fossils from quaternary fluvial archives sources of biostratigraphical biogeographical and palaeoclimatic evidence fluvial sedimentary archives have the potential to preserve a wide variety of palaeontological evidence ranging from robust bones and teeth found in coarse gravel aggradations to delicate insect remains and plant macrofossils from fine grained deposits over the last decade advances in quaternary biostratigraphy based on vertebrate and invertebrate fossils primarily mammals and molluscs have been made in many parts of the world resulting in improved relative chronologies for fluviatile sequences complementary fossil groups such as insects ostracods and plant macrofossils are also increasingly used in multi proxy palaeoclimatic and palaeoenvironmental reconstructions allowing direct comparison of the climates and environments that prevailed at different times across widely separated regions this paper reviews these topics on a regional basis with an emphasis on the latest published information and represents an update to the 2007 review compiled by the flag inspired igcp 449 biostratigraphy subgroup disparities in the level of detail available for different regions can largely be attributed to varying potential for preservation of fossil material which is especially poor in areas of non calcareous bedrock but to some extent also reflect research priorities in different parts of the world recognition of the value of biostratigraphical and palaeoclimatic frameworks which have been refined over many decades in the core regions for such research particularly for the late middle and late pleistocene of nw europe has focussed attention on the need to accumulate similar palaeontological datasets in areas lacking such long research histories although the emerging datasets from these understudied regions currently allow only tentative conclusions to be drawn they represent an important stage in the development of independent biostratigraphical and palaeoenvironmental schemes which can then be compared and contrasted

oxygen isotope mapping in the panorama vms district pilbara craton western australia applications to estimating temperatures of alteration and to exploration whole rock oxygen isotope data are presented for the panorama district in the archean pilbara craton of western australia where near perfect exposure reveals a cross section through a complete volcanogenic massive sulfide vms hydrothermal alteration system the 18o values decrease with depth in the volcanic pile across semi conformable alteration zones to values below 6 immediately above a large 180 km2 subvolcanic intrusion altered rocks in the upper parts of the subvolcanic intrusion have lower 18o values 6 8 than least altered granite 8 apart from sericite quartz altered zones which are slightly higher 8 10 corridors of low 18o values crosscut this regional zonation and are coincident with transgressive feldspar destructive alteration zones which underlie vms mineralization the whole rock oxygen isotope distribution patterns are interpreted to represent alteration temperature where high 18o values correspond to low temperature alteration and low 18o values correspond to high temperature alteration alteration temperatures which were calculated using modal alteration mineral abundances and an assumed fluid 18o are consistent with this interpretation increasing temperatures with depth in the volcanic pile and high temperatures in transgressive corridors leading up to vms deposits are consistent with a convective hydrothermal model in which heat from the subvolcanic intrusion drove seawater through the volcanic pile granite hosted sericite quartz alteration zones are 18o enriched and are tentatively interpreted to have formed from a mixed magmatic evolved seawater fluid

geochemical and oxygen isotope signature of sea floor alteration associated with a polydeformed and highly metamorphosed massive sulfide deposit ruostesuo central finland massive sulfide deposits in the vihanti pyhasalmi district central finland are hosted by a highly deformed and metamorphosed bimodal volcanic sequence alteration zones that envelop these deposits are composed of cordierite orthoamphibole garnet bearing rocks referred to as cor rocks belonging to upper amphibolite to granulite facies outcrops of mafic and felsic cor rocks mcor and fcor in the vicinity of the ruostesuo zn cu deposit define mappable layers with distinctive metamorphic mineral assemblages orthoamphibole cordierite plagioclase quartz m1cor garnet orthoamphibole cordierite plagioclase quartz m2cor quartz cordierite biotite orthoamphibole cummingtonite garnet plagioclase f1cor and quartz cordierite garnet sillimanite f2cor these rocks are interlayered with or grade into typical amphibolites i e hornblende plagioclase and quartz plagioclase bearing rocks that are interpreted as least altered mafic and felsic metavolcanic rocks respectively whole rock geochemical data for least altered metavolcanic rocks and cor rocks at ruostesuo define three mafic suites primitive basalts basaltic andesites and ferrobasalts and two felsic suites r1 and r2 rhyolites using a combination of high field strength element ratios and rare earth element profiles cor rocks can be assigned to all five volcanic suites calculated mass changes for the majority of exposed cor rocks at ruostesuo are similar to those reported for chlorite quartz assemblages found within the inner core of alteration pipes located below some sea floor massive sulfide deposits relative to least altered precursors mafic cor rocks have gained fe mg s and lost variable amounts of si ca na k rb ba sr and eu which resulted in an average net mass loss of about 10 percent the bulk composition of most altered mafic cor rocks near total loss of ca na k reflects the proportion of chlorite to quartz within the premetamorphic alteration assemblages and the composition of the chlorite mass change results for altered mafic rocks indicate that basalts at ruostesuo were altered by an evolved fe rich hydrothermal fluid at high water rock ratios mass changes for cor rocks of the r2 felsic volcanic suite are similar to those of the mafic rocks enriched in fe mg and depleted in ca na k rb ba sr and eu except for significant additions of si that resulted in net mass gains of 20 to 30 percent felsic cor rocks of the r1 volcanic suite show gains in k rb and ba that are attributed to the formation of premetamorphic sericite during an alteration stage dominated by hydrothermal seawater in comparison to least altered metavolcanic rocks mafic and felsic cor rocks are depleted in 18o with delta 18o values 2 to 5 per mil lower than precursor rocks estimated temperatures of alteration were 270 to 350 c these data indicate that the signature of a high temperature 300 c sea floor hydrothermal upflow zone is preserved within upper amphibolite to granulite facies rocks at ruostesuo the stratigraphic boundary between strongly chloritized mafic volcanic rocks and silicified felsic volcanic rocks marks a transition from net mass losses associated with hydrothermal fluid dominated alteration to net mass gains associated with seawater dominated alteration silicification at or near the boundary between mafic and felsic volcanic rocks may have been the result of conductive cooling or mixing with seawater from above in the absence of textural or crosscutting relationships indicative of a younging direction a stratigraphic model is proposed on the basis of the above geochemical constraints altered basalts at ruostesuo represent the exposed base of a chloritic stockwork zone that passes upsection into altered felsic volcanic rocks that host massive zn cu sulfides this stratigraphic model has significance for the interpretation of other massive sulfide deposits in the vihanti pyhasalmi district and exploration strategies that couple chemostratigraphy with mass change results more significantly the preservation of premetamorphic oxygen isotope values for strongly metamorphosed and locally migmatitic cor rocks indicate that oxygen isotope mapping is a viable exploration tool in the district and in other mineralized upper amphibolite to granulite facies terranes worldwide

thermoluminescence dating of the chelford interstadial abstract the sediments at chelford constitute one of the key devensian sequences in britain previous radiometric dating attempts using wood and peat from the interstadial deposits per se suggest its age is likely to be beyond the limits of resolution by radiocarbon using tl dating of feldspar and quartz mineral fractions from the host succesion of chelford sands a sequence of internally consistent dates is derived which accords with the existing litho and biostratigraphic evidence these suggest that the absolute age of the chelford interstadial is in the range 90 100 ka the chelford sands appear to be the product of at least two cold stages

progressive alteration associated with auriferous massive sulfide bodies at the dumagami mine abitibi greenstone belt quebec pyritite and massive sphalerite galena bodies are surrounded by two distinct concentric alteration zones within the metafelsites of the late archean blake river group at the dumagami au ag cu deposit southern abitibi belt northwestern quebec the inner alteration zone is characterized by andalusite bearing rocks and is interpreted as a metamorphosed advanced argillic alteration zone the outer zone is represented by white mica phyllonite and phyllonitic breccia and is interpreted as a metamorphosed sericitic alteration zone surrounding least altered rocks represented by massive quartziferous augen rocks and ribboned micaceous augen schists are composed of blue quartz and albite phenocrysts quartz biotite ilmenite and chlorite the sericite zone is characterized by the metamorphic mineral assemblage quartz sericite rutile pyrite or andesine and by the absence of albite phenocrysts biotite and ilmenite the andalusite zone is characterized by the metamorphic mineral assemblage quartz andalusite sericite rutile pyrite or kyanite and by the absence of albite phenocrysts andesine porphyro blasts biotite and ilmenite petrographic and geochemical features of least altered sericitic and andalusite bearing rocks indicate that felsic effusive rocks were the principal protolith strong leaching of alkali and alkaline earths especially mg within the inner alteration zone has resulted in a notable absence of chlorite a feature atypical of the alteration associated with archean massive sulfide deposits chemical and mineralogical changes from least altered to altered rocks suggest that highly acidic hydrothermal fluids were responsible for the premetamorphic formation of alteration assemblages at the dumagami deposit however gold transport in these fluids would be minimal and gold emplacement is linked instead to a late structural event

oxygen isotope zonation and alteration in the northern noranda district quebec evidence for hydrothermal fluid flow volcanic rocks of the new vauze norbec area central noranda volcanic complex consist of andesites and rhyolites that have been chemically and isotopically altered by synvolcanic semiconformable alteration processes including spilitization chloritization silicification and epidote quartz alteration andesites have whole rock delta 18 o values of 1 9 to 9 7 per mil those with megascopic mineralogical evidence of hydrothermal alteration have ones of 5 1 to 9 7 per mil rhyolites also show a broad range in delta 18 o values 4 4 to 13 7 per mil all of the volcanic rocks are either enriched or depleted in 18 o with respect to fresh rhyolite 8ppm or fresh andesite 6ppm a marked upward stratigraphic increase in delta 18 o values and the strata bound occurrence and regional zoning of alteration minerals provide evidence of district scale hydrothermal alteration these alteration patterns formed under the conditions of an increasing thermal gradient and a downward decrease in water rock ratio controlled by the cooling of the flavrian lake synvolcanic intrusion

palaeontology and taphonomy of late quaternary fossil assemblages at somersham cambridgeshire england and the problem of reworking assemblages of foraminifers ostracods and molluscs from temperate ipswichian stage last temperate stage sediments and overlying cold devensian stage last cold stage sediments at somersham in the southern fenland of cambridgeshire have been analysed the ipswichian sediments contain faunas consistent with temperate brackish water conditions under tidal influence the devensian assemblages were recovered from a series of sands and gravels laterally accreting in a channel cutting into ipswichian sediments in contrast to the ipswichian faunas the faunas of particular devensian samples show a complex mixture of temperate freshwater brackish and marine taxa the molluscs are mainly freshwater with few land snails they occur together with foraminifers and ostracods freshwater brackish water and marine ostracods are present with foraminifers a sample of devensian fine laminated sediment in the channel was analysed for pollen only abundant pre quaternary spores were present with abundant foraminifers in the same sample the taphonomy of the assemblages and the difficulties of their interpretation in environmental terms are discussed the importance of taphonomy in assessing environments climate range of taxa and dating is stressed

sedimentology palaeoecology and geochronology of last interglacial deposits from deeping st james lincolnshire england pollen plant macrofossil molluscan and coleopteran data from organic muds below the low terrace of the river welland at deeping st james lincolnshire indicate deposition in the mixed oak forest phase of a late pleistocene interglacial coleopteran and molluscan data suggest summer temperatures up to 4 c warmer than at present in eastern england and plant macrofossil material suggests a climate more continental than that of britain in the holocene no direct analogue of this biota however exists currently in europe biostratigraphical indications from the pollen coleoptera and mollusca suggest an age in the ipswichian interglacial thermoluminescence dates between 120 ka and 75 ka and amino acid ratios with a mean of 0 11 show that deposition of the sediments took place during oxygen isotope stage 5 this accurate dating of a partial ipswichian succession allows discussion of the ages of a number of other interglacial sites in eastern england of assumed ipswichian age copyright 1999 john wiley sons ltd

a comparison of the horne volcanogenic massive sulfide deposit and intracauldron deposits of the mine sequence noranda quebec most of the massive sulfide deposits of the rouyn noranda area are associated with rhyolite and andesite flows of the mine sequence and occur within the noranda cauldron a volcanic subsidence structure related to partial evacuation of an underlying magma chamber the flavrian pluton the horne massive sulfide orebodies lie within a sequence of rhyolitic breccias located just south of the inferred margin of the subsidence structure and are separated from the mine sequence by the horne creek fault traditionally the horne deposits and the intracauldron deposits have been interpreted to occur within the same stratigraphic interval even though they share some characteristics such as mineral zoning patterns alteration assemblages and an association with synvolcanic faults the two deposit groups are clearly distinguishable intracauldron massive sulfide deposits are small 5 mt cu zn rich concordant mounds associated with interflow horizons and are closely linked to vent zones where synvolcanic faulting provided hydrothermal fluids with cross stratal structural permeability the three major sulfide deposits at the horne mine are much larger 20 150 mt and formed in a fault bounded sediment filled graben on the flank of a rhyolitic vent complex the orebodies are au cu rich but zn poor and have bowl shaped morphologies which resulted from extensive subsea floor sulfide precipitation whereas the intracauldron sulfide deposits lie within a bimodal flow dominated succession consisting mainly of andesite basalt and high silica rhyolite with volumetrically insignificant pyroclastic rocks the horne orebodies occur in felsic fragmental rocks and rhyolite flows which are part of a stratigraphic sequence which contains virtually no mafic volcanic rocks also compared to all intracauldron rhyolites the horne rhyolites show a fundamental depletion in incompatible trace elements such as the high field strength and rare earth elements which implies that the horne rhyolites may have followed a different magmatic evolutionary path such differences in deposit characteristics their paleoenvironments of formation and the physical volcanology and geochemistry of their host volcanic successions suggest that contrary to previous interpretations the massive sulfide deposits of the intracauldron mine sequence and those of the horne sequence may have formed at different stages in the evolution of the noranda cauldron

some petrologic and oxygen isotopic relationships in the amulet mine noranda quebec and their bearing on the origin of archean massive sulfide deposits a concentrically zoned alteration pipe is present at the amulet a cu zn mine in the archean abitibi greenstone belt the pipe consists of a central core zone of so called dalmatianite spotted cordierite anthophyllite rock surrounded by a zone of biotite bearing grid fracture alteration study of the dalmatianite indicates that these rocks experienced two episodes of recrystallization first the original andesite was completely reconstituted during a hydrothermal event producing a quartz chlorite assemblage this transformation was associated with the formation of the massive sulfide lens and presumably took place in a submarine environment later contact metamorphism associated with the intrusion of the nearby lake dufault granodiorite resulted in partial recrystallization of the chlorite and quartz to cordierite and anthophyllite whole rock delta 18 o values decrease from about 6 to 10 in most of the abitibi belt to 5 to 7 in the country rocks surrounding the ore deposit to values as low as 3 6 in the core of the dalmatianite zone this oxygen isotopic zoning must have been produced by the hydrothermal activity because the dehydration reactions associated with contact metamorphism cannot have affected delta 18 o by more than 0 5 per mil assuming an alteration temperature of 300 degrees or 50 degrees c and a water rock ratio greater than two the hydrothermal fluid must have had delta 18 o 0 5 or 1 0 this indicates that the amulet ore deposit formed from a hydrothermal fluid that had a delta 18 o value similar both to modern seawater and to the fluids which formed the phanerozoic massive sulfide deposits of the kuroko and cyprus types the apparent constancy of delta 18 o of seawater during the precambrian and the continued importance of seawater hydrothermal processes are important constraints which must be considered in developing models of the history of the earth

regional evolution of hydrothermal fluids in the noranda district quebec evidence from delta 18 o values from volcanogenic massive sulfide deposits the results of oxygen isotope analysis of hydrothermally altered volcanic rocks are used to define the thermal and isotopic characteristics of the ore forming fluids which produced several volcanogenic massive sulfide deposits in the noranda district these deposits corbet ansil norbec horne and mobrun formed during temporally distinct events that span much of the volcanic stratigraphy in the district the data show that the delta 18 o values of the altered rocks and the size economic tonnage of each deposit increase upward through the volcanic stratigraphy from low delta 18 o values at the corbet 2 2 to 4 8ppm and ansil 0 8 to 5 0ppm deposits to intermediate delta 18 o values at the amulet 3 6 6 7ppm and norbec 3 6 10 5ppm deposits to high delta 18 o values at the horne 4 2 11 6ppm and mobrun 6 0 13 8ppm deposits a corresponding increase is indicated for the delta 18 o values of the discharging hydrothermal fluids from 2 or 2 per mil at the corbet deposit to 3 0 or 1 5 per mil at the horne deposit alteration in most of the deposits is shown to have resulted from the flow of fluids having temperatures of 300 degrees or 50 degrees c with the exception of the pyrite rich mobrun deposit where slightly lower temperatures 200 degrees or 50 degrees c are indicated these observations are interpreted to indicate that the duration of hydrothermal discharge as indicated by deposit size at a given site increased upward through the volcanic stratigraphy since the fluid and thus the altered rock delta 18 o values normally evolve from low to high with time in a volcanogenic massive sulfide forming system e g cathles 1983 the duration of fluid discharge is a primary factor in controlling the isotopic signature retained at a given deposit in the noranda district the duration of fluid discharge depended strongly on the rate of volcanic accumulation with short lived systems e g corbet ansil forming during periods of rapid accumulation of extrusive volcanic rocks and longer lived systems forming during more quiescent periods e g norbec or at sites where the accumulation of extrusive material was limited by topography e g horne

geology of the bousquet 2 mine an example of a deformed gold bearing polymetallic sulfide deposit the bousquet 2 mine is a deformed pyritic polymetallic archean gold deposit located within a zone of intense ductile brittle deformation composed of highly sheared and altered metamorphic tectonites of contrasting rheological properties the ore occurs in a metamorphosed zone of aluminous alteration and is composed of foliation parallel massive and semimassive pyritic lenses overprinted by late en echelon extensional veinlets containing au ag cu mineralization structural and textural analyses show that the gold bearing sulfide bodies and enclosing host rocks contain discrete tectono metamorphic features resulting from two principal episodes of metamorphism m 1 and m 2 the earlier prograde event m 1 and coeval regional deformation d 1 were accompanied by overall ductile deformation of sulfides and by recrystallization and remobilization of the mineralization parallel to foliation m 1 caused development of a pervasive east west trending metamorphic layering of the pyritic mineralization transposition and elongation of the pyritic bodies parallel to mineral stretching l 1 lineations meter scale folding of sulfides sulfide brecciation coarsening and annealing recrystallization of pyrite and ductile remobilization of incompetent sulfides and gold into interstices and triple point junctions of juxtaposed pyrite grains extensive differential remobilization of ductile sulfides mainly sphalerite pyrrhotite galena chalcopyrite chalcocite and bornite and gold took place during m 1 and gave rise to planar zones enriched in au ag cu mineralization along the interfaces of pyritic lenses and their adjacent silicate rocks m 2 metamorphism is chronologically related to a late brittle incremental stage of the progressive deformation and is characterized by high fluid influx pervasive retrogression of peak metamorphic minerals and remobilization of sulfides and gold into transgressive structures the retrograde mineralization displays a wide range of small scale structures resulting from fluid assisted remobilization of ductile sulfides including piercement and injection structures as well as foliation oblique extensional veinlets metamorphic remobilization of ore constituents took place mainly at ore wall rock interfaces fe pb zn and au ag cu bearing extensional veinlets generally occur in foliation parallel protores of similar mineralogical composition and are interpreted as having resulted from in situ metamorphic remobilization gold and copper show a corelationship throughout the deposit the highest gold and copper values occur within extensional veins overprinting previously au cu enriched planar zones mineralogical zoning in the sulfide masses is structurally controlled and can be related directly to abundant au cu bearing veinlets that represent mineralized segments of a systematic joint system structural and textural evidence suggests that gold mineralization with its present textural relations formed during m 1 and m 2 but that a large proportion of the structurally controlled vein mineralization resulted from in situ remobilization rather than from additions from an external source

the peterborough member callovian middle jurassic of the oxford clay formation at peterborough uk king s dyke brick pit whittlesey near peterborough cambridgeshire provides a continuous section through the peterborough member formerly known as the lower oxford clay of the oxford clay formation and is here described as its type section it also shows parts of the underlying kellaways formation and of the overlying stewartby member of the oxford clay formation other sections in the peterborough district are discussed and related to the type section the peterborough member is developed throughout southern england and aspects of its stratigraphy palaeogeography and burial history are briefly reviewed

evidence for the early onset of the ipswichian thermal optimum palaeoecology of last interglacial deposits at whittlesey eastern england fossiliferous deposits infilling a channel at whittlesey eastern england are dated by amino acid racemization to the last interglacial and pollen analysis indicates deposition in ipswichian biozones ip ib and ip iib multidisciplinary palaeoenvironmental analyses of these deposits provide a rare insight into ip ib subzone conditions specifically the ip ib deposits contain exotic thermophiles naias minor belgrandia marginata bembidion elongatum pelochares versicolor caccobius schreberi onthophagus massai and emys orbicularis usually associated with ip iib combined palaeotemperature reconstructions based on beetle ostracod and vertebrate assemblages of the ip ib deposits indicate that summers mean july range 19 to 22 c were at least 2 c warmer than at present whereas winters mean january air temperature range 0 to 7 c were probably similar to those of today these palaeotemperature ranges encompass those for ip iib deposits at trafalgar square 20 to 21 c and 1 5 to 3 c previously considered the only ipswichian site to record temperatures significantly warmer than holocene temperatures of particular significance is that thermal optimal conditions commenced in ip ib rather than being confined to ip iib this demonstrates rapid warming and biological response to early ipswichian climate amelioration which accords with the deep sea last interglacial and european eemian records supplementary material supplementary tables s1 s7 are available at http doi org 10 6084 m9 figshare c 3830221

u pb geochronology of the eastern abitibi subprovince part 2 noranda kirkland lake area u pb zircon ages for 15 volcanic and plutonic units in the noranda and kirkland lake areas help constrain the history of volcanism plutonism sedimentation and deformation in the south central part of the abitibi belt volcanism occurred over an interval of at least 50 ma beginning with the deposition of the volcanic and volcaniclastic units within the pacaud structural complex at 2747 ma following a period of apparent quiescence magmatism resumed at 2730 2725 ma with the eruption of volcanic rocks in the normetal and lac abitibi area from 2715 until about 2698 ma volcanism occurred sporadically throughout much of the area culminating in the eruption of the blake river group from 2703 to 2698 ma several large intrusive bodies yield ages that indicate that they are plutonic equivalents of the blake river group plutons that are considered to have been emplaced during the kenoran orogeny give ages that are only slightly younger than the youngest volcanic units of the blake river group emphasizing

the gold content of volcanogenic massive sulfide deposits volcanogenic massive sulfide deposits contain variable amounts of gold both in terms of average grade and total gold content with some vms deposits hosting world class gold mines with more than 100 t au previous studies have identified gold rich vms as having an average gold grade expressed in g t exceeding the total abundance of base metals expressed in wt however statistically meaningful criteria for the identification of truly anomalous deposits have not been established this paper presents a more extensive analysis of gold grades and tonnages of 513 vms deposits worldwide revealing a number of important features in the distribution of the data a large proportion of deposits are characterized by a relatively low gold grade 2 g t with a gradual decrease in frequency towards maximum gold grades defining a log normal distribution in the analysis presented in this paper the geometric mean and geometric standard deviation appear to be the simplest metric for identifying subclasses of vms deposits based on gold grade especially when comparing deposits within individual belts and districts the geometric mean gold grade of 513 vms deposits worldwide is 0 76 g t the geometric standard deviation is 2 70 g t au in this analysis deposits with more than 3 46 g t au geometric mean plus one geometric standard deviation are considered auriferous the geometric mean gold content is 4 7 t au with a geometric standard deviation of 26 3 t au deposits containing 31 t au or more geometric mean plus one geometric standard deviation are also considered to be anomalous in terms of gold content irrespective of the gold grade deposits with more than 3 46 g t au and 31 t au are considered gold rich vms a large proportion of the total gold hosted in vms worldwide is found in a relatively small number of such deposits the identification of these truly anomalous systems helps shed light on the geological parameters that control unusual enrichment of gold in vms at the district scale the gold rich deposits occupy a stratigraphic position and volcanic setting that commonly differs from other deposits of the district possibly due to a step change in the geodynamic and magmatic evolution of local volcanic complexes the gold rich vms are commonly associated with transitional to calc alkaline intermediate to felsic volcanic rocks which may reflect a particularly fertile geodynamic setting and or timing e g early arc rifting or rifting front at the deposit scale uncommon alteration assemblages e g advanced argillic aluminous strongly siliceous or potassium feldspar alteration and trace element signatures may be recognized e g au ag as sb bi hg te suggesting a direct magmatic input in some systems

oxygen isotope and palaeotemperature records from six greenland ice core stations camp century dye 3 grip gisp2 renland and northgrip oxygen isotope variations spanning the last glacial cycle and the holocene derived from ice core records for six sites in greenland camp century dye 3 grip gisp2 renland and northgrip show strong similarities this suggests that the dominant influence on oxygen isotope variations reflected in the ice sheet records was regional climatic change differences in detail between the records probably reflect the effects of basal deformation in the ice as well as geographical gradients in atmospheric isotope ratios palaeotemperature estimates have been obtained from the records using three approaches i inferences based on the measured relationship between mean annual 18o of snow and of mean annual surface temperature over greenland ii modelled inversion of the borehole temperature profile constrained either by the dated isotopic profile or iii by using monte carlo simulation techniques the third of these approaches was adopted to reconstruct holocene temperature variations for the dye 3 and grip temperature profiles which yields remarkably compatible results a new record of holocene isotope variations obtained from the northgrip ice core matches the grip short term isotope record and also shows similar long term trends to the dye 3 and grip inverted temperature data the northgrip isotope record reflects i a generally stronger isotopic signal than is found in the grip record ii several short lived temperature fluctuations during the first 1500 yr of the holocene iii a marked cold event at ca 8 2 ka the 8 2 ka event iv optimum temperatures for the holocene between ca 8 6 and 4 3 ka a signal that is 0 6 stronger than for the grip profile v a clear signal for the little ice age and vi a clear signal of climate warming during the last century these data suggest that the northgrip stable isotope record responded in a sensitive manner to temperature fluctuations during the holocene copyright 2001 john wiley sons ltd

a middle devensian woolly rhinoceros coelodonta antiquitatis from whitemoor haye quarry staffordshire uk palaeoenvironmental context and significance this paper reports the discovery of a rare partial skeleton of a woolly rhinoceros coelodonta antiquitatis blumenbach 1799 and associated fauna from a low pleistocene terrace of the river tame at whitemoor haye staffordshire uk a study of the sedimentary deposits around the rhino skeleton and associated organic rich clasts containing pollen plant and arthropod remains suggests that the animal was rapidly buried on a braided river floodplain surrounded by a predominantly treeless herb rich grassland highlights of the study include the oldest british chironomid record published to date and novel analysis of the palaeoflow regime using caddisfly remains for the first time comparative calculations of coleopteran and chironomid palaeotemperatures have been made on the same samples suggesting a mean july temperature of 8 11 c and a mean december temperature of between 22 and 16 c radiocarbon age estimates on skeletal material supported by optically stimulated luminescence ages from surrounding sediments indicate that the rhino lived around 41 43 k cal a bp the combined geochronological stratigraphic and palaeoenvironmental evidence places the assemblage firmly within the middle devensian marine oxygen isotope stage 3 this would agree with other regional evidence for the timing of aggradation for the lowest terrace of the trent and its tributary systems copyright 2012 john wiley sons ltd

archean wrench fault tectonics and structural evolution of the blake river group abitibi belt quebec structural analysis of the blake river group volcanic rocks in the rouyn noranda region shows the formations to be distributed largely in z shapes resulting from the interference of two early fold systems oriented west northwest east southeast and east west respectively the first of these two fold systems is probably related to the shortening associated with left lateral movement along the two major fractures in the region namely the porcupine destor and larder lake cadillac faults the second system appears to be the result of north south compression perpendicular to the two major fractures the two major faults the first system of early folding the normal and reverse faults and the minor dextral and sinistral strike slip faults that have been observed in the blake river group rocks can all be integrated into one tectonic system that of wrench fault tectonics the orientations of the principal structures recognized in the abitibi belt major shear zones folding and faulting suggest that the d

the balderton sand and gravel pre ipswichian cold stage fluvial deposits near lincoln england the balderton terrace marks a former course of the river trent between newark and the lincoln gap the principal deposit the balderton sand and gravel is interpreted as a braided river sediment ice wedge casts truncated by intraformational erosion surfaces at many levels indicate syndepositional permafrost remnant cover deposits overlying the balderton sand and gravel include the partly aeolian whisby sand locally both the upper part of the balderton sand and gravel and the cover deposits exhibit features indicative of temperate climate pedogenesis all these deposits are affected by subsequent cryoturbation on the basis of these features and the geomorphological and topographical relationship to other terrace deposits of the area the balderton sand and gravel and whisby sand are regarded as post hoxnian and pre lpswichian i e wolstonian electron spin resonance age determinations for fossil elephant teeth and amino acid analyses on molluscs from the balderton sand and gravel suggest correlation with oxygen isotope stage 6 the balderton sand and gravel has yielded a cold climate mammalian fauna dominated by woolly mammoth and woolly rhinoceros though rarer species suggest periods of milder climate silts from channels near the base of the deposit have produced pollen mollusc ostracod and beetle assemblages also indicating a cold climate

oxygen isotope alteration in the noranda mining district abitibi greenstone belt quebec a regional whole rock oxygen isotope survey carried out in the noranda district shows how oxygen isotope alteration can be used to guide exploration for massive sulfide deposits the survey is based on 588 outcrop whole rock oxygen isotope determinations from 478 sites in a approximately 35 by 50 km area between the destor porcupine and cadillac larder lake breaks from east of the horne mine to west of the magusi river mine the mean isotopic composition of all samples is 7 4 or 2 per mil smow nested analysis of variance of 478 isotopic determinations from 371 of these sites shows that 74 percent of the total variance in whole rock delta 18 o r r whole rock is associated with outcrop location 21 percent with outcrop sampling and 5 percent with sample analysis an analysis of 259 determinations indicates that rock type is statistically no more important than outcrop sampling the statistical analysis indicates that isotopic variations greater than or 1 per mil can be used to map the hydrothermal circulation responsible for massive sulfide mineralization specific traverses visually confirm the lack of 18 o dependence on rock type and the utility of a 2 per mil interpretive band the large scale pattern of isotopic alteration in the noranda district is dominated by a nearly continuous 2 to 3 km wide annulus at the margins of the flavrian pluton of delta 18 o r 18 o r 18 o r depletion is surrounded up section by a approximately 10 km wide band of patchy but intense 18 o enrichment 8 5 14ppm the combined pattern of concentric light and heavy alteration has a diameter of approximately 30 km the clericy intrusion shows a similar pattern of isotope alteration on a smaller 10 km diam scale the lake dufault pluton seems to have been isotopically altered by continuing convection driven by the flavrian hydrothermal system modeling suggests that the 18 o depletion is produced by water circulating toward and along the edges of an intrusion and that the surrounding heavy alteration is produced either by seawater recharge or limited hydrothermal discharge the large scale and coherency of the alteration pattern centered on the flavrian pluton is remarkable and indicates that this pluton drove a major long lived approximately 10 m y hydrothermal system in which convection penetrated to an 8 kin depth the intensity and coherency of the 18 o depletion correlates with the tonnage of associated massive sulfide mineralization oxygen isotope depletion may in general mark the margins of plutons that have driven sufficient hydrothermal circulation to produce economic massive sulfide deposits up section it may be possible to screen plutons for up section massive sulfide exploration potential by collecting and isotopically analyzing approximately 50 samples from five traverses across a pluton9s margins additional samples may provide details light fingers that guide exploration to particular deposits

oxygen isotope composition of alteration zones of highly metamorphosed volcanogenic massive sulfide deposits geco canada and palmeiropolis brazil the large geco canada and small palmeiropolis brazil precambrian metamorphosed volcanogenic massive sulfide deposits have several features in common including footwall hydrothermal alteration zones formed mainly by anthophyllite cordierite biotite rocks these rocks are interpreted to be basalts that had undergone hydrothermal alteration during ore deposition and subsequently were metamorphosed to upper amphibolite facies geco has a large volume of these rocks but no associated unaltered protoliths in contrast to palmeiropolis where recognizable protoliths are intercalated with altered rocks chemically the anthophyllite cordierite biotite rocks with their strong depletions of alkalies and enrichments of magnesium aluminum and ore metals resemble the chlorite zones that underlie many nonmetamorphosed volcanogenic massive sulfide deposits the delta 18 o value for geco amphibolite outside the mine area is 7 6 per mil whereas the alteration zone has values between 3 6 and 9 4 per mil the rocks having the lowest delta 18 o values chemically resemble those of primary chlorite alteration zones from nonmetamorphosed volcanogenic massive sulfide deposits the host amphibolite from palmeiropolis has whole rock delta 18 o values between 5 6 and 7 9 per mil the altered anthrophyllite biotite rocks have similar delta 18 o values 5 2 7 9 per mil and these are much higher than those commonly reported for chlorite zones associated with other volcanogenic massive sulfide deposits because no isotopic distinction exists between host and alteration zone rocks at palmeiropolis rehomogenization by pervasive fluid flow during metamorphism is suggested the difference in isotope behavior between the two deposits may reflect the volume of altered rocks present the small size of the alteration zone and the close spatial at palmeiropolis facilitated isotopic reequilibration at geco the much larger alteration zone was an effectively closed isotopic system which retained its distinctive low delta 18 o signature through high grade metamorphism oxygen isotopes may be a useful exploration tool in highly metamorphosed terranes if used with caution large areas affected by hydrothermal alteration and consequently large orebodies such as geco may be identifiable using this technique however areas characterized by small hydrothermal cells such as palmeiropolis are likely to have undergone isotopic reequilibration during high grade metamorphism and would be undetectable

oblique archean subduction accretion and exhumation of an oceanic arc during dextral transpression southern volcanic zone abitibi subprovince canada abstract the archean abitibi subprovince divided into northern nvz and southern svz volcanic zones is characterized by the crustal scale destor porcupine manneville fault zone dpmfz which links the svz and nvz and the cadillac larder lake fault zone cllfz which separates the abitibi and pontiac subprovinces the dpmfz and cllfz represent major deformation zones that record over 60 million years of archean deformation the dextral transpressional phase in the nvz which represents incipient svz deformation occurred between 2700 and 2692 ma and is characterized by southeast se trending dextral faults e g macamic fault synorogenic flysch sedimentation is focussed at the interface between the svz nvz and pontiac abitibi subprovinces the se trending parfouru fault linking the two major trench fault systems is interpreted as a reactivated leaky transform fault and is associated with synorogenic flysch sedimentation the early monzodioritic suite of the preissac lacorne batholith was related to dpmfz thrusting ca 2692 2690 ma the change from early thrusting to transcurrent motion is recorded in the duparquet strike slip basin which formed between 2690 and 2680 ma along the dpmfz and the granada pull apart basin which evolved between 2680 and 2670 ma along the cllfz the timing of these basins indicates a diachronous evolution renewed thrusting affected the granada basin but not the northern duparquet strike slip basin so that a southward migrating deformation front is inferred late exhumation resulted in extension along both fault zones and was responsible for the juxtaposition of medium and low grade metamorphic rocks the monzogranitic suite of the lamotte pluton which occurred between 2660 and 2642 ma is linked to exhumation final dextral transpression post dating exhumation produced shearing and folding the svz of the abitibi subprovince shows the salient attributes of modern oblique orogenic collisions with alternating phases of thrusting and strike slip movement along crustal scale faults during dextral transpression

luminescence dating indicates radiocarbon age underestimation in late pleistocene fluvial deposits from eastern england robust geochronological control is crucial for interpreting and correlating the environmental record from fragmentary terrestrial sequences from the last glacial period traditional terrestrial stratigraphies are typically reliant on radiocarbon dating although estimates of antiquity for samples older than 40 ka may be unreliable optically stimulated luminescence osl dating of sediments is an alternative for dating the whole of the last glacial period and also provides the opportunity to independently test radiocarbon based chronologies this paper presents a set of nine directly comparable paired osl and accelerator mass spectrometry ams radiocarbon ages from multiple sites within devensian fluvial sediments in lowland britain and shows that it is possible to obtain robust osl age estimates throughout this time period the two techniques agree well for ages younger than ca 29 14c ka bp ca 35 cal ka bp but disagree beyond ca 35 14c ka bp ca 40 cal ka bp this is thought to be due to radiocarbon ages on older organic material having been contaminated by low levels of modern carbon it is therefore suggested that all conventionally pre treated radiocarbon ages greater than 35 14c ka bp should be treated with extreme caution copyright 2009 john wiley sons ltd

origin of the eskay creek precious metal rich volcanogenic massive sulfide deposit fluid inclusion and stable isotope evidence the eskay creek deposit is an unusual polymetallic au ag rich volcanogenic sulfide sulfosalt deposit located in the iskut river area of northwestern british columbia canada economic concentrations of precious and base metals are contained in the 21 zone which is divided into a number of subzones as of december 31 1998 total production and proven probable reserves are 1 9 million tons mt at 60 2 g t au 2 652 g t ag 3 2 percent pb 5 2 percent zn and 0 7 percent cu the 21b zone which contains the bulk of the reserves began production in 1995 the mineralization occurs mainly as well preserved stratiform clastic beds of sulfide sulfosalt debris and also as discordant footwall quartz sulfide veins the hydrothermal system that formed the eskay deposit was low temperature

u pb geochronology of archean metasedimentary rocks in the pontiac and abitibi subprovinces quebec constraints on timing provenance and regional tectonics abstract u pb isotopic ages of single detrital zircons have been obtained from metasandstones in the northern part of the pontiac subprovince and from the cadillac kewagama and lac caste groups within the southern abitibi subprovince youngest detrital zircon ages from these sequences are 2685 2686 2687 and 2693 ma respectively the lac fourniere pluton which intrudes pontiac group metasedimentary rocks is dated at 2682 1 ma a similar age was previously measured from a pluton that cuts the kewagama group these data bracket deposition of greywacke in the pontiac and abitibi subprovinces to 2685 3 ma in contrast the youngest zircon found in a volcaniclastic unit interbedded with timiskaming group metawacke is 2673 2 ma while the age of a pluton that intrudes the timiskaming is 2672 1 ma thus the timiskaming group is distinctly younger than the other metasedimentary rocks the normalized probability distributions of detrital zircon ages from the pontiac and the abitibi metasedimentary rocks as well as of dated igneous rocks from the southern abitibi subprovince all show that their major zircon populations formed in the age range 2685 2710 ma the distributions for the abitibi metaturbidites and dated igneous rocks are very similar suggesting that metasedimentary rocks in the abitibi belt were mostly derived from the surrounding granite greenstone terrain the largest peak of the pontiac distribution is a few million years younger than that from the abitibi metasedimentary rocks but there is a correlation between major peaks and both groups show similar age ranges for older pre abitibi components 2750 2850 and 3020 3030 ma deposition of the ca 2685 ma sediments was virtually syn deformational based on previous field geochemical and isotopic studies as well as the detrital zircon age data the pontiac group may represent a foreland basin that may have developed from an accretionary prism the source of much of the sediment may have been an uplifted extinct continental arc to the north the arc was mostly eroded into the sediment basin and perhaps tectonically overridden by a southward advancing nappe complex comprised of its back arc basin now partly preserved in the southern volcanic zone of the abitibi subprovince metaturbidites exposed between metavolcanic assemblages within the greenstone belt may represent overturned unconformities at the structural base of the greenstones these were brought up by high angle faults which also localized deposition of non marine timiskaming type sediments it is tentatively suggested that pontiac type metasedimentary rocks extend most of the way beneath the abitibi subprovince the oldest part of the basin emerging as the quetico group in the western superior province

a field chemical and stable isotope study of subseafloor metamorphism of the josephine ophiolite california oregon the josephine ophiolite is a large complete ophiolite generated in a late jurassic back arc basin along western north america the ophiolite underwent subseafloor metamorphism under a steep thermal gradient as indicated by downward changes in mineralogy and 18o values characteristic mineral zonation includes mica orthoclase and hematite in the lower extrusives greenschist facies assemblages in the upper sheeted dikes and amphibolite facies assemblages in the lower sheeted dikes and high level gabbro cumulate gabbros are only incipiently altered but are depleted in 18o indicating high temperature alteration with fluids that evolved at low water w rock r ratios a second off axis circulation system is recorded by metalliferous sediments that occur 8 21 m above the ophiolite alteration in the upper sheeted dike complex and especially the extrusive sequence is heterogeneous at outcrop scale as indicated by large variations in mineralogy chemistry and 18o values within individual pillows and dikes the heterogenity is due to 1 variations in w r ratio and starting material during alteration by downwelling seawater e g pillow cores versus glassy rims and 2 localized discharge mineralization mostly epidosites superimposed on the background recharge alteration epidosites occur largely as dike parallel stringers irregular replacement of pillow and massive lava and replacement of interpillow and pillow breccia matrices the chemistry of most extrusives and sheeted dikes is characterized by loss of ca and gain in na and mg consistent with alteration by downwelling fluids in addition the sheeted dikes are depleted in k2o and the lower sheeted dikes and high level gabbros are depleted in zn and cu the 18o and d values for most samples from the extrusive sequence indicate alteration by seawater at 50 rotation of the entire crustal sequence at the spreading axis suggests that the ophiolite formed at a slow spreading center where magma chambers were episodic

late middle pleistocene deposits at norton farm on the west sussex coastal plain southern england the coastal plain of west sussex southern england is internationally important because of the sequence of discrete high sea level events preserved at various elevations across it new evidence is presented from a site at norton farm near chichester on the lower coastal plain where pleistocene marine sands fining upwards into silts occur between 5 3 m and 9 1 m od the sequence reflects a regressive tendency at the transition from an interglacial to a cold stage the marine sands have yielded foraminifera ostracods and molluscs that indicate a declining marine influence through the sequence culminating in a tidal mudflat strongly weathered in places cool climate foraminifera including elphidium clavatum cassidulina reniformis and elphidium albiumbilicatum and ostracods have been recovered from the marine sands some species with an apparent preference for warmer water conditions however are also present freshwater taxa washed into the terminal marine sediments include some cold climate indicators such as pisidium stewarti and p obtusale lapponicum additional evidence for cool climatic conditions during the deposition of the upper part of the marine sequence is provided by the lack of tree taxa in the pollen record and by features of the micromorphology the marine sediments probably began accumulating during ois 7 a conclusion based on their elevation on amino acid ratios from shells but especially on vertebrate evidence particularly the presence of a small form of horse together with a large distinctive form of northern vole microtus oeconomus the occurrence of cool climate indicators in these marine sediments may demonstrate a lag between the climatic deterioration and the expected glacio eustatic fall in relative sea level this evidence appears to support the conclusions drawn from the study of coral terraces in barbados such a scenario would provide the conditions necessary for the emplacement of the large erratic boulders reported from the lower coastal plain of west sussex copyright c 2000 john wiley sons ltd

an oxygen isotope study of the kidd creek ontario volcanogenic massive sulfide deposits evidence for a high 18 o ore fluid the hydrothermally altered rhyolites delta 18 o 10 16ppm at the kidd creek cu zn ag pb volcanogenic massive sulfide deposit archean abitibi greenstone belt are all markedly enriched in 18 o compared to almost all other massive sulfide deposits a chalcopyrite stockwork zone forming a concordant keel stratigraphically below the massive sulfide typically has whole rock delta 18 o 10 to 12 per mil beneath the stockwork keel rhyolite delta 18 o values systematically increase stratigraphically downward for about 50 m below this level all of the footwall rhyolites in the kidd creek area display exceptionally high delta 18 o values of 13 to 16 per mil the groundmass quartz in the rhyolites ranges from 13 6 to 15 5 per mil and crosscutting quartz veins associated with the chalcopyrite stockwork mineralization have delta 18 o 11 9 per mil by contrast the postore basalts of the hanging wall are weakly altered show only modest 18 o enrichments delta 18 o 8 10ppm and are isotopically similar to the volcanic rocks in other parts of the abitibi greenstone belt petrographically all of the kidd creek footwall rhyolites are intensely altered typically containing 76 90 wt sio 2 indicating that the high 18 o characteristics are not primary magmatic features but are the result of hydrothermal alteration several disequilibrium oxygen isotope relationships are present for example volcaniclastic rhyolites consist of extremely 18 o rich chlorite rich and sericite rich clasts enclosed within a lower 18 o sericitically altered rhyolite tuff matrix this implies at least a two stage hydrothermal history involving either different temperatures of alteration or different fluid sources or both using a temperature of 300 degrees to 350 degrees c the main ore forming fluid must have had delta 18 o 6 to 9 per mil inasmuch as the associated felsic volcanic rocks were apparently erupted in a shallow subaqueous locally subaerial environment the most plausible origin of the ore fluid is evaporation and enrichment in 18 o of normal seawater in a closed basin at the western edge of the abitibi belt this would produce a strongly 18 o shifted high salinity fluid that would have been capable of transporting large amounts of metals the high 18 o signature of the kidd creek timmins volcanic rocks may constitute an exploration target that warrants further study and evaluation in other areas

middle to late pleistocene palaeoecological reconstructions and palaeotemperature estimates for cold cool stage deposits at whittlesey eastern england fossiliferous beds in a complex sequence of late middle to late pleistocene deposits at whittlesey eastern england provided a rare opportunity for a multidisciplinary study of the palaeoecology of cool cold stage deposits from different glacial stages the fossiliferous sediments investigated form part of the river nene 1st terrace three of the four fossil assemblages investigated pre date the last interglacial stage ipswichian eemian marine oxygen isotope stage mis 5e whereas the other dates to part of the mis 3 interstadial complex middle devensian weichselian pollen plant macrofossil molluscan coleopteran ostracod foraminifera and vertebrate data are available to a greater or lesser extent for each cool cold stage assemblage and they broadly present the same ecological picture for each one a continuum from low energy permanent to non permanent aquatic habitats through marshland with associated waterside taxa together with flood influxes of fluvial riparian and ruderal taxa although each fossil assemblage records cool cold climatic conditions to a greater or lesser extent these conditions are more apparent in the insect and ostracod faunas in comparison with results published for the last glacial maximum lgm stadial in the netherlands palaeotemperature estimates based on ranges of mutual agreement between independent coleopteran and ostracod methods for the three pre ipswichian eemian assemblages indicate minimum mean july air temperatures that are from 1 to 3 c warmer but january values that embrace the 8 c estimate for the lgm there is however a disparity between the coleopteran and ostracod palaeotemperature estimates for the middle devensian weichselian fossil assemblage which are based on two different sample stratigraphic levels the lower coleopteran assemblage is indicative of very cool continental climates whereas the stratigraphically slightly higher ostracod assemblage suggests a climatic amelioration lack of numerical age estimates prevents a robust stratigraphical interpretation but the youngest pre ipswichian eemian fossil assemblage could date to the mis 7 6 transition at a time when cooling possibly preceded glacially driven sea level fall it is apparent from the rich coleopteran data that some continental cold indicator taxa also appeared in pre ipswichian eemian cold stages and therefore assignment of continental cold indicator taxa to particular devensian weichselian intervals should be undertaken with care

marine isotope stage 7 6 transition age for beach sediments at morston north norfolk uk implications for pleistocene chronology stratigraphy and tectonics optically stimulated luminescence age estimates for the pleistocene beach at morston north norfolk uk obtained by the single aliquot regenerative dose protocol indicate a marine isotope stage mis 7 6 transition date the view that the beach is of ipswichian mis 5e age held virtually unanimously for the last 75 years may now be discarded the extant beach sequence lies up to 5 m od yet global models suggest that mis 7 6 sea levels were typically substantially below that of today the explanation may lie with poorly understood regional tectonic movements the mis 7 6 date helps to constrain the ages of glacial deposits that bracket the beach sediments at morston the underlying marly drift till cannot be younger than mis 8 this may also be true for the complex assemblage of glaciogenic landforms and sediments including the blakeney esker in the adjacent lower glaven valley the well established late devensian mis 2 age of the hunstanton till is not compromised by the date of the morston beach there is no indication of a proposed briton s lane glaciation during mis 6 times copyright 2009 john wiley sons ltd

structural geology of the blake river group at the bousquet mine abitibi quebec in the bousquet mining district metamorphosed volcanic rocks of the blake river group brg exhibit discrete strain features resulting from three generations of structures d1 d2 and d3 deformat

possible submarine advanced argillic alteration at the basin lake prospect western tasmania australia the basin lake copper gold prospect lies in western tasmania s mount read volcanics and is hosted in a series of calc alkaline andesites quartz feldspar porphyries mudstones carbonates and sandstones between the tyndall group and the central volcanic complex alteration at the basin lake prospect occurs over a strike length of 1 4 km and includes thin strata bound pyrophyllite quartz paragonite kaolinite pyrite alunite alteration zones up to 12 m wide and containing up to 50 wt percent pyrophyllite with local fluorite veining these zones grade out to paragonite muscovite kaolinite quartz pyrite and muscovite carbonate chlorite alteration zones extensive propylitic alteration chlorite carbonate epidote affects most other rocks outside these zones mineralization consists of thin strata bound zones of massive and vein pyrite tennantite and chalcopyrite with trace covellite and galena hosted mainly within an intensely silicified core of the pyrophyllite quartzsericite alteration zone pyrite has 34s values of 1 4 to 6 9 per mil although marginal vein pyrite in the propylitic zone has 34s values around 12 4 per mil large silicified glacial erratic boulders at surface contain massive and vein pyrite enargite and tennantite with minor barite and trace covellite stannoidite and mawsonite pyrite and enargite have 34s values of 1 7 to 6 8 per mil barite has 34s values around 35 2 per mil with 87sr 86sr around 0 7108 the alteration and mineralization at the basin lake prospect is similar to that associated with high sulfidation copper gold systems formed by acidic relatively oxidized fluids a new geochemical vector here termed the advanced argillic alteration index aaai 100 sio2 sio2 10mgo 10cao 10na2o has been devised to help quantify the intensity of alteration the values of the aaai at basin lake are similar to those of several high sulfidation epithermal deposits the low sulfide 34s values are similar to those at other sulfide occurrences in the mount read volcanics that have previously been considered to be barren are lower than those of nearby volcanic hosted massive sulfide deposits and may indicate a magmatic fluid component however the 34s and 87sr 86sr values of basin lake barite at the assumed highest exposed level of the system and higher 34s values in pyrite from marginal veins are similar to those of cambrian volcanic hosted massive sulfide systems indicating the involvement of reduced seawater sulfate at these locations calcite carbon and oxygen isotope values silicate oxygen isotope values and the unusual abundance of carbonate close to advanced argillic alteration indicate fluid mixing and suggest that acidic magmatic fluids were likely neutralized by seawater this occurrence strengthens the case for prospecting the mount read volcanics and other similar submarine volcanic belts for copper gold and gold only deposits that formed by the actions of hyperacid oxidized fluids

palaeoecology of a late mis 7 interglacial deposit from eastern england a multidisciplinary investigation was undertaken to establish the palaeoecology of three different fluvial depositional environments in the basal sediments of a richly fossiliferous channel infill at whittlesey eastern england which is dated by amino acid racemization aar to marine oxygen isotope stage mis 7 molluscan and coleopteran data indicate that the river flowed throughout the year supporting extensive adjacent marshland palaeobotanical and insect evidence indicates that extensive deciduous woodland was present and the ostracod evidence indicates that saline habitats were available locally suggesting that sea level at the time was not much different to today pollen and insect data do not differentiate thethree different depositional environments in contrast to the molluscan and ostracod evidence temperature estimates based on insect and ostracod data indicate a mutual mutual mean july temperature of 16 21 c and 1 to 3 c for january this is the first fully interglacial fluvial fossil assemblage described so far for the river nene catchment that is reliably dated to mis 7 of particular note is the molluscan assemblage which contains eight exotic species including theodoxus danubialis a species described previously in the united kingdom only in mis 11 deposits associated with the river thames catchment also of note is the insect assemblage which in contrast contains no exotic species unlike other mis 7 insect assemblages recorded so far in the united kingdom together these faunal assemblages may suggest a hitherto uninvestigated phase of a british interglacial stage which the aar data indicate could be late in mis 7 the possibility that this so far unique interglacial fossil assemblage is the result of acombination of local preservation potential and environmental factors however cannot be ruled out 2013 elsevier ltd and inqua

low temperature alteration at the world class laronde penna archean au rich volcanogenic massive sulfide deposit abitibi subprovince quebec canada evidence from whole rock oxygen isotopes the oxygen isotope composition of 169 whole rock samples from the world class laronde penna au rich volcanogenic massive sulfide deposit range from 6 5 to 22 0 fractional crystallization from basalt to rhyolite accounts for a variation of approximately 2 in primary whole rock 18o values the remaining variance in whole rock 18o values found at laronde penna must therefore be ascribed to water rock exchange with hydrothermal fluids the metamorphosed hydrothermally altered host rocks have been subdivided according to mineralogical assemblages which display weak covariance with 18o values and whole rock geochemical alteration indices water rock equilibrium exchange models indicate that the high 18o values that characterize the laronde penna deposit are compatible with low temperature 150oc hydrothermal alteration at high water rock oxygen atomic ratios 1 50 zones of lower 18o values stratigraphically beneath the principal ore lens 20 north indicate local zones of higher temperature hydrothermal alteration the oxygen isotope composition of the hydrothermal fluid is estimated to have been 5 as a consequence of mixing between seawater 18o 0 and a component of magmatic water degassed from the volcanic and intrusive rocks associated with the laronde penna deposit

corrigendum to eyewitness stratigraphy chemistry and eruptive dynamics of the 1913 plinian eruption of volcan de colima mexico journal of volcanology and geothermal research 191 2010 149 166 a universidad autonoma de san luis potosi instituto de geologia fac ingenieria av manuel nava no 5 zona universitario 78240 san luis potosi s l p mexico b departamento de vulcanologia instituto de geofisica universidad nacional autonoma de mexico coyoacan d f 04510 mexico c facultad de ciencias universidad de colima bernal diaz del castillo 340 col villas san sebastian c p 28045 mexico d departamento de geologia regional instituto de geologia universidad nacional autonoma de mexico coyoacan d f 04510 mexico e institute de physique du globe de paris paris france f department of geological sciences the university of texas at austin texas 78712 united states g escuela de ciencias de la tierra universidad autonoma de guerrero taxco guerrero mexico

evidence for late middle pleistocene glaciation of the british margin of the southern north sea the timing and extent of late middle pleistocene glaciations in england and the southern north sea are controversial topics the recent trent valley palaeolithic project uncovered evidence for a post anglian pre devensian glaciation that affected much of central and eastern england the wragby till of lincolnshire is associated with this glacial event attributed here to marine oxygen isotope stage mis 8 coeval glacigenic deposits in the middle trent suggest that both western and eastern lobes of mis 8 ice reached the derby area these various deposits have been assigned previously to mis 12 10 or 6 although the last can be excluded for the wragby till which is overlain by trent terrace deposits assigned to mis 7 from biostratigraphy and amino acid dating the disposition of these glacigenic deposits within the landscape particularly in relation to terrace deposits of the ancestral river trent and the absence of mis 11 and 9 deposits within the footprint of the glaciation also provide compelling evidence at its maximum extent in eastern england the mis 8 ice reached the peterborough area identifying its extension or otherwise into areas such as north west norfolk and the west midlands requires further work

extreme 18o enriched volcanics and 18o evolved marine water aljustrel iberian pyrite belt transition from high to low rayleigh number convective regimes abstract quartz eye keratophyric tuffs at aljustrel s portugal iberian pyrite belt possess unusually high uniform whole rock values up to 18 1 with a mean of 16 7 0 7 because the quartz eye cores have 18o 12 0 to 13 5 the felsic tuffs may have had an original whole rock oxygen isotope composition of 10 to 11 the deduced enrichments of up to 8 in keratophyric derivatives is attributed to isotope exchange with abundant marine water under temperatures which diminished to 100 c during thermally driven convective cooling the isotopic uniformity requires elevated permeability of 10 8 cm2 such that the second critical rayleigh number was exceeded and drifting non steady state convection cells dominated with relatively smooth thermal structures in mineralised counterparts of the tuffs beneath the feitais estacao zn pb cu massive sulphide orebodies whole rock values are 12 and quartz 13 3 15 4 chlorite 3 2 6 3 fractionations correspond to temperatures of 220 270 c and a calculated fluid 18o of 1 4 to 5 7 this local isotopic overprinting in vent domains of the regionally high 18o was induced by a stable second stage convective regime imposed by drastic reduction of permeability accompanying capping of the geothermal discharge by hydrothermal cherts and or progressive spilitisation of the tuffs at lower water rock coupled with higher temperatures the recirculating marine water underwent variable 18o enrichment up to 5 7 by exchange with the high 18o tuffs an upwards increase in 18o quartz and quartz reflects progressive cooling of the geothermal discharge from 15 4 270 c in the stockwork through 18 3 220 240 c in the orebody to 20 1 110 130 c in overlying hydrothermal cherts probably induced by entrainment of ambient marine bottom water in sub seafloor aquifers

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

fluvial system response to late devensian weichselian aridity baston lincolnshire england little is known about the impact of late devensian weichselian aridity on lowland british landscapes largely because they lack the widespread coversand deposits of the adjacent continent the concentration of large interformational ice wedge casts in the upper part of many devensian fluvial sequences suggests that fluvial activity may have decreased considerably during this time the development of optically stimulated luminescence osl dating enables this period of ice wedge cast formation to be constrained for the first time in eastern england where a marked horizon of ice wedge casts is found between two distinctive dateable facies associations contrasts between this horizon and adjacent sediments show clear changes in environment and fluvial system behaviour in response to changing water supply in line with palaeontological evidence in addition to providing chronological control on the period of ice wedge formation the study shows good agreement of the radiocarbon and osl dating techniques during the middle and late devensian with direct comparison of these techniques beyond 15 000 yr for the first time in britain it is suggested that aridity during the late devensian forced a significant decrease in fluvial activity compared with preceding and following periods initiating a system with low peak flows and widespread permafrost development

pleistocene fluvial sediments palaeontology and archaeology of the upper river thames at latton wiltshire england pleistocene fluvial sediments of the northmoor member of the upper thames formation exposed at latton wiltshire record episodic deposition close to the churn thames confluence possibly spanning the interval from marine isotope stages mis 7 to 2 the sequence is dominated by gravel facies indicating deposition by a high energy gravel bed river a number of fine grained organic sediment bodies within the sequence have yielded palaeoenvironmental and biostratigraphical data from mollusca coleoptera vertebrates pollen and plant macrofossils the basal deposit facies association a contains faunal material indicating temperate conditions most of the palaeontological evidence including a distinctive small form of mammoth mammuthus cf trogontherii together with the u series age estimate of 147 4 20 kyr suggest correlation with mis 7 the overlying deposits facies associations b and c represent deposition under a range of climatic conditions two fine grained organic deposits occurred within association b one association ba in the northern part of the pit as a channel fill and the other association bb in its southern part as a scour fill deposit the coleopteran assemblages from ba indicate that it accumulated under temperate oceanic conditions while bb which also yielded a radiocarbon age estimate of 39 560 780 14c yr bp was formed under much colder and more continental climatic conditions the sequence is considered to represent deposition within an alluvial fan formed at the churn thames confluence a depositional scenario which may account for the juxtaposition of sediments and fossils of widely differing age within the same altitudinal range

regional stable isotope systematics of hydrothermal alteration and massive sulfide deposition in the west shasta district california the west shasta cu zn district is located in california at the southern end of the klamath mountains and contains numerous pyrite dominant volcanogenic massive sulfide deposits the deposits are hosted in a bimodal suite of intrusive and extrusive basalt to andesite copley greenstone and rhyolite balaklala rhyolite of devonian age regional variations in oxygen hydrogen and sulfur isotope ratios in the copley greenstone balaklala rhyolite and mule mountain trondhjemite record hydrothermal alteration which took place over a large range in temperature from 18 o values vary for the copley greenstone from 3 5 to 11 6 per mil and for the balaklala rhyolite from 7 6 to 13 3 per mil delta d values of the copley range from 71 to 42 per mil and for most samples of the balaklala from 73 to 46 per mil the isotopic variation reflects changing mineralogy in addition to a range of alteration temperatures with progressive chloritization the water content of the copley greenstone increases from 1 51 to 8 34 wt percent h 2 o whereas the delta 18 o values decrease water rock mass ratios calculated from the oxygen isotope data are 1 8 to 2 8 for high temperature alteration regional variations in delta d and delta 18 o values of the copley greenstone indicate higher temperatures of alteration and greater water rock interaction adjacent to the mule mountain stock beneath the area of the iron mountain mine largest of the massive sulfide deposits this suggests that the stock is the heat source responsible for the iron mountain deposit the alteration pattern associated with the stock and the low temperature isotopic alteration of the capping porphyry upper unit of the balaklala indicate that the mule mountain stock was coeval with the middle unit of the balaklala estimates of the oxygen isotope compositions of the balaklala and mule mountain magmas delta 18 o approximately 6 5ppm from analyses of quartz phenocrysts suggest that the two magmas or magma types are consanguineous and were derived from the same source as the copley greenstone sulfur isotope data support this interpretation there is no clear evidence for temporal variations in the isotopic composition of the magmas mass balance considerations and data on the isotopic composition and content of sulfur in the copley greenstone most 95 percent of the sulfur in the ore deposits could have been leached from the copley greenstone during hydrothermal alteration the variation in delta 34 s values of whole rock samples is larger for the copley 4 0 to 22 4ppm most 0 0 to 6 0ppm than for either the balaklala 3 3 to 4 9ppm or the massive sulfide deposits 0 5 to 6 0ppm but most 3 0 to 5 0ppm no correlation is found between the abundance and isotopic composition of sulfur in the copley greenstone isotopic fractionation effects during transport and local reprecipitation of leached sulfur can explain the sulfur isotope variability of the copley greenstone sulfur isotope data also support degassing of the mule mountain or related magmas as a sulfur source

evolution of the southern abitibi greenstone belt based on u pb geochronology autochthonous volcanic construction followed by plutonism regional deformation and sedimentation abstract new mapping and u pb zircon geochronological results in the southern abitibi greenstone belt sagb support an autochthonous regional stratigraphy comprised of nine supracrustal assemblages rather than the collage of allochthonous terranes proposed in recent publications based on lithological and geochronological criteria these supracrustal assemblages also encompass the swayze shining tree and montcalm greenstone belts indicating that despite separation by large granitic intrusions they are in fact part of one extensive greenstone belt in conjunction with the mapping the geochronological results support coherent upward facing stratigraphic sections with about 20 of the samples containing inherited zircons with ages similar to those found in underlying assemblages the seven oldest assemblages represent semi continuous volcanism from 2750 to 2697 ma the volcanism is compositionally diverse ranging from komatiite and tholeiitic basalt to calc alkaline mafic to felsic lavas intimate intermingling of the different magma clans occurs throughout much of the stratigraphic section regional fault control on the distribution of the volcanic assemblages provides evidence for early dip slip movement associated with volcanic extension dating back to at least 2725 ma the two youngest assemblages are dominantly sedimentary and were unconformably deposited on the volcanic assemblages in close proximity to regional faults the earlier sedimentary assemblage consists of turbidites and minor iron formation deposited from 2696 to 2692 ma and the youngest one of subaerial conglomerates fluvial sandstones and alkalic to shoshonitic volcanic rocks ranging in age from 2687 to 2675 ma the sedimentary assemblages are broadly contemporaneous with the emplacement of syntectonic granitic plutons regional folding and reactivated movement on the regional faults probably related to accretion of the abitibi to the superior province craton autochthonous repetition of different geodynamic environments over the 50 million years of volcanic activity with five dominantly tholeiitic komatiitic assemblages and two dominantly calc alkaline assemblages as well as the extensive intermingling of these different magma clans in a number of the assemblages appears to be unique to the archean it suggests complex large scale and long lived interaction between mantle plumes and subduction zone magmas the nd isotope data indicate a derivation of the diverse volcanic magmas from homogeneously depleted sources with end 2 5 0 5 demonstrating a lack of contamination by ancient enriched components

late and middle pleistocene deposits at somersham cambridgeshire u k a model for reconstructing fluvial estuarine depositional environments gravel quarries at somersham cambridgeshire have yielded evidence for a pleistocene channel of the r great ouse containing temperate stage sediments between cold stage sediments in the earlier cold stage fluviatile gravels and floodplain loessic sediment accumulated in the later cold stage a further series of gravel units and floodplain sediments were deposited together with lake sediments the lake sediments are associated with lake sparks dammed by late devensian ice in the wash at ca 18 5 ka bp the lake sediments overlie gravels with a radiocarbon date from an organic horizon indicating a middle devensian age clast lithological analyses from the earlier and later gravels suggest that reworking of gravels has occurred within a relatively stable catchment the petrography of the earlier cold stage loessic sediment and temperate stage fine sediment indicates an anglian affinity which conflicts with the biostratigraphic interpretation pollen and macroscopic plant remains from sediments of both cold stages and from the temperate stage indicate respectively assemblages with a typical full glacial aspect with a rich flora of shrubs and open ground herbs including an assemblage at ca 18 ka and temperate freshwater and marine influenced organic sediments on the basis of pollen analysis these are ascribed to substages ip ii and iii of the ipswichian stage o i s 5e with a pinus quercus corylus biozone in the former and a biozone with carpinus in the latter marine influenced sediments at 3 7 to 0 3 m od indicate transgression in ip ii and regression in ip iii molluscan assemblages from the temperate stage and the later cold stage are described two are from the late devensian at a time near the maximum extension of ice into the wash foraminifer and ostracod faunas are described from post ipswichian sediments and may be reworked radiocarbon dates confirm the age of the later gravel suite as devensian and a calibration of the measurements is given amino acid ratios from corbicula fluminalis valves from temperate stage sediments are reported with measurements from different parts of the valve the results tend to support an ipswichian age tl measurements of the earlier cold stage loessic sediment and associated sand indicate a pre ipswichian age for the sediments the earlier cold stage is correlated with the pre ipswichian cold stage the wolstonian of mitchell et al 1973 problems with this correlation are discussed various periglacial phenomena including thermal contraction networks and cracks diapirs involutions and coversand are associated with the devensian sequence the complex environmental history based on stratigraphy and palaeontology is described and related to other nearby sites in southern fenland