sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

unravelling the moisture sources of the alpine glaciers using tunnel valleys as constraints a lack of archives has impeded reconstructions of moisture pathways for past glaciations in the european alps here we focus on the confluence area of two palaeoglaciers in the swiss plateau that were sourced on the northern aare glacier and southern sides valais glacier of the european alps we mapped tunnel valleys in the region using a drilling database based on which we inferred the relative extent of each glacier c 270 ka ago when the valleys were formed we then compared this situation with that of the lgm we found that while the valais glacier expanded farther into the foreland than the aare glacier during the lgm the opposite was the case c 270 ka ago we also found that lgm glaciers were non erosive in the distal foreland these contrasts in extents and erosional efficiencies imply differences in moisture pathways between the lgm and the time when the tunnel valleys were formed

inversion of controlled source audio frequency magnetotellurics data for a horizontally layered earth we present a technique for inverting controlled source audio frequency magnetotelluric csamt data to recover a 1 d conductivity structure the earth is modeled as a set of horizontal layers with constant conductivity and the data are apparent resistivities and phases computed from orthogonal electric and magnetic fields due to a finite dipole source the earth model has many layers compared to the number of data points and therefore the solution is nonunique among the possible solutions we seek a model with desired character by minimizing a particular model objective function traditionally csamt data are inverted either by using the far field data where magnetotelluric mt equations are valid or by correcting the near field data to an equivalent plane wave approximation here we invert both apparent resistivity and phase data from the near field transition zone and the far field regions in the full csamt inversion without any correction our inversion is compared with that obtained by inverting near field corrected data using an mt algorithm both synthetic and field data examples indicate that a full csamt inversion provides improved information about subsurface conductivity

organic carbon and pyrite sulphur relationships as evidences of bottom water conditions of sedimentation albert formation fine grained lacustrine sediments new brunswick canada the late devonian to early carboniferous albert formation of the moncton subbasin new brunswick was deposited in a pull apart basin in a variety of subenvironments that include alluvial fans deltas shallow to deep lacustrine environments carbonate mudflats and algal swamps this study examined the role of organic carbon organic matter reactivity mineralogy iron content and sulphate availability on pyrite formation and bottom water conditions during sedimentation of the fine grained lacustrine sediments the fine grained deep lacustrine sediments have higher total organic carbon toc values 5 61 3 33 than the fine grained shallow marginal lacustrine sediments 0 97 0 82 the deep lacustrine sediments have slightly lower pyrite sulphur 0 82 0 46 than the shallow marginal lacustrine sediments 1 86 1 98 the adequate presence of reactive organic carbon in both these environments is supported by high hydrogen indices 658 181 the presence of sufficient iron for pyritization is evidenced from the association of early diagenetic siderite and pyrite least squares linear regression parameters indicate low slopes 0 03 and low positive intercepts 0 8 on the sulphur axis suggesting pyrite formation in euxinic environment the deep lacustrine sediments have higher c s ratios 6 84 0 67 than the shallow marginal lacustrine sediments 1 49 0 14 the slope and intercept of the regression equation and c s ratios suggest the existence of a sulphate gradient from the shallow marginal areas to the deep water areas of the lake 34s isotope values of pyrite 23 06 to 16 23 cdt suggest pyrite formation from bacterial reduction of sulphates of lacustrine and marine origin

the cosmic ray exposure history of the twannberg iron meteorite iig the twannberg iron meteorite is one out of only six members of the group iig the combined noble gas and radionuclide data obtained in this new systematic study indicate that twannberg with its 570 recently recovered specimens was a large object with a preatmospheric radius in the range of 2 m which corresponds to 250 9 10 kg the cosmic ray exposure age for twannberg is 182 45 ma the most surprising result is the long terrestrial age of tterr 202 33 34 ka which is unexpected considering the humid conditions in switzerland however this age is in accord with glaciation events indicating that the less shielded samples from mt sujet were found close to the position of the original strewn field whereas the samples from gruebmatt and twannbach which are from more shielded positions were glacially transported to the east northeast during the second last ice age 185 130 ka ago from an original position west of mt sujet

some remarks about a new last glacial record from the western salzach foreland glacier basin southern germany the amount of glacial advances into the alpine foreland during the pleistocene is still a matter of discussion the big four glaciations of the classical approach were originally derived from outwash sequences from glacial basins only very few long records and studies are known in the context of a geological mapping programme of the bavarian environment agency a research drilling through the salzach foreland glacier area was undertaken continuous coring reached the base of the glacial basin sequence 117 m below surface geological and geophysical logging pollen sampling and dating attempts of core material were conducted while age constraints for the lower part of the sequence are still uncertain the upper part can be ascribed to the last glacial cycle the interpretation of diamictons from the early part of the last glacial cycle is discussed a validation compared to other stratigraphic observations and interpretations from northern alpine quaternary records is presented

distribution and inferred age of exfoliation joints in the aar granite of the central swiss alps and relationship to quaternary landscape evolution abstract exfoliation joints are well known natural fractures limited to near the ground surface relatively few details however are known about their distribution and age in the swiss alps exfoliation joints follow the landscape surface at the time of their formation the age of the associated landscape feature then provides a maximum age of exfoliation joints while landscape forms can change through time exfoliation joints preserve elements of former landscape morphologies by their undisturbed orientations the grimsel region of the central alps is well suited for analyzing the impact of erosional episodes and accompanying stress changes on exfoliation joint formation in granitic rocks mapping above and below ground revealed that exfoliation joints are widespread and occur between valley bottoms and mountain crests within glacial inner and hanging u shaped trough valleys glacial cirques and steep mountain crests and predominantly fluvial landforms gently inclined linear slopes above the inner trough valleys narrow inner valley gorges and steep v shaped side gullies based primarily on their geometric properties at the ground surface three exfoliation joint types were distinguished in our study area 1 closely spaced

evolution of an overdeepened trough in the northern alpine foreland at niederweningen switzerland quaternary deposits in the overdeepened wehntal switzerland were investigated using both seismicprofiling and the analysis of 93 6 m long drill core using sedimentology geochemistry palynology

the most complete quaternary record of the swiss alpine foreland abstract the open pit section at thalgut near berne switzerland had already been considered as a quite complete reference section with interglacial lacustrine beds complex glacial sequences and evidence for morphogenetic activity during an earlier interglacial by a drilling operation this section has been extended and completed a long core of a still older interglacial has been recovered containing palynostratigraphic segments characterized by high percentages of pterocarya and fagus pollen assemblages with this discovery the thalgut section has become the most complete quaternary sequence of the northern alpine foreland with two different interglacial lacustrine beds and with a relic paleosoil separated each by complex glacial and glaciolacustrine sediments this record also implies a much older age for maximum erosion in the alpine foreland

geochronology for some key sites along the coast of sardinia italy recent stratigraphic surveys and facies analyses have questioned long held interpretations of the development and furthermore the age of quaternary sediments along the coast of sardinia the matter of debate is whether the investigated sediments were deposited during the late wurmian and holocene or during marine isotope stage mis 5 and older stages optically stimulated luminescence standard blue optically stimulated luminescence osl post infrared ir pulsed blue osl and post ir infrared stimulated luminescence irsl dating was applied to shallow marine and aeolian deposits as well as radiocarbon dating to bulk organic material in palaeosols radiocarbon dates suggest sedimentation during the late wurmian and holocene whilst the luminescence results for both quartz and potassium feldspar indicate a depositional age for most of the investigated sites prior to and during mis 5 from a geochronological point of view the luminescence ages are considered reliable because they passed all quality tests furthermore there is good agreement of two dosimeters with different bleaching and luminescence properties the radiocarbon ages might suffer from underestimation due to some contamination with young carbon which however cannot be large enough to yield such young ages

tensor csamt studies at the buchans mine in central newfoundland a novel application of the tensor controlled source audio magnetotelluric csamt method was part of a multidisciplinary geophysical study of an existing mine site at buchans newfoundland the orthogonal components of the horizontal electromagnetic fields used for magnetotelluric and csamt interpretation of the earth s conductivity structure were found to be inappropriate at buchans because of strong scattering in the electric fields instead the length of the major axes of the electric and magnetic field polarization ellipses and the vertical magnetic field were used as data the data from two bipole sources demonstrate that the bulk response of the earth in the vicinity of buchans is predominantly one dimensional 1 d these data were inverted to layered earth models with a first order correction for electric field distortions the parameter space considered during the inversion was contracted substantially by incorporating the vertical magnetic field data and by using depths to interfaces as determi

a large gyromagnetic effect in greigite summary rotational and anhysteretic remanent magnetization rrm and arm acquisition curves of two sediment samples containing greigite have been measured up to peak fields of 80 mt at rotation frequencies between 5 and 95 revolutions per second rps at 95 rps the arm 70 mt direct field applied antiparallel to the rrm increased almost linearly with peak field but the rrm increased approximately exponentially the effective field bg defined in this case as 70rrrm arm was about 1100 mt for the two samples after the application of an alternating field af of 80 mt peak bg is approximately 10 times higher than previously observed for magnetite of size 1 mm although greigite is the dominant ferrimagnetic mineral present in these samples other studies snowball 1997a have shown that low concentrations of detrital multidomain magnetite are also present so that the high value of bg must be regarded as a lower limit unlike a magnetite sample that was used for comparison both greigite samples had a negative rrm at all rotation frequencies below 50 rps but like magnetite there was an increase in rrm when it changed from negative to positive at 50 rps in addition unlike magnetite the arm was not constant but approximately halved as the rrm became strong and positive above 50 rps arm antiparallel to rrm thus there appeared to be an interaction between the arm and the rrm further investigation of this interaction by applying weak direct fields parallel and then antiparallel to the rrm 80 mt peak af 95 rps rotation rate showed that the arm was linear with direct field but was indeed always smaller when the direct field producing it was antiparallel to the rrm at present it is not clear why gyromagnetic remanences are so strong in greigite such high values of bg have never been observed before except in the very special case of a self reversing lithium chromium ferrite near its moment compensation temperature these high values of bg might enable rrm to be used as an indicator for greigite if they turn out to be unique to this mineral

radiocarbon chronology of the mammoth site at niederweningen switzerland results from dating bones teeth wood and peat abstract the peat section at niederweningen is a site of spectacular excavations of numerous bones of mammoth and other animals that was first recognized in the late 19th century in 1987 1990 new excavations provided more peat material which was radiocarbon dated to 33 000 14 c years bp and 42 000 14 c years bp the first ams radiocarbon ages of mammoth bones from 1890 1891 excavations placed the age between 33 000 14 c years bp and 35 000 14 c years bp in this study new results were obtained on bones teeth wood and peat from the layer that buried the mammoths the ages confirm that the mammoths as well as the peat section in which they were found are older than 40 000 14 c years bp in order to explain the discrepancy between the previous chronology and the new results two preparation techniques were applied for the dating of bones an organic fraction called collagen used to obtain the first radiocarbon ages was dated as well as gelatine prepared using the modified longin method the differences of up to 7000 years between ages obtained on collagen and gelatine fractions show contamination of the collagen fraction with modern carbon the oldest age of 45 870 1080 14 c years bp was obtained on base cleaned gelatine from mammoth bone this age is close to an age of 45 430 1020 14 c years bp obtained for the peat layer that buried the mammoths

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

luminescence dating of glaciofluvial deposits linked to the penultimate glaciation in the eastern alps during the penultimate glaciation vast areas of the alps were glaciated with piedmont glaciers protruding into the foreland in the easternmost part of the northward draining valleys of the alps the glaciers did not reach the foreland but formed valley glaciers confined by the mountainous terrain this also applies to the ybbs valley where samples for luminescence dating out of glaciofluvial gravel accumulations were taken at three locations along the present day river course in a highly dynamic depositional environment such as a glacier fed river system incomplete resetting of the luminescence signal is possible in particular when transport distances are short in such cases quartz usually is the preferred mineral over feldspar especially if dose rates are low and may theoretically allow obtaining quartz ages beyond 150 ka because previous research has shown and as corroborated within this study quartz from the research area exhibits analytical problems in the high age range therefore luminescence properties of coarse grain 100 200 m quartz and in addition k rich feldspar were investigated with the aim to reconstruct the chronology of the glacial processes within the ybbs catchment area issues of incomplete bleaching were pirir225 encountered and addressed by comparing quartz osl fading corrected k feldspar ir50 and pirir225 to identify reliable ages depositional ages based on quartz osl and feldspar pirir225 signals revealed deposition of ice marginal kame terraces and glaciofluvial foreland terraces during late to middle mis 6 in combination with results from previous studies we could reconstruct the valley evolution during the riss glaciation newly gained luminescence ages of the deglaciation in the easternmost alps coincide with osl dated deglaciation events in the western alps indicating that climatic change along the north side of the alps happened simultaneously

first results of cosmogenic dated pre last glaciation erratics from the montoz area jura mountains switzerland the jura mountains are a perialpine chain bending from the sw to the nw of switzerland alpine ice reached only marginal areas of this chain during the last glacial maximum lgm but remaining erratic boulders of alpine origin indicate older glaciations of unknown age tentatively correlated either with the classical rissian or with the most extensive glaciation presented here are the first results of dating these pre lgm boulders by using cosmogenic radionuclides 10be and noble gases 21ne both data sets are in good agreement within 1 error with radionuclide apparent exposure ages ranging from 60 to 107 ka and noble gas apparent ages from 73 to 123 ka considering the importance of erosion on older boulders the age of the erratics corresponds most probably to marine isotope stage 6 these results are encouraging for further studies on pre lgm erratic boulders in the mid latitudes

a stable isotope study of pyrite formation in the late pleistocene and holocene sediments of the black sea the abundance and isotopic composition of total and pyrite sulphur have been determined in a core in the central black sea pyrite varies in concentration from roughly 2 wt in the sapropel unit 2 to 0 8 wt in the modern horizon unit 1 and ca 0 1 wt in the lowermost horizons of unit 3 lake beds an intermediate mud flow horizon and the upper part of the lake beds have similar values to those in the modern sediments the degree of pyritization dop is lowest 0 05 in the lower lake beds and highest 0 55 in unit 1 the sapropel has values of ca 0 48 34spyrite varies from a minimum of 37 in the sapropel to 33 in unit 1 up to 15 in the upper lake beds and 0 in the lower lake beds the unit 1 and sapropel values are similar to the 34s values reported by fry et al 1991 of dissolved sulphide immediately below the water column oxic anoxic interface 36 to 38 but significantly heavier than those in the deep waters of the basin ca 41 these results are interpreted as a reflection of the presence of four different types of pyrite in the sediments of the black sea 1 pyrite in units 1 and 2 that is formed within the upper part of the water column immediately below the oxic anoxic interface where 34s of dissolved sulphide is 36 2 pyrite in the mud flow layer lying between unit 1 and the sapropel unit 2 with a significantly heavier isotopic composition that was formed around the margins of the basin under conditions that were probably more closed with respect to dissolved sulphate than those in which the pyrite in units 1 and 2 were formed 3 pyrite in the upper part of the lake beds unit 3 that was formed under closed system conditions by reaction between excess reducible fe remaining in these freshwater sediments and downward diffusing sulphate and or sulphide from the overlying organic rich sapropel and 4 pyrite in the lower part of the unit 3 representing a phase formed from the ambient sulphate in the freshwaters of the late pleistocene lake the isotopic information supports earlier suggestions that pyrite in the modern sediments of the black sea forms mainly in the water column with only minor amounts forming in the sediment because of the severe fe limitation of the bottom sediments that accumulate 2 000 m below the main fe and hs reaction zone at the oxic anoxic interface at shallow depths in the water column

the lincolnshire limestone hydrogeochemical evolution over a ten year period abstract in the lincolnshire jurassic limestone of britain a sequence of hydrogeochemical processes along a 28 km flow line was defined in 1969 these processes include solution redox and ion exchange reactions sulphate reduction and mixing with saline formation water resampling of the aquifer profile after 10 years has confirmed the overall sequence although downgradient increases in both sulphate and calcium together with changes in redox system can be recognised these changes are related to the migration of agrichemical pollutants and the results demonstrate that the aquifer must have a significant capacity for in situ nitrate reduction

luminescence dating of the niederweningen mammoth site switzerland abstract luminescence dating is used to further constrain the so far controversial age of the mammoth site at niederweningen switzerland gamma spectrometric analyses reveal the presence of radioactive disequilibria in the uranium decay chain in most of the samples but these cause only minor uncertainties in the age estimates the major uncertainty is actually related to the problem of estimating the average water content for the whole burial time nevertheless even considering these problems involved with dose rate determination the dating results clearly indicate that the peat is significantly younger than early wurmian in contrast to some previous assumptions together with the results of radiocarbon dating and pollen analyses the luminescence ages point to a correlation of the mammoth peat with interstadial conditions during the early part of the middle wurmian at around 45 ka ago

an attempt at correlation between the velay pollen sequence and the middle pleistocene stratigraphy from central europe abstract long continuous lacustrine sequences constitute on the continent a precious tool for coupling the long term continental environmental changes with deep sea and ice core records using the count from the top method moreover they can contribute to long distance correlation on the continent itself and thus help to classify discontinuous sedimentary records palynostratigraphical correlation is proposed here between the velay long sequence and the late middle pleistocene series from central europe with special attention to temperate episodes the similarities between the praclaux and the holsteinian interglacial suggest that they are both contemporaneous with marine isotopic stage mis 11 even if absolute dates are still divergent the evidence of two major warm periods with an interglacial type of vegetation between the holsteinian and the eemian is confirmed by the velay record

summer temperatures and lake development during the mis 5a interstadial new data from the unterangerberg palaeolake in the eastern alps austria abstract investigations of interstadials during early stages of glacial periods are of special interest because they featured large scale transformations of the climate system and the build up of land based ice sheets lacustrine sediment sequences are considered to be important natural archives that register past climate and environmental signals here we present new multi proxy data obtained from a palaeolake succession preserved in the inner alpine terrace of unterangerberg eastern alps these sediments formed during the second early wurmian interstadial equivalent to marine isotope stage mis 5a and were used to reconstruct changes in lake conditions and to infer past air temperatures the sediment geochemical data and subfossil aquatic biota provide evidence of a cyclic lake fen lake development during this interstadial the proxy records reveal stable lacustrine conditions with dense charophyte meadows and abundant aquatic fauna during the early part of the interstadial a progressive shallowing of the lake resulting in the spreading out of fen vegetation in the middle part and a transition from wetland to a renewed shallow lake stage towards the end of the interstadial chironomids were used to reconstruct mean july air temperatures employing a combined norwegian swiss chironomid temperature inference model the reconstruction indicates a temperature close to present day values of ca 18 c in the middle part of the record while temperatures of ca 13 14 c are recorded for the lower and upper parts the proxy data from this palaeolake provide evidence of heat and drought in the middle part of mis 5a supported by the chironomid based temperature reconstruction our reconstruction shows a climate pattern broadly similar to that found in pollen based estimates of mean july air temperatures from sites in the northern alpine foreland and compares well to other european palaeoclimatic reconstructions of mis 5a climate

palaeobotanical investigations at the mammoth site of niederweningen kanton zurich switzerland palaeobotanical investigations at the niederweningen 2003 mammoth site concentrated on the middle peat layer in which the remains of mammoth and other vertebrates have been found this peat developed during an interstadial characterised by the presence of picea the slopes around the site were occupied by open forest tundra composed of species such as picea abies larix and probably betula pendula pubescens the herb vegetation was similar to that of modern subalpine grasslands pinus cembra and pinus mugo were present at higher elevations on the surrounding hills during the time of peat growth the mire development started with overgrowth processes during the interstadial the succession developed towards a wetland complex with different mire associations where among other species betula nana was abundant the middle peat layer is intercalated with lake sediments which were deposited during stadial climatic conditions without any noteworthy growth of trees the pollen spectrum as well as radiocarbon and luminescence dating place the peat into the middle wurmian marine isotope stage 3 the peat with the mammoth findings is hence significantly younger than the peat layers previously investigated in cores from two nearby drilling sites

re interpretation of the meikirch pollen record swiss alpine foreland and implications for middle pleistocene chronostratigraphy the meikirch drilling site in the swiss midlands north of bern is re interpreted using a combination of sedimentological logging pollen analyses and luminescence dating the sedimentary sequence comprises about 70 m of lacustrine deposits overlain by about 39 m of coarse glacial outwash interpreted to represent at least two independent ice advances pollen analyses of the apparently complete limnic sequence reveal a basal late glacial period followed by three warm phases that are interrupted by two stadial periods meikirch complex the warm periods were previously correlated with the holsteinian and eemian interglacials according to luminescence dating and with consideration of evidence for middle pleistocene climate patterns at other central european sites a correlation of the meikirch complex with marine isotope stage mis 7 is now proposed if this correlation is correct it implies the presence of three intervals with interglacial character during mis 7 however the late middle pleistocene vegetational features of the meikirch complex show significant differences when compared with the pollen record from the velay region central france possible explanations for this discrepancy are distinct middle pleistocene patterns of atmospheric circulation over central europe and a different distribution of vegetation refugia compared to the eemian interglacial and the holocene copyright 2005 john wiley sons ltd

numerical 230th u dating and a palynological review of the holsteinian hoxnian interglacial abstract earth scientists increasingly consider the holsteinian interglacial and mis 11 as synonyms despite the limited number of numerical dates and ambiguous stratigraphic and palynological correlation with the numerical marine isotope timescale hence we present new tims 230th u dates from two fen peat layers of the holsteinian reference site at bossel in northern germany and re evaluate published numerical data from two sites with hoxnian deposits in england a new method for the calculation of methodically controlled minimum 230th u ages mcma was developed the synopsis of the 230th u dates allows a correlation of both the holsteinian and hoxnian interglacials to mis 9 this correlation is supported by supplementary 230th u dates of fen peat from several pre eemian but non holsteinian sites in germany there is palynological evidence for a reliable correlation between precisely investigated and numerically dated holsteinian deposits in poland germany england sw ireland and france an apparently contradictory palynological correlation from the french central massif is discussed

the glacially overdeepened trough of the salzach valley austria bedrock geometry and sedimentary fill of a major alpine subglacial basin abstract overdeepened valleys are unambiguous features of glacially sculpted landscapes they result from erosion at the bed of the glacier and their size and shape is determined by ice dynamics and the characteristics of the underlying bedrock major overdeepened valleys representing vertical bedrock erosion of several hundreds of meters are characteristic features of many trunk valleys in the formerly glaciated parts of the alpine mountain belt the thick sedimentary fill usually hinders attempts to unravel bedrock geometry formation history and fill characteristics based on reflection seismic data and core logs from multiple deep drillings we construct a detailed bedrock model of the lower salzach valley trough one of the largest overdeepened valleys in the european alps the analysed overdeepened structure characterized by a strongly undulating topography two reaches of enhanced erosion can be identified and are suggested to be related to variations in bedrock erodibility and a triple glacier confluence the sedimentary fill shows clear characteristics of rapid infilling and subaqueous fan delta deposits indicate a strong influence of tributary streams associated surface lowering of the valley floor had a major impact on tributary stream incision but also on the available ice accumulation area at subsequent glaciations the extent to which fills of earlier glaciations have been preserved from erosion during the last glacial maximum remains ambiguous and demands further exploration to our knowledge the presented bedrock model is one of the best defined of any major overdeepened trunk valley

the sedimentary history of the inner alpine inn valley austria extending the baumkirchen type section further back in time with new drilling the baumkirchen clay pit near innsbruck western austria is a well known site in alpine quaternary stratigraphy lacustrine sediments from the last glacial cycle from within the alps provide a unique opportunity to investigate the regional palaeoclimate recent drilling has extended the known sequence to a total length of at least 250 m consisting of almost entirely well laminated clayey silt luminescence dating identified two lake sequences separated by a hiatus of ca 7000 15 000 years lake phase 1 spans the period ca 77 55 ka i e from about marine isotope stage mis 5 4 to the mis 4 3 transition lake phase 2 extends from mid to late mis 3 between ca 45 and 33 ka down core x ray fluorescence core scanning confirmed the presence of the lake phases in the sediment composition suggesting different sediment sources and or transport mechanisms during these two intervals a unique section of exotic angular silt matrix supported gravel at the top of lake phase 1 is interpreted as ice rafted debris luminescence dating constrains this layer to ca 55 ka thus providing the first evidence of a late mis 4 or early mis 3 ice advance confined to the interior of the eastern alps a conceptual model of the sedimentary history of the valley is presented

on results of a controlled source audiofrequency magnetotelluric survey at the puhimau thermal area kilauea volcano hawaii by l c bartel and r d jacobson geophysics 52 665 677 may 1987 bartel and jacobson try to correct apparent resistivity values from csamt measurements where the plane wave approximation is not valid they want to convert csamt curves to passive mt curves cagniard curves which can be interpreted by 2 d modeling the measured csamt a value is projected onto the a axis in parallel with the half space curves of a horizontal electrical dipole in the given distance between receiver and transmitter the example looks convincing and it may be supposed to be a simple near field correction

age limits on middle pleistocene glacial sediments from osl dating north norfolk uk the lowland region of north norfolk contains some of the best preserved evidence for glacial deposition during the middle pleistocene in northwest europe despite the importance of these deposits there is limited chronological control and it is debated whether they belong to a single glaciation equated to the anglian glaciation marine isotope stage 12 or represent deposition over a number of middle pleistocene cold stages in order to develop an improved chronology for glaciation in this region we obtained 18 samples for optical stimulated luminescence osl dating from glacial outwash facies samples of coarse grained quartz sand were measured using the sar single aliquot regenerative dose protocol the low radioactive isotope concentrations in sediments of this region enable the traditionally accepted age limit of luminescence dating to be extended the form of the dose response curves pre heat plateaux tests and dose recovery experiments also indicate that laboratory doses can be reliably measured in these samples age overestimation due to partial bleaching is thought to be insignificant the osl ages suggest that the glacial sediments studied were deposited during mis 12 rather than in different post mis 12 stages

chronology and the upper dating limit for loess samples from luochuan section in the chinese loess plateau using quartz osl sar protocol abstract luminescence dating of loess older than 100 ka has long been a challenge it has been recently reported that using optically stimulated luminescence osl of fine grained quartz 4 11 m extracted from loess the range of luminescence dating could be pushed to 0 6 ma with osl ages being in agreement with independent ages watanuki t murray a s tsukamoto s 2005 quartz and polymineral luminescence dating of japanese loess over the last 0 6 ma comparison with an independent chronology earth and planetary science letters 240 774 789 the aim of this study is to provide a luminescence chronology 20 samples for the standard luochuan loess section and to further examine the upper limit of quartz osl dating for chinese loess the growth curve does not saturate at 700 gy and should allow reliable equivalent dose d e determination up to at least 400 gy however when compared with independent chronological control the d e that could be treated as reliable is less than 230 gy corresponding to 70 ka in age for chinese loess and the d e larger than 230 gy should be underestimated ages for samples from the lower part of palaeosol s1 are severely underestimated with the maximum age of 95 ka for a sample from the bottom of this palaeosol much younger than the expected age of 128 ka the maximum d e obtained for sample l9 m collected from loess layer l9 which is below the matuyama brunhes b m boundary whose age is 780 ka is only 403 gy which corresponds to an age of 107 ka the cause of underestimation is not yet clear the previous results by watunuki et al 2005 on the extension of osl dating of loess to 0 6 ma is not confirmed when evaluating the validity of osl ages in s1 another possibility is to question the already established chronological frame for luochuan section which is based on the hypothesis of continuous dust deposition the assumption of an erosion hiatus between l2 and s1 could make the osl ages look reasonable however if this is the case then it is difficult to explain why the age of sample l9 m is only 107 ka which could be treated as a saturation age while the osl can provide a correct age for loess as old as 94 9 ka for sample lc22 collected from the bottom of s1 much work is required to clarify these confusions

evaluation of the regional vegetation and climate in the eastern alps austria during mis 3 4 based on pollen analysis of the classical baumkirchen paleolake sequence the pre last glacial maximum paleolake sediments at baumkirchen western austria are well known in alpine quaternary stratigraphy as being the type locality of the middle to upper wurmian transition their location provides a rare opportunity to investigate the vegetation history of the interior of the alps during the last glacial cycle a recent renewed research effort involving new drilling revealed a 250 m thick lacustrine sequence with an older ca marine oxygen isotope stage mis 4 phase and a younger mid to late mis 3 phase pollen analysis reveals generally poor preservation and very low pollen concentration due to very high sedimentation rates on the basis of pollen percentages and influx rates six pollen zones pz were assigned pz1 and 2 correspond to the entire ca mis 4 section and are characterized by only scattered vegetation representing an extremely cold and dry climate two stadials and two interstadials were identified in the mis 3 section the interstadials are characterized by well developed open vegetation with some stands of trees with the upper pz6 being better developed but still forest free on the basis of previous radiocarbon dating this zone pz6 is correlated to greenland interstadial gi 7 and the lower interstadial pz4 tentatively to gi 8

methane derived carbonates and authigenic pyrite from the northwestern black sea abstract methane seeps in the northwestern black sea are accompanied by carbonate and pyrite precipitates sediments were sampled at locations on the romanian 120 m depth and ukrainian 180 200 m depth shelf and slope layered carbonate crusts are formed of i carbonate cemented siliciclastic sediment containing dreissenoid bivalves ii microcrystalline high mg calcite or aragonite and iii aragonitic cement the dreissena sediment is subrecent and was deposited during the freshwater phase of the black sea it has been affected by seepage of methane rich fluids which induced intergranular precipitation of authigenic carbonates the microcrystalline carbonates exhibit an intense autofluorescence high mg calcite contains 11 14 mol mgco3 the aragonitic cement 8300 9500 ppm sr forms either isopachous layers or botryoids microbial filaments about 10 20 m in diameter and up to 900 m in length are preserved within and on carbonate crusts the carbonates are depleted in 13c microcrystalline carbonate ranges from 27 to 41 pdb and botryoidal aragonite ranges from 26 to 38 pdb the 13c depletion indicates that the carbonates predominantly derive from the microbial oxidation of methane carbonate deposits do not project up into the oxic water column they are restricted to the anoxic water column and to anoxic sediments revealing the crucial role of anaerobic methane oxidation for carbonate precipitation 14c contents give apparent radiocarbon ages of 20 640 180 a bp for a sample of botryoidal aragonite and 19 110 180 a bp for a sample of microcrystalline carbonate compatible with minimum ages of carbon derived from a fossil hydrocarbon source the 18o values of methane derived carbonates show a narrow range from 1 2 to 0 2 pdb 87sr 86sr ratios of microcrystalline carbonate mean 0 70927 and aragonitic cement mean 0 70918 are indistinguishable from ambient seawater mean 0 70917 and thus indicate a shallow sr source higher 87sr 86sr ratios of the dreissena sediment mean 0 71005 are probably caused by sr derived from detrital mica carbonates are accompanied by blocks and crusts composed of pyrite the framboidal sulphide exhibits a palisade like fabric with framboids arranged to parallel pillars sulphur isotopic ratios 34s ranging from 16 8 to 19 7 cdt indicate that the sulphur derives not from the 34s depleted h2s of the water column or the uppermost sediment layers most likely pyrite formed in the lacustrine sediments after the first incursion of mediterranean seawater

greigite detected as dominating remanence carrier in late pleistocene sediments lisan formation from lake kinneret sea of galilee israel summary a rock magnetic investigation of three sedimentary cores of lisan formation of late pleistocene age from lake kinneret sea of galilee northern israel demonstrates that the magnetization of these sediments is controlled by various degrees of a secondary chemical remanent magnetization crm carried by greigite fe3s4 this crm is superimposed on a primary detrital remanent magnetization drm that resides in ti magnetite this finding is independently confirmed by x ray diffraction xrd measurements performed on magnetic extracts of the sediments the domain state of the greigite is largely single domain behaviour sd thus dominating the magnetization therefore the magnetic record retrieve from of these sediments is not reflecting geomagnetic variations but rather chemical rock magnetic properties resulting from diagenetic processes the results of our study suggest that paleomagnetic record of greigite bearing sediments should be interpreted with caution because of the following reasons 1 geomagnetic secular variations can be biased due to large coercivity overlap between magnetite and greigite 2 alternating field af demagnetization can produce erroneous directions due to vector distortion by acquisition of a gyro remnant magnetization grm 3 estimation of relative paleointensity can be hampered by large scale variations in natural remnant magnetization nrm intensity caused by the acquisition of a secondary crm of unknown age and unknown extent superimposed on the drm the precipitation of greigite requires reducing conditions at the sediment water interface and or interstitial water associated with the presence of sulphur and iron oxides reducing conditions are typical of stratified lakes and other stratified water bodies such as the dead sea paleo lake lisan temporarily the eastern mediterranean sea the caspian sea the black sea and many other marine basins according to our findings paleomagnetic records from such environments carried dominantly by greigite therefore should be treated with care

the last and penultimate glaciation in the north alpine foreland new stratigraphical and chronological data from the salzach glacier abstract the northern alpine foreland was repeatedly covered by massive piedmont glaciers during quaternary glacial maxima the salzach palaeoglacier lobe austria germany was the easternmost of a series of pleistocene piedmont glaciers entering the foreland through major alpine valleys it covered an area of more than 1000 km2 during at least four glacial maxima here we aim to bring more light into its history by analyzing multiple drill log data two major outcrops topographic data and absolute chronologies of sediments stratigraphic and lithofacies investigations are focused on proximal i e near the lobe axis and distal i e near terminal moraine deposits of the salzach glacier lobe the glacial carving into the miocene bedrock occurred during early glacial maxima and was rather uniform across the lobe with larger values only in the proximal parts of the glacier more than 100 m of accumulated sediments during later glacial maxima indicate a change in ice sheet dynamics and a characteristic sequence development which varies from proximal to distal lobe positions new luminescence ages suggest a depositional focus at the penultimate glacial period while the impact of the lgm was rather minor sediments of gravelly braided rivers dominate the proximal parts of the former lobe where meltwater discharge was generally high while sheetflood deposits dominate the distal near terminal lobe positions

loess and soils in the eastern ebro basin abstract wind blown sandy and silty deposits were formed during the late quaternary in the ne iberian peninsula they are the most significant in the west mediterranean region together with those described in the tagus river basin iberian south subplateau forming small scattered patches across parts of the se ebro depression and sw catalan mediterranean range two major depositional environments are distinguished the first largest outcrop covers the lower ebro reaches on the se border of the ebro depression the prelitoral coastal range and the mora d ebre basin a second outcrop to the north consists of a few patches scattered over a wide amphitheatre surrounding the western tributaries of the segre river from the wind exposed segria platforms to the almenara range in its northernmost part they consist of highly sorted fine sands and silts 1 12 m thick though most typically 3 4 m thick and coarser than typical loess they are highly uniform lack any sedimentary structures and are pale ochre the deposits are calcareous 30 45 caco3 basic to alkaline and with some soluble salts five selected sequences of primary loess namely mas de l alerany tivissa guiamets batea and almenara were studied to ascertain deposit characteristics and soil development all sections show a consistent vertical granulometric variability that may be attributed to wind intensity changes and hinders the recognition of spatial particle size distribution pedogenesis is mostly related to calcium carbonate redistribution which accumulates as nodules large rhizocretions or biogenic calcite secondary gypsum batea and almenara sequences is probably related to primary gypsum blown from the source areas that was redistributed by leaching and precipitation at the bottom of the profiles in a few places mas de l alerany outcrop a fersialitic rubefacted recalcified soil indicates the presence of an older generation of loess while the dominant wnw winds and particle coarseness suggest that the loess originates from nearby alluvial fans and fluvial plains the presence of gypsum and mg anomalies may be evidence of more distant sources of the central ebro depression and ondara corb alluvial fans optical stimulated luminiscence osl ages for the more recent deposits guiamets batea almenara are between 18 and 34 ka while the old mas de l alerany sequence is more than 115 ka these ages indicate loess deposition during the last cold phases of the quaternary and with pedogenesis occuring during warm interglacial periods

the mammoth site of niederweningen switzerland abstract in 1890 more than 100 bones molar teeth and tusks of at least seven different individuals of mammoths including a very young calf were found in a peat horizon at the base of a gravel pit at the village of niederweningen 20 km northwest of zurich further fragmentary fossils have been identified as remains of woolly rhino wild horse bison wolf lemming vole frog and bird in 2003 and 2004 new fossils and good sections of the peat horizon were studied in large construction pits located close to the old niederweningen mammoth site the highlight was a well preserved articulated mammoth skeleton with an estimated height of about 3 50 m new 14 c ams dating confirm that bones and teeth of mammoth peat and wood found in association with mammoth have an age of about 45 ka bp luminescence dating of one section provides time control with ages of 70 80 ka for the sediments below the peat and 40 ka above the peat first studies on pollen seeds wood and beetle allow the reconstruction of environment and climate during this time interval in the middle part of the last glacial cycle middle wurmian