb detrital zircon ages 330 310 ma from metapelites in the oldest unit of the pyeongan supergroup in the study area combined with the previous data on sandstone compositions indicate magmatic activity that was contemporaneous with the initial deposition of the pyeongan supergroup this also suggests that the pyeongan supergroup was deposited in an arc related foreland basin at an active continental margin during the late carboniferous and permian time two contractional deformation events d1 and d3 and two events related to gravitational flattening d2 and d4 along with barrovian type medium pressure regional metamorphism may have resulted from the late permian triassic songrim orogeny related to collision between the north and south china blocks and or collision between the eastern eurasia margin and the proto japan terrane

role of epikarst in near surface hydrological processes in a soil mantled subtropical dolomite karst slope implications of field rainfall simulation experiments epikarst exerts a strong control on run off generation in karst regions but it is still unclear in karst regions our study aimed to demonstrate the effect of epikarst on near surface hydrological processes in a subtropical cockpit karst region of southwest china using plot scale rainfall simulation experiments with different rainfall intensities low and high and antecedent moisture conditions dry and wet a trench excavated to the epikarst lower boundary allowed identification of flow pathways in the entire soil epikarst architecture system thus facilitating the water balance calculations using a conceptual model with the assumption of a two stage hydrological evolution more than 70 of the total rainfall water moved vertically through the shallow soil layer and then was redistributed by the epikarst as subsurface flow occurring on the soil epikarst interface depression filling on epikarst surface water held by epikarst and deep percolation epikarst water regulation capacity defined as the sum of depression filling on epikarst surface water held by epikarst epikarst seepage flow and deep percolation was 58 mm wet antecedent condition and 223 mm dry antecedent condition total run off from the soil epikarst system was dominated by saturated subsurface flow showing a threshold process controlled by epikarst storage capacity storing as much as 181 mm of rainfall water under dry antecedent condition our study proved that despite the epikarst being relatively poorly developed and covered by a soil mantle it still exerted a strong influence on near surface hydrological processes and thus should be adequately considered in future modelling of water recharge and depletion dynamics in this integrated soil epikarst system copyright 2015 john wiley sons ltd

life span and fate of basins the life span of each main class of sedimentary basin is estimated from published data life spans vary over at least three orders of magnitude from 100 m y for passive margin and intracratonic basins the life span estimates are used to calibrate a chart of basin groups that focuses on the likely basin fates i e depositional deformational or thermal consequent fates predetermined by the tectonic setting of a particular basin class are distinguished from contingent fates which are independent of basin type accretion of trench basin fill is for example a consequent fate whereas inversion far field shortening of a rift basin is a contingent fate life span data are also used to calibrate the wilson cycle and indicate that it has an average duration of 260 m y this is certainly an underestimate because basin life spans are an imperfect proxy for the duration of subduction and collision zones

isotope geochemistry of the tieluping silver lead deposit henan china a case study of orogenic silver dominated deposits and related tectonic setting the tieluping silver deposit which is sited along ne trending faults within the high grade metamorphic basement of the xiong er terrane in the qinling orogenic belt is part of an important recently discovered mesozoic orogenic type ag pb belt ore formation includes three stages an early barren quartz pyrite stage e an intermediate polymetallic sulfide ore stage m and a late barren carbonate stage l carbon sulfur and lead isotope systematics indicate that the e stage fluids are deeply sourced the l stage fluids are shallow sourced meteoric water whereas the m stage fluids are a mix of deep sourced and shallow sourced fluids sulfur and lead isotope data show that the ore forming fluids must have originated from a source with elevated radiogenic lead and low 34s values that differs significantly from exposed geologic units in the xiong er terrane the lower crust and the mantle this supports the view that the carbonate shale chert sequences of the guandaokou and luanchuan groups south of the machaoying fault might be the favorable sources although little is known about their isotopic compositions a tectonic model that combines collisional orogeny metallogeny and hydrothermal fluid flow is proposed to explain the formation of the tieluping silver deposit during the mesozoic collision between the north china craton and south china block early mid triassic indosinian orogeny crustal slabs containing the carbonate shale chert sequences of the guandaokou and luanchuan groups locally rich in organic matter carbonaceous shale were thrust northwards beneath the xiong er terrane along the machaoying fault metamorphic devolatilisation of this underthrust slab probably provided the ore forming fluids to develop the ag pb ore belt which includes the tieluping silver deposit fluids and magmas were emplaced during extensional stages related to the jurassic cretaceous yanshanian orogeny

the effect of allanite inclusions on u pb step leaching ages and sm nd isotope systematics of garnet from the ogcheon metamorphic belt south korea abstract the ogcheon metamorphic belt consists primarily of metasedimentary and metavolcanic rocks that have experienced polyphase tectonometamorphism since the neoproterozoic peak metamorphism reaching up to lower amphibolite facies produced ubiquitous garnet porphyroblasts in pelitic and mafic schists to determine the timing of their formation step leaching experiments were undertaken for five garnet fractions separated from pelitic and quartz hornblende garnet schists the u pb ages from three samples are identical within 2 errors ranging from 291 41 ma to 276 29 ma the quasi linearity of leachates in 238u 206pb and 208pb 206pb diagrams suggests that u and pb are released from a single mineral phase and that minor chemical fractionation between u and pb may have occurred during the leaching experiment deviations of residues and bulk garnet fractions from the linear trend are attributed to partial dissolution of refractory inclusions of detrital zircon th u ratios of leachates are in the range of 3 4 12 much higher than those of pure garnet and suggest the contribution of allanite negative relationships in the sm nd isochron diagram and similar 147sm 144nd ratios between whole rock and garnet corroborate the influence of light rare earth element lree rich allanite on the sm nd isotopic system simple mass balance calculations indicate that only a trace amount 0 35 modal of allanite inclusions should govern the u th pb systematics of garnet petrographic evidence together with the consistency in u pb ages suggests that allanite is a product of prograde metamorphism thus peak metamorphism responsible for the growth of allanite bearing garnet porphyroblasts in the ogcheon metamorphic belt is best estimated to be early permian

spatial variability of saturated hydraulic conductivity in shallow macroporous soils in a forested basin field single ring infiltrometer and laboratory constant head parameter measurements of saturated hydraulic conductivity kh were used in combination to examine macropore effects on kh in shallow forest soils in a small basin in southern ontario canada soil matrix kh generally decreased with depth for hillslope podzols and stream valley gleysols differences in average maximum and minimum matrix kh were observed between soil types with lowest values occurring in the valley gleysols bulk profile kh assumed to include the effects of macropores had no apparent spatial pattern within a given soil type and mean bulk kh did not differ between soil types kh of macroporous soil was similar to matrix hydraulic conductivities for the porous hillslope podzols however it could be several orders of magnitude greater than the minimum matrix kh observed at a given site for the gleysols this difference increased with total profile thickness geostatistical analyses revealed anisotropic distributions of both bulk and matrix kh in the basin with the maximum and minimum directions of spatial correlation being parallel and normal to the stream valley respectively degree of anisotropy and scale of spatial dependence were lower for bulk kh relative to the minimum matrix kh values

paleoproterozoic orogeny in south korea evidence from sm nd and pb step leaching garnet ages of precambrian basement rocks abstract geology and tectonics of the korean peninsula have been considered to be closely associated with those of the adjacent chinese continent although phanerozoic connections between the two areas have been reasonably well worked out precambrian ones are less well established we obtained sm nd and u pb garnet ages of 12 metamorphic rocks from widely separated parts of the gyeonggi and yeongnam massifs in south korea to better understand their precambrian history the two massifs consist of late archean to paleoproterozoic basement rocks and meso to neoproterozoic supracrustal rocks previous studies have shown that the two massifs experienced upper amphibolite to granulite facies metamorphism of medium pressure type with clockwise p t time paths suggesting that the two massifs may represent remnants of a collisional orogen pb pb and u pb garnet ages give two distinct age groups ten paleoproterozoic 1989 34 to 1835 56 ma ages of basement rocks from the two massifs and one late permian 265 8 ma age of a supracrustal rock from the gyeonggi massif that corroborates previous estimates of permo triassic 298 245 ma metamorphic age for the supracrustal rocks on the other hand sm nd garnet ages are less precise and display a wide range of ages from 2257 to 413 ma for the basement rocks when we compare the sm nd and pb pb ages from the same sample the sm nd age is similar to or younger than the pb pb age suggesting that the blocking temperature of the sm nd garnet system may be lower than that of the u pb system 800 c we interpret the pb pb and u pb ages as representing the timing of metamorphic garnet growth since the blocking temperature of the u pb garnet system is similar to or higher than the metamorphic temperature of the analyzed samples apparently the younger metamorphism possibly associated with the permo triassic collision between the north and south china cratons was not strong enough to reset the older metamorphic age similar paleoproterozoic metamorphic ages for basement rocks of the two massifs suggest that they may have come from the same precambrian terrane the metamorphic ages of the basement rocks of south korea agree very well with those of the central zone orogenic belt in the north china craton suggesting a possible correlation between the two terranes

continental origin of the bibong eclogite southwestern gyeonggi massif south korea eclogite is a high pressure hp metamorphic rock that provides important information about the subduction of both continental and oceanic crusts in this study we present shrimp zircon u pb isotopic data for a suite of the basement gneisses to investigate the origin of the proterozoic bibong eclogite in the hongseong area south korea zircon grains from the basement felsic gneisses yielded paleoproterozoic protolith ages ranging from ca 2197 to 1880 ma and were intruded by syenite at ca 750 ma a hp regional metamorphic event of triassic age ca 255 227 ma is recorded in the zircon rims of the country rocks which is also observed in the zircons from the eclogite the contacts between the bibong eclogite and its host rocks support an origin for the proterozoic protoliths indicating continental intrusions the hongseong area thus preserves evidence for the triassic collision indicating a tectonic linkage among the northeast asian continents

possible eastward extension of chinese collision belt in south korea the imjingang belt structural petrological and geochronological data from the middle korean peninsula indicate that the qinling dabie sulu collisional belt of east central china crosses the yellow sea and extends into the imjingang belt the yeoncheon complex first identified as the western imjingang belt comprises primarily north dipping metamorphic sequences 1 the northern jingok unit consisting of barrovian type metapelites and 2 the southern samgot unit consisting of calc silicate and amphibolitic rocks south vergent structures with reverse sense shearing are dominant in the jingok unit whereas late normal sense shearing is pervasive in the samgot unit and the deformed granitoid to the south these structural patterns are interpreted to correspond to extensional deformation associated with uplift following compression in a collisional belt pressure temperature p t estimates from the amphibolites suggest a high p amphibolite facies metamorphism 8 13 kbar and 630 790 c possibly evolving from eclogite facies conditions along a clockwise p t path sm nd and rb sr geochronological data suggest that the amphibolites emplaced in late proterozoic time were metamorphosed during permian triassic time

geochronology and geochemical and nd sr isotopic characteristics of triassic plutonic rocks in the gyeonggi massif south korea constraints on triassic post collisional magmatism abstract sensitive high resolution ion microprobe shrimp zircon u pb ages and whole rock chemical and isotopic sr nd compositions have been measured on some middle triassic plutonic rocks associated with post collisional magmatism in the gyeonggi massif hongseong namyang and yangpyeong areas south korea plutonic rocks from the southwest hongseong and central yangpyeong gyeonggi massif and central okcheon belt cheongsan have ages of ca 227 226 231 and 225 ma respectively the plutonic rocks from hongseong are dominated by granite and quartz syenite from namyang by granite and from yangpyeong by quartz monzonite to quartz syenite and gabbro three rocks from the gyeonggi massif have the depletions in ta nb p and ti and enrichment in large ion lithophile elements lile characteristic of plutonic rocks that are subduction related or derived from an arc related crustal source the hongseong quartz syenite and yangpyeong quartz monzonite to quartz syenite have features of shoshonitic and high ba sr granitoids with lree enrichment and no significant eu anomaly the plutonic rocks from the gyeonggi massif have high initial 87 sr 86 sr ratios 0 7083 0 7144 and strongly negative e nd t 20 3 to 10 4 indicating derivation of the magmas from sources in the middle to upper crust these high k calc alkaline and shoshonitic plutonic rocks formed during periods of relaxation that separated the culminations of post orogenic uplift collapse in the transitions from orogenic to anorogenic events after the early middle triassic continent continent collision 249 229 ma between the north and south china blocks in south korea the plutonic rocks of the gyeonggi massif support therefore a possible eastern extension of the early middle triassic dabie sulu collision belt in china

u pb ages and lu hf isotopes of detrital zircons from the southern qinling orogen implications for precambrian to phanerozoic tectonics in central china abstract the qinling orogen central china was constructed during the mesozoic collision between the north china and yangtze continental plates the orogen includes four tectonic units from north to south the huaxiong block reactivated southern margin of the north china craton north qinling accretion belt south qinling fold belt or block and songpan fold belt evolved from the northernmost paleo tethys ocean separating the gondwana and laurentia supercontinents here we employ detrital zircons from the early cretaceous alluvial sediments within the qinling orogen to trace the tectonic evolution of the orogen the u pb ages of the detrital zircon grains from the early cretaceous donghe group sediments in the south qinling fold belt cluster around 2600 2300 ma 2050 1800 ma 1200 700 ma 650 400 ma and 350 200 ma corresponding to the global kenorland columbia rodinia gondwana and pangaea supercontinent events respectively the distributions of ages and ehf t values of zircon grains show that the donghe group sediments have a complex source comprising components mainly recycled from the north qinling accretion belt and the north china craton suggesting that the south qinling fold belt was a part of the united qinling north china continental plate rather than an isolated microcontinent during the devonian triassic the youngest age peak of 350 200 ma reflects the magmatic event related to subduction and termination of the mian lue oceanic plate followed by the collision between the yangtze craton and the united qinling north china continent that came into existence at the triassic jurassic transition the interval of 208 145 ma between the sedimentation of the early cretaceous donghe group and the youngest age of detrital zircons was coeval with the post subduction collision between the yangtze and the north china continental plates in jurassic

detrital zircon u pb geochronology and tectonic implications of the paleozoic sequences in western south korea abstract the middle paleozoic metasedimentary sequences of the western gyeonggi massif taean formation and wolhyeonri complex imjingang belt and southwestern okcheon belt provide clues to the successive tectonic events that occurred during the evolution of the korean peninsula in this study we present shrimp u pb ages of detrital zircon grains from the metasandstones of the taean formation and yeoncheon group of the imjingang belt and from quartzites in three paleozoic formations of the southwestern okcheon belt the zircon grains from all of the samples yielded similar u pb age spectra of paleoarchean neoarchean to middle paleozoic with a dominant age population within the paleozoic the maximum ages of deposition estimated from the youngest dominant concordant detrital zircons were 431 457 ma for the western gyeonggi massif and imjingang belt and 380 355 ma for the southwestern okcheon belt permian metamorphic zircon overgrowths correlated with subduction prior to the triassic collision were also found middle paleozoic metamorphic zircon overgrowths that can be compared to those of the yunkai wuishan orogenic belt of the cathaysia block were indentified in the wolhyeonri complex the dominant zircon populations of this study and the available data for the korean peninsula compare well with those from the yangtze block cathaysia block and qilian qinling orogenic belt which were located at the northeastern margin of eastern gondwana during the early paleozoic

vertical variation of near saturated hydraulic conductivity in three soil profiles abstract hydraulic conductivity is an important parameter of water and solute transport in soils hydraulic conductivity is known to be highly variable in space but its dependence on soil horizonation has seldom been explored we measured the near saturated hydraulic conductivity of three soils located in the centre of france a neoluvisol a calcisol and a calcosol according to the referentiel pedologique using tension disc infiltrometry the reynolds and elrick s multipotential technique has been applied to the steady state infiltration kinetics measured at potentials 1 5 0 6 0 3 0 1 and 0 05 kpa to derive the hydraulic conductivity values each horizon of the three soil profiles has been characterised at least once at three locations 50 cm apart from each other on a flat surface prepared within the same access pit some horizons have been characterised on a second occasion in other access pits opened at nearly 10 m from the previous ones on average hydraulic conductivity values increased from 1 3 10 7 m s at 1 5 kpa to 2 5 10 6 m s at 0 3 kpa saturated hydraulic conductivity varied between 3 6 10 6 m s for the ploughed layer of the calcosol and 4 9 10 3 m s for the calcosol substrate c horizon the various horizons of the neoluvisol had hydraulic conductivity values which were not significantly different from each other except the ploughed layer which had lower hydraulic conductivity values than the underlying horizons the tilled layers of the calcisol and the calcosol also had lower hydraulic conductivity values than their respective underlying cambic horizons further the hydraulic conductivity of the tilled layer of the calcosol was lower than that of the tilled layers of the calcisol and the neoluvisol this difference was attributed to the effect of different tillage systems the calcosol being superficially tilled while the calcisol and neoluvisol were ploughed each year the structural s cambic horizons of the calcisol and calcosol had similar hydraulic conductivities but lower than their respective substrate limestone

effects of land use land cover and rainfall regimes on the surface runoff and soil loss on karst slopes in southwest china abstract surface runoff and soil loss from 2007 to 2010 related to land use and rainfall regimes in karst hill slopes in guizhou province southwest china were analyzed using the hierarchical clustering method sixty one rainfall events under the subtropical monsoon climate condition were classified into 5 types of rainfall regimes according to the depth maximum 30 min intensity and duration of rainfall in our study we first demonstrated that the amounts of surface runoff and soil loss on the karst hill slopes were very small compared to the non karst areas because the dual hydrological structure in the karst region including ground and underground drainage systems could influence the processes of rainfall recharge and runoff generation most rainfall water was transported underground through limestone fissures and fractures while little was in the form of surface runoff second the runoff and soil loss were affected by land use management and vegetation cover soil loss was intensified in a descending order to five types of land uses pastureland burned area cropland combination vegetation land young forestland third the runoff and soil loss exhibited remarkable variances among different rainfall regimes large runoff and soil loss were mainly created by heavy rainfall storms with a rainfall depth of more than 40 mm and a maximum 30 min rainfall intensity of over 30 mm h 1 in addition rainfall storms with large antecedent precipitations could also produce large runoff and soil loss these observations indicated that limestone fissures and fractures play important roles in surface runoff generation on karst limestone slopes due to their large storage capacity and high infiltration rate lastly the soil erosion risk in the karst pure limestone slope is quite high and should be paid particular attention especially in regards to over grazing because the soil loss created by a single heavy rainstorm in pastureland was 5 times the annual soil loss tolerance

storm influenced siliciclastic and carbonate ramp deposits the lower ordovician dumugol formation south korea the dumugol formation lower ordovician in the southern part of the baegunsan syncline south korea contains mixed siliciclastic and carbonate ramp deposits the ramp sediments were frequently influenced by storm events resulting in tempestites of sandstone mudstone couplets bioclastic grainstones to packstones flat pebble conglomerates a skeletal lag layer and laminated calcisiltites all tempestites are characterized by an erosive to sharp base poor grading and a transitional upper boundary the difference in lithology of tempestites appears to have been controlled by the nature of substrates and by proximality for example laminated calcisiltites have developed on the shallow carbonate ramp flat pebble conglomerates are closely associated with nodular limestones on shallow and deep ramps and thin skeletal lag layers from fossiliferous argillaceous sediments formed in a basinal setting the stratigraphic succession of the dumugol formation represents an initial transgression followed by a regression the vertical facies change records the transition from a shallow siliciclastic ramp to a deep carbonate ramp to a basin shallowing to a deep carbonate ramp and to a shallow carbonate ramp storm effects are mostly well preserved in shallow to deep ramp deposits

sequence stratigraphy of the taebaek group cambrian ordovician mideast korea abstract this study focuses on the sequence stratigraphic implications of the taebaek group cambrian ordovician a mixed carbonate siliciclastic sequence ca 1200 m thick in the mideastern part of the korean peninsula the group contains 11 lithologic units formations that can be partitioned into four packages supersequences i iv each package comprises alternation of siliciclastic and carbonate successions corresponding to the second order sequence supersequence formed in a period of 10 100 m y supersequence i jangsan myeonsan myobong and daegi fms represents the initial inundation and subsequent drowning during the late early to middle middle cambrian it experienced the drowning between the middle and late middle cambrian forming type 3 sequence boundary supersequence ii sesong and hwajeol fms was formed by prolonged marine flooding during the late middle and late cambrian it was terminated by a large supply of siliciclastics due to the rejuvenation of the drainage basin and the subsequent shallowing at the cambrian ordovician boundary type 2 sequence boundary supersequence iii dongjeom dumugol and makgol fms comprises the lowstand coarse grained siliciclastics transgressive shale by marine flooding and shallow platform carbonates by highstand progradation in the early ordovician following the large scale eustatic fall of sea level in the earliest middle ordovician supersequence iv jigunsan and duwibong fms formed on the subaerial exposure surface type 1 sequence boundary by resumed marine flooding in the middle ordovician this study provides basis for basin scale correlation with the coeval sequences in northeastern china

lithostratigraphy and depositional environments of the pyeongan supergroup carboniferous permian in the taebaek area mid east korea abstract the pyeongan supergroup carboniferous permian consists of a thick siliciclastic sequence 1700 m thick recent sedimentological work in the taebaek area has refined the lithostratigraphic units manhang geumcheon jangseong hambaeksan dosagok gohan and donggo formations in ascending order the entire sequence is represented by thirteen sedimentary facies which can be organized into seven facies associations fa the lower part of the manhang formation fa 1 moscovian consists of crudely cross stratified conglomerate massive sandstone and gray homogeneous siltstone formed in shoreface off river mouth whereas purple siltstone and grainstone of the upper part fa 2 probably formed in a coastal plain environment the geumcheon jangseong formation moscovian artinskian consists of dark gray sandstone dark gray shale coal and bioturbated wackestone fa 3 formed in a lagoonal environment the hambaeksan formation kungurian comprises milky white crudely stratified conglomerate gray coarse sandstone and partly laminated black shale fa 4 representing a shoreface progradation the dosagok formation late permian is characterized by an alternation of purple fine sandstone and conglomerate fa 5 formed in a bedload dominated fluvial system the gohan formation late permian is mostly composed of upward fining units massive sandstone to dark gray siltstone fa 6 suggesting a restricted inter distributary bay environment the donggo formation late permian consists of cross stratified coarse sandstone and purple sandstone fa 7 interpreted as deposits of perennial sandy braided river system

phanerozoic high pressure eclogite and intermediate pressure granulite facies metamorphism in the gyeonggi massif south korea implications for the eastward extension of the dabie sulu continental collision zone abstract petrological analysis zircon trace element analysis and shrimp zircon u pb dating of retrogressed eclogite and garnet granulite from bibong hongseong area sw gyeonggi massif south korea provide compelling evidence for triassic 231 4 3 3 ma high pressure hp eclogite facies m1 metamorphisms at a peak pressure temperature p t of ca 16 5 20 0 kb and 775 850 c this was followed by isothermal decompression itd with a sharp decrease in pressure from 20 to 10 kb and a slight temperature rise from eclogite facies m1 to granulite facies m2 followed by uplift and cooling granitic orthogneiss surrounding the baekdong garnet granulite and the ophiolite related ultramafic lenticular body near bibong records evidence for a later silurian 418 8 ma intermediate high pressure ihp granulite facies metamorphism and a prograde p t path with peak p t conditions of ca 13 5 kb and 800 c k ar ages of biotite from garnet granulites amphibolites and granitic orthogneisses in and around the bibong metabasite lenticular body are 208 219 ma recording cooling to about 310 c after the early triassic metamorphic peak neoproterozoic zircon cores in the retrogressed eclogite and granitic orthogneiss provide evidence that the protoliths of these rocks were 800 and 900 ma old respectively similar to the ages of tectonic episodes in the central orogenic belt of china this and the evidence for triassic hp uhp metamorphism in both china and korea is consistent with a regional tectonic link within northeast asia from the time of rodinia amalgamation to triassic continent continent collision between the north and south china blocks and with an eastward extension of the dabie sulu suture zone into the hongseong area of south korea

three dimensional numerical modeling of earthquake migration along a northwestern pacific subduction slab three dimensional numerical modeling has been performed to account for possible earthquake migration phenomena along a northwestern pacific subduction slab on the assumption that the lithosphere is a linear visco elastic body but the asthenosphere and the mesosphere respond to the applied stress as non linear newtonian materials obeying the power law of creep on the basis of a three dimensional thermal structure of the northwestern pacific region the preliminarily computed stress regimes show that 1 to induce a stick slip type trench event prefailures at a depth of about 40 km in the front of the locked zone between two lithospheric plates are required 2 the compositional density contrast due to phase change at typical depths is prerequisite of stress concentration to cause a dislocation type deep focus earthquake and 3 the co seismic change in gravitational potential is a controlling factor for earthquake migration downward along the subduction slab

u pb and hf isotope analyses of detrital zircons from late paleozoic sediments insights into interactions of the north china craton with surrounding plates abstract u pb dating and hf isotope analyses were performed on detrital zircons from the upper permian sandstones in the ordos and jiyuan basins with aims of defining the sediment provenance and by inference to determine the influence of the surrounding plates on the evolution of the north china craton ncc detrital zircons from these two basins fall into three major groups based on their u pb ages phanerozoic paleoproterozoic and neoarchean the youngest grain from every sample is only slightly younger than the real depositional age of strata the phanerozoic zircons from the jiyuan basin 244 390 ma show ehf t ranging from 30 3 to 1 3 suggesting a provenance from the inner mongolia paleo uplift 245 376 ma ehf t 18 9 to 1 7 a bi modal distribution of ages and ehf t is noted for detrital zircons from the ordos basin one resembles that of the jiyuan basin the other is characterized by early paleozoic ages and relatively high ehf t values 10 9 to 7 7 a hybrid source is thus inferred for the ordos sediments the northern qinling orogen 428 478 ma ehf t 10 9 7 7 must have served as a source in addition to the inner mongolia paleo uplift source this interpretation is consistent with the fact that the northern qinling orogen was an active margin during the early paleozoic and suggests that the western part of the northern qinling orogen was elevated relative to the center of the craton during the late paleozoic it is likely that the early paleozoic arc trench in the northern part of the dabie orogen was under thrusted below the ncc due to the subduction of the yangtze plate during the triassic the inner mongolia paleo uplift was strongly uplifted by subduction of the paleo asian ocean plate underneath the northern ncc and functioned as a sediment source for the inner craton during the late paleozoic these results reveal a heterogeneous pattern of destruction of the north china craton with its northern margin starting to be activated no later than late paleozoic

water source utilization by woody plants growing on dolomite outcrops and nearby soils during dry seasons in karst region of southwest china summary in the seasonally dry karst region of southwest china woodland vegetation is frequently associated with rocky outcrops we used stable isotope techniques to determine the water sources of two woody plant species the semideciduous tree rademachera sinica and the deciduous shrub alchornea trewioides across three surface types continuous and isolated dolomite outcrops as well as adjacent surfaces with soils main water sources for r sinica growing on the continuous outcrops shifted from deep water sources e g water in the saturated zone on march 23 2009 the late dry season of 2008 2009 to rainwater stored in rock fissures of the unsaturated zone on november 8 2009 the early dry season of 2009 2010 r sinica growing on nearby thin soils exhibited a similar shift of main water sources from deep water sources in the late dry season to shallow soil water 0 30 cm in the early dry season however they extracted deep water sources from the bottom of nearby outcrops rather than from deeper layers below the soil surface main water sources for r sinica growing on the isolated outcrops shifted from previous one to two months ago rainwater in the late dry season to the mixture of recent within the last one month and previous rainwater in the early dry season while using little or no deep water sources in contrast a trewioides growing on these two kinds of outcrops always relied on recent rainwater while those growing on soils always relied on shallow soil water the shift of water sources for tree species especially those growing on continuous rock outcrops and nearby soils may allow them to maintain normal transpiration throughout the year which increases the amount of evapotranspiration in the watershed and further enhances the water storage capacity of the study area

a paleozoic subduction complex in korea shrimp zircon u pb ages and tectonic implications abstract the wolhyeonri complex in the southwestern margin of the korean peninsula is divided into three lithotectonic units late paleozoic zone i to the west middle paleozoic zone ii in the middle and early paleozoic zone iii to the east zones ii and iii display characteristics of continental arc magmatic sequence zone ii is dominated by mafic metavolcanics whereas zone iii is characterized by the presence of dismembered serpentinite bodies including chaotic melange these zones are proposed to have been formed in a convergent margin setting associated with subduction here we present zircon shrimp u pb ages from the various units within the wolhyeonri complex which reveal the paleozoic tectonic history of the region the late carboniferous ages obtained from the main shear zone between the wolhyeonri complex and the paleoproterozoic gyeonggi massif are thought to mark the timing of continental arc magmatism associated with the subduction process in contrast zone i with neoproterozoic arc magmatic remnants might indicate deposition in a forearc basin the wolhyeonri complex also preserves strong imprints of the triassic collisional event including the presence of middle triassic high pressure metabasites and eclogites near the eastern boundary of the zone iii these range of radiogenic ages derived from the wolhyeonri complex correlate well with subduction and accretion history between the north and south china cratons similar geochronological features have also been indentified from the qinling tongbai xinxian and northern dabie areas in east central china the existence of paleozoic coeval subduction in east asia prior to the triassic collision is broadly consistent with a regional tectonic linkage to gondwana

components and episodic growth of precambrian crust in the cathaysia block south china evidence from u pb ages and hf isotopes of zircons in neoproterozoic sediments abstract detailed lam icpms u pb dating and lam mc icpms lu hf isotope analysis were carried out on zircons from nine samples of basement metamorphic rocks in the southern cathaysia block south china the chemical compositions of these metamorphic rocks and zircon morphology indicate that their protoliths were sedimentary zircon u pb dating results show they mainly formed during the late neoproterozoic the precambrian crust of the cathaysia block can be divided into two distinct tectonic domains the wuyishan terrane to the northeast and the nanling yunkai terrane to the southwest the nearly e w boundary between these two terranes is also supported by geophysical petrological and geochemical evidence and the basement rocks of the two terranes are comprised of different components the wuyishan terrane is characterized by dominant paleoproterozoic 1 86 ga and lesser neoarchean magmatism and the southern central part of the terrane suffered strong neoproterozoic and early paleozoic tectonothermal reworking the zircon data suggest that there were five important episodes of juvenile crust generation 3 6 ga 2 8 ga 2 6 2 4 ga 1 85 ga and 0 8 0 7 ga in the wuyishan terrane strong paleoproterozoic 1 85 ga magmatism in northern wuyishan and neoproterozoic 0 8 0 7 ga magmatism in central and southern wuyishan both principally involved the remelting of old crust with minor input of juvenile material in contrast the nanling yunkai terrane contains abundant neoarchean and grenvillian zircons some evidence of mesoproterozoic activity and rare paleo to meso archean and neoproterozoic zircons u pb ages and hf isotopic compositions of the detrital zircons from the late neoproterozoic to early paleozoic meta sedimentary rocks in the nanling yunkai area suggest that the growth of juvenile crust mainly occurred at 3 6 ga 3 3 ga 2 5 2 6 ga 1 6 ga 1 0 ga and 0 8 0 7 ga neoarchaean 2 6 2 5 ga grenvillian 1 0 ga and neoproterozoic 0 8 0 7 ga magmatism mainly involved the recycling of old crust minor remnants of 4 1 ga crust may remain in the terrane this crustal history is distinct from that of the wuyishan terrane and analogous to those recorded for the eastern india east antarctic domain of northern gondwanaland suggesting that they probably were once linked

forearc serpentinite melange from the hongseong suture south korea abstract the signature of a prolonged subduction accretion history from paleozoic to early mesozoic is preserved within the dismembered serpentinite melanges within the hongseong suture here we present major and trace element data from the mafic fragments blocks within the baekdong serpentinite melange revealing their arc like tholeiite affinity within a suprasubduction zone tectonic setting chromian spinel compositions from the baekdong hydrated mantle peridotite serpentinite are characterized by high cr 0 53 0 67 and fe 2 fe 3 ratio medium mg 0 42 0 55 and al 2 o 3 contents 17 25 wt indicating a forearc tectonic environment for the hydrated mantle peridotite the estimated melting degree 17 6 and feo mgo of the parental melt 0 9 1 3 are consistent with that of forearc magmas shrimp zircon u pb ages from a high grade mafic rock and an anorthosite from the study area give protolith ages of 310 ma and 228 ma respectively zircons from an associated orthogneiss block within the melange yield a neoproterozoic crystallization age of 748 ma these results together with the recent shrimp zircon ages from other dismembered serpentinite melanges within the wolhyeonri complex suggest that paleozoic to early mesozoic subduction and subsequent collision events led to the exhumation of the hydrated forearc mantle peridotites from a metasomatized mantle wedge the hongseong region preserves important clues to a long lived subduction system related to global events associated with the final amalgamation of the pangaea supercontinent

detrital zircon u pb ages of the jangsan formation in the northeastern okcheon belt korea and its implications for material source provenance and tectonic setting abstract the jangsan formation distributed in the taebaeksan basin central eastern korea is unfossiliferous and is composed of quartz arenite this formation is conventionally believed to be the lowermost stratigraphic unit of the lower paleozoic sequence deposited on the yeongnam massif in south korea corresponding to early cambrian in age u pb dating of detrital zircon grains using a laser ablation inductively coupled mass spectrometer yields ages ranging from archean to middle proterozoic 1738 67 ma to 3058 53 ma detrital zircons show no ages younger than 1 8 ga suggesting that the jangsan formation was deposited at some time after this age but much prior to ca 520 ma the depositional age of the immediately overlying myobong formation this interpretation is supported by the recent report on the presence of the unconformity between the jangsan and the myobong formations kim and lee 2006 zircon ages from jangsan sandstones define two major groups archean age grains with a maximum frequency at about 2 5 ga and paleoproterozoic age grains with maximum frequencies at about 2 1 and 1 8 ga the observed zircon age distribution in the jangsan sandstones may represent that of the yeongnam massif on which the jangsan formation was deposited such an age distribution of the yeongnam massif matches well with that the north china block suggestive of the yeongnam massif being a part of the sino korean craton during the precambrian

numerical modeling of ground deformation and source mechanism related to co seismic change in gravitational potential abstract the release of gravitational potential energy is implicit in ground surface deformation as was seen in the 1954 fairview peak 1964 alaska and 1976 tangshan earthquakes where more energy was released by surface subsidence than was radiated as seismic waves based on the numerical results of dip and thrust faulting driven by either gravitational tectonic stress alone or additional external forces the elastic stress accumulation process in the front of the fault tip is required as is usual prior to any faulting slip but the energy release would be mainly derived from the downward movement of the hanging wall of a normal fault or the footwall of a thrust fault in other words there will be a decrease in gravitational potential energy in the upper part of the subsiding wall to generate seismic waves and an increase in elastic strain energy in the lower part either to cause after shocks or to bring about cessation of further fault movement in addition by geodetic surveying along a fault prior to an earthquake opportunities exist to judge the nature of the tectonic force and the damage zonation

microblock amalgamation in the north china craton evidence from neoarchaean magmatic suite in the western margin of the jiaoliao block abstract the archaean earth is considered to have been characterized by microcontinents that formed dominantly through the accretion of oceanic arcs and plateaus the north china craton ncc provides a typical case where at least seven ancient microcontinental nuclei with distinct lithological features and independent tectonic histories were amalgamated into the cratonic framework at the end of the archaean here we investigate a suite of magmatic rocks developed at the periphery of one of these microblocks the jiaoliao block that forms part of the composite eastern block of the ncc we present petrological geochemical and zircon u pb geochronological data from the taipingzhai charnockite suite and associated amphibolites metagabbros and orthogneisses from the qianxi complex geochemically the rocks show a wide range of sio 2 charnockite suite 52 57 75 50 wt metagabbro 43 71 wt amphibolite 50 24 wt garnet bearing biotite 63 73 wt and mgo charnockite suite 0 89 5 01 wt metagabbro 3 99 wt amphibolite 6 23 wt garnet bearing biotite 2 08 wt the composition of the felsic units straddle from diorite through syeno diorite to granite with both alkalic and subalkalic affinity with dominantly magnesian composition and arc related features their immobile trace element relationships suggest calc alkaline affinity they show positive pb ba la nd and gd and negative nb ta sr th and ti anomalies with slightly negative anomalies of ce and y attesting to arc related features in tectonic classification diagrams the rocks plot in the vag syn colg field or the vag area suggesting subduction related origin the dominant population of zircons in all these rocks displays magmatic crystallization features including high th u values with core rims textures indicating subsequent thermal events the zircon u pb data yield upper intercept ages of 2587 10 ma to 2543 17 ma and 207 pb 206 pb mean ages of 2578 7 3 ma to 2536 8 ma for the charnockite suite marking the timing of emplacement of the arc magmas the overgrowth rims as well as discrete neoformed grains are interpreted as dating subsequent metamorphism and yield 207 pb 206 pb ages between 2533 ma to 2490 ma zircons in the metagabbro preserve upper intercept ages of 2556 20 ma representing the crystallization age of this rock the younger ages of 2449 58 ma upper intercept age and 1845 25 ma 207 pb 206 pb spot age are interpreted to represent subsequent multiple thermal events in this area zircons in the amphibolite preserve the 207 pb 206 pb mean age of 2539 9 ma representing the crystallization age of this rock the garnet bearing biotite gneiss shows an upper intercept age of 2562 10 ma mswd 0 66 n 36 and the 207 pb 206 pb mean age of 2561 9 ma mswd 0 63 n 33 which is taken to represent the crystallization age of this rock some inherited zircons are also identified with 207 pb 206 pb ages of 2664 26 ma and 2628 26 ma zircon lu hf data show dominantly positive ehf t values and combined with crustal residence ages the results suggest mesoarchean to neoarchean juvenile crust formation in the ncc we interpret the data presented here to represent a phase of major late neoarchaean arc magmatism along the western margin of the jiaoliao block related to the birth of microcontinental nuclei within the ncc our data suggest that the western and eastern blocks might not have existed as discrete crustal blocks and that the construction of the ncc is a result of the assembly of several microblocks or terranes at the end of archaean similar archean cratonic nuclei in other regions of the world might have formed part of a primitive supercontinent in the early earth

spatial variability of surface soil saturated hydraulic conductivity in a small karst catchment of southwest china soil saturated hydraulic conductivity ks is one of the most important parameters that determine soil water redistribution however it is little known in a karst area with thin discontinuous and rocky soils the purpose of this paper was to investigate the spatial variability of ks and its influencing factors in a small karst catchment with high heterogeneity in southwest china undisturbed surface 0 10 cm soil samples were collected with metal cylinders from an 80 m 80 m grid for measuring ks bulk density b non capillary porosity ncp and capillary porosity cp disturbed surface samples were taken with a shovel to measure soil organic carbon soc and rock fragment content rc environmental factors including topographical location slope and depression land use type forestland shrubland shrub grassland and farmland slope gradient slope exposure and elevation were investigated for each sampling point the results showed that ks value was relatively high 9 10 m d with a moderate variation and had a strong spatial dependence nugget sill value 0 06 ncp showed a very significantly p 0 05 but their interaction effects were significant this suggested that the influencing factors were more complex and they should be considered together in a karst area the mean ks value was the lowest in the forestland on the hillslope and in the farmland in the depression indicating where the surface runoff may appear easily such results could help to better understand the soil hydrological processes and contribute to the building of hydrological models in small karst catchments

spatial distribution of rock fragments on steep hillslopes in karst region of northwest guangxi china abstract rock fragments 5 mm in diameter at the soil surface and within the topsoil have a large effect on the intensity of various hydrologic and geomorphic processes however little information is available on the spatial distribution of rock fragments in subtropical regions the objective of this paper was to investigate the relationship between the spatial distribution of rock fragments and landforms on two different steep karst hillslopes in northwest guangxi southwest china on the first hillslope a disintegrated landslide failure with the presence of several large rock outcrops 2 m in height the spatial distribution of rock fragment cover had no obvious relationship with topographic position except that the mean cover percentage of small rock fragments 5 20 mm decreased from bottom to top on the second hillslope an avalanche slope without the presence of large rock outcrops the mean total rock fragment cover 5 600 mm increased from bottom 5 to top 21 with decreasing variability and rock fragments with various sizes 5 20 20 75 and 75 250 mm showed a similar increasing trend the mean total rock fragment cover increased linearly with slope gradient on the second hillslope and tended to increase and then decrease with gradient but their relationship was not obvious on the first hillslope this indicated that the spatial distribution of surface rock fragment cover had a close relationship with the presence of large rock outcrops and slope gradient however the median diameter d50 of the surface rock fragments had an increase decrease trend with slope gradient but there was no obvious relationship on both hillslopes with low overland flow therefore the dominant factor for the spatial distribution of rock fragment cover and size at the soil surface might not be soil erosion by water but slope gradient vegetation and geomorphologic condition of the slope the mean total volumetric rock fragment content 5 250 mm within the topsoil 10 20 cm thick increased linearly from bottom 16 to top 39 with slope gradient on the first hillslope and had a logarithmic increase from bottom 10 to top 27 with gradient on the second hillslope this suggested that rock fragment content within the topsoil was mostly controlled by slope gradient and topographic positions and had not a close relationship with the presence of large rock outcrops

the effect of vegetation on infiltration in shallow soils underlain by fissured bedrock abstract mean annual infiltration above the high level waste repository proposed to be sited at yucca mountain nevada has a large impact on assessments of repository performance ongoing investigations of infiltration processes have identified the relatively horizontal caprock environment above portions of the repository as a potentially large source of infiltrating waters due to shallow permeable soils above a moderately welded tuff with large soil filled fissures the combination of shallow soils and fissured bedrock allows rapid penetration of wetting pulses to below the rooting zone plant uptake can strongly reduce net infiltration in arid environments with high water storage capacity and despite the low water storage capacity there is a relatively high vegetation density in this environment the apparent discrepancy between high vegetation density and low water storage motivates the study of plant hydrologic interactions in this semiarid environment field observations were coupled with plant and landscape scale models to provide insight into plant hydrologic interactions several lines of evidence including i linear plant growth features observed on aerial photographs ii comparisons of plant cover within the fissured environment and comparable environments lacking fissures and iii direct excavations all suggest that the widely spaced soil filled fissures are conducive to plant growth even when fissures are buried at soil depths exceeding 30 cm results from a mechanistic simulation model for root growth into fissures suggest that the additional sheltered plant available soil water within fissures provides a competitive advantage for plant establishment therefore plants that germinate above a fissure are more likely to survive in turn developing linear features above fissures having established that plants preferentially root within soil filled fissures in the caprock environment a set of simulations were performed to examine the hydrologic consequence of plant roots within fissures at the landscape scale the response to three rainfall amounts was simulated for the largest storm fluxes at the fissure bottom peaked at 1 4 weeks after the storm when plant uptake was not active but were eliminated when fissures had active vegetation when plants were active within a fissure uptake eliminated net infiltration in the fissure regardless of the size of the storm two plant related mechanisms reduced total flux through the plant filled fissures i transpiration during fissure flow and ii wetting pulse retardation due to drier fissures prior to rain the first mechanism appears to be dominant in these simulations results suggest that transpiration may strongly limit net infiltration i e total deep percolation flux escaping the plant root zone significant infiltration can occur however when plants are dormant so that most infiltration would be expected to occur during winter

diagenesis of shallow marine sandstones the lower ordovician dongjeom formation korea response to relative sea level changes abstract this study deals with the diagenesis of shallow marine mature sandstones in the view of relationship between depositional conditions and diagenesis the dongjeom formation early ordovician korea is composed of three coarsening upward siliciclastic sequences deposited on an extensive carbonate platform dongjeom sandstones are divided into two facies according to depositional conditions with respect to changes in relative sea level transgressive facies and regressive facies the transgressive facies are characterized by calcareous sandstones and regressive facies by quartzose to feldspathic non calcareous sandstones dongjeom sandstones in the different facies experienced different pathways of diagenesis in the regressive facies siliciclastic deposition was dominant and feldspar grains were broken by active reworking and concentrated in the finer fraction with deep burial the regressive facies sandstones experienced significantly chemical compaction and quartz cementation in the transgressive facies carbonate grains were concentrated which was successively followed by extensive early calcite cementation such early calcite cementation prevented the transgressive facies sandstones from further significant diagenetic changes during deep burial the results of this study indicate that the composition early diagenesis and late diagenesis are intimately related to each other and that diagenesis of dongjeom sandstones was mainly controlled by depositional facies formed in response to relative sea level changes

shrimp u pb zircon geochronology and geochemistry of metavolcanic and metasedimentary rocks in northwestern fujian cathaysia block china tectonic implications and the need to redefine lithostratigraphic units abstract northwestern fujian province is one of the most important pre palaeozoic areas in the cathaysia block of south china metavolcano sedimentary and metasedimentary rocks of different types ages and metamorphic grades granulite to upper greenschist facies are present and previously were divided into several formations and groups tectonic contacts occur between some units whereas deformed unconformities have been reported between others new shrimp u pb zircon ages presented here indicate that the original lithostratigraphy and the old group and formation terminology should be abandoned thus the tianjingping formation was not formed in the archaean or palaeoproterozoic as previously considered but must be younger than its youngest detrital zircons 1790 ma but older than regional metamorphism 460 ma besides magmatic zircon ages of 807 ma obtained from metavolcano sedimentary rocks of the nanshan formation and 751 728 ma for the mamianshan group many inherited and detrital zircons with ages ranging from 1 0 to 0 8 ga were also found in them these ages indicate that the geological evolution of the study area may be related to the assembly and subsequent break up of the rodinia supercontinent the new zircon results poorly constrain the age of the mayuan group as neoproterozoic to early palaeozoic 728 458 ma and not palaeoproterozoic as previously thought many older inherited and detrital zircons with ages of 3 6 2 8 2 7 2 6 2 5 2 0 1 8 and 1 6 ga were found in this study a 3 6 ga detrital grain is the oldest one so far identified in northwestern fujian province as well as throughout the cathaysia block nd isotope tdm values of eight volcano sedimentary and clastic sedimentary rock samples centre on 2 73 1 68 ga being much older than the formation ages of their protoliths and thus showing that the recycling of older crust played an important role in their formation these rocks underwent high grade metamorphism in the early palaeozoic 458 425 ma during an important tectono thermal event in the cathaysia block