biogenic silica record of the lake baikal response to climatic forcing during the brunhes abstract this work presents a detailed orbitally tuned biogenic silica record of continental paleoclimate change during the brunhes chron the brunhes matuyama boundary lies within the warm isotopic stage 19 in baikal and the boundaries between eight lithological cycles correspond to terminations in the marine oxygen isotope record the high amplitude and resolution of climatically driven changes in biosi content in lake baikal sediments permits tuning of almost every precessional cycle during the brunhes and reveals the structure of interglacial stages for example the last three interglacial stages mis 5 7 and 9 clearly consist of five substages a b c d e corresponding to precessional insolation peaks abrupt and intense regional glaciations in siberia during substages 5d and 7d were driven by extreme insolation minima during substage 9d cooling was more gradual in response to more moderate forcing the impact of strong glaciation is also observed in the middle of stage 15 where full glacial conditions appear to have lasted for over 30 000 yr during substages 15d 15c and 15b marine oxygen isotopic stage 11 appears to be the warmest period during the brunhes in the lake baikal record with at least three substages a new hypothesis is presented regarding the response of the lake baikal biosi record to insolation forcing based on the mechanism controlling modern diatom blooms biogenic silica production is hypothesized to be dependent on changes in the heat balance of the lake and consequently on changes in the thermal structure of the water column this mechanism is also sensitive to short term sub milankovich cooling events such as the mid eemian cooling the montaigu event during substage 5c and a cooling which appears to be analogous to the montaigu event during substage 9c the continuity of the lake baikal paleoclimate record its sensitivity to orbital forcing and its high resolution make it an excellent candidate for a new paleoclimatic stratotype section for continental asia

infrared spectroscopic taxonomy for carbonaceous chondrites from speciation of hydrous components mid infrared absorption spectra for all types of carbonaceous chondrites were obtained in this study to establish a versatile method for spectroscopic classification of carbonaceous chondrites infrared spectra were measured using a conventional kbr pellet method and diamond press method spectra of hydrous carbonaceous chondrites exhibit intense o h stretching vibrations ci chondrites are identifiable by a characteristic sharp absorption band appearing at 3685 cm 1 which is mainly attributable to serpentine x ray diffraction analysis showed the presence of serpentine however yamato y 82162 c1 does not have the band at 3685 cm 1 because of its thermal metamorphism cm and cr chondrites have an intense absorption band at approximately 3600 cm 1 this absorption tends to appear in cm chondrites more strongly than cr chondrites because the intensity ratios of an oh stretching mode at 3520 cm 1 compared to 3400 cm 1 for cm chondrites are in the range of 0 95 1 04 which is systematically higher than those of cr chondrites 0 86 0 88 therefore the two types of chondrites are distinguishable by their respective infrared spectra the spectrum feature of the tagish lake meteorite is attributable to neither ci nor cm chondrites co chondrites are characterized by weak and broad absorption at 3400 cm 1 cv chondrites have weak or negligible absorption of water ck chondrites also have no water induced absorption ch and cb chondrites have a sharp absorption at 3692 cm 1 indicating the presence of chrysotile which is also supported by observations of x ray diffraction and tem the combination of spectroscopic classification and the diamond press method allows classification of carbonaceous chondrites of very valuable samples with small quantities as one example carbonaceous chondrite clasts in brecciated meteorites were classified using our technique infrared spectra for a fragment of carbonaceous clasts 1 g separated from willard b and tsukuba were measured the 3685 cm 1 band found in ci chondrites was clearly detected in the clasts indicating that they are ci like clasts

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

a reappraisal of the metamorphic history of eh3 and el3 enstatite chondrites abstract the thermal history of a series of eh3 and el3 chondrites has been investigated by studying the degree of structural order of the organic matter om located and characterized in matrix areas by raman micro spectroscopy by comparison with unequilibrated ordinary chondrites uocs and co and cv carbonaceous chondrites the following petrologic types have been assigned to various e chondrites sahara 97096 and allan hills 84206 3 1 3 4 allan hills 85170 and parsa 3 5 allan hills 85119 3 7 qingzhen macalpine hills 88136 and macalpine hills 88184 3 6 3 7 the petrologic type of qingzhen is consistent with the abundance of the p3 noble gas component a sensitive tracer of the grade of thermal metamorphism the petrologic types are qualitatively consistent with the abundance of fine grained matrix for the whole series no significant effects of shock processes on the structure of om were observed however such processes certainly compete with thermal metamorphism and the possibility of an effect cannot be fully discarded in particular in the less metamorphosed objects the om precursors accreted by the eh3 and el3 parent bodies appear to be fairly similar to those of uocs and co and cv carbonaceous chondrites raman data however show some slight structural differences that could be partly accounted for by shock processes the metamorphic history of eh3 and el3 chondrites has often been described as complex in particular regarding the combined action of shock and thermal metamorphism because om maturity is mostly controlled by the temperature of peak metamorphism it is possible to distinguish between the contributions of long duration thermal processes and that of shock processes comparison of the petrologic types with the closure temperatures previously derived from opaque mineral assemblages has revealed that the thermal history of eh3 and el3 chondrites is consistent with a simple asteroidal onion shell model thermal metamorphism in enstatite chondrites appears to be fairly similar to that which takes place in other chondrite classes the complex features recorded by mineralogy and petrology and widely reported in the literature appear to be mostly controlled by shock processes

new evidence for complex climate change in mis 11 from hoxne suffolk uk the climatic signal of marine isotope stage mis 11 is well documented in marine and ice sheet isotopic records and is known to comprise at least two major warm episodes with an intervening cool phase terrestrial records of mis 11 though of high resolution are often fragmentary and their chronology is poorly constrained however some notable exceptions include sequences from the maar lakes in france and tenaghi philippon in greece in the uk the hoxnian interglacial has been considered to correlate with mis 11 new investigations at hoxne suffolk provide an opportunity to re evaluate the terrestrial record of mis 11 at hoxne the type hoxnian interglacial sediments are overlain by a post hoxnian cold temperate sequence the interglacial sediments and the later temperate phase are separated by the so called arctic bed from which cold climate macroscopic plant and beetle remains have been recovered the later temperate phase was deposited during an episode of boreal woodland and is associated with the artefacts a diverse vertebrate fauna and molluscs new amino acid geochronological data and biostratigraphical considerations suggest that the post hoxnian sequence correlates with late substages of mis 11 the paper further investigates the correlation of the sequence at hoxne with the palynological sequences found elsewhere in europe and adjacent offshore areas

evolution of the raman spectrum of carbonaceous material in low grade metasediments of the glarus alps switzerland terra nova 22 354 360 2010 abstract the raman spectrum of carbonaceous material cm from advanced diagenesis 200 c to low grade metamorphism 320 c is documented in the helvetic flysch of the glarus alps switzerland the spectrum is complex with several defect bands at 1200 d4 1350 d1 1500 d3 and 1620 d2 cm 1 we document the evolution of these bands relative to the graphite g band with increasing metamorphic grade and we show that this qualitative evolution may be used as a proxy for temperature in the glarus alps we develop a robust peak fitting method and propose quantitative parameters that may be used as proxies for thermal metamorphism in this region further work in other geological contexts is needed to assess whether the spectral evolution observed in the glarus alps may be generalized and to critically assess the potential for calibrating a general empirical and quantitative thermometer based on the raman spectrum of cm in low grade rocks

extending the applicability of the raman carbonaceous material geothermometer using data from contact metamorphic rocks the degree of graphitization of carbonaceous material cm has been widely used as an indicator of metamorphic grade previous work has demonstrated that peak metamorphic temperature t o f regional metamorphic rocks can be estimated by an area ratio r2 of peaks recognized in raman spectra of cm the applicability of this method to low pressure 50 that adequately reflects the range of sample heterogeneity using this procedure with 532 nm laser and adapting our new calibration the errors of the raman cm geothermometer for contact metamorphic rocks decrease to 30 c

raman spectra of carbonaceous material in metasediments a new geothermometer metasedimentary rocks generally contain carbonaceous material cm deriving from the evolution of organic matter originally present in the host sedimentary rock during metamorphic processes this organic matter is progressively transformed into graphite s s and the degree of organisation of cm is known as a reliable indicator of metamorphic grade in this study the degree of organisation of cm was systematically characterised by raman microspectroscopy across several mesozoic and cenozoic reference metamorphic belts this degree of organisation including within sample heterogeneity was quantified by the relative area of the defect band r2 ratio the results from the schistes lustres western alps and sanbagawa japan cross sections show that 1 even through simple visual inspection changes in the cm raman spectrum appear sensitive to variations of metamorphic grade 2 there is an excellent agreement between the r2 values calculated for the two sections when considering samples with an equivalent metamorphic grade and 3 the evolution of the r2 ratio with metamorphic grade is controlled by temperature t along the tinos cross section greece which is characterised by a strong gradient of greenschist facies overprint on eclogite facies rocks the r2 ratio is nearly constant consequently the degree of organisation of cm is not affected by the retrogression and records peak metamorphic conditions more generally analysis of 54 samples representative of high temperature low pressure to high pressure low temperature metamorphic gradients shows that there is a linear correlation between the r2 ratio and the peak temperature t c 445 r2 641 whatever the metamorphic gradient and probably the organic precursor the raman spectrum of cm can therefore be used as a geothermometer of the maximum temperature conditions reached during regional metamorphism temperature can be estimated to 50 c in the range 330 650 c a few technical indications are given for optimal application

organic matter and metamorphic history of co chondrites abstract the metamorphic grades of a series of eight co3 chondrites alha77307 colony kainsaz felix lance ornans warrenton and isna have been quantified the method used was based on the structural grade of the organic matter trapped in the matrix which is irreversibly transformed by thermal metamorphism the maturation of the organic matter is independent with respect to the mineralogical context and aqueous alteration this metamorphic tracer is thus valid whatever the chemical class of chondrites moreover it is sensitive to the peak metamorphic temperature the structural grade of the organic matter was used along with other metamorphic tracers such as petrography of opaque minerals fa and fs silicate composition in type i chondrules presolar grains and noble gas p3 component abundance the deduced metamorphic hierarchy and the attributed petrographic types are the following alha77307 3 03 for most metamorphosed objects the peak metamorphic temperature can be estimated using a geothermometer calibrated with terrestrial metasediments beyssac o goffe b chopin c and rouzaud j n 2002 raman spectrum of carbonaceous material in metasediments a new geothermometer j metamorph geol 20 859 871 a value of 330 c was obtained for allende cv chondrite warrenton and isna consistent with temperatures estimated from fe diffusion weinbruch s armstrong j and palme h 1994 constraints on the thermal history of the allende parent body as derive from olivine spinel thermometry and fe mg interdiffusion in olivine geochim cosmochim acta 58 2 1019 1030 from the ni content in sulfide metal assemblages zanda b bourot denise m and hewins r 1995 condensate sulfide and its metamorphic transformations in primitive chondrites meteorit planet sci 30 a605 and from the d002 interlayer spacing in poorly graphitized carbon rietmeijer f and mackinnon i 1985 poorly graphitized carbon as a new cosmothermometer for primitive extraterrestrial materials nature 315 733 736 the trapped noble gas and c content appear to be sensitive but not precise metamorphic tracers indicating that the ornans paradox does not exist major problems with the current petrologic types derived from induced thermoluminescence are pointed out

riparian landscapes and human habitat preferences during the hoxnian mis 11 interglacial the archaeological environmental and geological data from hoxnian interglacial marine isotope stage mis 11 sites from britain are examined to elucidate the type of habitats that humans preferred during this temperate episode the conclusion is that humans avoided lacustrine situations but did make use of the full range of resources that fluvial environments provide this model is strengthened by the examination of other non archaeological hoxnian sites the problem of archaeological visibility in lacustrine sediment sequences is also discussed and methods of identifying other evidence of human presence are suggested that may offset the deficiencies in the lithic record these include presence of cut marked bone micro debitage and possibly charcoal in fine grained sediments deposited in distal settings the reasons for human selection of fluvial situations are discussed it is concluded that these environments provide a greater diversity of animal plant and lithic resources but also are major route ways through the landscape patterns of human site use are identified which seem to be triggered by local changes in hydrology and drainage themselves possibly caused by regional changes in climate finally lower palaeolithic sites on the interfluves are discussed although they lack environmental or dating evidence it is tentatively suggested that they were used during cooler episodes when more open conditions prevailed copyright 2006 john wiley sons ltd

presolar diamond sic and graphite in primitive chondrites abundances as a function of meteorite class and petrologic type abstract acid resistant residues were prepared for eighteen meteorites from seven chondrite classes using improved procedures designed to minimize loss of presolar grains noble gases were measured by stepped pyrolysis and the abundances of five exotic noble gas components were used to determine abundances of diamond sic and graphite diamond separates were prepared to check diamond abundances determined from noble gases diamond and sic were found in unmetamorphosed members of all seven chondrite classes and evidence for graphite was found in orgued ci and ll3 0 3 1 chondrites our data and noble gas and stable isotope data in the literature show that presolar grains were incorporated into all chondrite classes the grains are sited in the fine grained matrix and their abundances within the matrix reflect mainly the degree of metamorphism suffered by the host meteorite the pattern of metamorphic destruction differs from class to class in unequilibrated ordinary chondrites uocs graphite is most easily destroyed followed by sic and then diamond no presolar grains remain in uocs of petrologic type 3 8 whose matrices have been completely recrystallized in eh chondrites diamond and sic survive much more severe metamorphism than in uocs with sic apparently more stable than diamond presolar graphite was not detected in cv3 and c03 chondrites diamond appears to be more stable than sic and graphite again is missing inferred premetamorphic diamond abundances matrix normalized vary by a factor of 2 2 between classes with eh cv and co chondrites having higher initial abundances than orgueil similar diamond sic ratios are observed in most classes and differences in the ratio can be tied to secondary processing suggesting that all chondrite classes sampled the same solar system wide reservoir of presolar grains differences in initial abundances between classes appear to correlate with chemical and physical properties of the host meteorites these bulk properties and variations in presolar grain abundances both may be the result of thermal processing of presolar dust in the accretion disk

new kind of type 3 chondrite with a graphite magnetite matrix abstract we have discovered four clasts in three ordinary chondrite regolith breccias which are a new kind of type 3 chondrite like ordinary and carbonaceous type 3 chondrites they have distinct chondrules some of which contain glass highly heterogeneous olivines and pyroxenes and predominantly monoclinic low ca pyroxenes but instead of the usual fine grained fe rich silicate matrix the clasts have a matrix composed largely of aggregates of micron and submicron sized graphite and magnetite the bulk compositions of the clasts as well as the types of chondrules largely porphyritic are typical of type 3 ordinary chondrites although chondrules in the clasts are somewhat smaller 0 1 0 5 mm a close relationship with ordinary chondrites is also indicated by the presence of similar graphite magnetite aggregates in seven type 3 ordinary chondrites this new kind of chondrite is probably the source of the abundant graphite magnetite inclusions in ordinary chondrite regolith breccias and may be more common than indicated by the absence of whole meteorites made of chondrules and graphite magnetite

the precambrian terranes of yemen and their correlation with those of saudi arabia and somalia implications for the accretion of gondwana

nanosims isotopic investigation of xenolithic carbonaceous clasts from the kapoeta howardite abstract we report on the investigation of presolar grains and organic matter om in 14 xenolithic carbonaceous clasts c clasts identified in the kapoeta howardite based on high resolution nanosims hydrogen carbon nitrogen and oxygen isotopic imaging data the 14 c clasts are 50 200 m in size and consist of one cm like and 13 ci like clasts which are classified based on their mineralogies the clasts from this study are likely sourced from an ice bearing parent body either an icy asteroid or a comet originating from the outer solar system according to the following mineralogical observations 1 in two ci like clasts embayments of magnetite grains between the c clast and the host howardite point to aqueous alteration occurring on vesta as a result of melting the ice embedded in the c clasts 2 all of the c clasts especially the 13 ci like clasts likely originated from the same parent body because i the 14 c clasts are clustered in the thin section and ii the clasts show a much higher ratio of ci like to cm like clasts with respect to those reported in the literature four presolar silicon carbide sic and two presolar silicate grains were identified in the c clasts in addition all the c clasts contain moderate bulk d and 15n enrichments with the presence of sub micron to micron sized d and 15n hotspots indicating the presence of primitive organic material comparison of the abundances and isotopic compositions of presolar grains and om in these c clasts with literature data for different samples of primitive extraterrestrial material provides support for 1 the genetic linkage of xenolithic c clasts to highly aqueously altered but minimally heated carbonaceous chondritic materials and 2 a homogeneous distribution of circumstellar and interstellar materials in the protoplanetary disk the low amounts of heat experienced by the c clasts suggest that they arrived at vesta and or vestoids at low speeds after the late heavy bombardment in the inner solar system 3 5 4 0 gyr ago

cold climate during the closest stage 11 analog to recent millennia abstract the early part of marine isotopic stage 11 near 400 000 years ago provides the closest analog to holocene insolation levels of any interglaciation during the era of strong 100 000 year climatic cycles the ch 4 concentration measured in vostok ice fell to 450 ppb and co 2 values to 250 ppm these natural decreases contrast with the increases in recent millennia and support the early anthropogenic hypothesis of major gas emissions from late holocene farming during the same interval d values fell from typical interglacial to nearly glacial values indicating a major cooling in antarctica early in stage 11 other evidence suggests that new ice was accumulating during the closest insolation analog to the present day a major increase in 18 o atm at vostok a similar increase in marine 18 o values and re initiation of ice rafting in the nordic sea the evidence permits extended 20 000 year intervals of stage 11 interglacial warmth in the antarctic and north atlantic yet it also requires that this warmth ended and a new glacial era began when insolation was most similar to recent millennia the holocene co 2 anomaly was produced only in part by direct anthropogenic emissions over half of the anomaly resulted from the failure of co 2 values to fall as they had during previous interglaciations because of natural responses including a sea ice advance in the antarctic and ice sheet growth in the northern hemisphere

graphitization in a high pressure low temperature metamorphic gradient a raman microspectroscopy and hrtem study the graphitization of carbonaceous material cm in a high pressure metamorphic gradient is characterized along a cross section in the schistes lustres formation western alps along this 25 km cross section both the cm precursor and the host rock lithology are homogeneous and the prograde evolution of the pressure temperature metamorphic conditions from the lower blueschist facies 13 kbar 330 c to the eclogite facies 20 kbar 500 c is tightly constrained by literature data raman microspectroscopy shows that at the micrometre scale this process is progressive and continuous with increasing metamorphic grade and that the structure of cm is very sensitive to temperature variations at the nanometre scale hrtem the cm is composed of a mixture of a microporous phase and an onion ring like phase both known as non graphitizing under the effect of temperature at ambient pressure the hp lt graphitization produces structurally and microtexturally heterogeneous cm with increasing metamorphic grade the graphitization of the two types of cm proceeds up to the triperiodic graphite stage because of microtextural and structural changes that are specific to each type of cm the microporous material is progressively transformed into graphite through a macroporous transitional stage in this case graphitization mainly occurs on the pore walls as a result of pore growth in the case of concentric onion ring like material graphitization occurs in the regions with the largest radius of curvature i e on the outer part of the ring in comparison with 1 bar experiments pressure seems to induce microtextural changes which allows the subsequent structural modifications of the starting material

an integrated geophysical study for inferring the subsurface setting of water bearing aquifers case study at wadi al dawasir area saudi arabia wadi al dawasir area is very important province in saudi arabia it contains the main water aquifer that stores a proven groundwater reserve wajid aquifer this study aims to investigate the subsurface features of this aquifer thickness depth to basement and the structural elements using an integrated gravity 2d profiles and aeromagnetic data interpretation rtp low pass and high pass maps gravity data are measured in the field using cg 5 autograv while magnetic data are taken from a survey made by saudi geological survey the interpretation of aeromagnetic data revealed presence of interesting structural elements trending toward n s nne ssw wnw and nnw sse directions positive magnetic anomalies are found indicating the presence of anticlinal blocks and strike slip fault patterns these structural elements are associated with the prevailing najd fault and the transform fault systems gravity data showed that the depth to basement vary from 600 to 1150 m giving rise to local basins with a considerable range of aquifer thicknesses 250 700 m finally a basement relief map is conducted based on an integrated interpretation of the magnetic gravity and seismic outputs it shows an increase in depth aquifer thickness from south to north the petrophysical analysis of the wajid formation assigns good aquifer properties in the upper section in terms of subsurface features determinations the concluded results top of basement thickness of aquifer and the prevailing structural elements are matched with the interpreted seismic section indicating a good compatibility of data

late middle pleistocene pollen biostratigraphy in britain pitfalls and possibilities in the separation of interglacial sequences abstract recent work on late middle pleistocene interglacials in britain has shown that sites formerly attributed to the hoxnian include representatives of two different interglacials which have been correlated with oxygen isotope stages 11 and 9 palynology has long been used to characterize and correlate temperate sequences in britain however the quality of the palynological record is considerably better in lacustrine sequences than in fluvial and estuarine sediments the former have longer sequences and higher resolution whereas more rapid deposition in fluvial and estuarine environments leads to sequences representing only fragments of interglacials the latter type of site however is more likely to have multi proxy evidence and to be readily fitted into a stratigraphical framework the problems are reviewed in the light of new work in the west midlands where some of the most complete british late middle pleistocene lacustrine sequences are preserved lacustrine sites here have a strong affinity with hoxnian sites of the type area in east anglia a critical question remains as to whether the two interglacials conflated under the term hoxnian can be separately characterized in terms of their pollen assemblages details of lacustrine sequences in the north birmingham area and east anglia show remarkable similarities perhaps suggesting that the same interglacial is recorded in all of them as many of these sites are thought to be kettle holes or glacially overdeepened basins the first interglacial following the anglian glaciation is the most likely to be represented suggesting that all the lacustrine hoxnian sites might date from ois 11 in areas not glaciated since the anglian interglacials after ois 11 are likely to be represented only by fragmentary non lacustrine sequences difficult if not impossible to separate using palynology alone

graphite magnetite aggregates in ordinary chondritic meteorites aggregates consisting largely of submicrometre graphite and magnetite crystals have been identified in 14 unequilibrated and regolith breccia ordinary chondrites like other primitive components they formed before the meteorites accreted chondrite clasts rich in graphite magnetite occur in three regolith breccias and are a new kind of unequilibrated ordinary chondrite they were probably the source of graphite magnetite aggregates in regolith breccias

deuterium enrichments in chondritic macromolecular material implications for the origin and evolution of organics water and asteroids here we report the elemental and isotopic compositions of the insoluble organic material iom isolated from several previously unanalyzed meteorites as well as the reanalyses of h isotopic compositions of some previously measured samples alexander et al 2007 the iom in ordinary chondrites ocs has very large d enrichments that increase with increasing metamorphism and decreasing h c the most extreme d value measured being almost 12 000 we propose that such large isotopic fractionations could be produced in the oc parent bodies through the loss of isotopically very light h2 generated when fe was oxidized by water at low temperatures 200 c we suggest that similar isotopic fractionations were not generated in the iom of cv and co chondrites with similar metamorphic grades and iom h c ratios because proportionately less water was consumed during metamorphism and the remaining water buffered the h isotopic composition of the iom even a h was being lost from it hydrogen would also have been generated during the alteration of ci cm and cr carbonaceous chondrites the iom in these meteorites exhibit a considerable range in isotopic compositions but all are enriched in d as well as 15n relative to terrestrial values we explore whether these enrichments could also have been produced by the loss of h2 but conclude that the most isotopically anomalous iom compositions in meteorites from these groups are probably closest to their primordial values the less isotopically anomalous iom has probably been modified by parent body processes the response of iom to these processes was complex and varied presumably reflecting differences in conditions within and between parent bodies the d enrichments associated with h2 generation along with exchange between d rich iom and water in the parent bodies means that it is unlikely that any chondrites retain the primordial h isotopic composition of the water ice that they accreted the h isotopic compositions of the most water rich chondrites the cms and cis are probably the least modified and their compositions d 25 suggest that their water did not form at large radial distances from the sun where ice is predicted to be very d rich yet models to explain the o isotopic composition of inner solar system bodies require that large amounts of ice were transported from the outer to the inner solar system

the origin and evolution of chondrites recorded in the elemental and isotopic compositions of their macromolecular organic matter extraterrestrial organic matter in meteorites potentially retains a unique record of synthesis and chemical thermal modification by parent body nebular and even presolar processes in a survey of the elemental and isotopic compositions of insoluble organic matter iom from 75 carbonaceous ordinary and enstatite chondrites we find dramatic variations within and between chondrite classes there is no evidence that these variations correlate with the time and or location of chondrite formation or with any primary petrologic or bulk compositional features that are associated with nebular processes e g chondrule and volatile trace element abundances nor is there evidence for the formation of the iom by fischer tropsch type synthesis in the nebula or in the parent bodies the elemental variations are consistent with thermal maturation and or oxidation of a common precursor for reasons that are unclear there are large variations in isotopic composition within and between chondrite classes that do not correlate in a simple way with elemental composition or petrologic type nevertheless because of the pattern of elemental variations with petrologic type and the lack of any correlation with the primary features of the chondrite classes at present the most likely explanation is that all iom compositional variations are the result of parent body processing of a common precursor if correct the range of isotopic compositions within and between chondrite classes implies that the iom is composed of several isotopically distinct components whose relative stability varied with parent body conditions the most primitive iom is found in the cr chondrites and bells cm2 isotopically the iom from these meteorites resembles the iom in interplanetary dust particles chemically their iom resembles the chon particles of comet halley despite the large isotopic anomalies in the iom from these meteorites it is uncertain whether the iom formed in the interstellar medium or the outer solar system although the former is preferred here

raman spectroscopic carbonaceous material thermometry of low grade metamorphic rocks calibration and application to tectonic exhumation in crete greece we present new raman spectra data of carbonaceous material cm to extend the range of the raman spectra of cm thermometer rscm to temperatures as low as 100 8c previous work has demonstrated that raman spectroscopy is an excellent tool to describe the degree of graphitization of cm a process that is independent of pressure but strongly dependent on metamorphic temperature a linear relationship between temperature and the raman parameter r2 derived from the area of the defect band relative to the ordered graphite band forms the basis of a previous thermometer because r2 shows little variability in low temperature samples 330 8c serves as a lower limit on the existing thermometer herein we present raman spectra from a suite of low temperature 100 to 300 8c samples from the olympics mountains and describe other aspects of the raman spectra of cm that vary over this range in particular the raman parameter r1 the ratio of heights of the disordered peak to ordered peak varies regularly between 100 and 350 8c these data together with published results from higher temperature rocks are used to calibrate a modified rscm thermometer applicable from 100 to 700 8c application to low grade metasediments in the otago region in the south island of new zealand gives temperatures consistent with previous estimates demonstrating the reliability of the modified rscm thermometer we apply the modified rscm thermometer to 53 samples from crete to evaluate the role of the cretan detachment fault in exhuming miocene high pressure low temperature metamorphic rocks exposed there the metamorphic rocks below the detachment the plattenkalk and phyllite quartzite units give metamorphic temperatures that range from 250 to 400 8c consistent with previous petrologic estimates we also demonstrate that the tripolitza unit which lies directly above the detachment gives an average metamorphic temperature of about 260 8c the modest break in metamorphic temperature in central crete indicates that the cretan detachment accounts for only 5 to 7 km of exhumation of the underlying hp lt metamorphic rocks which were initially accreted at 35 km we argue that the bulk of the exhumation 28 km out of 35 km total occurred by pervasive brittle stretching and erosion of structural units above the detachment d 2005 elsevier b v all rights reserved

the late middle pleistocene biostratigraphy of the thames valley england new data from eastern essex abstract coring investigations at east hyde near tillingham essex have revealed a sequence of fluvial and estuarine deposits infilling a channel incised into london clay these deposits are of thames origin and were deposited after the river s diversion into eastern essex late in the anglian stage the detailed litho and biostratigraphy of the deposits are described ostracod and molluscan data confirm that the lower parts of the sequence accumulated in a quiet fluvial environment rich in aquatic vegetation the upper sediments accumulated in an inner estuarine environment under conditions of rising sea level pollen assemblages from both units show strong biostratigraphical affinities with the hoxnian stage particularly with the hoxnian late temperate substage ho iii the sequence has also yielded a rare assemblage of freshwater fluvial molluscs the rhenish fauna which migrated into the thames following a link with the rivers of continental europe the occurrence of theodoxus serratiliniformis is exceptionally rare representing only the second record of the species in the entire british pleistocene the molluscan assemblages show striking similarities with those at clacton in northeast essex and swanscombe kent and provide strong evidence that the three sites are contemporaneous and were connected in the same fluvial system the timing of the migration of the rhenish fauna into britain and the implications for sea level reconstruction in the southern north sea region are discussed the episode of major climatic warmth and high eustatic sea level represented at east hyde is correlated with stage 11 of the deep sea record

characterization of carbonaceous matter in xenolithic clasts from the sharps h3 4 meteorite constraints on the origin and thermal processing abstract primitive xenolithic clasts often referred to as dark clasts are well known in many regolith breccias the sharps h3 4 ordinary chondrite contains unusually large dark clasts up to 1 cm across poorly graphitized carbon pgc with fe ni metal and described as carbon rich aggregates has been reported in these clasts brearley 1990 we report detailed analyses of carbonaceous matter in several identical sharps clasts using ftir raman c xanes and tem that provide insight on the extent of thermal processing and possible origin of such clasts we also prepared acid residues of the clasts using the hcl hf method and conducted mass spectrometric analysis of the entrained noble gases carbonaceous matter is often used to infer thermal history due to its sensitivity to thermal processes the ftir spectra of the acid residue from the sharps clast suggest that carbonaceous matter in the clast contains less hydrogen and oxygen compared to acid residues from typical type 3 4 ordinary chondrites the metamorphic temperatures obtained by raman spectroscopy ranges between 380 c and 490 c tem observations indicate that the clasts experienced a peak temperature of 300 c to 400 c based on the carbon d002 layer lattice spacing of c rich aggregates these estimates are consistent with an earlier estimate of 330 50 c that is also estimated by the d002 layer lattice spacing brearley 1990 it should be noted that the lattice spacing thermometer is based on terrestrial metamorphose rocks and thus temperature was probably underestimated meanwhile the c xanes spectra of the c rich aggregates show high exciton intensities indicative of graphene structures that developed at around 700 800 c following an extensive period of time millions of years however the surrounding matrix areas experienced lower temperatures of less than 300 500 c noble gas analysis of the acid residue from the sharps clasts shows that the residue is almost identical with some material reported in carbonaceous chondrites i e heavily enriched in the q gas component as well as hl gas from presolar diamonds and ne e h from presolar sic these results indicate that the c rich aggregates in the sharps clasts formed under relatively high temperature conditions up to 800 c and were subsequently mixed with lower temperature matrix probably in a different parent body before they were incorporated into the final sharps lithology by collision

precursor and metamorphic condition effects on raman spectra of poorly ordered carbonaceous matter in chondrites and coals abstract geothermometers based on raman spectrometry of carbonaceous matter and covering a wide range of temperatures 100 650 c have been developed over recent years while raman data have been largely interpreted in terms of temperature they are also the fingerprint of certain metamorphic conditions especially in the low temperature range relevant to poorly ordered carbonaceous matter this study investigates the raman spectra of two series of chondritic carbonaceous matter and coal samples formed from different precursors and under different metamorphic conditions the raman spectra of polyaromatic carbonaceous matter pcm from 42 chondrites and 27 coal samples measured with visible 514 nm and ultra violet 244 nm excitation wavelengths are analyzed the raman spectra of low rank coals and chondrites of petrologic types 1 and 2 which contain the more disordered pcm reflect the distinct carbon structures of their precursors the 514 nm raman spectra of high rank coals and chondrites of petrologic type 3 exhibit continuous and systematic spectral differences reflecting different carbon structures present during the metamorphism event they result from differences in the chemical structures of the precursors concerning for instance the reticulation of polyaromatic units or an abundance of ether functional groups or possibly from a lack of carbonization processes to efficiently expel oxygen heteroatoms due to weak lithostatic pressure and confinement these results suggest that the use of low temperature carbon thermometers should be restricted to a given geological context at the same time the sensitivity of raman spectra to precursors and certain metamorphic conditions could be used to obtain information other than temperature the analysis also provides evidence of the accretion of relatively homogeneous pcm precursors among ordinary co and cv carbonaceous chondrite parent bodies given that the 514 nm raman spectra of pcm efficiently trace the metamorphism grades looking closer however the 514 nm raman data are more scattered in chondrites than in coals and the maturity tracers are less sensitive and miscorrelate with the atomic h c ratio suggesting slight compositional and structural differences among the pcm precursors accreted

middle pleistocene interglacial thames medway deposits at clacton on sea england reconsideration of the biostratigraphical and environmental context of the type clactonian palaeolithic industry abstract in 1987 an archaeological investigation was undertaken during redevelopment of the erstwhile butlin s holiday camp at clacton on sea on the grounds that the middle pleistocene clacton channel deposits containing the type clactonian palaeolithic industry were known to extend beneath the site excavations for a storm drain allowed sampling at points along a longitudinal traverse of the main clacton channel analysis of these samples has provided new palaeontological information including data pertaining to the rise in relative sea level during the interglacial represented systematic studies of molluscs and ostracods the latter undertaken at clacton for the first time have been particularly valuable information from the butlin s site supplements evidence previously gathered from the west cliff section and from other localities at clacton the calcareous clay marl that underlies the clacton golf course extends beneath butlin s where it was found to be part of the freshwater beds not the estuarine beds as hitherto supposed the clacton estuarine beds restricted to the eastern end of the site have their base just below 2 m o d implying that their superposition upon the clacton freshwater beds occurred when relative sea level in this area was close to present ordnance datum correlation of the clacton channel deposits with the interglacial immediately following the anglian elsterian stage appears secure equivalence with oxygen isotope stage 11 of the oceanic sequence is most probable a borehole survey and subsequent excavation revealed a holocene sequence of unlithified tufa and organic sediments beneath part of the site

excavations at the lower palaeolithic site at east farm barnham suffolk 1989 92 preliminary results are presented from three seasons9 work at the lower palaeolithic site at barnham the complex stratigraphy is described and a provisional interpretation given which suggests that the archaeological deposits date to a warm phase after the anglian middle pleistocene cold stage a fauna1 assemblage from the deposits is described providing an environmental and biostratigraphic context for the site further geochronological control is provided by amino acid ratios on shells from the sequence two flint assemblages have been excavated the first consisting of flakes and cores and the second including bifaces these assemblages and their position in the british sequence are considered in terms of their stratigraphic context and their relationship to other lower palaeolithic assemblages in the british isles

differentiation of the british late middle pleistocene interglacials the evidence from mammalian biostratigraphy abstract acknowledgement of the climatic complexities of the marine oxygen isotope 18o record has inspired fresh investigations into methods of identifying and separating interglacial deposits on land biostratigraphical analysis of fossil mammalian assemblages particularly those from long fluvial sequences has proved to be a uniquely valuable technique in the differentiation of the various temperate episodes of the late middle pleistocene in britain thereby enabling a sequence of diagnostic mammalian assemblage zones to be established the scheme has provided an important means of correlation between geographically distant localities and between different types of depositional environment using mammalian biostratigraphical information this paper explores the evidence for three post anglian interglacials prior to the last ipswichian interglacial correlated with stages 11 9 and 7 of the oxygen isotope record and presents the case for the recognition of much smaller scale environmental and climatic oscillations within these interglacials possibly corresponding to marine isotopic substages

determination of the petrologic type of cv3 chondrites by raman spectroscopy of included organic matter abstract this paper reports the first reliable quantitative determination of the thermal metamorphism grade of a series of nine cv3 chondrites allende axtell bali mokoia grosnaja efremovka vigarano leoville and kaba the maturity of the organic matter in matrix determined by raman spectroscopy has been used as a powerful metamorphic tracer independent of the mineralogical context and extent of aqueous alteration this tracer has been used along with other metamorphic tracers such as fe zoning in type i chondrules of olivine phenocrysts presolar grain abundance and noble gas abundance bulk and p3 component the study shows that the petrologic types determined earlier by induced thermoluminescence were underestimated and suggests the following values pt allende axtell 3 6 pt bali mokoia grosnaja 3 6 pt efremovka leoville vigarano 3 1 3 4 pt kaba 3 1 the most commonly studied cv3 allende is also the most metamorphosed bali is a breccia containing clasts of different petrologic types the attribution suggested by this study is that of clasts of the highest petrologic types as pointed out by iom maturity and noble gas bulk abundance cv3 chondrites have complex asteroidal backgrounds with various degrees of aqueous alteration and or thermal metamorphism leading to complex mineralogical and petrologic patterns fe mg chemical zoning in olivine phenocrysts on the borders of type i chondrules of porphyritic olivine and pyroxene rich textural types has been found to correlate with the metamorphism grade this suggests that chemical zoning in some chondrules often interpreted as exchanges between chondrules and nebular gas may well have an asteroidal origin furthermore the compositional range of olivine matrix is controlled both by thermal metamorphism and aqueous alteration this does not support evidence of a nebular origin and does not necessarily mirror the metamorphism grade through fe mg equilibration on the other hand it may provide clues on the degree of aqueous alteration vs thermal metamorphism and on the timing of both processes in particular mokoia experienced significant aqueous alteration after the metamorphism peak whereas grosnaja which has similar metamorphism grade did not

evidence from coleopteran assemblages for a short but intense cold interlude during the latter part of the mis11 interglacial from quinton west midlands uk abstract a sequence of fossiliferous organic sediments spanning the whole of an interglacial has been investigated from quinton near birmingham united kingdom this interglacial can be correlated on palynological grounds with the hoxnian interglacial of england equivalent to the holsteinian interglacial of central europe and to marine isotope stage 11 a pollen diagram and coleopteran spectrum were obtained from the same series of samples by using the mutual climatic range method on the coleopteran assemblages it has been possible to quantify the thermal climatic conditions at this time they show clear evidence for a sudden and intense climatic oscillation during the late temperate stage of the interglacial named the quinton cold interlude at this time mean temperatures of the warmest month july declined suddenly by at least 5 c and mean temperatures of the coldest months january and february by more than 10 c subsequently cool temperate conditions returned the pollen diagram through this interval shows little or no response to this climatic event it is too early yet to generalise about the regional significance of the quinton cold interlude but a similar climatic oscillation also occurs towards the closing stage of the mis11 interglacial at hoxne norfolk uk suggesting that the cold interlude was at least regional in extent a short climatic oscillation of similar intensity has also been interpreted from coleopteran evidence towards the end of the mis13 interglacial at waverley wood farm pit warwickshire uk indicating that such events may characterise the later stages of other interglacials these severe climatic oscillations towards the end of interglacials may have relevance to our understanding of the closing phase of the present interglacial

terrestrial environments during mis 11 evidence from the palaeolithic site at west stow suffolk uk abstract multidisciplinary investigations of the sequence at beeches pit west stow suffolk uk have a direct bearing the age of the hoxnian interglacial and its correlation with the continental holsteinian and with the global marine record at this site glacial deposits till and outwash gravels referable to the anglian lowestoft formation fill a subglacial channel cut in chalk bedrock above these glacial deposits a series of interglacial sediments occurs consisting of limnic tufaceous and colluvial silts lacking pollen but rich in shells ostracods and vertebrates lower palaeolithic flint artefacts of acheulian character have also been recovered including refitting examples charred material is abundant at certain horizons and many of the bones have been burned several discrete areas of burnt sediment are interpreted as hearths the molluscan fauna comprises some 78 taxa and includes species of considerable zoogeographical and biostratigraphical importance the land snail assemblage from the tufa consists of woodland taxa with no modern analogue including species that are either extinct e g zonitoides sepultus or which no longer live in britain e g platyla polita p similis neniatlanta pauli this is also the type locality of retinella lyrodiscus skertchlyi which belongs to a subgenus of zonitid land snail now living only on the canary islands there are indications from this fauna the lyrodiscus biome that the climate was wetter and perhaps warmer than the present day the vertebrate fauna is also noteworthy with species of open habitats such as rabbit oryctolagus cf cuniculus and of closed forest such as squirrel sciurus sp and garden dormouse eliomys quercinus present at different times the occurrence of southern thermophiles such as aesculapian snake zamenis longissimus indicates temperatures warmer than those of eastern england today the upper levels include much material reworked from the interglacial sediments although there is clear faunal evidence for climatic deterioration both the molluscan and vertebrate faunas suggest correlation of the interglacial sediments with the hoxnian uranium series dates from the tufa 455 ka bp tl dates from burnt flints 414 30 ka bp and a range of amino acid racemization data all support correlation of this interglacial with mis 11 however four osl dates from sand beneath the interglacial sequence yield a mean age of 261 31 ka bp far younger than all other age determinations and far younger than implied by the biostratigraphy archaeologically the site is unusual in showing prolonged human occupation within closed deciduous forest and evidence for controlled use of fire in a lower palaeolithic context biostratigraphical correlations with other lower palaeolithic sites support the suggestion that acheulian and clactonian industries both occurred in southern britain during the same substage of the hoxnian although not necessarily at precisely the same time the characteristics of the mis 11 interglacial in britain are discussed in the light of evidence from beeches pit and elsewhere

high resolution tem of chondritic carbonaceous matter metamorphic evolution and heterogeneity the insoluble carbonaceous matter from 12 chondrites ci cm co cv eh and uoc was characterized by high resolution transmission electron microscopy hrtem besides ubiquitous nanoglobules the insoluble organic matter from petrologic type 1 and 2 chondrites and semarkona ll 3 0 is composed of a highly disordered polyaromatic component no structural differences were observed between these ioms in agreement with the limited thermal metamorphism they all experienced in chondrites of petrologic type 3 0 the evolution of the iom is controlled by the extent of thermal metamorphism the polyaromatic layers shorter than 1 nm in petrologic type 3 0 chondrites grow up to sizes between 5 and 10 nm in petrologic type 3 6 chondrites contributing to the increase of the degree of structural order in addition we find rare but ubiquitous onion like carbons which may be the product of nanodiamond graphitization the insoluble carbonaceous matter of the enstatite chondrite sahara 97096 eh 3 is different from the other meteorites studied here it is more heterogeneous and displays a high abundance of graphitized particles this may be the result of a mixture between 1 the disordered carbon located in the matrix and 2 catalytic graphitized phases associated with metal potentially originating from partial melting events the structural and nanostructural evolution are similar in all ioms this suggests that the structure of the accreted precursors and the parent body conditions of their secondary thermal modifications temperature duration and pressure were similar the limited degree of organization of the most metamorphosed ioms compared with terrestrial rocks submitted to similar temperature suggests that the conditions are not favorable to graphitization processes due to the chemical nature of the precursor or the lack of confinement pressure

late proterozoic transpression on the nabitah fault system implications for the assembly of the arabian shield abstract the longest proposed suture zone in saudi arabia the nabitah suture can be traced as a string of ophiolite complexes for 1200 km along the north south axis of the arabian shield results of a field study in the north central shield between 23 and 26 n indicate that the nabitah suture is indeed a major crustal discontinuity across which hundreds of kilometers of displacement may have occurred on north south trending subvertical faults of the nabitah fault system although not a unique solution many structures within and near these faults can be reconciled with transpression i e convergent strike slip and syntectonic emplacement of calc alkaline plutonic rocks transcurrent motion on the nabitah fault system appears to have began prior to 710 ma was active circa 680 ma and terminated prior to significant left lateral strike slip on the najd fault system which began sometime after 650 ma northwest directed subduction in the eastern shield could have produced the observed association of calc alkaline magmatism and left lateral transpressive strike slip and is consistent with interpretation of the abt schist and sedimentary rocks of the murdama group as relics of the associated accretionary wedge and fore arc basin

abrupt climate events 500 000 to 340 000 years ago evidence from subpolar north atlantic sediments subpolar north atlantic proxy records document millennial scale climate variations 500 000 to 340 000 years ago the cycles have an approximately constant pacing that is similar to that documented for the last glacial cycle these findings suggest that such climate variations are inherent to the late pleistocene regardless of glacial state sea surface temperature during the warm peak of marine isotope stage 11 mis 11 varied by 0 5 to 1 c less than the 4 to 4 5 c estimated during times of ice growth and the 3 c estimated for glacial maxima coherent deep ocean circulation changes were associated with glacial oscillations in sea surface temperature

organic thermometry for chondritic parent bodies abstract a unique spectroscopic feature has been identified in a study of twenty five different samples of meteoritic insoluble organic matter iom spanning multiple chemical classes groups and petrologic types using carbon x ray absorption near edge structure xanes spectroscopy the intensity of this feature a 1s exciton appears to provide a precise measure of parent body metamorphism the intensity of this exciton is also shown to correlate well with a large negative paramagnetic shift observed through solid state 13c nmr experiments reveal that upon heating primitive iom is transformed into material that is indistinguishable from that in thermally processed chondrites including the development of the 1s exciton a thermo kinetic expression is derived from the experimental data that allows the intensity of the 1s exciton to be used to estimated the effective temperature integrated over time a good correlation is observed between the intensity of the 1s exciton and previously published microraman spectral data these data provide a self consistent organic derived temperature scale for the purpose of calibrating raman based thermometric expressions

sedimentology palaeontology and archaeology of late middle pleistocene river thames terrace deposits at purfleet essex uk middle pleistocene fluvial deposits of the corbets tey formation at purfleet essex provide evidence of an un named and previously poorly recognized interglacial thought to corrrelate with oxygen isotope stage ois 9 previous attributions of the sediments to the ipswichian last interglacial stage are refuted new investigations have yielded rich molluscan mammalian and ostracod assemblages that indicate fully temperate conditions and the distal influence of marine transgression pollen analyses suggest a previously unrecorded phase of interglacial vegetational development clast composition geomorphological evidence and the occurrence of molluscs that favour large rivers all point to deposition by the thames rather than in a minor tributary as suggested previously three separate palaeolithic industries in stratigraphical superposition are recognized at purfleet these being clactonian acheulean and levallois purfleet is therefore a key locality in the understanding of the early human occupation and exploitation of southern britain as well as for the interpretation and correlation of the terrace sequence in the thames valley

investigating the variations in carbon and nitrogen isotopes in carbonaceous chondrites the carbonaceous chondrites contain significant amounts of carbon and nitrogen bearing components the most abundant of which is organic matter stepped combustion data of whole rock and hf hcl residues of carbonaceous chondrites reveal that the organic material can be subdivided operationally into three components 1 free organic matter fom which is readily extractable from whole rock meteorites and is enriched in 13c and 15n 2 labile organic matter lom which has a macromolecular structure but is liberated by hydrous pyrolysis lom is the parent structure for some fom and is also enriched in 13c and 15n and 3 refractory organic matter rom which is also macromolecular but is virtually unaffected by hydrous pyrolysis and is relatively depleted in 13c and 15n the macromolecular entities lom and rom are by far the most abundant organic components present and as such the relative abundances of the 13c and 15n enriched lom and the 13c and 15n depleted rom will have a major influence on the overall isotopic composition of the whole rock meteorite laboratory experiments designed to simulate the effects of parent body aqueous alteration indicate that this form of processing removes lom from the macromolecular material allowing rom to exert a stronger influence on the overall isotopic compositions hence aqueous alteration of macromolecular materials on the meteorite parent body may have a significant control on the stable isotopic compositions of whole rock carbonaceous chondrites the enstatite chondrites are also carbon rich but have been subjected to high levels of thermal metamorphism on their parent body stepped combustion data of hf hcl residues of enstatite chondrites indicate that if they and carbonaceous chondrites inherited a common organic progenitor metamorphism under reducing conditions appears to incorporate and preserve some of the 13c enrichments in lom during graphitisation however when metamorphism is at its most extreme the 15n enrichments in lom are lost

land sea correlations in the pleistocene based on isoleucine epimerization in non marine molluscs the correlation between the oxygen isotope stratigraphy of the oceans and continental stratigraphic records is one of the main challenges for quaternary research most continental classifications however are based on techniques and hypotheses that predate recent advances nevertheless the deep sea oxygen isotope global stratigraphic framework has been extended to the continents by means of some long sequences1 but these are exceptional and regional geology is unsatisfactorily classified for correlation with the oxygen isotope signal because successive geological events produced similar evidence homotaxis geochronometric dating is essential for correlation but available methods are highly site regional or sample specific fortunately non marine molluscs are ubiquitous in time and space and here we use the time dependent epimerization of l isoleucine in these fossils to subdivide the pleistocene of the british isles and to identify more events than recognized by the existing classification2 by calibrating the relative aminostratigraphic scale with independent dating methods we have set up a geochronology which is the basis for land sea correlations back to oxygen isotope stage 15

u series dating of hoxnian interglacial deposits at marks tey essex england a u th dating study was carried out on the authigenic carbonate component of interglacial lake sediments at marks tey essex england isochron methods were necessary because of the presence of non carbonate detritus calculated dates around the limit of the u th method were obtained for two horizons error limits were determined by monte carlo sampling from the normal distributions of errors in the isotope ratios comparison of the resulting empirical distribution functions with the marine oxygen isotope time scale indicates with 87 confidence that the marks tey sediments correlate with ois 11 or some older stage as the marks tey deposits rest without stratigraphical break on anglian till and can be firmly correlated with the hoxnian interglacial type site at hoxne suffolk england this result implies that the anglian glaciation took place in ois 12 acid the hoxnian stage of the british chronostratigraphy commenced in ois 11 copyright c 1999 john wiley sons ltd

vegetation and climate during warmer intervals in the late pleistocene of western and central europe abstract many warmer intervals occurred during the last interglacial glacial cycle 130 10 ka in europe the vegetational record shows several types of such intervals among which the forest periods of the eemian interglacial and the amersfoort brorup interstadials of the early weichselian are of special interest a series of map reconstructions is used to present some of the relevant vegetational and paleoclimatic characterizations they represent two types of temperate intervals occurring in the late pleistocene in europe one with a rather uniform distribution of vegetation types a warmer oceanic climate and a high sea level the other type shows strong vegetation gradients both north south and east west a more continental climate and a relatively low sea level inland ice probably persisted in the far north during this last type of interval it is suggested that these two types of interglacial occurred throughout the pleistocene

asteroid 6 hebe the probable parent body of the h type ordinary chondrites and the iie iron meteorites the s iv type asteroid 6 hebe is identified as the probable parent body of the h type ordinary chondrites and of the iie iron meteorites the ordinary chondrites are the most common type of meteorites falling to earth but prior to the present study no large mainbelt source bodies have been confirmed hebe is located adjacent to both the v6 and 3 1 resonances and has been previously suggested as a major potential source of the terrestrial meteorite flux hebe exhibits subtle rotational spectral variations indicating the presence of some compositional variations across its surface the silicate portion of the surface assemblage of hebe is consistent both in overall average and in its range of variation with the silicate components in the suite of h type chondrites the high albedo of hebe rules out a lunar style space weathering process to produce the weakened absorption features and reddish spectral slope in the s type spectrum of hebe linear unmixing models show that a typical ni fe metal spectrum is consistent with the component that modifies an h chondrite spectrum to produce the s type spectrum of hebe on the basis of the association between the h chondrites and the he iron meteorites our model suggests that large impacts onto the relatively metal rich h chondrite target produced melt bodies sheets or pods that differentiated to form thin laterally extensive near surface layers of ni fe metal fragments of the upper silicate portions of these melt bodies are apparently represented by some of the igneous inclusions in h chondrite breccias alternately masses of metal could have been deposited on the surface of hebe by the impact of a core or core fragment from a differentiated parent body of h chondrite composition subsequent impacts preferentially eroded and depleted the overlying silicate and regolith components exposing and maintaining large masses of metal at the optical surface of hebe in this interpretation the nonmagmatic iie iron meteorites are samples of the ni fe metal masses on the surface of hebe whereas the h chondrites are samples from between and or beneath the metal masses