u series dating of the late pleistocene mammalian fauna from wood quarry steetley nottinghamshire uk we present the u series dating of bones from wood quarry steetley quarry cave using the diffusion adsorption model to account for uranium uptake the results give a weighted mean date of 66 8 3 0 kyr placing this assemblage within or just before marine oxygen isotope stage 4 the fauna is thought to correlate with the banwell bone cave mammal assemblage zone of the early devensian in britain our results support the idea that this assemblage zone immediately precedes the assemblage represented nearby at pin hole in creswell crags which is contemporary with the mid devensian and correlates with mis 3 our dates and dates for the banwell bone cave mammal assemblage zone from stump cross cavern and evidence from other sites may indicate a longevity for this fauna copyright 2005 john wiley sons ltd

magnetic mineralogy of sandstones from the lunde formation late triassic northern north sea uk origin of the palaeomagnetic signal the minerals responsible for the magnetic properties of the late triassic lunde formation have been examined using a combination of magnetic mineral extraction microscopy and rock magnetic measurements the magnetic mineralogy is controlled by the depositional environment and the effects of diagenesis by a process of differential preservation and modification of the original detrital minerals the magnetic susceptibility and remanence properties of the sediments are strongly influenced by the proportion of silt and clay sized clastic material which contains most of the magnetic minerals paramagnetic minerals both of depositional origin and produced during diagenesis are largely responsible for the magnetic susceptibility a suite of residual ferrimagnetic oxides chromite and mn substituted magnetite is responsible for the remanence properties in grey sandstones because most of the originally deposited magnetic fe ti oxides have been removed by reducing conditions during diagenesis however a small number of reddened horizons preserve a higher proportion of original detrital fe ti oxides ferrimagnetic ilmenite ferrimagnetic chromite and magnetite although authigenic hematite has replaced most of the original mineralogy in the reddened horizons magnetic oxide inclusions in quartz and feldspars are important contributors to the remanence signal particularly in horizons which have a low content of discrete detrital ferrimagnetic grains either through diagenetic dissolution or paucity of the silt and clay fraction within the grey sandstones the triassic palaeomagnetic signal is carried by magnetite as inclusions in detrital silicates with a contribution from detrital ferrimagnetic chromite a model of the effects of diagenesis on the magnetic mineralogy in deeply buried sequences is proposed

the continuous alteration of ilmenite through pseudorutile to leucoxene ore microscopic examinations and microprobe analyses show the alteration of ilmenite by leaching to be a continuous process proceeding from leached ilmenite through pseudorutile to leucoxene in this process which takes place near the surface and requires the presence of water a temperature of 50 c is not exceeded therefore diffusion processes are of no importance there are continuous phase transitions between ilmenite and its successive products pseudorutile with its iron poor members leached pseudorutile in particular is unstable and decomposes into leucoxene as a result of this and also of leucoxenic changes brought about by recrystallization there are sharp grain boundaries towards other alteration products simulating discontinuous leaching processes ilmenite leucoxene and their intermediate products are well distinguishable from each other by ore microscopic and subordinate also by x ray methods with ore microscopic studies enabling this distinction to be made faster and more easily water is the main agent in the leaching process which keeps going on as long as there is iron present that is able to migrate the continuous alteration of ilmenite can be expressed in terms of two reactions a 3fe2 tio3 fe3 x2 fe 23 x3 13 x ti3o9 in this equation x 0 3 x 0 corresponds to ilmenite x 3 to pseudorutile in the range of x 0 2 1 leached ilmenite occurs reaction a is established by oxidation and leaching of iron b fe23 ti3o9 fe2 y3 ti3o9 3y oh 3y in this equation y 0 2 y 0 corresponds to pseudorutile y 2 to leucoxene the range of y from 0 8 1 4 is identical with leached pseudorutile reaction b can be explained by hydrolization and leaching of iron whereas reaction a includes all phases representing oxides with different fe2 fe3 ratios reaction b comprises all phases with iron occurring in its trivalent state and the o oh ratio increasing as the fe3 content is decreasing

new data on speleothem deposition and palaeoclimate in britain over the last forty thousand years 230th 234u dates are presented for 26 speleothems from three areas in britain assynt n w scotland n w yorkshire mendip hills somerset these dates suggest that speleothem growth was widespread but rare in the period from 40 to 26 ka absent from 26 to 15 ka and abundant from 15 ka to the present the absence of speleothems between 26 and 15 ka is attributed to glaciation in yorkshire and assynt and tentatively to continuous permafrost development in the mendip hills the occurrence of speleothems before 26 ka places restrictions on the extent of any ice sheet which may have been present in scotland and indicates that n w scotland was not subjected to continuous permafrost at that time

late quaternary speleothem pollen in the british isles as with many terrestrial areas the british quaternary sequence is characterised by incomplete fragmentary records whose correlation is based on stratigraphic or biostratigraphic techniques due to the lack of radiometric ages beyond the 40 kyr limit of 14c dating speleothems secondary cave calcite deposits offer a significant advantage over many sources of palaeoenvironmental information they can be dated to a high precision and accuracy by uranium thorium 238u 230th thermal ionisation and inductively coupled plasma icp mass spectrometry in the time period back to 500 kyr they may also contain sufficient well preserved pollen representative of contemporary vegetation above the cave to allow palaeoenvironmental reconstruction this study adopts the novel approach of combining pollen and thermal ionisation mass spectrometric tims u th dating of british speleothems to produce well constrained palaeoenvironmental records we report for the first time precisely dated records of pollen assemblages from speleothems suggesting the presence of thermophilous arboreal species in phases previously considered to have been consistently cool or cold and devoid of trees copyright 2007 john wiley sons ltd

source of the climate signal recorded by magnetic susceptibility variations in indian ocean sediments the origins of magnetic susceptibility variations in deep sea sediments from the indian ocean ocean drilling program odp leg 117 have been examined to identify the specific connections between climate shifts and sediment magnetic properties in a previous study the magnetic susceptibility variations in odp hole 722b were identified as an outstanding proxy paleoceanographic record despite evidence of postdepositional loss of magnetic minerals through reductive diagenesis this paradox is addressed by assessing the contributions of ferrimagnetic detrital iron oxides bacterial magnetosomes and paramagnetic detrital fe silicate minerals to the magnetic susceptibility signal in addition to detailed magnetic analyses mineralogical morphological and grain size data have been obtained from representative magnetic extracts for hole 722b we find that magnetic responses to climate change result from 1 fluctuations in the volume magnetic susceptibility which is primarily controlled by carbonate dilution 2 a ferrimagnetic signal which is restricted to the upper 7 meters below sea floor mbsf and which largely reflects source area aridity and 3 a paramagnetic susceptibility record below 7 mbsf which is coincident in frequency with variations in lithogenic grain size

recent tims dating results from british late pleistocene vertebrate faunal localities context and interpretation new tims dates from british sites underpin and extend the growing model of mammalian faunal history during the late pleistocene the sequence of british faunas during the three successive warm phases of mis 5 presents a challenging model in which the mammal faunas of the first two temperate phases 5e and 5c is dominated by species of a classically interglacial character while that of the final phase sub stage 5a is dominated by bison and reindeer this we see as the cold fauna appearing in britain during the cool isotope sub stage 5b and subsequently isolated by the rising sea level of isotope sub stage 5a all these three faunas are true island faunas copyright 2007 john wiley sons ltd

nano crystal formation of tio2 polymorphs brookite and anatase due to organic inorganic rock fluid interactions the occurrence of the titania polymorphs brookite and anatase as nano crystals in organic matter rich sediments of differing age and thermal maturity has been investigated by means of a multidisciplinary analytical approach fib tem organic geochemistry and petrography it was the aim of the study to analyze the formation mechanisms fate and behavior of the titania nano crystals as a result of organic inorganic rock fluid interactions brookite nano crystals have been detected in immature mediterranean sapropels of quaternary age but anatase also occurs in deeper and older black shales furongian alum shale sweden devonian to carboniferous bakken shale williston basin usa whereas anatase prevails as single crystals brookite nano crystals often are agglomerated single brookite nano crystals from posidonia shale lower jurassic northern germany have increasing crystal diameters with increasing thermal maturity exclusively anatase nano crystals both as single crystals or as agglomerates have been detected at oil water contacts in oilfields and along fractures with fluid flow enriched in dissolved organic carbon titania nano crystal precipitation growth and agglomeration takes place in the pore water of micro environments at low to high temperatures and where low ph is coupled to the occurrence of dissolved organic components low sedimentation rates preserving a critical geochemical environment or higher temperatures seem major controls for the precipitation of anatase and its tendency not to agglomerate

ferrimagnetic cr and mn spinels in sediments residual magnetic minerals after diagenetic dissolution ferrimagnetic cr fe and mn fe spinels are the dominant remanence carrying phases in the late triassic lunde formation these have largely been identified by magnetic mineral extraction from the sediments combined with microscopy the extensive removal of most of the originally deposited magnetic fe ti oxides during diagenesis has left the cr fe and mn fe spinels as a mineral residue which is resistant to dissolution the rock magnetic signature of these minerals is not sufficiently known to be able to identify these minerals on the basis of their magnetic properties alone

dating of late pleistocene interglacial and interstadial periods in the united kingdom from speleothem growth frequency abstract the growth of speleothems is indicative of interglacial and interstadial conditions in the united kingdom since their growth is dependent on two factors first the occurrence of significant diffuse groundwater recharge and second the biogenic production of carbon dioxide in the soil both are dependent on temperature and water availability the growth frequency of speleothems is examined using a cumulative distributed error frequency method applied to 341 uncontaminated uranium series age determinations the curves derived are shown to be statistically stable and the ages of the peaks are interpreted as the best estimates of the ages of interglacial and interstadial periods ten such periods are recognized during the interval 220 000 to 20 000 yr b p considerably more than are currently recognized in the uk pollen and coleoptera based quaternary stratigraphy correlations between the speleothem growth frequency peaks and last interglacial ipswichian sites can be made but correlations with last glacial devensian interstadial sites are limited because of the paucity of dates the speleothem growth frequency record provides a well dated terrestrial chronology for the past 140 000 yr b p which directly reflects regional palaeoclimatic conditions in britain and should prove very useful in unravelling the complex stratigraphy of the devensian and ipswichian stages

authigenesis of titania minerals and the mobility of ti new evidence from pro deltaic sandstones cretaceous scotian basin canada titania tio2 minerals are minor diagenetic phases in many sandstone shale successions but the conditions of ti mobility and titania authigenesis are poorly known here new modes of occurrence of authigenic titania minerals filling pores and replacing phytodetritus are documented from lower cretaceous prodeltaic sandstones in the offshore scotian basin of southeastern canada textural relationships suggest that titania minerals formed at the same time as kaolinite most commonly below lowstand sequence boundaries related to flux of meteoric water such authigenic titania is most abundant in thin bedded sandstones interbedded with thick prodeltaic mudstone in which fine grained detrital ti rich minerals are concentrated textures in titania that has replaced uncompacted phytodetritus suggest microbial mediation in near surface eodiagenesis eogenetic titania is enriched in phosphorus 0 6 p2o5 and may co occur with authigenic fluorapatite and crandallite crystals such titania resulted from prolonged flow of meteoric water that dissolved p from apatite and feldspar thereby enhancing ti solubility in basins with supply of immature sediment from granitic terranes and important diagenesis by meteoric water the assumption that ti is an immobile element and that rutile or other titania minerals are exclusively of detrital origin may not be valid probable mesodiagenetic titania has low p content suggesting that ti mobility under these conditions was facilitated by some other agent probably organic acids the results of this study illustrate that even in cases where titania minerals are volumetrically insignificant their microtextures and trace element chemistry can provide important insights into the character of fluid flow during diagenesis of siliciclastic rocks

new constraints on the age of the last ice sheet glaciation in nw england using optically stimulated luminescence dating optically stimulated luminescence osl has been used to date silts interpreted as either primary or colluviated loess deposited in karstic depressions at three sites on the carboniferous limestone of nw england two of the ages presented here constrain the onset of the last late devensian ice in this region to later than ca 27 2 ka and the other two date initial deglaciation prior to ca 19 2 ka in the morecambe bay area and ca 17 2 ka in the karst of the yorkshire dales while these ages are broadly consistent with existing estimates from lacustrine and speleothem evidence they offer the tightest constraints yet published on the presence of the last ice sheet from northern england copyright 2009 john wiley sons ltd

microstructural trace element and geochronological characterization of tio 2 polymorphs and implications for mineral exploration abstract the geochemistry of rutile tio2 has recently found its use in mineral exploration with some studies reporting anomalous concentrations of fe w v sn and sb in rutile associated with mineralized ore systems however the use of rutile as a prospecting tool is likely to be complicated by the systematic changes in trace element composition with tio2 polymorph type anatase brookite and rutile here we present tio2 trace element and u pb geochronological data from the mineralized and barren portions of the palaeoproterozoic moorarie supersuite and capricorn orogen western australia with a focus on the minnie creek molybdenum prospect in the northern part of the gascoyne province the barren samples contain all three tio2 polymorphs anatase brookite and rutile textures suggest anatase and brookite may have formed during low t metamorphism either through replacement of previous rutile grains or titaniferous minerals rutile grains from barren samples yield variable u pb ages ca 3 0 2 2 ga as well as variable textures and chemical compositions suggesting detrital origins thus most likely representing metasedimentary units intruded by the moorarie supersuite rutile grains from the minnie creek prospect yield palaeoproterozoic ca 1 77 1 75 ga u pb cooling ages and nb ta concentrations of up to 17 wt that along with inclusions of manganocolumbite oscillatory and patchy zonation of nb and fe suggest a magmatic origin the commonly used pathfinder elements for gold and base metal mineralisation fe cr v w sn and sb are shown to be systematically lower in anatase and brookite thus yielding false negatives if polymorph type is not identified during reconnaissance studies for this reason a ternary diagram was constructed based on the systematic changes in chemistry of tio2 polymorphs to provide a relatively fast and easy chemical discrimination of polymorphs in large volumes of reconnaissance data furthermore it is shown that high al concentrations are characteristic of brookite and to a lesser degree anatase but not rutile in addition sn nb ta and w concentrations in rutile may be more sensitive to igneous processes and may be used to track processes occurring in strongly fractionated granitic magmas such as pegmatites and associated deposits

evidence of sea level change from coastal caves with raised beach deposits terrestrial faunas and dated stalagmites abstract investigation of interfingering marine and terrestrial quaternary deposits preserved in minchin hole and bacon hole on the coast of south wales uk provides evidence of two phases of high sea level equal to or greater than that of today the younger of these is assigned to the 125 000y by high sea level event of oxygen isotope sub stage 5e overlying the deposits which represent this event a series of terrestrial vertebrate faunas indicate a further significant cool warm oscillation before the onset of major frost shattering attributed to the devensian cold stage

uranium series age estimates and paleoclimatic significance of pleistocene tufas from the lahontan basin california and nevada abstract an extended chronology of lahontan basin lake levels based on uranium series age estimates correlates with the global ice volume record lake highstands occur at or shortly after times of maximum ice sheet size moderate size lakes occur when the global ice volume is about 80 of its maximum the data indicate that lake levels rise and fall relative to the proximity of the mean position of the jetstream when the continental ice sheet is above some threshold size or shape it appears that the large scale circulation and climatic conditions are right for producing lakes of moderate to large size within the lahontan basin

alteration of detrital fe ti oxides in sedimentary rocks scanning electron microscope study has revealed that in proterozoic sandstones shales and carbonate rocks of the visingso group in southern sweden detrital fe ti oxides have undergone alteration by dissolution and or replacement mainly by titanium oxides hematite reddish rocks or pyrite greenish sandstones shales and carbonate rocks the titanium oxides occur as either poorly crystalline masses cryptocrystalline aggregates or discrete euhedral crystals of anatase brookite and rutile that attain a variety of crystal habits microprobe analyses have shown that the alteration of ilmenite occurs through several intermediate phases each successively enriched in titanium and depleted in iron to an almost pure form of tio 2 some of the iron and titanium which is released during alteration of the fe ti oxides is incorporated in associated clay minerals

northwest european palaeoclimate as indicated by growth frequency variations of secondary calcite deposits a compilationn for the northwest of europe of over 500 uranium series speleothen and travertine dates is presented using a cumulative distributed error frequency approach these secondary carbonate deposits require both significant groundwater supply and a biogenic soil carbon dioxide source for their growth during glacial periods soil co2 production is inhibited and the water supply is ice locked therefore growth is slowed significantly if not stopped thus deposits can be used on a chronological basis to give a signal of glacial and non glacial periods however sensitivity to the groundwater supply modifies this signal with growth also limited in times of high aridity the palaeoclimatic signal is thus complex the compilation presented is used both as a chronology for comparison with the orbitally tuned marine oxygen isotope record and as a palaeoclimatic indicator attention is focused on two periods of the last glacial interglacial cycle where the record provides a significantly different palaeoclimatic record to other terrestrial and oceanic records these are the isotope stages 5 4 transition for which a relatively low cumulative growth frequency indicates an earlier increase in aridity than observed elsewhere and isotope stage 3 the pleniglacial where both statistically significant high 49 62 ka and low 22 35 44 46 ka levels of growth are observed and can be used to constrain the timing of many of the interstadial events within this period

ipswichian fauna of victoria cave and the marine palaeoclimatic record the lack of age dating methods which can be applied beyond the limit of radiocarbon dating makes the global correlation of continental climatic events and stratigraphic sequences with the continuous palaeoclimate record obtained by isotopic and faunal analysis of deep sea sediment cores1 3 a difficult task often only a relative time scale can be obtained using complex and perhaps tenuous litho and biostratigraphical data speleothems may assist in this correlation for embodied in their calcium carbonate structures are elemental and isotopic variations which indicate both their age and climatic conditions prevailing during their deposition speleothems may be reliably dated by the 230th 234u method to an age of 350 kyr bp providing they consist of non porous unrecrystallized calcite which is essentially free of clastic detrital sediments4 6 they may also provide palaeoclimatic information for previously glaciated areas 1 because their presence indicates that groundwater movement was not prevented by ice formation at the surface and co2 was produced in the soil zone by root respiration and plant decay limestone bedrock may then be dissolved and reprecipitated as speleothems in caves below the surface and 2 because of the variations in stable isotopic content and fluid inclusion waters contained therein4 7 8 additional climatic and chronological information may be obtained where speleothems are interstratified with deposits characteristic of a particular climatic regime and with deposits containing organic remains we describe here the results of dating speleothems encrusting the remains of mammals from victoria cave in northern england and discuss their significance in terms of the correlation between continental and oceanic palaeoclimatic records

a formal mammalian biostratigraphy for the late pleistocene of britain abstract a series of distinctive mammalian assemblages spanning much of the british late pleistocene is defined on the basis of type localities and a formal biozonation proposed the joint mitnor cave mammal assemblage zone includes the famous hippopotamus fauna of the early part of the last interglacial complex oxygen isotope substage 5e this is succeeded by the bacon hole mammal assemblage zone in which hippopotamus is no longer present and species like mammoth roe deer and northern vole re enter the british region this assemblage zone appears to represent the later substages of ois 5 a faunal grouping dominated by bison and reindeer is named the banwell bone cave mammal assemblage zone and is believed to correlate closely with the early devensian ois 4 the pin hole mammal assemblage zone includes the familiar mammoth steppe faunas of the middle devensian ois 3 dominated by horse woolly rhinoceros and mammoth the lateglacial interstadial is characterized by the gough s cave mammal assemblage zone in which horse red deer and humans are well represented part of ois 2 no definitive evidence for human activity can be found for a period spanning the last interglacial complex ois 5 and the early devensian ois 4 human populations return to britain with the pin hole mammal assemblage zone fauna during the middle devensian ois 3 and reappear after the dimlington stadial during the late devensian ois 2 but in a different faunal association

mass spectrometric dating of flowstones from stump cross caverns and lancaster hole yorkshire palaeoclimate implications a terrestrial flowstone sequence 97 cm thick from stump cross caverns yorkshire has been dated by both mass spectrometric and alpha spectrometric 238u 234u 230th dating and is demonstrated to have been deposited predominantly during interstadial periods over the last 170 ka with no growth in periods of glaciation or within the oxygen isotope stage 5 interglacial growth also occurs within oxygen isotope stages 4 and 6 the former possibly correlating with interstadials recognised in high resolution ice and ocean core records comparison with the timing of growth of a mass spectrometrically dated lancaster hole flowstone also from the same region demonstrates only limited agreement these differences are due to two factors limiting deposition at stump cross flooding of the cave passage in warm periods and the development of continuous permafrost or glacier cover in periods of severe climatic deterioration deposition at lancaster hole was controlled by limitations in ground water supply rather than flooding of the cave passage the results presented here demonstrate that in addition to regional palaeoclimate factors local site conditions may limit speleothem growth we conclude that in future palaeoclimate studies the growth record from several coeval speleothem samples must be considered before a regional palaeoclimate interpretation can be made

uranium series chronology and environmental applications of speleothems an increasing number of scientists recognize the value of speleothems1 as often extremely well preserved archives of information about past climate vegetation hydrology sea level nuclide migration water rock interaction landscape evolution tectonics and human action well constrained data are required to document past changes reconstruct past patterns and predict future responses of the earth system at a wide range of spatial and temporal scales speleothems are particularly useful in this regard because they can be found in many locations of the globe sampled at high resolution and reliably dated using high precision uranium series techniques speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave most speleothems are composed of calcite formed by slow degassing of co2 from supersaturated groundwater but aragonite and gypsum forms are also common particularly near cave entrances where evaporative effects are important a host of different speleothem types decorate the walls ceilings and floors of caves and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions temperature chemistry light in the air or water filled void subaerial forms include the familiar stalagmites stalactites draperies flowstones subaqueous forms include rimstone pools rafts mammillary calcite wall coatings and dog tooth spar for an extensive review of the types of speleothem that have been observed see hill and forti 1997 speleothems are used in a multitude of ways to explore past environmental conditions perhaps the most fundamental of which is their very presence or absence deposition of speleothems relies on sufficient water supply and soil co2 to enable dissolution and transport of reactants in the vadose zone to underlying caves in arid or glacial times conditions may not have been favorable for speleothem formation

uranium series dates from the windy pits of the north york moors united kingdom implications for late quaternary ice cover and timing of speleogenesis windy pits are open fissures within the corallian strata of the north york moors here we present nine thermal ionization mass spectrometry tims u th dates on speleothem from the windy pits the first radiometric dates on calcite for these features and for this region the dates cluster within three time periods the interglacial peaks of marine isotope stage mis 7 208 to 190 ka mis 5 127 ka to 109 ka and the holocene correlating with the marine isotope record and with the broad pattern of interglacial calcite deposition observed for northern england however of the two high resolution studies available for comparison the windy pit dates match only the lancaster hole dates the location of the windy pits outside of the devensian ice limits within the ice free but periglaciated region suggests that the region has remained ice free since some time before mis 7 the prevalence of widespread and prolonged permafrost conditions suggests a plausible mechanism for these open rift caves in slope side periglacial mass movement copyright 2008 john wiley sons ltd

the source and fate of massive carbon input during the latest paleocene thermal maximum lithologic faunal seismic and isotopic evidence from the blake nose subtropical western north atlantic links a massive release of biogenic methane 55 5 million years ago to a warming of deep ocean and high latitude surface waters a large perturbation in the combined ocean atmosphere carbon cycle the largest of the past 90 million years a mass extinction event in benthic faunas and a radiation of mammalian orders the deposition of a mud clast interval and seismic evidence for slope disturbance are associated with intermediate water warming massive carbon input to the global exogenic carbon cycle pelagic carbonate dissolution a decrease in dissolved oxygen and a benthic foraminiferal extinction event these events provide evidence to confirm the gas hydrate dissociation hypothesis and identify the blake nose as a site of methane release

absolute dating by uranium series disequilibrium of bones from the cave of la chaise de vouthon charente france animal bones associated with palaeolithic artefacts and skeletal remains of early hominids from the cave of la chaise de vouthon have been dated using a new approach to uranium series dating of bone speleothem cave calcite interstratified with bone bearing sediments in the two chambers of grotte bourgeois delaunay and grotte suard have previously been dated by the 230th 234 u method this provides a chronological control for the bone ages for which the method is still at an experimental stage a good agreement is shown in most cases between the calcite and the bone ages showing the cave to have been a stable environment for the deposition of bone and the acquisition of uranium

wolverine in northern england at about 83 000 yr b p faunal evidence for climatic change during isotope stage 5 abstract cave sediments from stump cross cave in northern england contain pleistocene mammal remains uranium series dating of calcium carbonate deposits closely associated with the fossiliferous horizons has established an absolute age of 83 000 6000 yr b p for a faunal assemblage largely comprised of wolverines gulo gulo this date lies firmly within the younger portion of oxygen isotope stage 5 the occurrence of wolverines in the vicinity of stump cross cave at ca 83 000 yr b p indicates a significant climatic deterioration from ca 120 000 yr b p when an ipswichian interglacial fauna with hippopotamus was present in this part of northern england

surface exposure dating 36cl and 10be of post last glacial maximum valley moraines lake district northwest england some issues and implications surface exposure ages 36cl and 10be have been obtained from 16 boulders at the margins of and within the limits of former valley glaciers at four sites in the lake district northwest england the established view is that the lake district functioned as an independent centre of ice dispersal during the last glacial maximum lgm 26 21 ka of the dimlington stade greenland stades 2 3 and that the glacial depositional landforms at the sampled sites are products of stillstands or readvances of the ice margins following the lgm however several of the apparent 36cl surface exposure ages pre date rather than post date the lgm it is inferred that these boulders retain levels of 36cl inherited from a previous period of exposure rather than indicating moraine formation prior to the lgm and their subsequent survival beneath lgm ice an implication is that lake district glaciers achieved limited erosion of bedrock during the build up to and at the maximum of the lgm and that glacial erosion rates increased at a late stage in that period single 36cl and 10be exposure ages from two sites suggest a stillstand or readvance of valley glaciers prior to the loch lomond younger dryas stade lls greenland stade 1 and windermere lateglacial interstade greenland interstade 1 but additional ages are required in order to confirm or refute these individual ages an lls age for glacial depositional landforms at both these sites had previously been proposed 36cl surface exposure ages for boulders on moraines within the lls limit do not fully support emplacement at that time there is a possibility that these moraines are associated with a pre lls stillstand or readvance of the valley glacier copyright 2013 john wiley sons ltd

palaeoclimate determination from cave calcite deposits calcite deposits formed in limestone caves have been found to be an excellent repository of palaeoclimatic data for terrestrial environments the very presence of a relict deposit indicates non glacial conditions at the time of formation and both 14c and uranium series methods can be used to date the deposit and hence the age of these climatic conditions variations in 13c and 18o content of the calcite in 2h and 18o content of fluid inclusions in trace element concentrations and more recently in pollen assemblages trapped in the calcite are all potentially available as synchronous palaeoclimatic indicators previous work has tended to concentrate mainly on abundance of deposits as a palaeoclimatic indicator for the last 300 000 years this literature is briefly reviewed here together with the theory and methods of analysis of the u series and stable isotopic techniques the combined use of u series ages and 13c and 18o variations in cave calcites illustrates the potential for palaeoclimate determination previously unpublished results of stable isotopic variations in dated calcites from caves in northern england indicate the level of detail of stable isotopic variations and time resolution that can be obtained and the complexity of interpretation that may arise tentative palaeoclimatic signals for the periods 90 125 ka and 170 300 ka are presented more comprehensive studies are needed in future work especially in view of the difficulty in obtaining suitable deposits and the ethics of cave deposits conservation

successful application of uranium series dating of fossil bone abstract a novel approach to uranium series disequilibrium dating is presented and used successfully to date bones from several european archaeological and palaeontological sites a method is described based on a proposed mechanism of uranium uptake and fixation derived from present understanding of the biochemistry of fossilizing bones and the geochemistry of uranium stability of uranium in fossil bone is predicted under particular conditions of local depositional environment and the importance of the inhomogeneous distribution of uranium through bone to uranium series dating is explained sample bones from several different sites have been examined taking into account the three factors of uptake mechanism uranium distribution and sedimentary environment and have yielded ages in good agreement with those derived by alternative dating methods or from chronologically fixed stratigraphical positions

archean cherts derived from chemical biogenic and clastic sedimentation in a shallow restricted basin examples from the gorge creek group in the pilbara block the 3ae0 ga chert sequence of the gorge creek group is exposed at ord ranges about 50 km east of port hedland in the pilbara block the chert sequence examined in this study is 15 m thick and consists of oxide rich laminated chert grey chert silicified clastic rock carbonaceous black chert and carbonate rich laminated chert although the cherts have undergone postdepositional silica enrichment such as cementation and metasomatic silicification primary precipitation of silica at the site of deposition is indicated by abundant microstructures mosaic and spherulitic structures other primary to early diagenetic components were carbonates sulphates gypsum and anhydrite and organic matter although these mineral associations on the whole correspond to those of modern marine evaporites they are different from modern equivalents with respect to abundant precipitation of amorphous silica and presumed primary precipitation of iron carbonate siderite this feature is a possible manifestation of peculiar physicochemical conditions in the water mass from which the chemical sediments were precipitated compared with modern ocean waters the concentrations of fe and si were significantly higher and the ph value might have been lower these conditions could be obtained by contributions of fe and si enriched hydrothermal solutions and continental run off to the site of deposition grey cherts contain detrital quartz and altered fe ti oxides and were formed in a period of input of terrigenous detrital materials they are characterized by higher concentrations of tio2 a l 2 o 3 cr ni zn rb and zr compared with the other types of chert and by very low 4 al2o3 tio2 values these features are attributed to the supply of terrigenous detrital materials that contain abundant fe ti oxides ilmenite and titanomagnetite and fine tio2 particles such detrital materials might have been formed by extensive chemical alteration of source rocks and residual enrichment of ti relative to al