oak leaves as biosensors of late neogene and early pleistocene paleoatmospheric co2 concentrations abstract complementary to the interpretation of 13 c values of biogenic carbonate and sedimentary organic carbon in marine sediments paleoatmospheric co 2 levels can be estimated by considering the inverse relationship between atmospheric co 2 concentration and stomatal parameters frequency size on leaves of land plants in woody plants the significance of this species specific physiological response to changing co 2 regimes is now repeatedly confirmed both experimentally and from historical sequences of leaves collected since the onset of industrialization a corollary of this relationship is that analysis of stomatal parameters on fossil leaves has the potential of determining changes in paleoatmospheric co 2 levels at different time scales well preserved cuticle remains of oak leaves from late miocene pliocene and early pleistocene sediments of the lower rhine embayment germany the netherlands give promise of extending the record of stomatal frequency response to the last 10 ma during intervals with warm temperate to subtropical climatic conditions oak leaves are characterized by a high stomatal resistance or low conductance to co 2 diffusion and low stomatal frequencies during cooler intervals we observe an opposite picture comparison with historical relations between co 2 concentration and stomatal properties suggests that paleoatmospheric co 2 concentrations were not significantly higher than during the last 200 years and fluctuated several times between 280 and 370 ppmv in covariation with contrasting regional climatic conditions on a global scale intervals with reduced co 2 levels match glacial pulses characterized by the occurrence of ice rafted detritus in high latitude oceanic sediments

constraining climatic controls on hillslope dynamics using a coupled model for the transport of soil and tracers application to loess mantled hillslopes south island new zealand 1 landscapes reflect a legacy of tectonic and climatic forcing as modulated by surface processes because the morphologic characteristics of landscapes often do not allow us to uniquely define the relative roles of tectonic deformation and climate additional constraints are required to interpret and predict landscape dynamics here we describe a coupled model for the transport of soil and tracer particles at the hillslope scale to illustrate the utility of this methodology we modeled the evolution of two synthetic hillslopes with identical initial and boundary conditions but different histories of climate induced changes in the efficiency of soil transport while one hillslope experienced an initial phase of rapid transport followed by a period of retarded transport the other hillslope experienced the opposite sequence both model hillslopes contain a subsurface layer of tracer particles that becomes exhumed and incorporated into the soil due to transport and mixing processes whereas the morphology of the two model hillslopes cannot be easily distinguished at the simulation conclusion the spatial distribution of tracer particles along the slope is distinctive for the two cases we applied the coupled model to our study site along the charwell river south island new zealand where tephra deposits within loess dominated soils have been exhumed and incorporated into an upper layer of bioturbated and mobile soil we reconstructed the late pleistocene hillslope geometry using soil stratigraphic data gathered along the study transect because bioturbation appears to be the predominant transport mechanism the efficiency of soil transport likely varies with time reflecting the influence of climate related changes in the dominant floral or faunal community the modeled evolution of hillslope form and tephra concentration along the study transect is consistent with observations obtained from topographic surveys and laboratory analysis of tephra concentrations in continuous core soil samples low transport rates are apparently associated with grass shrub dominated slopes during the late pleistocene whereas forest colonization during the holocene increased flux rates transforming flat locally incised slopes into broadly convex ones our results attest to the utility of coupled models for tasks such as deciphering landscape history and predicting the downslope flux of soil organic carbon

modeling suspended sediment discharge from the waipaoa river system new zealand the last 3000 years hydrotrend a hydrologic transport model is used to simulate the water and suspended sediment discharge of the waipaoa river system over the last 3 kyr a time period in which a well documented sequence of natural events and anthropogenic activities that profoundly impacted drainage basin processes occurred comparisons between observed and simulated data show that the model output replicates the frequency and distribution of flow events and the suspended sediment concentration discharge relationship and the long term trends in suspended sediment discharge are consistent with the sediment record preserved on the middle shelf water discharge tracks precipitation and average annual discharge may have been up to 20 higher and 6 lower at different times in the past suspended sediment discharge changed from 2 3 4 5 to 14 9 8 7 mt yr 1 during the anthropocene increasing by 140 after polynesian arrival by 350 after european colonization and by 660 after the catchment headwaters were deforested

extending the vostok ice core record of palaeoclimate to the penultimate glacial period the ice core record of local temperature dust accumulation and air composition at vostok station antarctica now extends back to the penultimate glacial period 140 200 kyr ago and the end of the preceding interglacial this yields a new glaciological timescale for the whole record which is consistent with ocean records temperatures at vostok appear to have been more uniformly cold in the penultimate glacial period than in the most recent one concentrations of co2 and ch4 correlate well with temperature throughout the record

landslide occurrence as a response to land use change a review of evidence from new zealand abstract vegetation cover is an important factor influencing the occurrence and movement of rainfall triggered landslides and changes to vegetation cover often result in modified landslide behaviour however it is difficult to relate the occurrence of landslides directly to variations in land use especially in some european countries in contrast new zealand provides a good opportunity to investigate geomorphic responses to anthropogenic land cover changes before european settlers first arrived in the 1840s hilly regions were only marginally influenced by human activity the maoris new zealand s first settlers lived largely on coastal plains or near lakes and rivers they influenced general vegetation cover only through localized burning practices in contrast european settlers moved into the back country and converted extensive hill areas from native forest and bush to pasture this reduced the strength of the regolith and rendered the slopes more susceptible to landslides pulses of natural sedimentation in the pre european period have been related to volcanic activity climatic variability including changes in frequency of cyclonic storms and wind erosion and fluvial erosion following forest fires initiated either by volcanic eruptions or lightning strikes since european deforestation began sediment production has largely been determined by landslide events on unstable slopes thousands of landslides were triggered by high magnitude low frequency climatic events during storms with estimated return periods in excess of 50 years in contrast low magnitude high frequency rainfall events have caused gully and channel erosion examples from different parts of new zealand indicate changes in sediment generating processes following land use modifications after deforestation landslides have contributed significantly to sediment sequences in depositional basins such as lakes swamps estuaries coastal wetlands and the nearshore and offshore zones of continental platforms

lyttelton volcano banks peninsula new zealand primary volcanic landforms and eruptive centre identification abstract lyttelton volcano banks peninsula new zealand has historically been viewed as a simple volcanic cone this paper uses digital terrain models dtm and primary volcanic landforms to reinterpret lyttelton volcano as having multiple eruptive centres primary volcanic landforms are features produced during active volcanism classified as constructional hypabyssal and erosional volcanic features constructional volcanic features are lava flows scoria cones and domes hypabyssal volcanic features are dykes and sills and erosional volcanic features are valley and ridge patterns and orientations lava flow trends are recognised from aerial photograph analysis and supported by field observations highlighting radiating lava trends around specific locations within lyttelton harbour scoria cones and domes occur on the outer flanks of volcanic cones and are used as such in the identification of remnant cone surfaces dyke orientations are plotted and then projected to the interior of the volcano defining 13 zones of convergence the projected arrays of these orientations highlight defined regions along the erosional crater rim each indicating a radial dyke swarm from which the projected trends of the associated dykes indicate an eruptive centre valley and ridge orientations are projected from the longest valley or ridge segment towards the inner harbour radiating erosive patterns are incepted during the growth and degradation of a volcanic cone with the resulting trends orienting to the summit zones of convergence eruptive centres are identified from lava flow orientations onlapping lava sequences scoria cones and intrusive locations the summit of a volcanic edifice can be identified from the orientations of valleys and ridges while radial dyke systems determine whether this summit was a volcanic centre or simply a local topographic high volcanic landforms are used to identify cone sectors the preserved sector associated with a particular eruptive centre cone sector limits are defined by a basal footprint and an erosional crater rim with similar arcuate features remnant cone features being exposed in the interior of the volcano lyttelton volcano comprises fifteen volcanic cones with vent locations controlled by underlying fault lineaments the growth and erosion of each volcanic cone is reflected in primary volcanic landforms with the preserved features of cones confined to cone sectors and cone artefacts

rockfalls triggered by the ad 1356 basle earthquake in the basle region of switzerland we demonstrate that rockfall blocks can be dated accurately using the radiocarbon method soil beneath rockfall blocks containing organic macro remains was sampled at four cliff sites in the tabular jura south east of basle a lightweight drilling rig drills a 101 mm diameter hole through rockfall blocks up to 6 m in height a downhole sampler is used to recover soil samples from below the blocks eighteen radiocarbon dates on charcoal wood needles of conifers and organic macro remains from 11 blocks gave dates between 970 and 440 bp calibrated ages range between ad 1210 and ad 1450 these results along with field observations and historical research suggest that a large number of blocks toppled as rockfalls within a short time interval in the epicentral area of the ad 1356 basle earthquake

constraints on timing of peak and retrograde metamorphism in the dabie shan ultrahigh pressure metamorphic belt east central china using u th pb dating of zircon and monazite abstract the dabie shan ultrahigh pressure metamorphic uhpm belt occupies the suture between the yangtze and sino korean blocks in east central china the timing of uhpm in the dabie belt is controversial and most recent data come from dating of zircons monazite has recently been recognized as useful for dating of multiple tectonic events due to its preservation of multiple growth zones and monazite growth has been documented to occur during prograde peak and retrograde metamorphism zircons and monazites from uhp mafic rocks from maowu and a uhp jadeite quartzite from shuanghe were imaged in thin sections and in mineral separates and dated using a high resolution ion microprobe maowu mafic rocks are unique in that they contain high light rare earth element concentrations and therefore contain abundant monazite maowu eclogites and garnet pyroxenites contain zircons with mean 206 pb 238 u age of 230 4 ma and monazites from a clinopyroxenite have 208 pb 232 th ages of 209 4 ma multiple lines of evidence suggest that the measured ages represent the timing of new growth and recrystallization and are not cooling ages i e they do not correspond to the cessation of diffusional pb loss as rocks cooled below the closure temperature during exhumation shuanghe jadeite quartzites contain zircons with cores that define a discordia with an upper intercept age 1921 22 ma and lower intercept age of 236 32 ma interpreted to represent the ages of the source rocks and of peak metamorphism respectively zircon rims contain jadeite inclusions that restrict growth to pressures greater than 1 5 gpa their pooled age of 238 3 ma agrees well with the lower intercept defined by cores suggesting that pb loss from cores and growth of new rims occurred during uhpm at 235 240 ma monazite records multiple events during retrograde metamorphism maowu clinopyroxenite and shuanghe jadeite quartzite experienced monazite growth at 209 ma interpreted to reflect regional amphibolite facies overprinting resulting from pervasive retrograde fluid infiltration only the jadeite quartzite records growth at 223 1 ma estimated exhumation rates for maowu are 7 8 km ma

lichen dating of coseismic landslide hazards in alpine mountains abstract studies of rockfalls and block slides provide insight about seismic shaking hazards in alpine mountains subject to earthquakes large samples of the longest axis of the largest lichen on each block can be used to identify regional landslide events lichen size distributions for many sites cluster consistenly at the same sizes the coseismic rockfall lichenometry model can be used to 1 date and locate prehistorical earthquakes 2 document regional frequency of earthquakes and 3 describe regional patterns of seismic shaking determination of colonization time great growth phase and especially uniform phase rates of lichen growth are essential for dating regional landslide events rocks that tumble downhill during historical earthquakes allow accurate calibration of the growth rate for rhizocarpon subgenus rhizocarpon these plentiful fresh substrates are dated to their day of formation an initial calibration of uniform growth rate based on historical and tree ring dated landslides was fine tuned by assigning earthquake dates to mean values of lichen size peaks for regional rockfall events that increase in abundance towards epicenters of historical earthquakes calibration for each new site is unnecessary in the southern alps of new zealand and in the sierra nevada of california because several species of yellow rhizocarpons within each climatic region have constant growth rates that are independent of altitude or substrate lithology

use of carbon isotopes in paleosols as an indicator of the p co2 of the paleoatmosphere measurements of carbon isotopic composition of coexisting paleosol organic matter and carbonate results in improved estimates of the paleo p co2 content of the paleoatmosphere measurements from tertiary paleosols indicate that the levels of co2 in the early eocene middle and late miocene and pliocene were less than 1000 ppmv early cretaceous levels of p co2 were significantly higher of the order of 1500 to 3000 ppmv

multiple zircon growth during fast exhumation of diamondiferous deeply subducted continental crust kokchetav massif kazakhstan diamondiferous rocks from the kokchetav massif kazakhstan represent deeply subducted continental crust in order to constrain the age of ultra high pressure uhp metamorphism and subsequent retrogression during exhumation zircons from diamondiferous gneisses and metacarbonates have been investigated by a combined petrological and isotopic study four different zircon domains were distinguished on the basis of transmitted light microscopy cathodoluminescence trace element contents and mineral inclusions mineral inclusions and trace element characteristics of the zircon domains permit us to relate zircon growth to metamorphic conditions domain 1 consists of rounded cores and lacks evidence of uhp metamorphism domain 2 contains diamond coesite omphacite and titanian phengite inclusions providing evidence that it formed at uhp metamorphic conditions p 43 kbar t 950 c domain 3 is characterised by low pressure mineral inclusions such as garnet biotite and plagioclase which are common minerals in the granulite facies overprint of the gneisses p 10 kbar t 800 c this multi stage zircon growth during cooling and exhumation of the diamondiferous rocks can be best explained by zircon growth from zr saturated partial melts present in the gneisses domain 4 forms idiomorphic overgrowths and the rare earth element pattern indicates that it formed without coexisting garnet most probably at amphibolite facies conditions p 5 kbar t 600 c the metamorphic zircon domains were dated by shrimp ion microprobe and yielded ages of 527 5 528 8 and 526 5 ma for domains 2 3 and 4 respectively these indistinguishable ages provide evidence for a fast exhumation beyond the resolution of shrimp dating the mean age of all zircons formed between uhp metamorphic conditions and granulite facies metamorphism is 528 3 ma indicating that decompression took place in less than 6 ma hence the deeply subducted continental crust was exhumed from mantle depth to the base of the crust at rates higher than 1 8 cm year we propose a two stage exhumation model to explain the obtained p t t path fast exhumation on top of the subducted slab from depth 140 to 35 km was driven by buoyancy and facilitated by the presence of partial melts a period of near isobaric cooling was followed by a second decompression event probably related to extension in a late stage of continental collision

classic and new dating methods for assessing the temporal occurrence of mass movements abstract establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research and for the assessment of landslide hazards as part of applied geomorphology we discuss the applicability of different methods for determining landslide chronologies frequencies and dynamics in relation to the type of material being dated sampling location and type of mass movement the emphasis is on the possibilities and limitations of the different dating methods established methods such as radiocarbon dating lichenometry and dendrochronology are briefly discussed the paper focuses however on 1 new analytical techniques like accelerator mass spectrometry ams thermally ionising mass spectrometry tims and laser fusion which have led to significant improvements of established dating methods and on 2 new dating methods like optically stimulated luminescence osl dating and alpha recoil track art dating

fossil plants record an atmospheric 12co2 and temperature spike across the palaeocene eocene transition in nw europe the large negative excursion of carbon isotope composition 13 c recorded from foraminifera and bulk carbonates indicates a major anomaly in the operation of the global carbon cycle across the palaeocene eocene boundary therefore we sought terrestrial evidence for the transfer of isotopically light carbon 12 co 2 from the ocean to the atmosphere by making systematic 13 c measurements or well dated sequences of fossil pollen from nw europe the results indicate an atmospheric 12 co 2 spike of c 2 between 58 and 55 ma coincident with the ocean isotopic anomalies pollen spectra from these sequences suggest a marked shift in dominance from mixed mesophytic to paratropical forests synchronous with the terrestrial isotope excursion

a δ 13 c record of late quaternary climate change from tropical peats in southern india stable isotope ratios of carbon in soils or lake sediments1 3 and of oxygen and hydrogen in peats4 5 have been found to reflect past moisture variations and hence to provide valuable palaeoclimate records previous applications of the technique to peat have been restricted to temperate regions largely because tropical climate variations are less pronounced making them harder to resolve here we present a 13c record spanning the past 20 kyr from peats in the nilgiri hills southern india because the site is at high altitude 2 000 m above sea level it is possible to resolve a clear climate signal we observe the key climate shifts that are already known to have occurred during the last glacial maximum 18 kyr ago and the subsequent deglaciation in addition we observe an arid phase from 6 to 3 5 kyr ago and a short wet phase about 600 years ago the latter appears to correspond to the mediaeval warm period which previously was believed to be confined to europe and north america6 7 our results therefore suggest that this event may have extended over the entire northern hemisphere

variations in the carbon isotope composition of late holocene plant macrofossils a comparison of whole leaf and cellulose trends stable carbon isotope measurements 13c made on quaternary sequences of terrestrial plant subfos sils are frequently used to infer palaeoclimatic trends however differential decomposition of individual con stituents during incorporation of plant material into lake sediments could influence these interpretations there fore we investigated down core variations in the carbon isotope composition 13c of subfossil leaves of salixherbacea l and their holocellulose component from a late holocene c 0 3300 years ago site in northern sweden locally weighted regression curves fitted to both 13c data sets showed similar but conserved temporal patterns of change and there was no evidence for systematic shifts in the holocellulose yields or c n ratios of leaves with age small d13c variations over the past 3300 years probably reflect natural variations in microclimate within the lake catchment area this interpretation is quantitatively consistent with the variability determ ined from measurements made

an isotopic study of biogeochemical relationships between carbonates and organic carbon in the greenhorn formation carbon isotopic compositions of total carbonate inoceramid carbonate micritic carbonate secondary cements total organic carbon and geoporphyrins have been measured in 76 different beds within a 17 m interval of a core through the greenhorn formation an interbedded limestone and calcareous shale unit of cretaceous age cenomanian turonian from the western interior seaway of north america results are considered in terms of variations in the processes of primary production which led to the biosynthesis of the molecular precursors of the geoporphyrins and in secondary processes those mediating the transformation of primary organic material into sedimentary total organic carbon it is shown that the porphyrin isotopic record reflects primary isotopic variations more closely than the toc isotopic record and that in these sediments toc is enriched in 13c relative to its primary precursor by 0 6 to 2 8 this enrichment is attributed to isotope effects within the consumer foodweb and is associated with respiratory heterotrophy variations in this secondary enrichment are correlated with variations in the isotopic composition of marine carbonate this correlation is attributed to effects of environmental changes on the marine foodweb these may have included increased atmospheric oxygen associated with the cenomanian turonian oceanic anoxic event the isotopic fractionation associated with fixation of carbon by primary producers is observed to have varied by 1 5 during the interval of deposition it is suggested that this change is due to a variation in the makeup of the community of primary producers and or to a decrease in the atmospheric abundance of co2 during the oceanic anoxic event

holocene rockwall retreat in svalbard a triple rate evolution volumetric calculations of slope deposits direct measurements of rockwall retreat and chronological control based on lichenometry provide a wide range of rockwall retreat rates in svalbard 0 1580 mm ka 1 that appears consistent with previous evaluations from other arctic areas in northwest and central spitsbergen 79 n a triple rate rockwall retreat is suggested for the last two millennia very slow biogenic flaking 2 mm ka 1 moderate retreat due to frost shattering 100 ka 1 and rapid retreat associated with post glacial stress relaxation c 1000 mm ka 1 examination of the distribution of various processes indicates that the holocene retreat of most rockwalls has not exceeded one or two metres bedrock conditions appear to be the main control on retreat rates the massiveness of igneous and metamorphic outcrops widespread in arctic shield areas largely accounts for the slowness of rockwall retreat which on these lithologies is primarily due to chemical and biological processes more rapid rates are usually associated with stress relaxation following glacial surges or with local frost susceptibility of bedrock often where faulting has induced high joint density at such sites rockwall retreat rates are of the same order of magnitude as those reported from alpine areas 1000 3000 mm ka 1 where both bedrock weakening due to tectonic stresses and the greater height of steep rockwalls account for the more rapid rockwall retreat rate 1997 by john wiley sons ltd

holocene slip rate on the sabzevar thrust fault ne iran determined using optically stimulated luminescence osl abstract fault slip rates and the recurrence interval between earthquakes can be determined from reliable dating of deformed sediments we report optically stimulated luminescence osl ages of alluvial gravels fine grained sediments and colluvial deposits associated with the sabzevar thrust fault in northeastern iran six samples of the late quaternary deposits were dated by osl using the single aliquot regenerative dose sar protocol the osl ages indicate deposition of alluvial gravels in the study region between 30 and 9 13 ka followed by a period of fluvial incision which is ongoing at the present day the alluvial deposits have been uplifted by 9 5 m relative to the river level indicating a holocene slip rate of 1 mm yr and a rate of convergence across the fault of 0 4 0 6 mm yr assuming a maximum fault dip of 60 the average interval between large earthquakes on the sabzevar fault will be 3000 years if the fault dips 60 and less if the fault dip is less the last earthquake to destroy sabzevar was in 1052 a d

late permian global coal hiatus linked to 13c depleted co2 flux into the atmosphere during the final consolidation of pangea at a time when all continents were finally arrayed in their pangea supercontinental configuration 250 50 ma earth9s stratigraphy records a global and very abrupt coal discontinuity from the tartarian stage of the late permian to the middle triassic reduced coal productivity and or preservation overlaps with a period of anomalous oceanic and atmospheric decrease in 13 c as recorded in marine carbonates and organic matter and terrestrial plant and animal fossils from the northern and southern hemispheres during the same short period the peripheral margin of the entire supercontinent pangea except for the southern shores of tethys was effectively under compressive stress this unique tectonic state caused deformation and uplift of coal bearing foreland basins and oxidation of pangea9s vast peat deposits the latter resulted in a rapid massive 13 c depleted co 2 flux into the atmosphere which in turn may have forced global warming

tectonics of the dabieshan eastern china and possible exhumation mechanism of ultra high pressure rocks the dabieshan is divided into three tectonic domains the southern dabieshan is a stack of allochtons from top to bottom i unmetamorphosed cambrian early triassic series unconformably covered by jurassic sandstone ii weakly metamorphosed proterozoic slate iii hp rocks mostly retrogressed into greenschist facies iv uhp allochton v uhp free gneisses these units exhibit a nw se lineation and top to the nw shearing reworked by s verging folds the central dabieshan is a migmatitic dome superimposed on uhp metamorphism and bounded by a detachement fault responsible for the exhumation of the uhp unit during its retrogression into amphibolite facies in the northern dabieshan early foliation and n s trending compressional lineation are deformed by n verging folds coeval to the syn exhumation ductile structures of the central dabieshan a geodynamic model involving coeval thrusting and normal faulting is discussed

too young or too old evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages cosmogenic exposure dating has greatly enhanced our ability to define glacial chronologies spanning several global cold periods and glacial boulder exposure ages are now routinely used to constrai

application of stable carbon isotopes to early biochemical evolution on earth the emergence and early evolution of life on earth have long been intriguing subjects for scientific inquiry and a continuous source of intel lectual excitement current work at this frontier proceeds along a number of different avenues and comprises a variety of disciplinary approaches that together strongly suggest that the earth was inhabited by life as early as almost 4 gyr ago the present state of the field as inferred from the results of a broad interdisciplinary approach has recently been summarized by j w schopf and coworkers cf schopf 1 983 it is with the advantage of such a synoptic view that the present review addresses a single facet of the theme namely the potential isotopic infer ences of the presence of co2 fixing autotrophic organisms for the carbon cycle of the early earth with biologically derived organic carbon as well as carbonates limestone dolomite etc abundantly preserved in sediments relevant isotopic evidence should have been encoded in the geologic record from its onset about 3 8 gyr ago it has been known since the pioneering studies by nier gulbransen 1939 murphey nier 1941 and rankama 1948 that the trans formation of inorganic carbon into living matter entails a marked bias in favor of the light isotope c2c with the heavy species l3c retained in the inorganic reservoir subsequent work performed by many investigators e g craig 1953 park epstein 1960 has confirmed that all common

the timing of partial melting barrovian metamorphism and granite intrusion in the naxos metamorphic core complex cyclades aegean sea greece abstract the relationship between partial melting and granite intrusion in a classic barrovian metamorphic terrane has been assessed thirteen samples were dated by shrimp u pb zircon geochronology from the island of naxos greece one of the aegean metamorphic core complexes the effect of partial melting during peak barrovian metamorphism on naxos is recorded by fine

pedogenesis by upbuilding in an extreme leaching and weathering environment and slow loess accretion south westland new zealand abstract soil formation is usually envisaged as acting from the surface downwards in many environments however the accumulation of sediment and soil formation are contemporaneous it is only where the rate of one process far exceeds the rate of the other that assumptions of topdown pedogenesis are appropriate the aspect of upbuilding pedogenesis that distinguishes it from topdown pedogenesis is that each increment of soil below the a horizon has experienced processes characteristic of all horizons above it this study examines the influence of upbuilding soil formation in a high rainfall environment of rapid soil formation and slow loess accretion an environment where upbuilding could have a noticeable influence on soil properties soils formed by topdown soil formation topdown soils are compared with soils formed in loess that accumulated from early last glaciation to the holocene upbuilding soils soils are compared in two environments alaquods on poorly drained terraces and placorthods or dystrochrepts on well drained moraine crests we have assumed that properties of the upbuilding soils inherited during the current topdown phase of pedogenesis beginning in the holocene are analogous to those in the topdown soils in this manner soil properties evolved during upbuilding are distinguished in well drained upbuilding soils on moraines subsoil organic carbon has mineralised so that profile trends are very similar to corresponding topdown soils upbuilding has enhanced weathering in subsoils which is reflected in lower ph lower total p and lower primary inorganic p than in topdown soil counterparts total p concentrations in upbuilding soils are much lower than unweathered loess and constant throughout the subsoil and there is almost no p in primary forms in contrast total p in c horizons of topdown soils reaches concentrations typical of the parent material and more than 30 of this is in a primary inorganic form the differences are attributed to each subsoil increment of upbuilding soils having been part of acid a and e horizons oxalate extractable fe and al data indicate that podzolisation was active during upbuilding poorly drained upbuilding soils on terraces have higher subsoil organic carbon inherited from former a or o horizons than comparable topdown soils buried a and o horizons inherited during upbuilding and preserved in the reducing conditions have acted as sinks for mobile al and now resemble podzolic illuvial bh horizons upbuilding through addition of loess to soils promotes a pedogenic pathway distinct from topdown pedogenesis consequently soil chronosequence studies that include soils on old loess mantled surfaces do not strictly satisfy the assumptions of soil chronosequences the nature and rate of soil processes inferred from these studies need revisiting the findings of this study are transferable to other environments where the rate of soil formation and sediment accumulation are comparable

environmental and sea level changes on banks peninsula canterbury new zealand through three glaciation interglaciation cycles abstract a greater than 200 ka record of marine transgressions and regressions is recorded from a 75 m core from banks peninsula canterbury new zealand this record comprises thick suites of muddy sediments attributed to back barrier lake and lagoonal environments alternating with thin soil and loess complexes these deposits have been dated using radiocarbon and thermoluminescence tl techniques supported by proxy data diatoms phytoliths pollen and sedimentology the aqueous deposits are attributed to three interglacials and an interstadial marine isotope stages 1 5a 5c 6 and 7 the loesses and paleosols date to the intervening stadials isotope stages 2 5d or 6 and probably 8 on the basis of transgressive beach facies back barrier swamps and barrier blocked lake deposits a partial sea level curve including data from isotope stage 5 is presented our data indicate that banks peninsula has been tectonically stable over that period and we provide sea level points that support the existing isotope curve during stages 5 and 6 detailed diatom records are limited to isotope stage 1 and the latter part of stage 5 diatom histories recorded from these stages are remarkably consistent both indicate a progressive floral change from marine types through freshwater colonising species to freshwater planktonic assemblages these reflect parallel histories of coastal evolution during the two interglacials in both cases marine transgression in the early part of the isotope phase was followed by lagoon development implying that a gravel spit extended across the embayment from the west this was succeeded by lake development when the lagoon was cut off by the juncture of the spit with banks peninsula this lake deepened as the coast rotated into swash alignment and the spit was converted into a gravel barrier the vegetation history of the site indicates that mixed podocarp broadleaf forests similar to the pre european flora of banks peninsula occupied the region during isotope stages 1 and 7 this contrasts with the palynological interpretation of a marine record dsdp site 594 from off the canterbury coast which suggested that isotope stage 7 was markedly cooler than the holocene during glacial periods forest was eliminated and replaced by a tall shrubland of mixed montane and coastal affinities

geochemical and sr nd pb isotopic compositions of cretaceous granitoids constraints on tectonic framework and crustal structure of the dabieshan ultrahigh pressure metamorphic belt china abstract the dabie orogenic belt can be divided into four tectonic and lithological units they are from north to south the north huaiyang nhy unit the northern dabie complex ndc unit the ultrahigh pressure uhp metamorphic unit and high pressure hp metamorphic unit cretaceous granitoids from the four tectonic units irrespective of tectonic unit and lithology show surprisingly similar major and trace element and particularly sr nd pb isotopic compositions indicating a similar crustal source for their magma genesis they have initial 87 sr 86 sr t values of 0 7068 0 7091 and nd depleted mantle model ages of 1 6 2 4 ga and e nd t values at the time of their emplacement 120 ma ranging from 13 to 26 their present day pb isotopic compositions are 206 pb 204 pb 15 62 17 06 207 pb 204 pb 15 21 15 44 and 208 pb 204 pb 36 59 37 81 with comparison to the sr nd pb isotopic compositions of the basement rocks in the dabie orogenic belt the isotopic compositions of the cretaceous granitoids indicate a source that is similar to the northern dabie complex but distinct from the ultrahigh pressure metamorphic unit this strongly suggests that the exposed northern dabie complex extends in the deep crust southward beneath the uhp hp metamorphic units and northward beneath the north huaiyang unit the northern dabie complex is best interpreted as the core of a dome within the dabie orogenic belt the uhp hp metamorphic unit is only a thin skinned slab confined in shallower crustal levels over the northern dabie complex present tectonic framework for the uhp hp terrain was formed by extensional tectonics and post the uhp hp metamorphism the northern dabie complex has an affinity to the yangtze craton the similar source for the cretaceous granitoids also suggests that the suture between the north china and the yangtze cratons is marked by the xiaotian mozitang fault separating the north huaiyang unit and the northern dabie complex rather than the previously thought wuhe shuiko fault which separates the northern dabie complex and the uhp unit

landscape development in an hyperarid sandstone environment along the margins of the dead sea fault implications from dated rock falls in this study we explored the spatial and temporal relations between boulders and their original in situ locations on sandstone bedrock cliffs thiswas accomplished bycombining field observations withdating methods using cosmogenicisotopes 10 be and 14 c and optically stimulated luminescence osl our conclusions bear both on the landscape evolution and cliff retreat process in the hyperarid region of timna and on the methodology of estimating exposure ages using cosmogenic isotopes we recognize three discrete rock fall events at 31 ka 15 ka and 4 ka in this hyperarid region the most plausible triggering mechanism for rock fall events is strong ground acceleration caused by earthquakes generated by the nearby dead sea fault dsf our record however under represents the regional earthquake record implying that ongoing development of detachment cracks prior to the triggering event might be slower than the earthquake cycle cliff retreat rates calculated using the timing of rock fall events and estimated thickness of rock removed in each event range between 0 14 m ky 1 and 2 m ky 1 when only full cycles are considered we derive a more realistic range of 0 4 m ky 1 to 0 7 mk y 1 these rates are an order of magnitude faster than the calculated rate of surface lowering in the area we conclude that sandstone cliffs at timna retreat through episodic rock fall events that preserve the sharp imposing landscape characteristic to this region and that ongoing weathering of the cliff faces is minor a 10 20 difference in the 10 be concentrations in samples from matching boulder and cliff faces that have identical exposure histories and are located only a few meters apart indicates that cosmogenic nuclide production rates are sensitive to

concentration of carbon dioxide in the late cretaceous atmosphere stable carbon isotope data from late cretaceous maastrichtian palaeosols in india are used to estimate the concentration of carbon dioxide in the late cretaceous atmosphere we show that the maastrichtian atmosphere is unlikely to have contained more than about 1300 ppm by volume of co 2 this value agrees with an independently modeled value of co 2 in the late cretaceous atmosphere a low concentration of the greenhouse gas carbon dioxide in the maastrichtian atmosphere relative to concentrations in the earlier cretaceous is consistent with palaeotemperature information from terrestrial plant and marine fossils which suggest that the global climate cooled toward the end of the cretaceous period

a revised age for the kawakawa oruanui tephra a key marker for the last glacial maximum in new zealand abstract the kawakawa oruanui tephra kot is a key chronostratigraphic marker in terrestrial and marine deposits of the new zealand nz sector of the southwest pacific erupted early during the last glacial maximum lgm the wide distribution of the kot enables inter regional alignment of proxy records and facilitates comparison between nz climatic variations and those from well dated records elsewhere we present 22 new radiocarbon ages for the kot from sites and materials considered optimal for dating and apply bayesian statistical methods via oxcal4 1 7 that incorporate stratigraphic information to develop a new age probability model for kot the revised calibrated age 2 standard deviations for the eruption of the kot is 25 360 160 cal yr bp the age revision provides a basis for refining marine reservoir ages for the lgm in the southwest pacific

episodic late quaternary slopewash deposition as recorded in colluvial aprons southeastern wyoming abstract colluvial aprons found along fluvial terraces of the laramie river and sybille creek in southeastern wyoming are interpreted as late quaternary slopewash deposits each apron studied contained multiple buried soils interpreted to indicate that slopewash activity was episodic and short lived and was followed by relatively long periods of landscape stability and soil development apron deposits were described and subsequently correlated based on their internal stratigraphy and their relative degree of soil development optical dating was used to chronologically constrain periods of slopewash deposition and based on 17 optical ages taken from five aprons aggradation occurred at 65 56 16 0 12 9 11 8 8 1 7 3 5 0 and 1 7 ka several of these events correspond with climatic transitions such as the termination of heinrich event 1 the onset and termination of the younger dryas and the 8 2 ka event suggesting that apron aggradation was driven by changes in climatic regime although either increased aridity or a change in precipitation regime could result in increased erosion of terrace scarps apron aggradation events do not correlate with regional records of aridity instead periods of increased precipitation intensity and or frequency that occur during climatic transitions most likely drive apron aggradation events

soil transport driven by biological processes over millennial time scales downslope soil transport in the absence of overland flow has been attributed to numerous mechanisms including particle by particle creep and disturbances associated with biological activity process stochasticity and difficulties associated with field measurement have obscured the characterization of relevant long term soil transport rates and mechanisms in a series of incised fluvial terraces along the charwell river south island new zealand we documented vertical profiles of tephra concentration and topographic derivatives along a hillslope transect to quantify soil transport processes along the undissected hilltop we observed a thin primary tephra layer ca 22 6 ka within loess deposits 80 cm below the landscape surface in the downslope direction the depth to the highly concentrated tephra layer decreases coincident with an increase in hillslope convexity which is proportional to landscape lowering rate if soil flux varies linearly with hillslope gradient exhumation of the tephra layer results from landscape lowering due to disturbance driven soil transport approximately 20 m downslope of the interfluve the depth to the tephra layer declines to 40 50 cm peak tephra concentrations decrease by a factor of 4 and tephra is distributed uniformly within the upper 40 cm of soil the transition from a thin highly concentrated tephra layer at depth to less concentrated widely distributed tephra in the upper soil may result from soil mixing and transport by biological disturbances along our transect the depth to this transition is 50 cm coincident with the rooting depth of podocarp and nothofagus trees that populated the region during much of the holocene our observations can be used to calibrate the linear transport model but more important they suggest that over geomorphic time scales stochastic bioturbation may generate a well mixed and mobile soil layer the depth of which is primarily determined by flora characteristics

changes in carbon isotope ratios in the late permian recorded in therapsid tooth apatite the end of the permian witnessed global extinctions of marine and terrestrial fauna1 as marine biogenic carbonate and atmospheric carbon dioxide are in long term isotopic equilibrium changes in carbon isotope ratios in marine carbonate strata should record changes that occurred at that time in atmospheric ratios one might then expect a correlation between 13c 12c ratios in such marine sequences and those in terrestrial records that derive from carbon bearing materials that incorporate atmospheric co2 an example of the latter is fossil tooth apatite from herbivorous fauna correlations of this sort between marine and terrestrial records are however difficult to establish as they rely on particular characteristics of the isotope curves here we show that stable carbon isotope ratios in tooth apatite from diictodon a mammal like reptile in the late permian lower beaufort succession of the south african karoo 260 245 myr show a progressive depletion in 13c that is very similar to trends in marine carbonates from late permian deposits in eurasia2 7 these results suggest that global changes in total biomass occurred towards the end of the permian primary production decreased and continental aridity increased8 leading to a depletion of 13c in atmospheric and oceanic co2

a unique geochemical record at the permian triassic boundary a 330 metre core drilled through the marine permian triassic boundary in the carnic alps of austria allows closely correlated studies of geochemistry petrography and palaeontology across the boundary the isotope shifts and metal concentrations are extended multiple and complex and do not resemble those seen at the cretaceous tertiary boundary both the carbon isotope shifts and the chemical events including an indium anomaly may have causes related to a major regression of the sea

stochastic processes of soil production and transport erosion rates topographic variation and cosmogenic nuclides in the oregon coast range landscapes in areas of active uplift and erosion can only remain soil mantled if the local production of soil equals or exceeds the local erosion rate the soil production rate varies with soil depth hence local variation in soil depth may provide clues about spatial variation in erosion rates if uplift and the consequent erosion rates are sufficiently uniform in space and time then there will be tendency toward equilibrium landforms shaped by the erosional processes soil mantle thickness would adjust such that soil production matched the erosion previous work in the oregon coast range suggested that there may be a tendency locally toward equilibrium between hillslope erosion and sediment yield here results from a new methodology based on cosmogenic radionuclide accumulation in bedrock minerals at the base of the soil column are reported we quantify how soil production varies with soil thickness in the southern oregon coast range and explore further the issue of landscape equilibrium apparent soil production is determined to be an inverse exponential function of soil depth with a maximum inferred production rate of 268 m ma 1 occurring under zero soil depth this rate depends however on the degree of weathering of the underlying bedrock the stochastic and large scale nature of soil production by biogenic processes leads to large temporal and spatial variations in soil depth the spatial variation of soil depth neither supports nor rejects equilibrium morphology our observed catchment averaged erosion rate of 117 m ma 1 is however similar to that estimated for the region by others and to soil production rates under thin and intermediate soils typical for the steep ridges we suggest that portions of the oregon coast range may be eroding at roughly the same rate but that local competition between drainage networks and episodic erosional events leads to landforms that are out of equilibrium locally and have a spatially varying soil mantle copyright 2001 john wiley sons ltd

interpreting environmental and biological signals from the stable carbon isotope composition of fossilized organic and inorganic carbon stable carbon isotope studies on marine and terrestrial organic and inorganic carbon provide a means for detecting global climate change and for reconstructing past concentrations of atmospheric co 2 comparison between the co 2 estimates reconstructed from carbon isotope studies for the past 150ma show good agreement with the predictions of a long term carbon cycle model based on mass balance studies further the co 2 estimates from these sources over the entire phanerozoic show agreement with the fossil record of leaf stomatal density change a feature inversely related to the concentration of atmospheric co 2 isotopic studies on temporal sequences of fossilized terrestrial organic matter have contributed to palaeoecological studies on shifts in the dominance of plants with the c 4 photosynthetic pathway in ecosystems and historical changes in the metabolic processes of leaves of individual species the long term perspective offered by these studies provides critical information for assessing the responses of biological systems to future global environmental change

sulphur and carbon isotopic composition of power supply coals in the pannonian basin hungary abstract the present work is an attempt to establish the stable isotope database for mesozoic to tertiary coals from the pannonian basin hungary maceral composition proximate analysis sulphur form sulphur isotopes organic and pyritic and carbon isotopes were determined this database supports the assessment of the environmental risks associated with energy generation the characterization of the formation and the distribution of sulphur in the coals used the maceral composition the sulphur composition the c s isotopic signatures and some of the geological evidences published earlier show that the majority of these coals were deposited in freshwater and brackish water environments despite the relatively high average sulphur content however the upper cretaceous eocene and lower miocene formations also contain coal seams of marine origin as indicated by their maceral composition and sulphur and carbon chemistry the majority of the sulphur in these coals occurs in the organic form all studied sulphur phases are relatively rich in 34s isotopes 34sorganic 12 74 34spyrite 10 06 on average this indicates that marine bacterial sulphate reduction played a minor role in their formation in the sense that isotopic fractionation was limited it seems that the interstitial spaces of the peat closed rapidly during early diagenesis due to a regime of high depositional rate leading to a relative enrichment of the heavy sulphur isotopes

strong proximal earthquakes revealed by cosmogenic 3he dating of prehistoric rockfalls christchurch new zealand the 2011 rupture of previously undetected blind faults beneath christchurch new zealand in moment magnitude m w 6 2 and 6 0 earthquakes triggered major rockfalls that caused fatalities and infrastructure damage here we use field geospatial seismologic numerical modeling and cosmogenic 3 he data to provide first evidence for prehistoric rockfall ca 8 6 ka and a possible preceding event ca 14 13 ka at a site where extensive rockfall occurred in the christchurch earthquakes the long 7 1 k y time intervals between successive rockfall events and the high peak ground velocity thresholds required for rockfall initiation at this site 20 30 cm s preclude earthquakes from major identified seismic sources including the plate boundary alpine fault as likely rockfall triggering sources rockfalls were probably triggered by strong paleoearthquakes sourced from active faults proximal i e 10 20 km to christchurch including the sources of the 2011 christchurch earthquakes and or other currently unidentified faults given the inherent incompleteness of seismic source catalogues and challenges in obtaining earthquake chronologies for blind faults high scientific priority should be given to the search for and analysis of geologic records of strong earthquake shaking near populated areas

parallel trends in organic and inorganic carbon isotopes across the permian triassic boundary stable carbon isotope ratios in both inorganic and organic reservoirs have been widely applied to model environmental and sedimentological changes on a global scale most studies dealing with major extinction events have used the record of inorganic carbon in this paper the authors report the relation between shifts in carbon 13 content of organic matter and coexisting carbonate fractions at a major extinction event the permian triassic boundary they found that both delta sup 13 c sub carb and delta sup 13 c sub org of the surface ocean varied dramatically across the boundary but the fractionation delta sup 13 c between organic matter and carbonate remained constant this result appreciably restricts the interpretation of changes in the carbon cycle during this critical interval the new data are best explained by a combination of two mechanisms for variation in delta sup 13 c sub carb 1 burial and erosion of organic carbon with a long time constant and 2 sequestration of organic carbon into shallow and deep oceanic reservoirs with a shorter time constant for application to their case the first mechanism is limited by possible buildup of marine pco sub 2 which would increase the isotopic fractionation factor the second mechanism is limited in application to short term transient variations in delta sup 13 c modelingmore of the carbon cycle and its variations of delta sup 13 c must take both mechanisms into account less

rapid late glacial atmospheric co2 changes reconstructed from the stomatal density record of fossil leaves the younger dryas stadial 11 000 10 000 yr bp was an abrupt return to a glacial climate during the termination of the last glaciation we have reconstructed atmospheric co2 concentrations from a high resolution sequence of fossil salix herbacea leaves through this climatic oscillation from krakenes western norway using the relationship between leaf stomatal density and atmospheric co2 concentration high allerod co2 values median 273 ppmv decreased rapidly during 130 200 14c years of the late allerod to ca 210 ppmv at the start of the younger dryas they then increased steadily through the younger dryas reaching typical interglacial values once more ca 275 ppmv in the holocene the rapid late allerod decrease in co2 concentration preceded the younger dryas temperature drop possibly by several decades this striking pattern of changes has not so far been recorded unambiguously in temporally coarse measurements of atmospheric co2 from ice cores our observed late glacial co2 changes have implications for global modelling of the ocean atmosphere biosphere over the last glacial interglacial transition

the sino korean craton and supercontinent history problems and perspectives abstract the sino korean craton skc is an enigmatic block in the history of supercontinents older than pangea its accretion to eurasia and the effect of the broad region of mesozoic cenozoic extension in northern eurasia that crosses the eastern part of the skc are among several problems that need to be resolved in understanding the configuration of skc and the overprinting of earlier histories in this block we present a synopsis of these problems and perspectives for future research

trace element signature and u pb geochronology of eclogite facies zircon bergen arcs caledonides of w norway secondary ion mass spectrometry sims u pb and trace element data are reported for zircon to address the controversial geochronology of eclogite facies metamorphism in the lindas nappe bergen arcs caledonides of w norway caledonian eclogite facies overprint in the nappe was controlled by fracturing and introduction of fluid in the proterozoic sveconorwegian granulite facies meta anorthosite norite protolith zircon grains in one massive eclogite display a core rim structure sveconorwegian cores have trace element signatures identical with those of zircon in the granulite protolith i e 0 31 th u 0 89 heavy rare earth element hree enrichment and negative eu anomaly weakly zoned to euhedral oscillatory zoned caledonian rims are characterized by th u 0 13 low lree content minimum normalized abundance for pr or nd variable enrichment in hree and no eu anomaly a decrease of ree towards the outermost rim especially hree is documented this signature reflects co precipitation of zircon with garnet and clinozoisite in a feldspar absent assemblage and consequently links zircon to the eclogite facies overprint the rims provide a mean 206pb 238u crystallization age of 423 4 ma this age reflects eclogite forming reactions and fluid rock interaction this age indicates that eclogite facies overprint in the lindas nappe took place at the onset of the scandian silurian collision between laurentia and baltica

lateglacial landscape and vegetation change and the younger dryas climatic oscillation in new zealand abstract lateglacial sequences in new zealand show progressive afforestation and landscape stabilization reflecting a warming climate between 14 500 bp and 11 500 bp afforestation and landscape stability was achieved throughout most of the north island and the northwest sector of the south island in the south island scrub and tree ferns were replacing previous grasslands in the east by 11 000 bp and broadleaved forest was spreading in the west no significant reversals of these trends occurred and afforestation was complete by 9500 bp glaciers of the high central part of the southern alps made a series of advances between 14 000 and 9000 bp most of these advances are poorly dated but two moraines are of younger dryas age glacial advances in the face of the general lateglacial warming trend may have been driven by stronger westerly winds increasing snowfall on high altitude neves and by reduced ablation as a consequence of moist cloudy low insolation summers the cause of the northern hemisphere younger dryas cooling is still uncertain and expected southern hemisphere responses may differ according to the mechanism proposed for the cooling poor chronological resolution and apparent conflict between the various types of evidence for climatic change make detection of an unambiguous younger dryas in new zealand problematical

animating the biodynamics of soil thickness using process vector analysis a dynamic denudation approach to soil formation this paper expands the dynamic denudation framework of landscape evolution by providing new process insights and details on how soil and its signature morphological feature the biomantle form and function in the environment we examine soils and their biomantles from disparate parts of the world from the tropics through midlatitudes and hyperarid through perhumid a range that exhibits varying environments for and of life we then explicate the process pathways that cause soils to thicken and thin and to even disappear then reform we do this by examining thickness relationships where soil thickness st and biomantle thickness bt are functions of upbuilding u and deepening d minus removal r processes hence st bt f u d r upbuilding has two subsets u1 which includes all exogenous allochthonous outside mineral and or organic inputs to the soil system and u2 which includes all endogenous autochthonous in situ processes and productions including weathering exogenous u1 inputs include eolian and slopewash inputs sedimentations of mineral and organic materials mass wasting accumulations and the like endogenous u2 processes and productions include the sum of in situ bioturbations biosynthetic productions organic accumulations biovoid productions weathering and volume increases caused by their sum endogenous upbuildings which dominantly occur in the biomantle are basically biodynamic bd processes and productions hence u2 bd therefore if exogenous upbuildings u1 are minimal or zero then biomantle thickness bt is expressed by bt f u2 r or bt f bd r drawing on these relationships we employ a graphic conceptual device called process vector analysis in a digital animation see supplementary materials or cf https netfiles uiuc edu jdomier www temp biomantle html that illustrates the main pathways that form both earth s soil and its unique epidermis the biomantle we then discuss the main elements of the animation using still frames that represent thickness turning points we end by encouraging researchers instructors and students to view earth s landforms and soils as integrated dynamic entities that are constantly coevolving elements of a global subaerial subaqueous continuum

impacts of land use change on patterns of sediment flux in weraamaia catchment new zealand forest clearance between the 1890s and the early 1920s subsequent scrub growth and commencement of an afforestation program in 1979 modified the pattern and rate of sediment delivery to valley floors via shallow landslides and gully complexes in a steep headwater catchment 4 8 km2 in new zealand analysis of the historical record air photograph interpretation and field survey indicates that both erosion types occurred across the catchment in the 1938 storm aggrading channel beds and widening the active channel zone in contrast a 1 in 100 year event in 1988 cyclone bola induced numerous shallow landslides but erosion of gully complexes was largely restricted to subcatchments that retained pasture and the geomorphic impact of this event on channels was small the changing volume and calibre of materials delivered to the valley floor and the distribution of gully complexes altered patterns and rates of channel adjustment after the events and the resulting sediment flux development of gully complexes maintained coupling processes with channels for periods up to 102 years forming wide channels in downstream reaches upstream downstream connectivity along the trunk stream was altered by the formation of a large debris fan at the confluence with a tributary subjected to gully complex erosion in contrast slopes subjected to shallow landslides became decoupled from channels within 10 years accelerating channel degradation and narrowing effective conveyance of a large volume of fine grained materials promoted immediate aggradation of gentle gradient channels downstream as gully complex areas stabilized following an increase in forest and scrub cover channel courses became significant sediment sources although shallow landslide activity will continue to induce intermittent aggradation in the future it is inferred that average sediment yield will continue to diminish to levels approaching those experienced prior to clearcutting and the pattern of sediment flux will recover by 2030

luminescence dating of hillslope deposits a review abstract luminescence dating determines the last exposure to light of quartz and feldspar mineral grains and thus the time a sediment was laid down prerequisite is that the sediment grains were sufficiently exposed to light prior to deposition for eolian deposits this seems a fair assumption although exceptions may well exist for other depositional environments light exposure prior to burial is often restricted in duration intensity and spectral composition and may result in an age overestimation recent developments now allow dating of sediments that were exposed to only little light prior to deposition the main developments are single aliquot techniques and statistical tests that allow extraction of valid age estimates even from deposits in which bleached and unbleached grains are mixed these developments in combination with the fact that the great majority of sediments near the earth s surface are not of eolian origin have resulted in the large interest in the luminescence dating of non eolian deposits here we review possibilities and challenges of luminescence dating of colluvial deposits we summarize techniques for the detection and handling of insufficiently bleached sediments a common condition in colluvial deposits we give an overview how luminescence dating has been applied on hillslope sediments for reconstructing landscape response to climate change to analyze past fault activity and unravel human induced soil erosion we discuss sampling strategies and give guidelines as to which techniques are best suited to establish luminescence chronologies for colluvium

assessing the carbon dioxide content of ancient atmospheres using palaeocalcretes theoretical and empirical contraints recent suggestions that the 13 c composition of calcretes can be used to determine the p co 2 of ancient atmospheres is critically evaluated the problem of differentiating pedogenic calcretes from groundwater ones which could not be used for p co 2 determinations is considered a critical problem a basic tenet of the use of calcretes for assessing p co 2 is that plants using c 4 or cras sulacean acid metabolism photosynthetic pathways were unimportant until the miocene this view is questioned and evidence is presented from carboniferous calcified root mats that non c 3 plants were probably present at this time confirming speculations by palaeobotanists that crassulacean acid metabolism or c 4 photosynthesis may have arisen numerous times during the evolution of higher plants

carbon isotope evidence for cam photosynthesis in the mesozoic crassulacean acid metabolism cam photosynthesis a flexible adaptation to water stress has not been shown to occur before the pleistocene despite suggestions that cam first evolved in the mesozoic or earlier here we report on multiple 7 positive organic carbon isotope excursions d 13 corg 20 i n late triassic and early jurassic c 200 ma sedimentary rocks from an arid terrestrial ecosystem in south africa these excursions are interpreted as evidence of the episodic domin ance of cam plants in response to heightened aridity in the heartland of gondwana and hint at climatic instability in a greenhouse world

the history of holocene soil erosion in the phlious basin ne peloponnese greece based on optical dating anthropogenic induced soil erosion has occurred in the mediterranean during historic and pre historic times but precise timeframes for periods of past soil erosion are largely missing due to the lack of datable material and suitable dating methods in this study optical dating of colluvial sediments from the phlious basin ne peloponnese greece was applied the results show that soil erosion derived colluvium formed under a mediterranean type climate can be successfully dated by optical stimulated luminescence osl and a high resolution chronology of holocene soil erosion could be established colluvial formation occurred in the early holocene but increased distinctly in the seventh millennium parallel with the onset of the neolithic the start of farming activities other periods of strong colluviation are the middle and late bronze age second millennium the roman period first century to sixth century and the period since the sixteenth century rates of reduced colluviation occurred during

petrochemistry and sr pb and nd isotopic geochemistry of early precambrian rocks wutaishan and taihangshan areas china abstract in the wutaishan and taihangshan region china the lowermost high grade metamorphic complex of grey gneiss and amphibolite the fuping complex gives a 2 2 0 2 ga pb pb isochron age with a first stage growth 7 73 and a 2 37 0 07 ga sm nd isochron age with 143nd 144nd 0 0 50963 0 00005 or nd t 1 50 nd depleted mantle model dates tdm of amhibolites 2 48 to 2 60 ga those of gneisses are 2 43 to 2 46 ga the unconformably overlying medium to low grade metavolcanic complex the wutai complex gives a 2 0 0 1 ga rb sr isochron age with 87 86sr 0 0 7025 2 a 2 27 0 02 ga pb pb isochron date with afirst stage growth 7 73 and a 2 26 0 06 ga sm nd isochron first stage 143nd 144nd 0 0 5097 2 or nd t 1 08 individual sample nd depleted mantle model date are 2 5 ga metavolcanic samples from low grade metasedimentary rocks of the hutuo group all lie close to a 2 3 ga reference line on a rb sr isochron plot have nd tdm 2 32 2 34 and 2 62 ga from previous geological work published u pb zircon dating and ourisotopic and geochemical results we infer that the fuping rocks formed 2 6 ga ago in an environment like a modern island arc the wutai complex formed by 2 5 ga ago mostly formed in a tectonic setting similar to that of the fuping complex with the exception that one volcanic cycle formed in an environment like a modern mor and one unit formed in an environment transitional between modern within plate and plate margin settings the hutuo group formed 2 4 ga ago in a within plate tectonic environment there is no evidence for continental crust before 2 6 ga in the wutaishan and taihangshan region this contradicts previous assignment of the fuping complex to 2 8 ga ol older the fuping complex is not an early nucleus of the sino korean craton the new data also confirm that the wutai complex is older than its original assignment as early proterozoic the sm nd systems for metabasaltic rocks in the region either in amphibolite facies or in greenschist facies are all significantly disturbed in contrast with the undisturbed sm nd reported in previous studies of the sino korea craton this study provides further evidence that the archean igneous rocks in china formed at different times from heterogeneous and depleted mantle sources

chronology and processes of late quaternary hillslope sedimentation in the eastern south island new zealand optical and radiocarbon dating of loessic hillslope sediments in new zealand s south island is used to constrain the timing of prehistoric rockfalls and associated seismic events and quantify spatial and temporal patterns of hillslope sedimentation including responses to seismic and anthropogenic forcing trenches adjacent to prehistoric boulders enable stratigraphic analysis of loess and loess colluvium pre and post dating boulder emplacement respectively luminescence ages from loessic sediments constrain the timing of boulder emplacement to between 3 0 and 12 5 ka well before the arrival of polynesians ca ad 1280 and europeans ca ad 1800 in new zealand and suggest loess accumulation was continuing at the study site until 12 13 ka large 5 m3 prehistoric rockfall boulders preserve an important record of holocene hillslope sedimentation by creating local traps i e accommodation space for sediment aggradation i e colluvial wedges and upbuilding soil formation sediment accumulation rates increased considerably 10 factor increase following human arrival and associated anthropogenic burning of hillslope vegetation our study presents new numerical ages to place the evolution of loess mantled hillslopes in new zealand s south island into a longer temporal framework and highlights the roles of earthquakes and humans on hillslope surface process

biogeochemical evolution of cryoconite holes on canada glacier taylor valley antarctica 1 the cryoconite holes of the mcmurdo dry valleys are simple closed biogeochemical systems involving water ice mineral and organic debris which serve as ecosystems for consortia of microorganisms this study is the first to document the seasonal and annual chemical evolution of solutes in cryoconite holes samples of glacier ice frozen cryoconite holes and those containing water were collected during the austral summer of 2005 2006 the isolation age was calculated from the excess cl in the holes and varied from 0 to 5 years a consistent with the last hot summer when the cryoconite holes were open to the atmosphere the holes progressively deepen with isolation age variations in dic doc k and so42 suggest that dissolution of primary minerals in the cryoconite debris cyclical precipitation and dissolution of secondary carbonates net photosynthesis over summer and net respiration during the autumnal freeze are the principal reactions which perturb the seasonal and annual solute concentrations in the holes doc is generated in the holes at a rate of 7 5 g c cm 2 a 1 and non sea salt k accumulates in frozen holes at a rate of 0 073 eq cm 2 a 1 we infer that c cycling is complex even in these otherwise simple systems

late quaternary loess landscape evolution on an active tectonic margin charwell basin south island new zealand abstract loess deposits constitute an important archive of aeolian deposition reflecting wider patterns of glacial atmospheric circulation and more localised interactions between riverine source areas loess trapping efficiency and geomorphic controls on erosion rate conceptual models have been formulated to explain the coeval evolution of loess mantles and associated landscapes loess landscape models but none apply to areas of tectonically induced base level lowering this study uses an age sequence of alluvial fill terraces in the charwell basin north eastern south island new zealand which straddles the transpressive hope fault to investigate geomorphic controls on loess landscape evolution in an active tectonic region we hypothesize that the more evolved drainage networks on older terraces will more effectively propagate base level lowering by way of a greater areal proportion of steep and convex hillslopes and a smaller proportion of non eroding interfluves eventually as the proportion of interfluves diminishes and hillslope convexity increases terraces shift from being net loess accumulators to areas of net loess erosion we investigate the nature of erosion and the geomorphic thresholds associated with this transition morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo concave land elements the number of loess sheets and the thickness of loess increased across the three youngest terraces the next oldest ca 150 ka terrace remnant had the greatest maximum number of loess sheets 3 and loess thickness 8 m but the loess mantle was highly variable a detailed loess stratigraphic analysis and the morphometric analysis place this terrace in a transition between dominantly planar uniformly loess mantled landforms and loess free ridge and valley terrain exemplified by the oldest terrace remnant variations in thickness and preservation of loess sheets demonstrated spatially and temporally variable erosion during loess accumulation to test our hypothesis of loess persistence we calculated critical steady state hillslope curvatures from a soil transport model calibrated for the study area above which the uppermost loess sheet l1 max thickness 1 8 m should be completely eroded we compared loess distribution mapped in the field to values of slope curvature calculated from topographic surveys and found two of three critical curvature values had acceptable predictive ability where predictions failed this is probably due to transient responses related to active steam incision because all critical curvature values predicted presence of loess on the oldest terrace remnant where there is none we conclude that important factors other than morphometric ones are important in determining loess distribution in loess landscapes in active tectonic regions these may include internal changes to regolith affecting erodibility or vegetation or topographic interaction with wind patterns affecting loess trapping

environmental history of the german lower rhine embayment during the middle miocene as reflected by carbon isotopes in brown coal stable carbon isotope investigations have been carried out on miocene brown coal from the garzweiler seam of the german lower rhine embayment material studied included fossil wood from seven different taxa and brown coal matrix isotope results from macrofossil analysis show variations of more than 6 within individual samples and reveal a general isotopic difference between angiosperm and gymnosperm wood specimens according to mean carbon isotope values found for gymnosperms angiosperms and brown coal matrix 23 3 26 0 and 25 8 the peat forming vegetation of the garzweiler seam was dominated by angiosperm taxa results from brown coal matrix establish a continuous high resolution depth profile of carbon isotope variations during the late middle miocene they show a significant and characteristic isotope pattern with distinct medium and short term cycles high frequency variations in the two main units of garzweiler seam locally split into three units the medium term 13c variations are most likely caused by varying proportions of gymnosperms within the peat forming vegetation while high frequency oscillations seem to be a direct signal of environmental changes a long term decline of carbon isotope values observed within the complete garzweiler seam from base to top is presumably due to a cooling trend in the miocene

contrasting geochemical and sm nd isotopic compositions of archean metasediments from the kongling high grade terrain of the yangtze craton evidence for cratonic evolution and redistribution of ree during crustal anatexis abstract twenty three clastic metasediments from the kongling high grade terrain of the yangtze craton south china were analyzed for major trace and rare earth elements and sm nd isotopic ratios associated dioritic tonalitic trondhjemitic dtt and granitic gneisses as well as amphibolites were also analyzed in order to constrain provenance the results show that the clastic metasediments can be classified into 3 distinct groups in terms of mineralogical geochemical and sm nd isotopic compositions group a is characterized by having no to slight negative eu anomalies eu eu 0 82 1 07 being high in cr 191 396 ppm and ni 68 137 ppm and low in th 3 3 7 8 ppm and ree ree 99 156 ppm these characteristics are similar to those of metasediments from archean greenstone belts in addition the group a metasediments have the value of the chemical index of alteration ciw close to felsic gneisses their sm nd isotopic ree and trace element compositions can be interpreted by mixtures of the dtt gneisses and amphibolites dating of detrital zircons from 2 group a samples by shrimp reveals a major concordant age group of 2 87 3 0 ga which is identical to the age of the trondhjemitic gneiss these results strongly suggest that group a was principally the first cycle erosion product of the local kongling dtt gneiss and amphibolite moreover the higher than amphibolite cr content and slight eu depletion exhibited by some samples from this group infer that ultramafic rocks like komatiite and granite of probably 3 0 3 3 ga in age also played a role group b is characterized by the presence of graphite and shows a more evolved composition similar to post archean shales with a prominent negative eu anomaly eu eu 0 48 0 77 and high ciw on paired cr th vs la co and co th plots group b samples conform to a two end member mixing line of the kongling granitic gneiss and amphibolite however data on nd model age and ciw suggest that the granite component should be younger than the sampled granitic gneiss and derived from a distal source both groups a and b exhibit a clear positive correlation between ciw and tdm and a negative one between ciw and eu eu these correlations point to the crustal evolution of the yangtze craton towards coupled increasing ciw and eu depletion with decreasing age this in turn reflects the change of granitoid magmatism from local na rich dioritic tonalitic trondhjemitic rocks to widespread k feldspar granite the change led to the intracrustal differentiation stabilization and growth of the craton group c is restite and contains abundant sillimanite and garnet and unusually high ilmenite 7 11vol which can be seen to be dehydration melting products of biotite under the microscope this group shows extremely varied ree distributions from lree enriched to depleted and from negative to strong positive eu eu 1 63 eu anomalies compared to groups a and b group c is severely depleted in na2o k2o lree rb and ba whereas tio2 co v sc and hree and y are considerably enriched this is accompanied by anomalous high sm nd 0 21 0 28 147sm 144nd 0 1361 0 1738 and 143nd 144nd 0 511589 0 511958 ratios tdm correlates clearly with sm nd ratio and 2 out of 3 samples give significantly older to unrealistic tdm 3 9 4 9 ga the results document redistribution of ree and an open behavior of the sm nd isotope system during the biotite dehydration melting of metasediments

3800 to 2500 ma crustal evolution in the anshan area of liaoning province northeastern china shrimp u pb zircon geochronology has revealed several generations of granitoids and gneisses from the anshan area of northeastern china two samples of the baijiafen granite sensu lato 3804 5 and 3812 4 ma chentaigou granite 3306 13 ma lishan granite 3142 7 ma east and west anshan granites 3001 4 and 2994 8 ma tiejiashan granite 2962 4 and 2964 6 ma and qidashan granite 2475 ma the 3800 ma baijiafen granite consists of banded migmatitic trondhjemitic gneisses and forms only a small part of the area nonetheless they are the oldest known rocks in asia and are one of very few locations in the world where rocks of this antiquity have been found the younger suites are predominantly granite sensu stricto in composition and although foliated they have not been transformed into banded gneisses nd isotopic data suggest that the 3800 ma granites were produced at least in part by remelting of very ancient lree enriched sources perhaps like the exposed remnants of the 3800 ma rocks the chentaigou supracrustals contain layered mafic and ultramafic rocks banded iron formation bif and siliceous layered rocks of probable volcanogenic origin a sample of the latter has yielded a concordant u pb zircon age of 3362 5 ma interpreted as the age of deposition a trondhjemitic sheet cutting these rocks has yielded a u pb zircon age of 3342 6 ma the chentaigou supracrustals are the oldest recognised in the area younger supracrustal sequences collectively known as the anshan group contains the main economic bif units in the area bif is intruded by the 2475 ma qidashan granite indicating that the anshan group is archaean or earliest proterozoic in age

zircon u pb age and trace element evidence for paleoproterozoic granulite facies metamorphism and archean crustal rocks in the dabie orogen abstract zircon u pb ages and trace elements were determined for granulites and gneiss at huangtuling which are hosted by ultrahigh pressure metamorphic rocks in the dabie orogen east central china cl images reveal core rim structure for most zircons in the granulites the cores show oscillatory zoning relatively high th u ratios and hree enriched patterns consistent with a magmatic origin they gave a weighted mean 207pb 206pb age of 2766 9 ma interpreted as dating magma emplacement of the protolith the rims are characterized by sector or planar zoning low th u ratios negative eu anomalies and flat hree patterns consistent with their formation under granulite facies metamorphic conditions zircon u pb dating yields a weighted mean 207pb 206pb age of 2029 13 ma which is interpreted to record a metamorphic event possibly during assembly of the supercontinent columbia the gneiss has a protolith age of 1982 14 ma which is younger than the zircon age of the granulite facies metamorphism suggesting a generally delay between ht metamorphism and the intrusion of post collisional granites a few inherited cores with igneous characteristics have 207pb 206pb ages of 2 90 3 28 and 3 53 ga suggesting the presence of mesoarchean to paleoarchean crustal remnants in the yangtze craton a few cretaceous metamorphic ages were also obtained suggesting the influence of post collisional collapse in response to cretaceous extension of the dabie orogen it is inferred that the recently discovered archean basement of the yangtze craton occurs as far north as the dabie orogen

thermoluminescence ages of post glacial loess rakaia river south island new zealand abstract we applied the partial bleach r beta thermoluminescence tl dating technique to two samples from massive post glacial loess overlying the last major aggradation gravel burnham formation near barrhill on the south bank of the rakaia river this site is roughly midway between the coast and the front range of canterbury previously the time of initiation of deposition of such loess in the region was only poorly constrained to somewhere between the interval 16 32 ka and ca 11 ka loess deposition has continued until today along margins of major braided rivers sample bhl 5 30 cm above the gravel gave a tl age of 11 7 1 9 1 ka and sample bhl 1 1 35 m above bhl 5 and 1 9 m below the surface gave an age of 5 49 0 70 ka thus age depth extrapolation at the barrhill site implies that loess deposition began at 13 2 ka and continued through the holocene to the present the average rate of deposition between the two tl samples was 0 22 0 07 mm year analytical error only and possibly greater thereafter the presence of the loess wedge dating from 13 2 ka indicates that the rakaia river began to entrench at about this time in this middle segment of the piedmont plain

dispersed angiosperm cuticles their history preparation and application to the rise of angiosperms in cretaceous and paleocene coals southern western interior of north america abstract cuticle the decay resistant outer layer of leaves and young stems provides a reliable means of identifying fossil plant remains and reflects the vegetative adaptations of plants to climate and other environmental parameters the study of dispersed angiosperm cuticles originated prior to world war ii and has focused on the origin and paleoecology of coal activity in dispersed cuticles reached a high point during the 1950s and 1960s with the study of tertiary lignites in central europe then subsided in central europe as workers from other regions expanded the technique to other time periods and geographic regions data from dispersed cuticles augment data from palynomorphs because dispersed cuticles originate from a different generation of the vascular plant life cycle and have different taphonomic histories because the analysis of dispersed angiosperm cuticles is unfamiliar to many geologists methods for the analysis and preparation of dispersed angiosperm cuticles are detailed in an appendix dispersed cuticle assemblages from coals in the upper albian longford member of the kiowa formation and the maastrichtian paleocene raton formation of the southern western interior provide new constraints on the times that angiosperms entered coal swamps and rose to dominance the kiowa assemblages indicate that angiosperms first entered coal swamp environments by the late albian while the raton assemblages indicate that angiosperms dominated primary productivity in some subtropical coal swamps by the late maastrichtian angiosperms in kiowa coals probably comprised pioneer species in conifer dominated vegetation the most common family of angiosperms was chloranthaceae angiosperms in upper maastrichtian raton coals comprised the dominant seed plants to the exclusion of conifers magnoliid dicots and monocots were the dominant taxa and comprised diverse genera and families evidence from palynology and types of preserved cuticle indicates that ferns were subordinate to seed plants in biomass in raton coals in contrast to some described assemblages from the northern western interior paleocene coals from the raton basin show the loss of many cretaceous angiosperm taxa as well as the appearance of new taxa including conifers belonging to taxodiaceae however these taxodiaceae were evergreen and subordinate in abundance to angiosperms vegetational patterns shown by cretaceous paleocene coals of the southern western interior contrast with those of more northerly regions and indicate a poleward gradient in the timing of angiosperm dominance in coal swamps

well preserved garnet growth zoning in granulite from the dabie mountains central china ultra high pressure eclogites and granulites both occur in the dabie mountains central china a garnet porphyroblast from felsic granulite in the dabie mountains has been analysed for compositional zoning by electron microprobe two segments of the porphyroblast have opposite compositional variations segment i from centre outward 9 mm to analytical point 18 has decreasing xsps and increasing xpyr while segment ii from analytical point 18 1 mm outward to the rim has increasing xsps and xalm and decreasing xpyr and xgrs the compositional zoning in segment i is considered as growth zoning and that in segment ii as diffusive retrograde zoning garnet growth zoning records a p t path prior to the peak granulite metamorphism the minimum p t conditions are estimated to be 1 35 gpa and 850 c for peak metamorphism based on the highest mg fe mg composition in the garnet analytical point 18 and matrix hypersthene biotite and plagioclase a symplectitic corona surrounds the porphyroblast and appears to have formed at 0 6 gpa and 700 c the well preserved growth zoning in garnet suggests a short residence time for the granulite at peak metamorphism and thus rapid tectonic uplift history the p t path is consistent with that of ultra high pressure eclogite in the area tectonic movements during a collisional event could have brought both the granulite and the eclogite to their present positions

modelling the phanerozoic carbon cycle and climate constraints from the 87sr 86sr isotopic ratio of seawater a numerical model describing the coupled evolution of the biogeochemical cycles of carbon sulfur calcium magnesium phosphorus and strontium has been developed to describe the long term changes of atmospheric carbon dioxide and climate during the phanerozoic the emphasis is on the effects of coupling the cycles of carbon and strontium various interpretations of the observed phanerozoic history of the seawater 87sr 86sr ratio are investigated with the model more specifically the abilities of continental weathering volcanism and surface lithology in generating that signal are tested and compared it is suggested that the observed fluctuations are mostly due to a changing weatherability over time it is shown that such a conclusion is very important for the modelling of the carbon cycle indeed it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of co2 and the rate of silicate weathering is not true rather carbon exchanges between the mantle and the exogenic system are likely to have played a key role too further the increase of the global weathering rates with increasing surface temperature and or atmospheric co2 pressure usually postulated in long term carbon cycle and climate modelling is also inconsistent with the new model other factors appear to have modulated the weatherability of the continents through time such as mountain building and the existence of glaciers and ice sheets based on these observations a history of atmospheric carbon dioxide and climate during phanerozoic time consistent with the strontium isotopic data is reconstructed with the model and is shown to be compatible with paleoclimatic indicators such as the timing of glaciation and the estimates of cretaceous paleotemperatures