stable isotope geochemistry of crude oils and of possible source rocks from new zealand 2 sulfur abstract the sulfur isotopic composition of new zealand low s crude oils and components asphaltenes absorptive filtration fractions and source rock components extracted hydrocarbons kerogen pyrite sulfates were determined oils from the taranaki basin have 34s values from 3 to 14 o the lower values possibly represent plant assimilation of fresh water sulphate higher values particularly those from the west coast basin around 20 suggest closed ocean basin conditions or fast sedimentation rate whereas negative 34s values from east coast basin suggest open ocean or low sedimentation rate conditions it is suggested than an oil source rock relation should show as a similarity in 34s values for total oil and source rock extract kerogen and pyrite shale samples analysed plot outside the corresponding oil range and cannot be considered as possible source rocks however coal samples from the maui 4 well and nelson outcrops show strong isotopic correlations with the taranaki oils

intra annual variation of wave number 4 structure of vertical e b drifts in the equatorial ionosphere seen from rocsat 1 1 this paper studies the intra annual variation of the wave number 4 structure in the equatorial vertical e b drifts at high solar flux level based on of the rocsat 1 observations during the interval from 1999 to 2004 it is found that the daytime longitudinal structure is significant in northern summer and early autumn but weak in northern winter this is consistent with the intra annual variations of the tidal mode de3 at night the intra annual variation of the wave number 4 structure shows some differences from that in daytime which may relate to different dynamo mechanisms operating in different local time we also found that the wave number 4 structure mainly shifts eastward during daytime in most of months which is coincident with the eastward propagation of the de3 tide however it is largely disturbed near sunrise and sunset we attribute this disturbance as the jumping of the main dynamo region between e and f layers as well as the different dynamo mechanisms in different dynamo regions

a geochemical study of oil migration at source rock reservoir contacts stable isotopes abstract whereas organic geochemical analyses of oils and potential source rocks have enabled correlations to be drawn and have been utilized to suggest modes of migration only limited data has been published relating a known source rock in contact with an oil filled reservoir this paper presents initial results from the examination of an approximately 100 m continuous core through the kimmeridge shale of the north sea the variability in extractable source rock hydrocarbon contents kerogen toc asphaltene and their carbon isotopic contents are documented nitrogen isotopic content of kerogens and asphaltenes as well as kerogen and asphaltene ton are relatively constant carbon isotopic compositions of kerogen extractable hydrocarbons and asphaltenes covaried significantly as did nitrogen isotopic compositions of kerogen and asphaltenes average isotopic compositions of the asphaltene free extracts and asphaltenes were nearly identical to the oil in the primary reservoir small chemical differences are noted among extracts

longitudinal variability of low latitude total electron content tidal influences 1 recently nighttime ultraviolet uv observations obtained by image fuv and timed guvi instruments have revealed a longitudinal wave number four pattern in the nighttime airglow intensity and in the position of the equatorial anomalies during equinox and high solar flux conditions in the present study we have extended this work and determined the longitudinal variability of the low latitude total electron content tec climatology during different geophysical conditions with a special emphasis on the longitudinal wave number four structure in the low latitude ionosphere we have used more than 5 million low latitude topex tec observations covering the entire 13 years of topex tec data from august 1992 until october 2005 this data set was used to determine the local time seasonal solar cycle and geomagnetic activity dependence of the longitudinal variability of tec at equatorial and low latitudes and in particular to address the existence and evolution of the wave number four longitudinal pattern under these conditions our study shows that the wave number four pattern is created during the daytime hours at equinox and june solstice but is absent or washed out by other processes during december solstice during equinox the wave number four pattern is created around noon with well defined longitudinal enhancements in the low latitude tec these enhancements which are symmetric about the geomagnetic equator during this season last for many hours and can be clearly seen past midnight the longitudinal patterns are found to be nearly identical between the vernal march april and autumnal september october equinoxes and largely independent of the solar cycle conditions the wave number four pattern is also observed during geomagnetically active conditions indicating that the processes that create this pattern are also present during active times the variations between the well defined longitudinal maxima and minima are of the order of 20 during june solstice the wave number four pattern is also observed in the afternoon hours but in contrast to the equinox cases it exhibits a strong hemispheric asymmetry and is not observed during the night the low latitude tec exhibits clear longitudinal variations during december solstice with large daytime enhancements over the east asian and pacific regions and a third enhancement emerging in the afternoon over the atlantic ocean but a clear wave number four pattern is not observed during this season although the equatorial and low latitude tec values exhibit clear longitudinal patterns during all seasons a significant amount of scatter remains in the tec data that is not accounted for by changes in the solar cycle the season or the local time or by the longitudinal variability this remaining scatter is largest near the poleward edges of the anomalies and is of the order of 40

invariance and scaling properties in the distributions of contributing area and energy in drainage basins a the cumulative probability distributions for stream order stream length contributing area and energy dissipation per unit length of channel are derived for an ordered drainage system from horton s laws of network composition it is shown how these distributions can be related to the fractal nature of single rivers and river networks finally it is shown that the structure proposed here for these probability distributions is able to fit the observed frequency distri butions and their deviations from straight lines in a log log plot

gully channel and hillslope erosion an assessment for a traditionally managed catchment understanding landscape features such as gullying and soil erosion is an important issue in the long term dynamics and evolution of both natural agricultural and rehabilitated i e post mining landscapes considerable research has been undertaken examining the initiation movement and overall dynamics of such features this study reports on a series of 34 gully heads and other erosion features such as scour holes five in total located in channels in a catchment largely undisturbed by european activity in the northern territory australia over a 5 year period 2002 2007 during this period the erosion features were monitored for their headward advance retreat enlargement or in filling the erosion features ranged in depth from 0 2 m to 1 5 m and widths of 0 3 m to 8 m hillslope erosion was also monitored using erosion pins the catchment was subject to a range of rainfall regimes including extreme rainfall and a category 5 cyclone and also was burnt every second year so that all grass cover was removed according to traditional management practice the results of this monitoring show that the erosion features have changed little during this 5 year period a remote sensing assessment found no relationship between erosion feature morphology and hillslope erosion the monitored gullies heads and scour holes appear to be resilient landscape features yet have a morphology that suggests they are ready for rapid headward movement and expansion leading to a destabilisation of the catchment hillslope erosion was found to be related to wetness indices derived from a digital elevation model significant linkages were found between hillslope erosion and change in erosion feature depth indicative of a strong hillslope channel coupling copyright 2010 commonwealth of australia

geochemical variations among eastern saudi arabian paleozoic condensates related to different source kitchen areas abstract large reserves of gas and condensate are found in paleozoic reservoirs khuff unayzah and jauf in the ghawar area of eastern saudi arabia the source rock for these hydrocarbons is the basal organic rich hot shale of the qusaiba member of the silurian qalibah formation this is the same prolific source rock that generated the sweet light crude oil and condensate found in the unayzah reservoirs in central saudi arabia thermal maturity modeling of the source rock identifies two kitchen areas to the east and west of the ghawar structure the west kitchen was well into the oil window by 210 ma while the east kitchen was just entering the oil window large areas of both kitchens were in the wet gas window by 125 ma and by 90 ma most of the area north of ghawar was generating dry gas in eastern saudi arabia paleozoic oil and condensate are found in early formed structures carboniferous and early triassic growth whereas late cretaceous and tertiary structures contain only dry gas the geochemistry of the oils and condensates indicates two groups each generated from a different hydrocarbon kitchen suggesting that the two kitchens differ slightly in organic facies within each group variations among hydrocarbons are related to the thermal maturity of the source rock during generation within the khuff reservoir gas souring is caused by thermochemical sulfate reduction

geochemical characterization of selected western canada oils by c5 c8 compound specific isotope correlation csic abstract forty two oils condensates from the western canada sedimentary basin wcsb ranging in reservoir age from devonian to cretaceous are compared using the stable carbon isotopic ratio of individual hydrocarbons in the gasoline range fraction c 5 c 8 of these oils continuous flow isotope ratio mass spectrometry cf irms using a modified solid dilution purge and trap inletting system can provide reproducible isotopic ratios for the ca 26 dominant n iso and cyclo alkanes and aromatics in the gasoline range the resulting isotopic signatures or gasoline isotopograms for oils condensates provide a diagnostic geochemical technique for oil oil and oil source correlations in many instances the non straight chained hydrocarbons are more diagnostic than n alkanes hierarchical cluster analysis provides a non subjective approach to the treatment of individual isotopic information this study confirms that oils from similar or the same sources produce isotopic signatures that are highly correlated clear carbon isotopic relationships between individual hydrocarbon compounds in the oils suggest a steady state kinetic relationship for the generation of oil and gas as opposed to a thermodynamic equilibrium relationship this mechanism explains the consistent shift in isotopic ratios between similar compounds such as the methylalkanes and dimethylalkanes

deep hydrocarbons in the northwestern junggar basin nw china geochemistry origin and implications for the oil vs gas generation potential of post mature saline lacustrine source rocks abstract deep 4500 m sedimentary units in petroliferous basins are a frontier field for petroleum exploration and exploitation worldwide this study focuses on the northwestern junggar basin of nw china and presents the results of a comprehensive geochemical analysis of the source rocks and hydrocarbons hosted by deep reservoirs in this region including data obtained from rock eval pyrolysis carbon isotope biomarker and light hydrocarbon analyses these data provide insights into the exploration potential of deep hydrocarbons in the study area and in other areas with similar geologic settings i e saline lacustrine petroleum systems results indicate that the deep hydrocarbons in the northwestern junggar basin are dominated by oil with both the oil and natural gas being derived mainly from the lower permian fengcheng formation this formation was deposited in a heterogeneous saline lacustrine environment which led to the generation of geochemically diverse oil compositions consequently fengcheng derived oils can be divided into subcategories based on source rock lithology i e hypersaline alkaline muddy dolomites saline dolomitic mudstones and brackish mudstones a small number of deep oils in the study area were derived from the carboniferous lower permian jiamuhe formation the deep hydrocarbons in the study area generally accumulated in near source environments indicating that prospective areas are present in the form of fengcheng derived oils in the depocenter of the mahu sag especially oils derived from hypersaline alkaline muddy dolomites and saline dolomitic mudstones these source rocks are likely to have generated oil even under the highly mature conditions associated with deep burial this might explain why discoveries within saline lacustrine basins are generally dominated by oil implying that these conditions might also exist within the deeper parts of saline lacustrine basins worldwide

δ13c compositions of saturate and aromatic fractions of lacustrine oils and bitumens evidence for water column stratification abstract saturate fractions of oils and source rocks are generally depleted in 13 c relative to the aromatic fraction the isotopic difference between these two fractions aro sat is largest typically in lacustrine oils and bitumens and smallest in marine samples depletions of 13 c in saturate fractions in samples from three lacustrine basins china argentina and u s a correlate strongly with hopane abundance extremely 13 c depleted hopanes have been documented in ancient and modern lacustrine settings and are explained by input from methanotrophic bacteria as these bacteria thrive at the chemocline of stratified lakes extremely 13 c depleted hopanes in geologic samples is evidence for paleostratification comparatively low aro sat values in marine samples are related to abundant sulfate in marine environments since sulfate reducers out compete methanogens for metabolic intermediates and attenuate the methane cycle the strong positive correlation of quantitative hopane abundance with the 13 c depletion in saturate fractions of lacustrine samples provides circumstantial evidence for biogenic input from methanotrophic bacteria and for stratified water columns during source rock deposition further this observation explains why the sofer plot effectively differentiates stratified lacustrine samples from open marine and non stratified lacustrine samples the wide distribution of our sample set suggests that this is a global phenomenon

catchment reconstruction erosional stability at millennial time scales using landscape evolution models abstract an important part of planning for the rehabilitation of a mine site is the design of stable final landforms for waste rock dumps or spoil piles whilst able to be assessed over the short term years to decades the longer term behaviour centuries to millennia of such landscapes is not within any meaningful human time frame of observation predictive numerical models therefore form an important tool with which current landscape behaviour and longer term trajectory can be assessed however an important issue associated with the use of models is the ability to assess the reliability and accuracy of the model here the siberia and caesar lisflood landscape evolution models lems are used to simulate and assess the geomorphic stability of a conceptual rehabilitated landform of the ranger uranium mine in the northern territory australia for a simulated period of up to 1000 years utilising both models in this study enabled an independent assessment of likely landscape processes and evolution as well as each model results show that siberia and caesar lisflood produce erosion rates and patterns that are broadly similar at millennial time scales short term processes such as gullying appear to be the dominant erosion features in the proposed landforms and may produce substantial erosion in terms of size and amount of hillslope material eroded and transported downslope vegetation was found to have a major effect on the erosion potential of the landform surface overall both models produce very similar results

major volatiles evolved from eolian materials in gale crater the sample analysis at mars sam on the curiosity rover analyzed the major volatile content of four eolian samples at three locations in gale crater the rocknest sample was taken from an inactive sand shadow with a significant component of dust sized grains while gobabeb and ogunquit beach samples were taken from different locations in the bagnold dune field and had dust free fine sand sized grains all eolian samples possessed more oxychlorine carbon and nitrate relative to sedimentary materials in gale crater evolved co2 above 450 c was consistent with 0 7 and 0 4 wt carbonate in the bagnold dunes and rocknest materials respectively with a regional source inside gale crater the fine grained phase of rocknest was enriched in adsorbed water and perhaps in fe sulfate and fe nitrate nitrite compared to coarser bagnold materials and was estimated to contain up to 0 1 wt of organic carbon

the interaction between armouring and particle weathering for eroding landscapes the interaction between particle weathering and surface armouring and its effect on erosion has been investigated the effect of soil armouring is to decrease sediment transport with time by preferentially stripping away fine particles on the other hand the effect of weathering which breaks down the particles in the armour is generally believed to increase erosion by extending an existing armouring model armour and using a variety of published weathering mechanisms this interaction has been explored the model predicts that while this is generally true in some cases erosion can be decreased by weathering when the particles generated by weathering were approximately of equal diameter erosion increased while armouring decreased when weathering produced very fine particles by spalling erosion increased and armouring also increased when weathering produced a range of particles from fine to coarse the armour layer broke down and erosion decreased relative to the no weathering case this latter decrease in erosion was due to the high entrainment of coarser transportable materials from the bed decreasing the sediment transport capacity of the flow in these studies clear regimes could be identified where erosion was limited by either the energy of the flow alone i e transport limited or the rate of weathering weathering limited however for some mechanisms there was an interaction between the two which we called weathering transport limited copyright 2006 john wiley sons ltd

the effect of spatial heterogeneities on geomorphic expression in a model of basin evolution spatial variability is a basic component of all natural systems the system being studied here is the topography of an evolving drainage basin spatially heterogeneous erosivity within the drainage basin influences the structure of the drainage network the roughness of small scale features and the overall appearance of the simulated topography the presence of heterogeneities does not simply blur and smear analytical relationships the heterogeneities themselves introduce new structure to the organization of the drainage basin three measures the slope area relationship the cumulative area relationship and the hypsometric distribution are all systematically affected by spatial heterogeneity we will demonstrate how and why these relationships are affected and also how different structures in the heterogeneities themselves are manifested in the resulting simulated topography

the stable carbon isotopic composition of oil from the taranaki basin of new zealand abstract the average stable carbon isotope ratio of 21 oils from the taranaki basin of new zealand suggests that the source rocks date from the cretaceous period when sedimentation in this basin began stable carbon isotope ratios also confirm the grouping of these oils into the genetic families which were previously suggested by the correlation of source related biomarkers stahl isotope type curves for the oils also reflect the correctness of these relationships a plot of the saturate versus aromatic 13c values for the new zealand oils is particularly valuable for oil correlation in this basin and clearly demonstrates that the ahuroa and stratford oils while separated from the mckee field by some 30 km probably originate from the same oil source formation as do the oils of the mckee field the plot also indicates that the kaimiro mangahewa pukearuhe and waihapa oils are discrete in situ accumulations of petroleum which do not have the characteristics of oils from adjacent fields these conclusions are further supported by the values of the sofer canonical variable for all of the oils additionally the sofer plot provides clear evidence of the predominantly terrigenous origin of the oils in the taranaki basin consideration of the data for these oils leads to a hypothesis that three independent sources of organic material microbes gymnosperms and angiosperms gave rise to the oils in this region

modelling landscape evolution geomorphology is currently in a period of resurgence as we seek to explain the diversity origins and dynamics of terrain on the earth and other planets in an era of increased environmental awareness yet there is a great deal we still do not know about the physics and chemistry of the processes that weaken rock and transport mass across a planet s surface discovering and refining the relevant geomorphic transport functions requires a combination of careful field measurements lab experiments and use of longer term natural experiments to test current theory and develop new understandings landscape evolution models have an important role to play in sharpening our thinking guiding us toward the right observables and mapping out the logical consequences of transport laws both alone and in combination with other salient processes improved quantitative characterization of terrain and process and an ever improving theory that describes the continual modification of topography by the many and varied processes that shape it together with improved observation and qualitative and quantitative modelling of geology vegetation and erosion processes will provide insights into the mechanisms that control catchment form and function this paper reviews landscape theory in the form of numerical models of drainage basin evolution and the current knowledge gaps and future computing challenges that exist copyright 2010 john wiley sons ltd

use of hydrogen and carbon stable isotopes characterizing oils from the potiguar basin onshore northeastern brazil hydrogen and carbon isotopic abundances were measured in representative samples of marine evaporitic lacustrine and mixed oils from the onshore potiguar basin the isotopic data together with chemical compositions and geological information were used to investigate relationships among ddoil and d13coil and source thermal maturity biodegradation mixing and the distance of secondary migration of these oils the marine evaporitic oils are depleted in deuterium 135 to 114 and the lacustrine oils are enriched 101 to 88 values of dd for mixed oils are intermediate 113 to 104 between those of marine evaporitic and lacustrine oils showing that ddoil is a reliable tool to identify oils that differ genetically values of ddoil were not directly related to thermal maturation biodegradation or distance of the secondary migration hydrogen isotopic compositions of the oils can be related mainly to the ddwater in the paleoenvironments in which the primary producers lived therefore ddoil values can provide rough estimates of ddwater in the depositional environments of the source rocks and consequently may provide evidence about paleoclimatic conditions at the site marine evaporitic oils are enriched in 13c 26 5 to 25 7 and lacustrine oils are depleted 33 6 to 30 2 in 13c relative contributions of marine evaporitic and lacustrine sources to mixed oils thus can be calculated independently from carbon or hydrogen isotopic mixing models when these calculations are done independently the mixed oils separate into two families and a previously unrecognized component possibly associated with environments that formed during the lacustrine to marine transition is revealed the investigation thus demonstrates the superior resolving power of two element mixing systematics

post generative alteration effects on petroleum in the onshore northwest java basin indonesia northwest java basin oils largely derived from the fluvial deltaic to nearshore marine talangakar formation of oligocene to early miocene range from heavy oils to extremely light oils and retrograde condensates with api gravities of a suite of oils ranging from about 17 to 53 heavy oils with api gravities less than 22 all of which are in shallow reservoirs are biodegraded pristine oils concomitant with related derivative residual and retrograde condensate oil types indicate evaporative fractionation phenomena post generative alteration processes are widespread in this highly faulted region pristane to phytane biomarker ratios of retrograde condensates and residual oils have been shown to be severely affected by evaporative fractionation principal component analysis pca of isotope and biomarker data identified two oil families associated with source rocks of the talangakar formation one group is suggested to be derived from more marine influenced delta front to prodelta depositional settings while the second group is attributed to a higher plant rich delta plain to delta front depositional environment correlation of these oil families with the varied depositional environments of the talangakar formation has allowed a more refined approach to the identification of hydrocarbon migration pathways in the northwest java basin multivariate statistical analysis is shown to be an effective tool in correlating high gravity condensate oil types

eroding australia rates and processes from bega valley to arnhem land we report erosion rates determined from in situ produced cosmogenic 10 be across a spectrum of australian climatic zones from the soil mantled se australian escarpment through semi arid bedrock ranges of southern and central australia to soil mantled ridges at a monsoonal tropical site near the arnhem escarpment climate has a major effect on the balance between erosion and transport and also on erosion rate the highest rates averaging 35 m ma 21 were from soil mantled transport limited spurs in the humid temperate region around the base of the se escarpment the lowest averaging about 1 5 m ma 21 were from the steep weathering limited rocky slopes of kings canyon and mt sonder in semi arid central australia between these extremes other factors come into play including rock type slope and recruitment of vegetation we measured intermediate average erosion rates from rocky slopes in the semi arid flinders and macdonnell ranges and from soil mantled sites at both semi arid tyler pass in central australia and the tropical monsoonal site at soil mantled sites in both the se and tropical north soil production generally declines exponentially with increasing soil thickness although at the tropical site this relationship does not persist under thin soil thicknesses and the relationship here is humped results from tyler pass show uniform soil thicknesses and soil production rates of about 6 5 m ma 21 supporting a longstanding hypothesis that equilibrium soil mantled hillslopes erode in concert with stream incision and form convex up spurs of constant curvature moreover weathering limited slopes and spurs also occur in the same region the average erosion rate for rocky sandstone spurs at glen helen is 7 m ma 21 similar to the tyler pass soil mantled slopes whereas the average rate for high quartzite spurs at mount sonder is 1 8 m ma 21 the extremely low rates measured across bedrock dominated landscapes suggest that the ridge valley topography observed today is likely to have been shaped as long ago as the late miocene these rates and processes quantified across different undisturbed landscapes provide critical data for landscape evolution models

longitudinal variation of the e region electric fields caused by atmospheric tides 1 polarization electric fields created by the e and f region dynamos cause the uplift of f region plasma the subsequent redistribution of that plasma along the magnetic field lines creates the equatorial ionospheric anomaly eia observations of the post sunset eia made by the image and timed satellites are compared here with champ orsted and sac c observations of the noontime equatorial electrojet eej during magnetically quiet periods around equinox the eia and eej show a remarkably similar four peaked wave like longitudinal variation its structure is consistent with the longitudinal variation in the strength of diurnal tides that drive the e region dynamo this indicates a strong vertical coupling between the ionosphere and troposphere because the four peaked tidal structure is driven by tropospheric weather furthermore the dayside ionospheric conditions are found to perform the global scale longitudinal structure of the post sunset ionosphere at low latitudes

stable sulfur and nitrogen isotopic compositions of crude oil fractions from southern germany abstract eleven samples of crude oil from the molasse basin of southern germany were fractionated and their contents of sulfur and nitrogen as well as the stable isotope compositions of these elements 34 s 32 s and 15 n 14 n resp investigated according to the 34s determinations all crude oils from the tertiary base of the western and eastern molasse belong to one oil family and differ significantly from the triassic and liassic oils in the western molasse an enrichment of 34s was observed with increasing polarity of crude oil fractions the isotope distributions of sulfur in the polar constituents of the biodegraded oils from the sandstones of ampfing however approach a homogeneous distribution the nitrogen isotope distribution is rather uniform in southern german oils a regional differentiation can be recognized although the overall isotopic variation is small the 15n values of the crudes and asphaltenes do not correlate

tidal variability in the ionospheric dynamo region 1 the seasonal and interannual variability of migrating sun synchronous and nonmigrating solar atmospheric tides at altitudes between 100 and 116 km are investigated using temperature measurements made with the saber instrument on the timed spacecraft during 2002 2006 quasi biennial variations of order 10 15 in migrating diurnal and semidiurnal tidal amplitudes are found presumably due to modulation by the quasi biennial oscillation qbo as the tides propagate from their troposphere and stratospheric sources to the lower thermosphere a number of nonmigrating tidal components are found that have the potential to produce significant longitudinal variability of the total tidal fields the most prominent of these i e those that appear at amplitudes of order 5 10 k in a 5 year mean climatology include the zonally symmetric s 0 diurnal tide d0 the eastward propagating diurnal and semidiurnal tides with zonal wave numbers s 2 de2 and se2 and s 3 de3 and se3 and the following westward propagating waves diurnal s 2 dw2 semidiurnal s 1 sw1 s 3 sw3 and s 4 sw4 and terdiurnal s 5 tw5 these waves can be plausibly accounted for by nonlinear interaction between migrating tidal components and stationary planetary waves with s 1 or s 2 or by longitudinal variations of tropospheric thermal forcing additional waves that occur during some years or undergo phase cancellation within construction of a 5 year climatology include dw5 se1 se4 sw6 te1 tw1 and tw7 it is anticipated that the winds that accompany all of these waves in the 100 170 km region will impose longitudinal variability in the electric fields produced through the ionospheric dynamo mechanism thereby modulating vertical motion of the equatorial ionosphere and the concomitant plasma densities in addition to the wave 4 modulation of the equatorial ionosphere that has recently been discovered and replicated in modeling studies the waves revealed here will generate wave 1 sw1 sw3 d0 dw2 wave 2 sw4 tw1 wave 3 de2 se1 wave 4 de3 se2 dw5 sw6 te1 tw7 wave 5 se3 and wave 6 se4 components of this ionospheric variability depending on year and time of year however the absolute and relative efficiencies with which these waves produce electric fields remains to be determined

power law distributions of discharge mass and energy in river basins river networks constitute dissipative systems with many spatial degrees of freedom previous work by mandelbrot 1983 and bak et al 1987 1988 1990 suggests that such systems will follow power law distributions in their mass and energy characteristics it is shown that this is the case for river networks where the exponent in the distribution p x x x is approximately equal to 0 45 and 0 90 for discharge and energy respectively in the case of several networks analyzed in north america when these variables are calculated for each individual link throughout the drainage network an explanation of the values of is offered based on the fractal structure of rivers and on principles of energy expenditure in river basins

geochemical characterization of qhd29 oils on the eastern margin of shijiutuo uplift bohai sea china insights from biomarker and stable carbon isotope analysis abstract toc and rock eval analyses were conducted on cutting samples 111 from various paleogene formations ed3 es1 and es3 in the qinnan sag the average values of total organic carbon toc content are 1 11 1 64 and 2 29 for ed3 es1 and es3 samples respectively the es1 and es3 source rocks are of relatively high s2 values ranging from 0 42 to 46 01 and 2 46 61 01mghc rock respectively the ed3 rocks have lower generative potential with s2 values ranging from 0 9 to 9 3 mg hc g rock moreover tmax values indicate that these source rocks are sufficiently mature for petroleum generation these analyses suggest that es1 and es3 are potential source rocks for oils produced from the qhd29 field eighteen oil samples from the qhd29 field were analyzed by gc and gc ms and 84 qhd29 oil 13 and source rock 71 samples were employed for stable carbon isotope analysis based on hierarchical cluster analysis of selected biomarker parameters the qhd29 oils can be identified into two groups group i and group ii oils are both derived from the eocene shahejie formation es1 and es3 displaying remarkable difference to the oligocene ed3 derived oils in comparison with group ii oils group i oils display relatively low 4msi and high g h indicating that group i oils have important contributions from es1 source rock deposited under more alkaline saline environment moreover these two group oils can be clearly separated by 13c values and group i oils are isotopically lighter than group ii oils difference occurs in stable carbon isotope distribution between es1 and es3 source rock extracts as well and es1 source rocks are characterized by relatively light carbon isotopic composition this implies that group i oil shares more es1 derived oil which is consistent with the results of biomarker analysis

the humped soil production function eroding arnhem land australia we report erosion rates and processes determined from in situ produced beryllium 10 10be and aluminum 26 26al across a soil mantled landscape of arnhem land northern australia soil production rates peak under a soil thickness of about 35 cm and we observe no soil thicknesses between exposed bedrock and this thickness these results thus quantify a well defined humped soil production function in contrast to functions reported for other landscapes we compare this function to a previously reported exponential decline of soil production rates with increasing soil thickness across the passive margin exposed in the bega valley south eastern australia and found remarkable similarities in rates the critical difference in this work was that the arnhem land landscapes were either bedrock or mantled with soils greater than about 35 cm deep with peak soil production rates of about 20 m ma under 35 40 cm of soil thus supporting previous theory and modeling results for a humped soil production function we also show how coupling point specific with catchment averaged erosion rate measurements lead to a better understanding of landscape denudation specifically we report a nested sampling scheme where we quantify average erosion rates from the first order upland catchments to the main sixth order channel of tin camp creek the low 5 m ma rates from the main channel sediments reflect contributions from the slowly eroding stony highlands while the channels draining our study area reflect local soil production rates 10 m ma off the rocky ridge 20 m ma from the soil mantled regions quantifying such rates and processes help determine spatial variations of soil thickness as well as helping to predict the sustainability of the earth s soil resource under different erosional regimes copyright 2009 john wiley sons ltd

stable carbon isotopic analysis of sedimentary organic matter by stepped combustion abstract a stepped combustion technique incremental heating in oxygen has been used to study the carbon isotopic composition of carbonaceous sediments this technique can afford data on the organic matter of the sediment and can give information on the structure namely the variations in the isotopic composition of different portions of the kerogen green river shale has been used as a model material and results indicate that it contains two distinct carbonaceous components a carbonate and kerogen isotopic compositions for the kerogen measured by stepped combustion closely match those obtained by normal methods following preconcentration of the kerogen by mineral removal and solvent extraction the variation in isotopic composition with combustion temperature has been used to investigate relationships with maturity and to look at its use as a possible correlation tool

dendrogeomorphic assessment and sediment transfer of natural vs mining induced debris flow activity in călimani mountains eastern carpathians romania abstract during the second half of the twentieth century in the central part of the c limani mountains the mining activities for sulfur rich ore extraction and processing produced significant landscape changes sediment transfers across the affected catchments started during the mining period and are still ongoing today more than two decades after the cessation of the mining activities in 1997 subsequently neither rehabilitation works nor erosion control measures were undertaken to stabilize the spoil heap deposits and natural reforestation also material consolidation was impeded by the highly unstable talus slopes moreover little is known about the frequency of the hydrogeomorphic processes responsible for sediment transfers and their consequences dendrogeomorphic investigations grain size analyses and topographic surveys were carried out to document the history of hydrogeomorphic activity the volume of material stored behind the retention dams and the rate of sediment accumulation tree ring analysis allowed us to reconstruct ten debris flow events in the natural environment as well as in mining disturbed environment for the period 1931 2017 and 1970 2017 respectively triggering of debris flows appears related to spring and summer precipitation originating from short duration convective systems or long lasting rainfalls in these remote mining areas the reconstructed frequency of debris flows return intervals of 8 1 and 4 7 years might be explained by the rainwater accumulation on the spoil heap platform and the availability of sediments which flow down the talus and then follow the stream channels to reach one of the sediment retention reservoirs 7 4 8 4 cm y 1

organic geochemistry of the san vicente zinc lead district eastern pucara basin peru abstract isotopic and chemical studies of organic matter of the san vicente mississippi valley type zn pb district hosted in the dolomitic units of the eastern pucara basin peru provide insight into the source of organic matter and of the organic matter ore relationship a large scatter exists in the 13c and 15n values of the highly mature kerogens these bulk data were combined with 13c covariations of the saturated and aromatic fractions of the rock extracts to indicate a contribution of continental higher plant lipids to the marine algal source of the organic matter disseminated in the host carbonate rocks an enrichment in 15n of the kerogens of mineralized samples compared to barren samples suggests that isotopically heavy nitrogen compounds were introduced to the ore fluid the fluid likely leached these compounds from the underlying clastic rocks and other detrital units of the pucara the extracts from mineralized samples are enriched in 13c compared to the associated kerogens this suggests that the rocks in the mineralized areas were stained by a mixture of extrinsic and indigenous bitumens by the use of novel instrumentation such as a gas chromatograph gc coupled to a stable isotope ratio mass spectrometer irms through a combustion c interface gc c irms stable carbon isotope analyses of individual hydrocarbons were also obtained both the molecular and isotopic signatures of the individual hydrocarbons are related to mineralization the variability in the organic molecular parameters and the 13c values of the individual n alkanes and isoprenoids indicate mixing of indigenous hydrocarbons with extrinsic 13c depleted microbially derived hydrocarbons the extrinsic source hydrocarbons were introduced to the mineralization site by the ore fluid or later fluids using the same porosity network oxidative alteration of the migrating hydrocarbons was involved in the thermochemical reduction of sulfate to h2s and precipitation of pyrobitumen large differences 12 in the carbon isotope compositions of long chain c20 n alkanes can be utilized in distinguishing sources of organics in the barren and mineralized samples

wavenumber 4 patterns of the total electron content over the low latitude ionosphere 1 the global ionospheric maps gims produced by jpl are used to investigate the longitudinal structure of the low latitude ionosphere as a proxy of the ionization parameter at low latitudes the latitudinally integrated total electron content itec is first extracted from low latitude gims and then fourier filtered to obtain the wavenumber 4 components we then study in detail the diurnal seasonal and solar cycle variations of the wave patterns it is found that the wavenumber 4 patterns are intense and well developed in boreal summer and early boreal autumn but quite weak in boreal winter this seasonal variation is consistent with that of the zonal wind of the non migrating tide mode de3 we also found that the wavenumber 4 patterns shift eastward with a shifting speed that is smaller in daytime than at night this is attributed to the contribution of both the eastward propagation of de3 in e region and the zonal e b ion drifts in f region our results support the suggestion that the longitudinal wavenumber 4 structure of the low latitude ionosphere should be originated from the non migrating tide mode de3

recent advances in petroleum isotope geochemistry abstract organic matter is isotopically heterogeneous lipids tend to be depleted in the heavy carbon and hydrogen isotopes as compared to carbohydrates and lignite the c and h isotopic composition of kerogens is determined by many factors such as environmental conditions during formation and deposition and variability of sources of organic matter stable isotope concentrations in mature kerogens are not significantly altered during maturation and hence reflect the variability of the organic matter during deposition isotope variations in kerogens therefore reflect to some extent the paleogeographic situation and can be used for paleoreconstruction a basin facies with anoxia and a marginal facies with detrital input can be differentiated isotopically in the toarcian of central europe coals are isotopically heterogeneous due to different isotopic composition of macerals inertinite and vitrinite tends to be enriched in deuterium as compared to exinite also boghead coals tend to be depleted in dueterium which possibly reflects various lipid contents of respective precursor materials petroleums can be genetically classified through the patterns of covariance of their compound classes carbonate and shale sourced petroleums may be additionally differentiated through their deuterium content the general world wide applicability of such genetic differentiations needs still to be proved carbon and hydrogen isotope variations in methane are genetically controlled bacterial methane in freshwater environments is characteristically depleted in deuterium even complex origins of natural gases can be unraveled using compositional and isotopic variations new analytical developments led to the application of carbon isotope analyses of gaseous hydrocarbons desorbed from sediments for geochemical surface exploration a discussion reveals that processes such as isotope effects during degassing and bacterial oxidation as well as indigenous formation of hydrocarbons may completely obscure the results

high resolution vertical e b drift model derived from rocsat 1 data 1 the measurements of vertical ion velocity from the first republic of china satellite rocsat 1 provide a unique database for the development of an annually and longitudinally high resolution vertical plasma drift model in the equatorial ionosphere currently the rocsat 1 based empirical vertical drift models are available for three seasons equinox and solstices however the vertical drift patterns are not precisely divided by the three seasons a monthly vertical drift model with high longitudinal resolution is desirable to accurately model the low latitude ionosphere and to identify the coupling between the ionosphere and atmospheric tide here we introduce an empirical vertical drift model derived by using the rocsat 1 data in three solar flux conditions f 10 7 180 under k p 3 the local time day of the year and longitude of the model are binned by 15 min 1 month and 10 respectively under each solar flux condition our vertical drift model is validated by comparing the model with the measurements of the vertical drift velocity at the jicamarca radio observatory the characteristics and variability of the vertical drift are briefly discussed

geochemistry of carbonaceous impactites from the gardnos impact structure norway abstract the gardnos impact structure in southern norway is one of only two known impact structures among 175 whose impactites contain significant amounts typically 0 2 1 0 wt of carbon or 5 to 10 times the amount present in the target rocks sudbury canada is the other this study extends a previous investigation of the geochemistry and petrology of gardnos impactites french et al 1997 with additional sampling and a detailed investigation of the nature and possible origin of the carbonaceous material present two principal carbon components have been identified in gardnos impactites 1 impact produced diamonds 0 5 to 1 m in size with a cubic crystal structure predominantly hexagonal morphologies with platey layers and an estimated concentration of geochemical data suggests that there are no suitable target rocks that could provide a single source for the carbon in gardnos impactites however raman spectroscopy stable isotope analysis and transmission electron microscopy of the impact diamonds and graphitic carbon suggests that there were at least two episodes of c emplacement in gardnos impactites an impact related incorporation and shock transformation of graphitic material from target rocks followed by later mobilization of c possibly during postimpact cooling or later regional metamorphism

equatorial longitude and local time variations of topside magnetic field aligned ion drifts at solar minimum 1 in the topside ionosphere the high mobility of the plasma along the magnetic field allows field aligned ion drifts to occur readily as a result of field aligned gravitational forces collisional forces or pressure gradients therefore variations in the field aligned ion drifts can be used to explore the influence of thermospheric electrodynamic and chemical processes on the ionosphere longitude and local time variations in the field aligned ion drifts near the magnetic equator are presented using observations from the coupled ion neutral dynamics investigation on board the communications navigation outage forecast system satellite these observations were obtained during the period of extremely low solar activity present in 2008 and 2009 allowing the seasonal local time and longitudinal variations to reveal the relative importance of the processes responsible for topside field aligned plasma drifts during solar minimum this investigation found that the low altitude winds and tides the net ionization or loss and the meridional e b drift were all influential in creating longitudinal and local time variations in the field aligned drift though the strength of the influence seen by each driver was found to vary with season local time and longitude

persistent longitudinal features in the low latitude ionosphere 1 various longitudinal wave patterns exist in the low latitude ionosphere but the investigation has been limited to the wave number wn 3 and 4 patterns this study extends the investigation to the wave patterns that have not yet been explored the persistent ionospheric wave patterns are investigated by using the measurements of the ion density during march 1999 june 2004 by the first republic of china satellite the investigation is performed with data sets in the magnetic south 20 s 0 and magnetic north 0 20 n the dominant wave features in plasma density are the wn1 wn2 wn3 and wn4 patterns among them the wn1 pattern in the magnetic south during the june solstice is the most pronounced feature except for this component the wn3 pattern is the most persistent and pronounced feature fundamental difference exists between the wn1 and wn2 patterns and the wn3 and wn4 patterns first the wave phases in the south and north are the same in the wn3 and wn4 patterns but they are opposite in the wn1 and wn2 patterns second the amplitudes of the wn3 and wn4 patterns show similar annual variation in the south and north but those of the wn1 and wn2 patterns show opposite annual trends in the opposite hemispheres these observations indicate that the wn1 and wn2 patterns and the wn3 and wn4 patterns are created by different mechanisms we discuss the creation of the wn1 and wn2 patterns in association with the geomagnetic field configuration

fracture controlled paleohydrogeology in a basement cored fault related fold sheep mountain anticline wyoming united states new geochemical and microstructural data constrain the origins and pathways of paleofluids during the growth of sheep mountain anticline wyoming united states oxygen carbon and strontium isotope studies were performed on prefolding and fold related calcite veins and their sedimentary host rocks and combined to fluid inclusion microthermometry results we show that most of the cements precipitated from paleogene meteoric fluid stable isotopes and fluid inclusion homogenization temperatures further indicate that most veins were mineralized from upward moving fluids after these fluids were heated at depth t 110 c this implies that fluids migrated along the basement thrust underlying the fold and or at the base of the cover above the fault tip the fluids circulated rapidly in the diffuse synfolding and early folding fracture network the zone of preferential migration of the warm fluids is currently located in the backlimb of the fold which supports some of the previously published structural interpretation of the subsurface this study also highlights the potential of combined fracture analysis and geochemical analyses of paleofluid flows in fractures to constrain both the deformation history and the fluid flow during basement involved shortening in laramide style forelands

post mining landform evolution modelling 2 effects of vegetation and surface ripping computer simulations of the topographic evolution of the proposed post mining rehabilitated landform for the era ranger mine showed that for the unvegetated and unripped case the landform at 1000 years would be dissected by localized erosion valleys maximum depth 7 6 m with fans maximum depth 14 8 m at the outlet of the valleys valley form simulated by siberia has been recognized in nature this indicates that siberia models natural processes efficiently for the vegetated and ripped case reduced valley development maximum 1000 year depth 2 4m and deposition maximum 1000 year depth 4 8m occurred in similar locations as for the unvegetated and unripped case i e on steep batter slopes and in the central depression areas of the landform for the vegetated and ripped condition simulated maximum valley depth in the capping over the tailings containment structure was c 2 2 m by modelling valley incision decisions can be made on the depth of tailings cover required to prevent tailings from being exposed to the environment within a certain time frame a reduction in thickness of 1 m of capping material over tailings equates to c 1 000 000 mm3 over a 1 km2 tailings dam area this represents a saving of c 1 500 000 in earthworks alone incorporation of siberia simulations in the design process may result in cost reduction while improving confidence in environmental protection mechanisms copyright 2000 environmental research institute of the supervising scientist commonwealth of australia

characterizing thermogenic coalbed gas from polish coals of different ranks by hydrous pyrolysis abstract to provide a better characterization of origin and volume of thermogenic gas generation from coals hydrous pyrolysis experiments were conducted at 360 c for 72 h on polish coals ranging in rank from lignite 0 3 r r to semi anthracite 2 0 r r under these conditions the lignites attained a medium volatile bituminous rank 1 5 r r high volatile bituminous coals attained a low volatile bituminous rank 1 7 r r and the semi anthracite obtained an anthracite rank 4 0 r r hydrous pyrolysis of a coal irrespective of rank provides a diagnostic 13 c value for its thermogenic hydrocarbon gases this value can be used quantitatively to interpret mixing of indigenous thermogenic gas with microbial methane or exogenous thermogenic gas from other sources thermogenic methane quantities range from 20 dm 3 kg of lignite 0 3 r r to 0 35 dm 3 kg of semi anthracite 2 0 r r at a vitrinite reflectance of 1 7 r r approximately 75 of the maximum potential for a coal to generate thermogenic methane has been expended at a vitrinite reflectance of 1 7 r r more than 90 of the maximum potential for a coal to generate co 2 has been expended assuming that these quantities of generated co 2 remain associated with a sourcing coal bed as uplift or erosion provide conditions conducive for microbial methanogenesis the resulting quantities of microbial methane generated by complete co 2 reduction can exceed the quantities of thermogenic methane generated from the same coal bed by a factor of 2 5

contaminated sediment flux from eroding abandoned historical metal mines spatial and temporal variability in geomorphological drivers abstract abandoned historical metal mines represent significant long term sediment source locations contributing highly contaminated anthropogenic legacy sediments to river systems despite this our understanding of spatial and temporal variability in the rates and geomorphological drivers of specific contaminated sediment source locations across abandoned mines remains poorly constrained in this study sediment flux from two abandoned historical lead mines in the north pennines uk was monitored over an 18 month period using repeat terrestrial laser scanning enabling the spatial and temporal significance of several common geomorphological processes to be quantified for the first time a novel contaminated sediment budget approach is used to integrate topographical change data with a pxrf survey of surface sediment metal concentrations approximately 434 t 289 t a 1 of eroded sediment entered the stream from a source area of 0 023 km2 the majority of the erosion was driven by two dominant processes with gullying accounting for 60 and bank erosion contributing 30 redeposition of eroded material within the survey area was minimal 3 indicating very high levels of coupling between source locations and the stream network and the export of the vast majority of eroded sediments 97 from the mined area rates for all erosive processes were highly episodic and primarily driven by high magnitude low frequency storm events metal concentrations in surface sediments exhibited considerable spatial variability with notable hotspots around the former ore processing areas and on the tailings heaps however 84 of all sediments sampled were in excess of available soil guideline values for pb and 65 in excess of equivalent guideline values for zn indicating that abandoned mine sites still have the potential to be significant sources of contaminant metals and pose a risk to the wider environment in total an estimated 4 59 t of pb and 2 14 t of zn entered the stream network in a sediment associated form during the 18 month monitoring period although these overall contaminated sediment inputs are high they are restricted to particular geomorphological processes are spatially variable in terms of the magnitude of specific source locations and are delivered in fairly discrete events this provides invaluable information for the future management of other abandoned mines and targeted mitigation of their potential legacy effects

the source of the longitudinal asymmetry in the ionospheric tidal structure 1 we examine the source of the longitudinal asymmetry in the ionospheric tidal structure by using the measurements of the plasma density and vertical plasma drift by the first republic of china satellite the consistent feature in plasma density and vertical plasma drift in all months is the development of the wave crests near 0 10 e and 90 100 e longitude the appearance of the global wave 4 or wave 3 structure is determined by the morphology between 150 e and 300 e longitude two crests are pronounced in july september and only one crest appears during the december solstice in that longitude region the crests of the wave 4 structure between 150 e and 300 e longitude are much weaker than the crests near the longitudes of 0 and 90 e during july september the wave 3 structure is pronounced in all months the phase difference between the wave 3 and wave 4 structures is small near the longitudes of 0 and 90 e and thus the superposition of the wave 3 structure amplifies the wave 4 crest intensity in those regions the phase difference is large between 150 e and 300 e longitude and thus the destructive superposition of the wave 3 component weakens the wave 4 crest in that region the wave 3 and wave 4 structures are the permanent ionospheric features and the significant portion of the longitudinal asymmetry is explained by the phase difference of the two structures

longitudinal variation of f region electron density and thermospheric zonal wind caused by atmospheric tides 1 simultaneous observations of the electron density and the zonal wind obtained by the champ satellite at 400 km are used to study systematic longitudinal variations the time period selected is august september 2004 allowing observations at pre noon and post sunset hours the equatorial ionization anomaly eia and the zonal delta wind deviation from zonal average show a persistent and dominant 4 peaked longitudinal variation we interpret this structure as caused by the wavenumber 3 nonmigrating diurnal tide de3 the eia and the zonal delta wind exhibit extrema at about the same longitudes but while the intensifications of the eia and the delta wind are in phase during the evening hours they are out of phase in the morning possible coupling mechanisms are investigated

the long term stability of engineered landforms of the ranger uranium mine northern territory australia application of a catchment evolution model there is a need to assess the long term stability of engineered landforms associated with the rehabilitation of ranger uranium mine northern territory australia as it is a requirement that mill tailings must be contained for periods in excess of 1000 years the geomorphic model siberia is calibrated on hydrologic and erosion data collected by a combination of monitoring and rainfall simulation experiments on the waste rock dumps of ranger preliminary analysis of ranger s preferred above grade option suggests that erosion of the order of 7 to 8 m will occur on the structure in a period of 1000 years this depth of erosion may be sufficient to compromise the integrity of containment it is shown that siberia has significant advantages over steady state erosion models suggestions are made for the design that will enhance the stability of the structure and extend the structural life of the containment 1998 john wiley sons ltd

a generalised one dimensional kinematic catchment model abstract a numerical model has been developed for the solution of the kinematic wave equation for a one dimensional catchment using the lax wendroff technique the model has been verified by comparing its solutions with some analytical solutions already available certain catchment parameters have been identified and the model applied with promising results to two actual catchments to ascertain their values

evaluation of the rhenium osmium geochronometer in the phosphoria petroleum system bighorn basin of wyoming and montana usa rhenium osmium re os geochronometry is applied to crude oils derived from the permian phosphoria formation of the bighorn basin in wyoming and montana to determine whether the radiogenic age reflects the timing of petroleum generation timing of migration age of the source rock or the timing of thermochemical sulfate reduction tsr the oils selected for this study are interpreted to be derived from the meade peak phosphatic shale and retort phosphatic shale members of the phosphoria formation based on oil oil and oil source rock correlations utilizing bulk properties elemental composition 13c and 34s values and biomarker distributions the 34s values of the oils range from 6 2 to 5 7 with oils heavier than 2 interpreted to be indicative of tsr the re and os isotope data of the phosphoria oils plot in two general trends 1 the main trend n 15 oils yielding a triassic age 239 43 ma with an initial 187os 188os value of 0 85 0 42 and a mean square weighted deviation mswd of 1596 and 2 the torchlight trend n 4 oils yielding a miocene age 9 24 0 39 ma with an initial 187os 188os value of 1 88 0 01 and a mswd of 0 05 the scatter high mswd in the main trend regression is due in part to tsr in reservoirs along the eastern margin of the basin excluding oils that have experienced tsr the regression is significantly improved yielding an age of 211 21 ma with a mswd of 148 this revised age is consistent with some studies that have proposed late triassic as the beginning of phosphoria oil generation and migration and does not seem to reflect the source rock age permian or the timing of re migration late cretaceous to eocene associated with the laramide orogeny the low precision of the revised regression 21 ma is not unexpected for this oil family given the long duration of generation from a large geographic area of mature phosphoria source rock and the possible range in the initial 187os 188os values of the meade peak and retort source units effects of re migration may have contributed to the scatter but thermal cracking and biodegradation likely have had minimal or no effect on the main trend regression the four phosphoria sourced oils from torchlight and lamb fields yield a precise miocene age re os isochron that may reflect the end of tsr in the reservoir due to cooling below a threshold temperature in the last 10 m y from uplift and erosion of overlying rocks the mechanism for the formation of a re os isotopic relationship in a family of crude oils may involve multiple steps in the petroleum generation process bitumen generation from the source rock kerogen may provide a reset of the isotopic chronometer and incremental expulsion of oil over the duration of the oil window may provide some of the variation seen in 187re 188os values from an oil family

human topographic signatures and derived geomorphic processes across landscapes abstract the earth s surface morphology in an abiotic context is a consequence of major forcings such as tectonic uplift erosion sediment transport and climate recently however it has become essential for the geomorphological community to also take into account biota as a geomorphological agent that has a role in shaping the landscape even if at a different scale and magnitude from that of geology although the modern literature is flourishing on the impacts of vegetation on geomorphic processes the study of anthropogenic pressures on geomorphology is still in its early stages topography emerges as a result of natural driving forces but some human activities such as mining agricultural practices and the construction of road networks directly or indirectly move large quantities of soil which leave clear topographic signatures embedded on the earth s morphology these signatures can cause drastic changes to the geomorphological organization of the landscape with direct consequences on earth surface processes this review provides an overview of the recent literature on the role of humans as a geological agent in shaping the morphology of the landscape we explore different contexts that are significantly characterized by anthropogenic topographic signatures landscapes affected by mining activities road networks and agricultural practices we underline the main characteristics of those landscapes and the implications of human impacts on earth surface processes the final section considers future challenges wherein we explore recent novelties and trials in the concept of anthropogenic geomorphology herein we focus on the role of high resolution topographic and remote sensing technologies the reconstruction or identification of artificial or anthropogenic topographies provides a mechanism for quantifying anthropogenic changes to landscape systems this study may allow an improved understanding and targeted mitigation of the processes driving geomorphic changes during anthropogenic development and help guide future research directions for development based watershed studies human society is deeply affecting the environment with consequences on the landscape therefore establishing improved management measures that consider the earth s rapidly changing systems is fundamental

environmental control of carbon isotope variations in pennsylvania black shale sequences midcontinent u s a abstract a reversal of the conventional carbon isotope relationship terrestrial lighter than marine organic matter has been documented for two pennsylvanian desmoinesian cyclothemic sequence cores from the midcontinent craton of the central united states deep water organic rich phosphatic black shales contain a significant proportion of algal derived marine organic matter as indicated by organic petrography rock eval hydrogen index and c 27 c 29 sterane ratios and display the lightest 13c values max 27 80 for kerogen while shallower water more oxic facies e g fossiliferous shales and limestones contain dominantly terrestrial organic matter and have heavier 13ckerogen values to 22 87 for a stratigraphically adjacent coal 13c values for extract fractions were relatively homogeneous for the organic rich black shales with the lightest fraction often the aromatics being only 1 or less more negative than the kerogen differences between extract fractions and kerogens were much greater for oxic facies and coals e g saturates nearly 5 lighter than the kerogen a proposed depositional model for the black shales calls upon a large influx of nutrients and humic detritus to the marine environment from the laterally adjacent extremely widespread pennsylvanian peat swamps which were rapidly submerged by transgression of the epicontinental seas in this setting marine organisms drew upon a co2 reservoir which was in a state of disequilibrium with the atmosphere being affected by isotopically light recycled co2 derived from the decomposition of peaty material in the water column and possibly from the anoxic diagenesis of organic matter in the sediments

origin and migration pathway of biodegraded oils pooled in multiple reservoirs of the chepaizi uplift junggar basin nw china insights from geochemical characterization and chemometrics methods abstract the chepaizi uplift possesses three sets of oil bearing reservoirs six sets of source intervals multiple episodes of hydrocarbon charging and variable physical properties of crude oils in this study based on geochemical characterization source intervals and the biodegradation rank of the crude oils four oil populations named as group a b c and d d1 d2 were defined the combined results of q cluster analysis qca and discriminant analysis da indicate that group a occurred mainly in lower neogene shawan formation n1s in the western chepaizi uplift and were primarily derived from the middle lower jurassic xishanyao badaowan sangonghe formations j2x j1b j1s and a little of paleogene anjihaihe formation e2 3a of the sikeshu sag group b occurred essentially in upper carboniferous xibeikulasi formation c2x of the western chepaizi and originated mainly from the j1b mudstone of the shawan sag in addition the crude oils of group c occurred mainly in the lower cretaceous tugulu group k1tg of the eastern chepaizi and were primarily derived from carboniferous sourced oil from the chepaizi uplift the crude oils of groups d d1 and d2 are mixed with permian p1f and p2w of shawan sag and carboniferous sourced oil from the chepaizi uplift based on the reconstruction of the migration history the oils of group a in the n1s formation of western chepaizi migrated predominantly from the south sikeshu sag to the north and northeast with wells su1 2 and c27 as the initial filling points the oils of group b in the n1s formation of the western chepaizi travelled predominantly from the southeast shawan sag to the north and northwest the oils of group d1 in the c2x formation of eastern chepaizi migrated mainly from the northeast and southeast shawan sag to the west with well p661 as the initial filling point wells sm011 and c64 are the initial filling points of the k1tg group in the hongche fault belt crude oils of group c in the k1tg group travelled predominantly from the southeast shawan sag and northeast to the west into the eastern chepaizi and from well p68 to the southwest according to the paleo oil preferential filling orientations and paleogeomorphology some favourable targets for petroleum exploration of the chepaizi uplift are forecast in this study

carbon isotope geochemistry of paleozoic oils from big horn basin abstract twenty crude oils from paleozoic reservoirs in the big horn basin wyoming were fractionated into light hydrocarbons saturates monoaromatics diaromatics polyaromatics and polars and asphaltenes amounts and isotopic composition of each fraction were found to be internally consistent with the degree of maturation of the oil confirming the established single source origin for these oils a variation of approximately three per mil in the carbon isotopic composition of the whole oil and individual fraction was explained as being caused by maturation the isotope type curves for these oils the variations in isotopic composition as a function of compound group type were not found to be as simple as commonly believed other alteration processes such as migration and deasphalting might have influenced the pattern of the isotope distributions among fractions the conservative nature of mass balance and subsequent isotope flows among various fractions of crude oil showed that the maturation of crude oil consists of consecutive processes leading from larger and more polar components into smaller and less polar components culminating in natural gas calculations were made to project the amount of condensates associated with the crude oils and the amount of natural gas which had been generated from crude oils of a given maturity

the design of post mining landscapes using geomorphic principles nature can provide analogues for post mining landscapes in terms of landscape stability and also in terms of the rehabilitated structure blending in with the surrounding undisturbed landscape in soil mantled landscapes hillslopes typically have a characteristic pro le that has a convex upper hillslope pro le with a concave pro le lower down the slope in this paper hillslope characteristic form is derived using the area slope relationship from pre mining topography at two sites in western australia using this relationship concave hillslope pro les are constructed and compared to linear hillslopes in terms of sediment loss using the siberia erosion model it is found that concave hillslopes can reduce sediment loss by up to ve times that of linear slopes concave slopes can therefore provide an alternative method for the construction of post mining landscapes an understanding of landscape geomorphological properties and the use of erosion models can greatly assist in the design of post mining landscapes copyright 2003 john wiley sons ltd

stable carbon isotope variation of n alkanes in central graben oils while isotope analysis of bulk fractions is a well tried and useful tool in oil correlation use of compound specific isotope ratio mass spectrometry cs irms of individual hydrocarbons is still in its infancy this technique has been developed over the past few years as a useful research tool but its potential in petroleum exploration has yet to be demonstrated in this paper both bulk fraction and individual hydrocarbon isotopic data were acquired their use was evaluated and compared with traditional geochemical measurements such as gas chromatography and gc ms data on 72 oils from the norwegian sector of the central graben were acquired data include 13c isotope composition of whole oil and topped oil as well as saturated and aromatic hydrocarbon nso and asphaltene fractions and 13c isotopic composition of individual n alkanes in the range nc4 to nc35 the same samples were also analysed by capillary gc and gc ms gc gc ms and bulk fraction isotope data suggest that many of the analysed greater ekofisk oils e g valhall edlfisk i e within the lindesnes ridge inversion zone have more than one source facies outside of this area particularly towards the northwest oils are probably mainly from a single source facies the isotopic compositions of individual hydrocarbon compounds also reveal the same divisions in addition several further features were observed the normal alkanes of many of the greater ekofisk oils are more depleted in 12c between nc20 nc25 than at higher or lower molecular weight possibly representative of the original microbial precursors other oils have relatively uniform n alkane isotope profiles with n alkanes which are enriched in 12c relative to the n alkanes of oils with the other type of profile the two different isotope profiles are interpreted as being separate source facies the least mature greater ekofisk oils also become more enriched in 12c with decreasing molecular weight mature oils from this area tend to have very similar n alkane isotope values throughout the measured n alkane range the higher maturity oils and condensates have n alkanes nc8 the tentative interpretation of this is that the highly mature oils condensates are sourced only from highly mature source rocks i e of a condensate window maturity and are not products of thermal alteration in the reservoir

improved understanding of the petroleum systems of the niger delta basin nigeria biomarker and n alkane compound specific stable carbon isotope analyses csia were carried out on 58 crude oil samples from shallow water and deepwater fields of the niger delta in order to predict the depositional environment and organic matter characteristics of their potential source rocks using a source organofacies prediction approach from oil geochemistry the presence in the western deepwater oils relatively abundant c27 steranes c30 24 n propyl cholestane low oleanane index relatively low pr ph ratios gammacerane and positive to nearly flat c12 c30 n alkane compound specific stable carbon isotope profiles suggests that the source facies that expelled these oils contain significant marine derived organic matter deposited under sub oxic and stratified water column conditions this contrasts with the terrigenous organic matter dominated source rocks accepted for shallow water niger delta oils oils in the shallow water accumulations can be separated into terrigenous and mixed marine terrigenous families the terrigenous family indicates expulsion from source rock s containing overwhelmingly higher plant source organic matter average oleanane index 0 48 high c29 steranes as well as having negative sloping n alkane isotope profiles oxic source depositional conditions pr ph 2 5 and non stratified conditions absence to low gammacerane content are inferred for the terrigenous family the mixed marine terrigenous family has biomarker properties that are a combination of the deepwater and terrigenous shallow water oils bitumen extracts of the sub delta late cretaceous araromi formation shale in the dahomey basin are comparable both molecularly and isotopically to the studied western deepwater oil set but with an over all poor geochemical correlation this poor geochemical match between araromi shale and the western deepwater oils does not downgrade the potential of sub delta cretaceous source rock contribution to the regional oil charge in the deepwater niger delta

a physical explanation of an observed link area slope relationship an observed log log linear relationship between channel slope and contributing area is explained by the erosional physics that lead to catchment form it is postulated that tectonic uplift is in balance with the fluvial erosion down wasting that dominates catchment erosion and it is shown that this relationship results in the observed log log linear relationship at dynamic equilibrium in addition it has been observed that there are deviations from this log log linear relationship near the catchment divide with observed slopes being lower than those predicted from the relationship this is explained by noting that for small areas fluvial erosion effects are dominated by soil creep and rain splash modeled by diffusive physics the area at which this deviation from log log linearity occurs is that point on the hillslope at which diffusive physics like soil creep and rain splash begin to dominate fluvial erosion these predictions are confirmed by numerical simulations using a catchment evolution model

results from a new model of river basin evolution this paper briefly describes a model of the erosional development of catchments and their channel networks the model differentiates between the dominant transport processes in hillslope and channels the development of channels and hillslopes occurs in an integrated manner as a function of physically observable mechanisms the growth of a river basin is qualitatively described the model concepts are used to study the basin during periods of growth transient periods as well as during dynamic equilibrium this leads to hypotheses about the relationship between slopes relief tectonic uplift erodability runoff and catchment area it is shown that the model leads to very reasonable and desirable behaviour of hillslopes during retreat and degradation

laboratory simulation of the salt weathering of schist 1 weathering of schist blocks in a seasonally wet tropical environment data describing sediment generation focusing on the temporal evolution of size gradation are required for the prediction of long term landform evolution this paper presents such data for the salt weathering of a quartz chlorite schist obtained from the ranger uranium mine in northern australia rock fragment samples are subjected to three different climate regimes 1 a dry season climate 2 a wet season climate both based on observations at the ranger site and 3 an oven drying sequence designed to test the sensitivity of the weathering process by exposing the rocks to more extreme temperatures two mgso4 salt solutions are applied one being typical of wet season runoff and the other a more concentrated solution salt solution is applied daily in the wet season experiments and once only at the beginning of the dry season experiments results of the experiments reveal four stages of weathering the kinetics of each stage are described and related to the formation of sediment of different sizes wet season climate conditions are shown to produce greater moisture variability and lead to faster weathering rates however salt concentrations in the wet season are typically lower and so when climate is combined with observed salt concentrations the dry and wet season experiments weather at approximately equal rates finally small variations in rock properties were shown to have a large impact on weathering rates leading to the conclusion that rock weathering experiments need to be carefully designed if results are to be used to help predict weathering behaviour at the landscape scale copyright 2006 john wiley sons ltd

longitudinal structure of the equatorial anomaly in the nighttime ionosphere observed by image fuv 1 the far ultraviolet imager fuv on board the image satellite provides an instantaneous global view of the oi 135 6 nm nightglow with 2 min time resolution because the oi 135 6 nm emission from the nighttime ionosphere is determined by the line of sight integrated plasma density the nightglow images are useful for studying the nighttime low latitude ionosphere globally with the image fuv 135 6 nm observations from march to june 2002 we have examined the global characteristics of the nighttime equatorial anomaly ea by constructing a constant local time map lt map in which pixels within an assigned local time range are extracted from the image fuv nightglow images obtained over an observation period of 3 days or more and are put together to compose a global distribution map of emission intensities at that local time these lt maps show that the development of the ea has a significant longitudinal structure in which peaks and dips of the crest emission intensity and the crest latitude have about 90 longitudinal separation in the longitude range from 0 to 250 although there is not enough data over the american sector this result suggests that the ea longitudinal structure has a prominent zonal component of the wave number 4 the observed longitudinal structure of the nighttime ea could not be fully explained by factors such as the empirical electric field and neutral wind models the geomagnetic declination angle or the displacement of the geomagnetic equator from the geographic equator to explain the observed longitudinal structure of the ea in particular the wave number 4 feature we may need to consider other forcing for example nonmigrating tide originated from the lower atmosphere

intra annual variability of the low latitude ionosphere due to nonmigrating tides 1 in situ plasma density measurements from the champ satellite between about 350 420 km altitude are used to delineate intra annual variations in the longitudinal structure of the f region ionosphere it is shown that the longitude structures during mid day local times are dominated by the space based longitudinal wavenumbers ks 2 4 and 3 in january july and december respectively these conform to the same dominating ks values characterizing solar thermal tide zonal winds in the dynamo region namely the westward propagating semidiurnal tide with planetary fixed zonal wavenumber s 4 sw4 and the eastward propagating diurnal tides with s 3 de3 and s 2 de2 respectively de3 is the dominating tide during the other months the results presented indicate that nonmigrating tides other than de3 may significantly impact the longitudinal structure of the low latitude ionosphere during certain months

an evaluation of an enhanced soil erosion and landscape evolution model a case study assessment of the former nabarlek uranium mine northern territory australia the assessment of post mining landscapes as case studies is an important part of the evaluation of current rehabilitation practices a necessary part of this assessment is to predict the surface stability of the landform using erosion and landform evolution modelling techniques in the short term erosion on a rehabilitated mine site can lead to increased sediment loads and transport of other mine related contaminants in downstream waterways it is well recognized that in many mine areas the erodibility of surface materials can and does vary this is a particularly significant issue on mine sites where the surface conditions may range from areas of undisturbed natural surface materials waste rock dumps constructed with materials exhumed from the sub surface and other areas that have a mix of waste rock and soil to enhance the growth of vegetation a further significant issue is that when the subsurface materials are exposed to surface conditions they can weather rapidly changing their erodibility this paper uses a new version of the siberia landscape evolution and soil erosion model to evaluate the former nabarlek uranium mine site in the northern territory australia this new version of siberia uses spatially variable erosion and hydrology parameters across the study domain to represent different erodibilities of surface materials thus allowing better representation of catchment heterogeneity the results demonstrate that the model predicts erosion rates similar to that of other modelled results and independent field data providing confidence in the model and its parameterization the tailings deposited in the mined out pit and capped with waste rock appear to be safely encapsulated for the modelled period copyright 2008 john wiley sons ltd and commonwealth of australia department of the environment and water resources supervising scientist

post mining landform evolution modelling 1 derivation of sediment transport model and rainfall runoff model parameters data were collected from three sites on the waste rock dump at era ranger mine 1 the cap site which was unvegetated and unripped with a surface slope of 2 8 per cent 2 the batter site surface slope 20 7 per cent also unvegetated and unripped but with a covering of coarse rock material and 3 the soil site surface slope 1 2 per cent which had c 90 per cent vegetation cover of low shrubs and grasses and had been topsoiled and surface ripped natural rainfall events were monitored on the sites to collect rainfall runoff and soil loss data to parameterize a sediment transport model of the form t s q dt and the distfw rainfall runoff model low frequency high intensity events resulted in the greatest soil loss to accurately predict sediment loss during high intensity events storms with a range of intensities were selected to derive the sediment transport model distfw hydrology model parameters were derived by fitting four monitored events simultaneously the selected parameters for the vegetated and ripped case may overpredict discharge for some rainfall events resulting in conservative design of erosion control features on rehabilitated landforms copyright 2000 environmental research institute of the supervising scientist commonwealth of australia

testing of the siberia landscape evolution model using the tin camp creek northern territory australia field catchment the siberia landscape evolution model was used to simulate the geomorphic development of the tin camp creek natural catchment over geological time measured hydrology erosion and geomorphic data were used to calibrate the siberia model which was then used to make independent predictions of the landform geomorphology of the study site the catchment located in the northern territory australia is relatively untouched by europeans so the hydrological and erosion processes that shaped the area can be assumed to be the same today as they have been in the past subject to the caveats regarding long term climate fluctuation a qualitative or visual comparison between the natural and simulated catchments indicates that siberia can match hillslope length and hillslope profile of the natural catchments a comparison of geomorphic and hydrological statistics such as the hypsometric curve width function cumulative area distribution and area slope relationship indicates that siberia can model the geomorphology of the selected tin camp creek catchments copyright 2002 environmental research institute of the supervising scientist commonwealth of australia

quiet time equatorial f region vertical plasma drift model derived from rocsat 1 observations 1 we have used five years of measurements on board the rocsat 1 satellite to develop a detailed quiet time global empirical model for equatorial f region vertical plasma drifts this model describes the local time seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions the model results are in excellent agreement with measurements from the jicamarca radar and also from other ground based and in situ probes we show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier especially during december and june solstice the late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons the morning and afternoon december solstice drifts have significantly different longitudinal dependence and the daytime upward drifts have strong wave number four signatures during equinox and june solstice the largest evening upward drifts occur during equinox and december solstice near the american sector the longitudinal variations of the evening prereversal velocity peaks during december and june solstice are anti correlated which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere

the influence of nonmigrating tides on the longitudinal variation of the equatorial electrojet 1 the climatological model of the equatorial electrojet eejm 1 derived from orsted champ and sac c satellite measurements provides the opportunity to investigate the longitudinal variation of the current strength in detail special emphasis is put in this study on the effect of nonmigrating tides we have found that the influence of the diurnal eastward propagating mode with wavenumber 3 de3 is particularly strong in polar orbiting satellite observations the de3 tidal signal appears as a four peaked longitudinal structure we have put special emphasis in our analysis to isolate the de3 contribution from other sources contributing to the wavenumber 4 structure in satellite data the amplitude of the de3 signature in the eej not only peaks during equinox seasons but is also strong around the june solstice when looking at the modulation of the eej intensity the de3 accounts for about 25 during the months of april through september it is thus the dominant cause for longitudinal variations during december solstice months the influence of de3 is negligible a secondary three peaked longitudinal pattern emerges during solstice seasons when the de3 influence is removed from the data available it is however not clear whether this pattern is related to any tidal drivers