quantitative remote sensing study indicates doubling of coastal erosion rate in past 50 yr along a segment of the arctic coast of alaska a new quantitative coastal land gained and lost method uses image analysis of topographic maps and landsat thematic mapper short wave infrared data to document accelerated coastal land loss and thermokarst lake expansion and drainage the data span 1955 2005 along the beaufort sea coast north of teshekpuk lake in the national petroleum reserve in alaska some areas have undergone as much as 0 9 km of coastal erosion in the past 50 yr land loss attributed to coastal erosion more than doubled from 0 48 km2 yr 1 during 1955 1985 to 1 08 km2 yr 1 during 1985 2005 coastal erosion has breached thermokarst lakes causing initial draining of the lakes followed by marine flooding although inland thermokarst lakes show some uniform expansion lakes breached by coastal erosion display lake expansion several orders of magnitude greater than inland lakes

stratigraphic signature of a terminal early cambrian regressive event in the iberian peninsula in the iberian peninsula the uppermost lower cambrian early bilbilian age is represented by the deposition of conglomerates and sandstones except in a northwestern region the cantabrian mountains where carbonate deposition took place these coarse siliciclastic deposits indicate a regressive trend called the daroca regression in its type area the iberian chains northeast spain this regressive episode represents a progradational highstand systems tract which did not result in widespread subaerial exposure of the shelf in addition the absence of important stratigraphical gaps and the good biostratigraphical control based on trilobites and acritarchs in the iberian chains permit a correlation of this regressive trend with other neighboring areas where the top of this trend is represented by a regional unconformity and a hiatus that began in the latest early cambrian and extended through early middle cambrian times

transition from slab to slabless results from the 1993 mendocino triple junction seismic experiment three seismic refraction reflection profiles part of the mendocino triple junction seismicexperiment allowustocompareandcontrastcrustanduppermantleofthenorth american margin before and after it is modified by passage of the mendocino triple junction upper crustal velocity models reveal an asymmetric great valley basin overlying sierran or ophiolitic rocks at the latitude of fort bragg california and overlying sierran or klamath rocks near redding california in addition the upper crustal velocity structure indicates that franciscan rocks underlie the klamath terrane east of eureka california thefranciscancomplexis onaverage laterallyhomogeneousandisthickestinthe triple junction region north of the triple junction the gorda slab can be traced 150 km inboardfromthecascadiasubductionzone southofthetriplejunction strongprecritical reflections indicate partial melt and or metamorphicfluids at the base of the crust or in theuppermantle breaksinthesereflectionsarecorrelatedwiththemaacamaandbartlett springs faults suggesting that these faults extend at least to the mantle we interpret our datatoindicatetectonicthickeningofthefranciscancomplexinresponsetopassageofthe mendocino triple junction and an associated thinning of these rocks south of the triple junction due to assimilation into melt triggered by upwelling asthenosphere the region of thickenedfranciscancomplexoverliesazoneofincreasedscattering intrinsicattenuation or both resulting from mechanical mixing of lithologies and or partial melt beneath the onshore projection of the mendocino fracture zone our data reveal that we have crossed thesouthernedgeofthegordaslabandthatthisedgeand ortheoverlyingnorthamerican crust may have fragmented because of the change in stress presented by the edge

strong climate coupling of terrestrial and marine environments in the miocene of northwest europe a palynological and organic geochemical record from a shallow marine paleoenvironmental setting in se netherlands documents the coupled marine and terrestrial climate evolution from the late burdigalian 17 ma through the early zanclean 4 5 ma proxy climate records show several coeval variations in both relative sea surface deduced from percent cool dinocysts and terrestrial subtropical vs cool temperate pollen temperature indices the terrestrial climatic trend is confirmed by a quantitative reconstruction of annual mean air temperature based on the distribution of fossil branched glycerol dialkyl glycerol tetraethers showing a cooling from 27 c to 14 c between 17 and 5 ma punctuated by short term variations decreases in sea surface temperature broadly correlate to inferred third order sea level variations and correspond to isotope glacial events mi 3 through mi 7 an additional strong sst decrease occurs around 8 4 ma coincident with a strong reduction and regional disappearance of subtropical pollen types this cooling phase seems associated with lowered sea levels but it has not yet been described from the deep sea 18o record 2009 elsevier b v

plate boundary observatory and related networks gps data analysis methods and geodetic products the geodesy advancing geosciences and earthscope gage facility global positioning system gps data analysis centers produce position times series velocities and other parameters for approximately two thousand continuously operating gps receivers spanning a quadrant of earth s surface encompassing the high arctic north america and caribbean the purpose of this review is to document the methodology for generating station positions and their evolution over time and to describe the requisite tradeoffs involved with combination of results gage gps analysis involves formal merging within a kalman filter of two independent loosely constrained solutions one is based on precise point positioning produced with the gps inferred positioning system orbit analysis simulation gipsy oasis software at central washington university cwu and the other is a network solution based on phase and range double differencing produced with the gps at mit gamit software at new mexico institute of mining and technology nmt the primary products generated are the position time series that show motions relative to a north america reference frame and secular motions of the stations represented in the velocity field the position time series themselves contain a multitude of signals in addition to the secular motions co seismic and post seismic signals seasonal signals from hydrology and transient events some understood and other not yet fully explained are all evident in the time series and ready for further analysis and interpretation we explore the impact of analysis assumptions on the reference frame realization and on the final solutions and we compare within the gage solutions and with others

alaska landfast sea ice links with bathymetry and atmospheric circulation 1 using radarsat synthetic aperture radar sar imagery of northern alaska and northwestern canada we calculated a mean climatology of the annual landfast ice cycle for the period 1996 2004 we also present the monthly minimum mean and maximum landfast ice extents throughout the study area these data reveal where and when the landfast is most stable and which sections of the coast are susceptible to midseason breakout events stabilization of landfast ice is strongly related to the advance of the seaward landfast ice edge slie into waters around 18 m deep isobaths near this depth are a good approximation for midseason landfast ice extent comparison with work from the 1970s suggests a reduced presence of landfast ice in this region of the arctic due to later formation and earlier breakup this will likely lead to an increase in coastal erosion and may also have profound effects upon subsistence activities which are intimately linked to the timing of marine mammal migration patterns interannually landfast ice formation correlates with the incursion of pack ice into coastal waters suggesting that the later mean date of formation in recent years may be related to the increasingly northward location of the perennial sea ice edge the timing of breakup correlates well with onset of thawing air temperatures analysis of regional data shows a multidecadal trend toward earlier thaw onset which suggests that the observed change in breakup dates may be part of a longer term trend

a lacustrine gdgt temperature calibration from the scandinavian arctic to antarctic renewed potential for the application of gdgt paleothermometry in lakes quantitative climate reconstructions are fundamental to understand long term trends in natural climate variability and to test climate models used to predict future climate change recent advances

palaeogeographical controls on the cambrian trilobite immigration and evolutionary patterns reported in the western gondwana margin abstract southward drifting of the western gondwanan margin during the cambrian has been demonstrated by means of both palaeomagnetic methods and lithological indicators of climate such as carbonates and evaporites recent improvements in biostratigraphical correlations permit an enhanced understanding of the climatic and palaeobiogeographical constraints that controlled the distribution of cambrian benthic communities palaeogeographical and biogeographical reconstructions based on trilobites are reported in this paper in order to test interaction between migration speciation and extinction rates the variability of the documented biogeographical patterns is directly related to species diversity in which wider distribution coincides with transgressive trends and subsequent connection of neighbouring platforms early cambrian trilobite faunas show a high degree of both substrate control and endemicity although transgressions led to parallel shifts in faunal compositions by contrast mid cambrian trilobite faunas are relatively uniform across western gondwana and latest mid and late cambrian associations document influence of an increased similarity with asian trilobite faunas

holocene paleoclimatology of the queen elizabeth islands canadian high arctic abstract a wide variety of evidence reflecting in different ways the changing climate of the queen elizabeth islands during the holocene is reviewed all proxies pertain to summer conditions many sources of information provide weak or equivocal paleoclimatic signals but a general pattern of events can be discerned temperatures in the early to mid holocene were highest comparable with or higher than temperatures prevailing for much of this century although much evidence points to a mid holocene thermal maximum there is also considerable evidence that conditions were warmer in the early holocene possibly related to orbitally induced radiation anomalies the apparent mid holocene thermal maximum may reflect lags in the response of the environment and of some proxies in recording paleoclimatic conditions more direct indices point to warmest conditions in the early holocene before 7500 bp temperatures declined from 3000 bp culminating in exceptionally low temperatures from 100 400 bp this may have been the coldest period of the entire holocene resulting in glacier advances to post glacial maximum positions the period since 1925 has witnessed a pronounced increase in temperature leading to negative mass balances on glaciers and ice sheets throughout the archipelago this period is the warmest for at least 1000 years and perhaps for several thousand years modern climate in the queen elizabeth islands may thus be characteristic of the early to mid holocene and atypical of conditions which prevailed for much of the last few thousand years

sedimentary patterns across the lower middle cambrian transition in the esla nappe cantabrian mountains northern spain in the carbonate platforms of the western gondwana margin the extinction recorded at the lower middle cambrian boundary is accompanied by a profound change in the style of carbonate deposition the lancara formation of the esla nappe cantabrian mountains northern spain contains a distinct sedimentary turnover due to a combination of tectonism eustatic fluctuations and immigration and colonization of new benthic communities such as the youngest archaeocyathan assemblage of the entire iberian peninsula during latest early cambrian times a regressive trend is recorded in the lancara formation this regression was recorded on a peritidal dominant homoclinal ramp that is topped by a tectonically induced discontinuity d1 the latter surface marks the beginning of a last prograding regressive tendency recorded on an intra shelf ramp with ooidal bioclastic shoals protecting archaeocyathan microbial patch reefs the overlying discontinuity d2 corresponds to a major erosive unconformity which coincides with the lower middle cambrian boundary in the cantabrian mountains the subsequent long term earliest middle cambrian rise in relative sea level allowed deposition of low relief bioclastic shoals bearing a diverse and cosmopolitan assemblage of benthic fauna finally the previous evolution is bounded by a third discontinuity d3 which marks the beginning of a rhythmic sedimentation indicative of a major phase of tectonic breakdown and drowning of platforms recognised throughout southwestern europe two associations of calcimicrobes occur in the latest early cambrian regressive trend of the lancara formation i proaulopora and subtiflora are identified in peritidal high energy settings lacking self supported structures whereas ii intergrowths of epiphyton renalcis and girvanella encrusted branching colonies and solitary archaeocyaths in protected back shoal patch reefs the latest early cambrian regression is correlated in southwestern europe in both siliciclastic iberian chains and ossa morena and carbonate dominant platforms cantabrian mountains montagne noire and sardinia its tops are recognised as diachronous unconformities ranging in age from early bilbilian to the bilbilian leonian or lower middle cambrian boundary

increasing long wavelength relief across the southeastern flank of the sierra nevada california abstract a high degree of correlation between present day relative rock uplift measured using continuous gps geodesy and spatially averaged surface elevations suggests that long wavelength topographic relief is presently increasing along the southeastern flank of the sierra nevada range and within an adjacent portion of the northern basin and range province current estimates for erosion rate are an order of magnitude smaller than the relative rates determined by geodesy thus although the uplift serves to enhance long wavelength relief it cannot be explained entirely as an isostatic response to erosion if uplift rates have been constant through time the duration over which the uplift could have been active

the lower middle cambrian stages and stratotypes from the iberian peninsula a revision lower middle cambrian regional stages of the iberian peninsula cordubian ovetian marianian bilbilian acadoparadoxides and solenopleuropsidae stages are now reconsidered in the light of new stratigraphic and palaeontological trace fossils trilobites and archaeocyaths studies these stages are re described with selected stratotypes and chronostratigraphic boundaries the names leonian and caesaraugustian are formally proposed to replace the provisional stages of acadoparadoxides and solenopleuropsidae respectively a correlation chart of the lower middle cambrian lithostratigraphic units from the iberian peninsula is also presented two regessive transgressive cycles are proposed to explain the lithological and palaeontological peculiarities through the lower middle cambrian sequence in the iberian peninsula

origin and distribution of terrestrial organic matter in the nw mediterranean gulf of lions exploring the newly developed bit index the branched and isoprenoid tetraether bit index is based on the relative abundance of nonisoprenoidal glycerol dialkyl glycerol tetraethers gdgts derived from organisms living in terrestrial environments versus a structurally related isoprenoid gdgt crenarchaeol produced by marine crenarchaeota the bit index varies between 0 and 1 representing marine and terrestrial organic matter om end members respectively hopmans et al earth planet sci lett 224 107 116 2004 in this study the applicability of the bit index to trace terrestrial om is tested in combination with other organic parameters toc c n ratio 13corg total lipid and n alkane in the gulf of lions a river dominated continental margin of the western mediterranean we analyzed a variety of soils and riverbed sediments from the continent as well as surface sediments from the shelf and canyons the bit index in soils and riverbed sediments shows high values 0 9 while it varies between 0 02 and 0 83 in marine sediments decreasing seaward from the inner shelf to the slope for marine surface sediments high bit values are associated with lower 13corg values as well as higher toc contents and higher n alkane concentrations our results confirm that the bit index can be applied in coastal marine environments in order to characterize terrestrial om as proposed by hopmans et al 2004 therefore the bit index is a useful addition to the proxies presently available for studying the origin and distribution of om in continental margins and especially valuable in multiproxy studies

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

guzhangian mid cambrian trilobites from siliceous concretions of the valtorres formation iberian chains ne spain in the carbonate siliciclastic strata of west gondwana e g in the montagne noire france the aftermath of the mid languedocian mid cambrian regression is characterized by a late languedocian major turnover of trilobite families and a furongian early tremadocian radiation related to the stepwise immigration of trilobite invaders from east gondwana under persistent transgressive conditions the scarcity of upper languedocian fossil accumulations in clayey substrates has inspired the sampling of the palaeogeographically most distal parts of the iberian chains spain where diagenetic dissolution of ubiquitous hexactinellid sponge spicules has favoured the formation of siliceous concretions these have yielded the trilobites peronopsis cf insignis oidalagnostus trispinifer proampyx difformis proampyx aculeatus bailiaspis glabrata holocephalina agrauloides by ontogeny holasaphus cf centropyge and a paradoxidid gen et sp indet despite preservation and sampling biases the identification of this taphonomic window in offshore clayey substrates of west gondwana allows the recognition of a strong biogeographical link with baltica and the correlation of the global guzhangian stage and the solenopleura brachymetopa zone of scandinavia with part of the mediterranean upper languedocian substage less

paleoenvironmental analyses of an organic deposit from an erosional landscape remnant arctic coastal plain of alaska abstract the dominant landscape process on the arctic coastal plain of northern alaska is the formation and drainage of thaw lakes lakes and drained thaw lake basins account for approximately 75 of the modern surface expression of the barrow peninsula the thaw lake cycle usually obliterates lacustrine or peat sediments from previous cycles which could otherwise be used for paleoecological reconstruction of long term landscape and vegetation changes several possible erosional remnants of a former topographic surface that predates the formation of the thaw lakes have been tentatively identified these remnants are characterized by a higher elevation a thick organic layer with very high ground ice content in the upper permafrost and a plant community somewhat atypical of the region ten soil cores were collected from one site and one core was intensively sampled for soil organic carbon content pollen analysis and 14c dating the lowest level of the organic sediments represents the earliest phase of plant growth and dates to ca 9000 cal bp palynological evidence indicates the presence of mesic shrub tundra including sedge birch willow and heath vegetation and microfossil indicators point to wetter eutrophic conditions during this period carbon accumulation was rapid due to high net primary productivity in a relatively nutrient rich environment these results are interpreted as the local response to ameliorating climate during the early holocene the middle holocene portion of the record contains an unconformity indicating that between 8200 and 4200 cal bp sediments were eroded from the site presumably in response to wind activity during a drier period centered around 4500 cal bp the modern vegetation community of the erosional remnant was established after 4200 cal bp and peat growth resumed during the late holocene carbon accumulation rates cars were greatly reduced in response to the combined effects of declining productivity associated with climatic cooling and increased nutrient stress as paludification and permafrost aggradation sequestered mineral nutrients

environmental controls on branched tetraether lipid distributions in tropical east african lake sediments abstract quantifying past continental temperature changes is an important aspect of paleoclimate research as it allows us to constrain the amplitude of natural variability test predictive climate models and provide a proper context for changes that may arise in response to anthropogenically induced climate change the recently developed biomarker based methylation index of branched tetraethers cyclization ratio of branched tetraethers mbt cbt proxy shows potential as a new method for continental temperature reconstruction but thus far it has only been applied successfully in ocean margin sediments to assess whether this proxy is also applicable to the sedimentary record in tropical lacustrine systems we investigated the distribution of branched glycerol dialkyl glycerol tetraethers gdgts in recently deposited sediments from 46 lakes in tropical east africa these lakes span a substantial range in surface elevation 770 4500 m above sea level and thus also a wide gradient of mean annual temperature we find that saline lakes excepted branched gdgts are universally abundant in the lakes investigated and can be used to predict mean annual air temperature maat with a high degree of accuracy however the existing global mbt cbt calibration for maat based on soils predicts inaccurate temperatures when applied to our african lake dataset this observation together with the fact that surface water ph and to lesser extent lake depth appear to influence the distribution of branched gdgts among sites leads us to conclude that in situ production of branched gdgts in lakes is likely the robust relationship between branched gdgt distribution and the temperature and ph of african freshwater lakes makes these compounds suitable for paleoenvironmental reconstruction however we urge caution in using branched gdgts in lake sediments to infer past temperatures unless their exact origin can be determined

rapid and widespread dispersal of flood sediment on the northern california margin the dispersal of flood sediment from small river systems is a poorly studied yet potentially important aspect of active continental margin sedimentation in january 1995 during a flood with a 30 yr return period the eel river northern california delivered an estimated 25 3 106 t metric tons of fine grained 62 m sediment to the ocean the flood formed a distinct layer on the sea bed that was centered on the 70 m isobath extended for 30 km along shelf and 8 km across shelf and was as thick as 8 5 cm but contained only 6 106 t of sediment thus 75 of the flood derived sediment did not form a recognizable deposit but was instead rapidly and widely dispersed over the continental margin stratigraphic models of and compilations of sediment flux to active continental margins need to take the dispersive nature of small river systems into account

the late cretaceous environment of the arctic a quantitative reassessment based on plant fossils abstract late cretaceous megafossil floras from the palaeo arctic of northeastern russia and northern alaska are reviewed in respect of their age composition structure and floral dynamics palaeofloral correlations and comparisons are made between the two regions nine angiosperm rich predominantly cenomanian to coniacian floras from the palaeo arctic are re evaluated using climate leaf analysis multivariate program clamp calibrated using a global gridded 0 5 0 5 climate data set derived from that used in climate modelling additional floras from lower palaeolatitudes were used to derive latitudinal temperature gradients seven from n america five from around 30 n palaeolatitude in europe and one from kazakhstan the arctic climatic determinations similar to previous estimates support the existence of a northern pacific ocean cold gyre and a warm arctic ocean at palaeolatitudes greater than 80 n floras are insufficiently diverse in woody dicot taxa to use clamp but using clamp derived latitudinal temperature gradients arctic ocean coastal environments at 70 ma and 82 n and which supported a diverse dinosaur magafauna are predicted to have experienced a mean annual temperature of 6 3 2 2 c a warm month mean of 14 5 3 1 c and a cold month mean no colder than 2 0 3 9 c all uncertainties are 2 the new estimates are in good agreement with a wide range of non palaeobotanical climate proxies and render as an outlier warmer temperature estimates for the arctic ocean derived from the tex 86 proxy modelling however shows that land to ocean temperature gradients could have been steep the clamp estimates also suggest high values for humidity and precipitation consistent with sedimentological indicators and coupled with warm temperatures support the existence of a persistent polar cloud cap that helped maintain high terrestrial air temperatures throughout prolonged periods up to 5 months of winter darkness

late neogene and quaternary landscape evolution of the northern california coast ranges evidence for mendocino triple junction tectonics a landscape records the surface response to tectonics at time scales intermediate between short time scale information derived from seismic imaging and global positioning systems and the long term geologic record we link late neogene and quaternary deposits and landforms in the northern california coast ranges to the tectonics of the mendocino triple junction in the northern california coast ranges the mendocino crustal conveyor geodynamic model describes crustal thickening thinning and dynamic topography that produce a double humped pattern of uplift that migrates northward with the mendocino triple junction the tectonics are manifest in the drainage system and elevation pattern of the coast ranges at long wavelengths the elevation pattern closely matches the predicted double peaked shape of mendocino crustal conveyor topography and the high points of uplift control the location of drainage divides presently the divide between the russian and eel rivers and the divide between the eel and van duzen rivers approximately correspond to the peaks of uplift predicted by the mendocino crustal conveyor model as the triple junction migrates northward the double humped pattern of uplift and subsidence migrates and the coast ranges emerge smaller drainages develop and evolve by stream capture and flow reversal and the two main divides migrate in concert with the triple junction in contrast to the systematic development of the small streams the largest trunk streams can maintain grade through regions of high uplift and coastal river mouths remain stationary despite the uplift moving north before ca 2 ma the majority of the coast range drainage flowed to a southern coastal outlet near the present mouth of the russian river at 2 ma facilitated by headwater stream capture at key locations the drainage direction reversed and the majority of coast range rivers now drain into the north flowing eel river the major drainage reorganization at 2 ma highlights the potential for complexity in geomorphic response to tectonics

fluxes and distribution of tetraether lipids in an equatorial african lake constraints on the application of the tex86 palaeothermometer and bit index in lacustrine settings abstract the distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether gdgt lipids was studied in material from various sources in and around lake challa a crater lake on the southeastern slope of mt kilimanjaro tanzania to examine the provenance of gdgts in lake sediments and their potential application as palaeoenvironmental and palaeoclimatic proxies the study material included samples collected at monthly intervals in a sediment trap over one complete annual cycle particles suspended in the stratified water column profundal surface sediments and soils surrounding the lake the sediment trap time series revealed that crenarchaeol and related isoprenoid gdgts were predominantly produced in january and february following the locally prominent short rain season november december the tex 86 inferred temperature derived from sedimenting particles corresponded well with lake surface water temperature at this time of largest crenarchaeol flux molecular ecological analysis showed that group 1 1a and 1 1b crenarchaeota are the most likely source organisms of these gdgts gdgt 0 in the lake sediments does not only originate from lake surface dwelling crenarchaeota but seems predominantly derived from archaea residing in the deeper anoxic part of the water column the main flux of branched gdgts to the sediment was during the short rain season and is most probably derived from eroded catchment soils in surface run off however a contribution from in situ production of branched gdgts in the lake sediment or water or in groundwater cannot be fully excluded we conclude that palaeoclimatic reconstruction based on branched gdgt distributions in lake sediments should only be performed when the origin of those branched gdgts is well constrained

coupled thermal and hydrological evolution of tropical africa over the last deglaciation we analyzed the distribution of branched tetraether membrane lipids derived from soil bacteria in a marine sediment record that was recovered close to the congo river outflow and the results enabled us to reconstruct large scale continental temperature changes in tropical africa that span the past 25 000 years tropical african temperatures gradually increased from 21 to 25 c over the last deglaciation which is a larger warming than estimated for the tropical atlantic ocean a direct comparison with sea surface temperature estimates from the same core revealed that the land sea temperature difference was through the thermal pressure gradient an important control on central african precipitation patterns

post middle miocene accretion of franciscan rocks northwestern california deformed sedimentary rocks assigned to the franciscan assemblage in the king range south of cape mendocino northern california are dominantly deep water argillite and sandstone occurring as thick to thin bedded locally channelized marine turbidites of arkosic to andesitic volcani clastic composition these rocks structurally overlie late cretaceous coniacian to campanian basaltic pillow flows flow breccias diabase sills and arkosic sandstone turbidites that also are assignable to the franciscan assemblage and are well exposed along the coast at point delgada radiolarians and planktic and benthic foraminifers indicate that the oldest rocks in the king range may be early tertiary and that the youngest rocks are middle miocene or younger the youngest rocks yet reported from the franciscan assemblage partly coeval miocene relizian and luisian to quaternary rocks representing shallower sedimentary facies of the inner shelf to outer continental slope occupy the eel river basin and isolated fault bounded slivers adjacent to the king range on the north and east wide zones of penetrative shearing that may delineate a middle miocene or younger suture separate the deep water franciscan rocks of the king range from less severely deformed neogene rocks of the eel river basin the king range appears to be a displaced terrane of oceanic basement overlain by paleogene and neogene sedimentary and igneous rocks of continental and oceanic derivation this terrane may have been displaced north or eastward and obductively accreted to california 15 m y ago before or perhaps during northward passage of the pacific farallon north american plate junction

coupling of air and sea surface temperatures in the eastern fram strait during the last 2000 years the arctic has undergone significant changes in the last 20 30 years the understanding of these changes is limited by the time span or resolution of existing climate records the main gateway of h

branched glycerol dialkyl glycerol tetraethers in arctic lake sediments sources and implications for paleothermometry at high latitudes branched glycerol dialkyl glycerol tetraethers brgdgts are analyzed in different lakes of the mackenzie canadian arctic and kolyma siberian arctic river basins to evaluate their sources and the implications for brgdgt based paleothermometry in high latitude lakes the comparison of brgdgt distributions and concentrations in the lakes with those in river suspended particulate matter riverbank sediments and permafrost material indicates that brgdgts in arctic lake sediments have mixed sources in contrast to global observations distributional offsets between brgdgts in arctic lakes and elsewhere in the catchment are minor likely due to the extreme seasonality and short window of biological production at high latitudes consequently both soil and lake calibrated brgdgt based temperature proxies return sensible temperature estimates even though the mean air temperature mat in the arctic is below the calibration range the original soil calibrated mbt cbt methylation of branched tetraethers cyclisation of branched tetraethers proxy generates mats similar to those in the studied river basins whereas using the recently revised mbt cbt calibration overestimates mat the application of the two global lake calibrations generating summer air temperatures sat and mat respectively illustrates the influence of seasonality on the production of brgdgts in lakes as the latter overestimates actual mat whereas the sat based lake calibration accounts for this influence and consequently returns more accurate temperatures our results in principle support the application of brgdgt based temperature proxies in high latitude lakes in order to obtain long term paleotemperature records for the arctic although the calibration and associated transfer function have to be selected with care

sources and distributions of tetraether lipids in surface sediments across a large river dominated continental margin glycerol dialkyl glycerol tetraether gdgt based proxies are increasingly used in modern carbon cycling and palaeoenvironmental investigations it is therefore crucial to examine the robustness sources transport and degradation of all gdgt based proxies in continental margins where sedimentation rates and extent of carbon cycling are high we have analyzed the distributions of gdgts in surface sediments from the lower yangtze river and east china sea ecs shelf the results revealed multiple sources and complex shelf processes that govern the distributions the isoprenoid gdgt inferred sea surface temperatures ssts are robust and reflect the satellite derived annual mean ssts on the shallow ecs shelf confirming an origin from surface water column dwelling crenarchaeota the input from methanogen sourced isoprenoid gdgts is significant in the river surface sediments but they are almost absent from the ecs shelf branched gdgts are also abundant in the river sediments but ca 95 are degraded in the yangtze estuary a much greater extent than observed for other terrigenous organic matter om proxies there is also evidence for production of branched gdgts in the oxic ecs shelf water column and the anoxic sediments waters of the lower yangtze river as a result branched gdgt based proxies in the lower river and ecs surface sediments do not reflect the catchment environmental conditions the effective degradation in the estuary and widespread aquatic contributions of branched gdgts improves our understanding of how to use branched gdgt based proxies in marginal seas

distributions of branched gdgts in soils and lake sediments from western uganda implications for a lacustrine paleothermometer bacterially produced branched glycerol dialkyl glycerol tetraethers gdgts are ubiquitous in soils and lake sediments and can potentially be used to reconstruct past temperatures in lakes however it is still unclear if these compounds are derived from eroded soils or if they are produced in situ to better understand environmental controls on the distributions of these compounds and the sources of branched gdgts to lake sediments we compare branched gdgt distributions and concentrations in lake sediments and catchment soils within a 3600 m altitudinal transect in western uganda reconstructed mean annual air temperature maat determined from the degree of methylation mbt and cyclisation cbt of branched gdgts in soils decreases with increasing altitude as is expected from the air temperature gradient in our transect however we observe significant offsets between observed and reconstructed temperatures in soils from wet high elevation soils but not in most dry low elevation soils branched gdgt distributions differ significantly between lake sediments and soils at all elevations with greater differences at low elevations than at high elevations these data support previous hypotheses that branched gdgts are produced in situ in lakes and suggest that the abundance of water in soil environments may play a role in controlling the distribution of branched gdgts while branched gdgts in lacustrine sediments can be used to reconstruct temporal temperature variations in lakes we urge caution in utilizing this proxy in lacustrine systems with high soil loadings especially if there is evidence of changing clastic fluxes through time

comparison of soil derived tetraether membrane lipid distributions and plant wax δd compositions for reconstruction of canadian arctic temperatures abstract polar amplification of climate warming has received much attention as these rapidly rising temperatures have the potential to alter ecosystem function and biogeochemical cycles in particular carbon preserved in arctic tundra soil and permafrost may be especially vulnerable resulting in carbon cycle perturbations providing an additional positive feedback to climate change reliable methods for reconstructing past temperature changes in polar regions have been established from ice cores and marine sediments however techniques for the continental terrestrial environments are lacking but are imperative to examine polar amplification of climate warming here we compare two molecular methods for reconstructing continental annual mean air temperature mat for the canadian arctic based on the distribution of soil bacterial derived glycerol dialkyl glycerol tetraether gdgt membrane lipids mbt cbt proxy and the hydrogen isotopic composition d of plant wax derived n alkanes these two proxies were applied to both modern soil and paleosols collected from the yukon territory canada to evaluate both the accuracy of the reconstructed absolute temperatures as well as the relative change in temperature between the last glacial and the holocene branched gdgt based estimates using the recently revised mbt cbt calibration are overall higher by ca 6 c compared to the original calibration mat estimates for modern soils based on the original mbt cbt calibration are comparable with those based on the d of extracted c29 n alkanes and instrumental data however produced a 6 c higher temperature signal for the glacial paleosols therefore branched gdgt based temperature reconstructions for glacial soils in the high arctic may represent the higher temperatures at the time of soil formation when bacterial activity was optimal whereas d of c29 n alkane plant lipids appear to integrate an average annual signal when used in tandem these geochemical proxies may provide a more comprehensive method for reconstructing arctic paleoclimate

constraints on the application of the mbt cbt palaeothermometer at high latitude environments svalbard norway abstract branched glycerol dialkyl glycerol tetraethers gdgts are membrane lipids of unknown bacteria that are ubiquitous in soil and peat two indices based on the distribution of these lipids in soils the cyclization of branched tetraethers cbt and the methylation of branched tetraethers mbt indices have been shown to correlate with soil ph and mean annual air temperature mat and soil ph respectively and can be used to reconstruct mat in palaeoenvironments to verify the extent to which branched gdgts in marine sediments reflect the distribution pattern on land and whether these proxies are applicable for palaeoclimate reconstruction in high latitude environments with a mat of

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

major changes in glacial and holocene terrestrial temperatures and sources of organic carbon recorded in the amazon fan by tetraether lipids the amazon basin is a major component of the global carbon and hydrological cycles a significant natural source of methane and home to remarkable biodiversity and endemism reconstructing past climate changes in the amazon basin is important for a better understanding of the effect of such changes on these critical functions of the basin using a novel biomarker proxy based on the membrane lipids of soil bacteria with a new regional calibration we present a reconstruction of changes in mean annual air temperatures for the amazon catchment during the last 37 kyr b p biomarkers were extracted from ocean drilling program sediment core odp942 recovered from the amazon fan the amazon fan is a major depository for terrestrial sediments with the advantage that the terrestrial material captured reflects a regional integration of the whole river catchment the reconstructed tropical amazonian temperatures were similar to 5 degrees c cooler at the last glacial maximum similar to 21 degrees c compared to modern values similar to 26 degrees c this is in agreement with previous estimates of tropical continental temperatures in the tropical amazon basin and tropical africa during the last glacial maximum moreover we also illustrate how the soil bacterial membrane lipid record reveals major changes in basin dynamics and sediment provenance during the glacial holocene transition impacting the biomarker reconstructions from similar to 11 kyr onward

geodetic constraint on the motion of a slab window implication for the mendocino crustal conveyor model the migration of the slab window in the northern california coast ranges provides a unique setting to study the viscous coupling between crust and asthenosphere flow the mechanisms of these dynamic processes are explained by the mendocino crustal conveyor model which predicts a 2 d double humped surface uplift rate pattern on a 400 km long profile to evaluate the mendocino crustal conveyor mcc model using accurate geodetic measurements we derive the vertical velocity field from 43 continuous gps cgps stations in the coast ranges region and project it onto the profile along three possible orientations of the slab window the cgps measured uplift rates are in good agreement with the mcc prediction when the slab window orientation is parallel to the symmetry axis of the region of thickened crust thus the cgps solutions not only provide a complementary means to diagnose the mcc model but also provide an effective way to constrain the orientation of the slab window

distributions of bacterial and archaeal membrane lipids in surface sediments reflect differences in input and loss of terrestrial organic carbon along a cross shelf arctic transect enhanced climate warming affecting the arctic region could have a dramatic impact on the terrigenous organic carbon terroc stored in the eurasian permafrost and could increase the amount of oc remobilized to the arctic shelves an improved understanding of the fate of this remobilized soil oc is essential for better understanding of the consequences for the arctic and global carbon cycle in this study glycerol dialkyl glycerol tetraethers gdgts and bacteriohopanepolyols bhps in surface sediments along a 500 km cross shelf transect from the mouth of the kolyma river to the middle of the vast east siberian sea were analysed to assess their potential and that of the associated branched and isoprenoid tetraether bit and r 0 soil indices for tracing terroc in arctic systems both bhp and gdgt contributions indicated the greatest contribution of terroc close to the river mouth while the associated indices showed declining trends in an offshore direction supporting an increasing marine oc input and or a decrease in terroc however while the bhps indicated a dominance of terroc at the start of the transect the gdgts suggested a much larger almost 50 marine oc input at this point in addition the bit index displayed an exponential decline controlled mainly by a substantial contribution of marine gdgts while

a record of climate over the last millennium based on varved lake sediments from the canadian high arctic a varved sediment record that extends back over the last millennium was recovered from lower murray lake northern ellesmere island nunavut canada 81 20 n 69 30 w flatbed scan images and back scattered electron images were analysed to provide varve thickness and other quantitative sedimentary indices on an annual basis in many studies of lakes from the high arctic varve thickness is a good proxy for summer temperature and we interpret the lower murray lake varves in this way on that basis the lower murray lake varve thickness record suggests that summer temperatures in recent decades were among the warmest of the last millennium comparable with conditions that last occurred in the early twelfth and late thirteenth centuries but estimates based on the sediment accumulation rate do not show such a recent increase the coldest conditions of the little ice age were experienced from ad 1700 to the mid nineteenth century when extensive ice cover on the lake led to widespread anoxic conditions in the deepest parts of the lake basin an overall decline in median grain size over the last 1000 years indicates a reduction in the energy available to transport sediment to the lake many of these features of the record are also observed in other palaeoclimatic records from the north american arctic the very recent appearance of the diatom campylodiscus which was not observed through out the record of the last millennium suggests that a new threshold in the ontogenetic development of the lake has now been passed

hydrologic and geomorphic processes in the colville river delta alaska the colville basin drains the north slope of alaska and is one of several large arctic river systems located within permafrost the timing and style of fluvial processes in the earth s permafrost regions differ from those occurring in midlatitude settings moreover in comparison to temperate zone systems rivers located entirely within permafrost perform most of their work during relatively short periods of time this paper examines river ice hydrology and the resulting geomorphic processes that occur within the colville delta alaska fluvial processes and landform development within the colville delta occur after the flood pulse is initiated by the breakup of river ice during this 4 month period the geomorphic processes are largely influenced by the movement of ice the flood pulse and accompanying river ice influences erosional and depositional processes and results in unique styles of sediment transport deposition and riverbank erosion

seasonal variability of branched glycerol dialkyl glycerol tetraethers brgdgts in a temperate lake system quantitative climate reconstructions are crucial for understanding the magnitude of and mechanisms behind natural and anthropogenic climate change yet there are few proxies that can reliably reconstruct terrestrial temperature branched glycerol dialkyl glycerol tetraethers brgdgts are bacterial membrane lipids that are increasingly used to reconstruct paleotemperature from lake sediments but despite their potential we have a poor understanding of 1 autochthonous vs allochthonous sources of brgdgts in lakes and 2 the seasonality of and environmental controls on brgdgt production within lakes to investigate these factors we examined water column suspended particulate matter spm and settling particles from a sediment trap collected on a biweekly to monthly basis over a period of three years at lower king pond a small kettle lake in northern vermont usa we also compared the concentration and fractional abundances of brgdgts in spm and settling particles with those of catchment soils river sediments and lake surface sediments to constrain the relative importance of brgdgts derived from the landscape versus brgdgts produced within the lake itself we find significant differences in concentrations and fractional abundances of brgdgts between soil and river sediment samples from the catchment and lake sediments indicating a mostly autochthonous source for lacustrine brgdgts brgdgt concentrations fluxes and fractional abundances in spm vary over the annual cycle indicating that brgdgts are produced throughout the year and respond to changes within the water column the total annual flux of brgdgts settling through the water column is comparable to the brgdgt accumulation rates in surface sediments indicating that in this lake brgdgts are mostly produced within the water column not in the sediment itself while brgdgts are produced in all seasons within the water column the flux to the sediments is highest during periods of spring and fall isothermal mixing potentially biasing paleotemperature reconstructions towards mixing season temperature because the seasonal timing and frequency of lake mixing varies as a function of regional climate lacustrine brgdgt calibrations should be regional in nature and comprise lakes with similar mixing regimes

influence of the mendocino triple junction on the tectonics of coastal california abstract the migration of the mendocino triple junction through central and northern california over the past 25 30 million years has led to a profound change in plate interactions along coastal california the tectonic consequences of the abrupt change from subduction plate interactions north of the triple junction to the development of the san andreas transform system south of the triple junction can be seen in the geologic record and geophysical observations the primary driver of this tectonism is a coupling among the subducting juan de fuca gorda north american and pacific plates that migrates with the triple junction this coupling leads to ephemeral thickening of the overlying north american crust associated uplift and subsequent subsidence and a distinctive sequence of fault development and volcanism

constraints on the sources of branched tetraether membrane lipids in distal marine sediments abstract branched glycerol dialkyl glycerol tetraethers brgdgts are membrane lipids produced by soil bacteria and occur in near coastal marine sediments as a result of soil organic matter input their abundance relative to marine derived crenarchaeol quantified in the bit index generally decreases offshore however in distal marine sediments low relative amounts of brgdgts can often still be observed sedimentary in situ production as well as dust input have been suggested as potential though as yet not well constrained sources in this study brgdgt distributions in dust were examined and compared with those in distal marine sediments dust was sampled along the equatorial west african coast and brgdgts were detected in most of the samples albeit in low abundance their degree of methylation and cyclisation expressed in the mbt methylation index of branched tetraethers and dc degree of cyclisation indices respectively were comparable with those for african soils their presumed source comparison of dc index values for brgdgts in global soils congo deep sea river fan sediments and dust with those of distal marine sediments clearly showed however that distal marine sediments had significantly higher values this distinctive distribution is suggestive of sedimentary in situ production as a source of brgdgts in marine sediments rather than dust input the presence of in situ produced brgdgts in marine sediments means that caution should be exercised when applying the mbt cbt palaeothermometer to sediments with low bit index values i e

erosional response to northward propagating crustal thickening in the coastal ranges of the u s pacific northwest we measured basin scale erosion rates using cosmogenic 10 be concen trations in quartz from fluvial sediment in rivers draining the coastal mountain ranges of the u s pacific northwest between 40 and 47 n apparent erosion rates are 0 1 to 0 2 mm yr 1 throughout the oregon coast ranges north of 43 n and increase to the south to 0 6 to 1 1 mm yr 1 in the northern california coast ranges near 40 n we propose that these observations display the erosional response to northward migrating crustal thickening associated with subduction of the mendocino triple junction north south variations in erosion rate range elevation and metrics of landscape relief and steepness are consistent with the hypotheses that i their primary cause is northward migrating crustal thickening ii erosion rates are strongly controlled by topographic relief and weakly if at all controlled by climate and iii the dependence of erosion on relief is nonlinear and obeys a threshold relief relationship

landslides threshold slopes and the survival of relict terrain in the wake of the mendocino triple junction establishing landscape response to uplift is critical for interpreting sediment fluxes hazard potential and topographic evolution we assess how landslides shape terrain in response to a wave of uplift traversing the northern california coast ranges united states in the wake of the mendocino triple junction we extracted knickpoints landslide erosion rates and topographic metrics across the region modified by mendocino triple junction migration landslide erosion rates mapped from aerial imagery are consistent with modeled uplift and exhumation while hillslope gradient is invariant across the region suggesting that landslides accommodate uplift as predicted by the threshold slope model landslides are concentrated along steepened channel reaches downstream of knickpoints generated by base level fall at channel outlets and limit slope angles and relief we find evidence that landslide derived coarse sediment delivery may suppress catchment wide channel incision and landscape denudation over the time required for the uplift wave to traverse the region we conclude that a landslide cover effect may provide a mechanism for the survival of relict terrain and orogenic relief in the northern californian coast ranges and elsewhere over millennial time scales

north atlantic holocene climate evolution recorded by high resolution terrestrial and marine biomarker records abstract holocene climatic change is driven by a plethora of forcing mechanisms acting on different time scales including insolation internal ocean e g atlantic meridional overturning circulation amoc and atmospheric e g north atlantic oscillation nao variability however it is unclear how these driving mechanisms interact with each other here we present five biomarker based paleoclimate records air sea surface temperature and precipitation from a fjordic sediment core revealing north atlantic terrestrial and marine climate in unprecedented detail the early holocene 10 7 7 8 kyrs bp is characterised by relatively high air temperatures while ssts are dampened by melt water events and relatively low precipitation the middle holocene 7 8 3 2 kyrs bp is characterised by peak ssts declining air temperatures and high precipitation a pronounced marine thermal maximum occurs between 7 5 5 kyrs bp 3000 years after the terrestrial thermal maximum driven by melt water cessation and an accelerating amoc the neoglacial cooling between 5 8 and 3 2 kyrs bp leads into the late holocene we demonstrate that an observed modern link between icelandic precipitation variability during different nao phases may have existed from 7 5 kyrs bp a simultaneous decoupling of both air and sea surface temperature records from declining insolation at 3 2 kyrs bp may indicate a threshold after which internal feedback mechanisms namely the nao evolved to be the primary drivers of icelandic climate on centennial time scales

calibration and application of the branched gdgt temperature proxy on east african lake sediments branched glycerol dialkyl glycerol tetraethers brgdgts are a novel proxy for mean annual air temperature maat and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments several calibrations have been put forth relating brgdgt distributions to maat using a variety of linear regressions including the methylation mbt and cyclization cbt indices of brgdgts the relative abundances of the major non cyclized brgdgts mbrgdgts and best subsets regression bsr of the fractional abundances of the nine most common brgdgts however these calibrations have rarely been applied to lake sediment cores to reconstruct temperatures and test the applicability of this proxy as a paleothermometer we present an expanded east african lakes surface sediment brgdgt dataset based upon 111 lakes and examine three methods of calibrating brgdgts to maat these methods include recalculations of the east african lake mbt cbt calibration and mbrgdgts calibrations as well as a new stepwise forward selection sfs calibration that uses the four combined brgdgts that explain the most variance in temperature in our calibration set we apply these new calibrations as well as five previously published lacustrine brgdgt calibrations to the brgdgt distributions of our surface sediment dataset and a 48 kyr sediment core from sacred lake mt kenya producing the first brgdgt temperature reconstruction available from a small tropical lake we compare the reconstructed temperatures to previously published paleotemperature records from east africa to help us assess the performance of the brgdgt calibrations we find that the sfs calibration has a consistently low root mean squared error of prediction rmsep over the entire range of maat while the mbt cbt and mbrgdgt calibrations have relatively large rmseps particularly between lakes with similar temperatures but variable ph this suggests that these techniques do not properly deconvolve the temperature and ph signals recorded in the distributions of the brgdgts we further find that only the sfs calibration produces a credible reconstructed temperature history from sacred lake when compared to other last glacial maximum paleotemperature estimates from east africa thus we advocate for the use of the sfs calibration when reconstructing paleotemperatures from brgdgts in east africa

distributions of branched gdgts in a tropical lake system implications for lacustrine application of the mbt cbt paleoproxy branched glycerol dialkyl glycerol tetraether gdgt lipids are abundant and ubiquitous in lake sediments potentially allowing for a paleolimnological application of the so called mbt cbt proxy methylation index of branched tetraethers cyclization ratio of branched tetraethers to investigate the origin and characteristics of these compounds in lacustrine environments we examined the distributions of gdgts in soils river sediments and lake sediments from lake towuti on the island of sulawesi indonesia we found significant differences in the degree of methylation and cyclization expressed by way of the mbt and cbt indices between the soil samples and the aquatic samples suggesting that there may be in situ production of gdgts in the aquatic environment based on these findings we urge caution in the application of the mbt cbt paleoproxy to lake sediments and encourage more rigorous study of these compounds in freshwater environments

in situ produced branched glycerol dialkyl glycerol tetraethers in suspended particulate matter from the yenisei river eastern siberia abstract soil derived branched glycerol dialkyl glycerol tetraethers brgdgts in marine river fan sediments have a potential use for determining changes in the mean annual temperature mat and ph of the river watershed soils prior to their incorporation in marine sediments the compounds are transported to the marine system by rivers however emerging evidence suggests that the brgdgts in freshwater systems can be derived from both soil run off and in situ production the production of brgdgts in the river system can complicate the interpretation of the brgdgt signal delivered to the marine system therefore we studied the distribution of brgdgt lipids in suspended particulate matter spm of the yenisei river chromatographic improvements allowed quantification of the recently described hexamethylated brgdgt isomer characterized by having two methyl groups at the 6 6 instead of the 5 5 positions in an environmental dataset for the first time this novel compound was the most abundant brgdgt in spm from the yenisei its fractional abundance correlated well with that of the 6 methyl isomer of the hexamethylated brgdgt that contains one cyclopentane moiety the yenisei river watershed is characterized by large differences in mat 11 c as it spans a large latitudinal range 46 73 n which would be expected to be reflected in brgdgt distributions of its soils however the brgdgt distributions in its spm show little variation furthermore the reconstructed ph values are high compared to the watershed soil ph we therefore hypothesize that the brgdgts in the yenisei river spm are predominantly produced in situ and not primarily derived from erosion of soil this accounts for the absence of a change in the temperature signal as the river water temperature is more stable using a lake calibration the reconstructed temperature values agree with the mean summer temperatures mst recorded the brgdgts delivered to the sea by the yenisei river during this season are thus not soil derived possibly complicating the use of brgdgts in marine sediments for palaeoclimate reconstructions

sources of local and regional variability in the mbt cbt paleotemperature proxy insights from a modern elevation transect across the eastern cordillera of colombia abstract distributions of brgdgts branched glycerol dialkyl glycerol tetraethers in soils have been utilized in the literature as a proxy for temperature and ph via the mbt and cbt indices methylation of branched tetraethers and cyclization of branched tetraethers respectively however there is substantial scatter in the empirical relationships between the global mbt cbt index and modern temperature resulting in uncertainty as large as 5 0 c in reconstructed paleotemperature in this study we sought to determine the magnitude of several sources of calibration error using a new set of samples spanning a large gradient in elevation ca 3000 m and temperature ca 16 c across an andean transect in the eastern cordillera of colombia using in situ temperature monitoring this field study of an equatorial montane location provided an opportunity to investigate several potential confounding factors affecting the mbt cbt paleothermometer including the mismatch between air temperature and actual soil temperature and the effect of soil moisture on brgdgt production in the well constrained environment of our study we determined the rmse root mean squared error for a local calibration of the mbt cbt proxy to be 3 0 c in contrast to the 5 0 c value reported in the most recent global calibration a comparison between in situ soil temperature measurements at our soil sampling locations and interpolated weather station temperature data indicates that errors in interpolation schemes are not likely to be a significant contributor to the observed scatter in the mbt cbt temperature relationship rather we conclude that the majority of the 3 c scatter in this calibration for the northern andes arises from transient site specific variation in factors such as soil moisture and nutrient availability with several cases showing a difference of up to 7 8 c between closely spaced sites

ephemeral crustal thickening at a triple junction the mendocino crustal conveyor as the north american crust interacts with the migrating mendocino triple junction the crust is first significantly thickened and then equivalently thinned over a distance of a few hundred kilometers within a time frame of 5 m y or less this process of ephemeral crustal thickening is proposed to result from viscous coupling between the northward migrating gorda slab and the base of north america south of the triple junction a time dependent thermal mechanical finite element model is developed to test this hypothesis of plate boundary tectonics results of the numerical simulations show patterns of crustal deformation consistent with the mapped sequence of folding and faulting in the area the observed crustal structure and triple junction regional seismicity and localized regions of crustal extension coincident with the position of a hypothesized lower crustal melt zone

sources and distributions of branched and isoprenoid tetraether lipids on the amazon shelf and fan implications for the use of gdgt based proxies in marine sediments branched glycerol dialkyl glycerol tetraethers brgdgts in river fan sediments have been used successfully to reconstruct mean annual air temperature maat and soil ph of the congo river drainage basin however in a previous study of amazon deep sea fan sediments the reconstructed maats were ca 10 c colder than the actual maat of the amazon basin in this study we investigated this apparent offset by comparing the concentrations and distributions of brgdgts in amazon river suspended particulate matter spm and sediments to those in marine spm and surface sediments the riverine brgdgt input was evident from the elevated brgdgt concentrations in marine spm and surface sediments close to the river mouth the distributions of brgdgts in marine spm and sediments varied widely but generally showed a higher relative abundance of methylated and cyclic brgdgts than those in the river since this difference in brgdgt distribution was also found in intact polar lipid ipl derived brgdgts which were more recently produced the change in the marine brgdgt distribution was most likely due to marine in situ production consequently the maats calculated based on the methylation of branched tetraethers mbt and the cyclisation of branched tetraethers cbt were lower and the cbt derived ph values were higher than those of the amazon basin however spm and sediments from stations close to the river mouth still showed mbt cbt values that were similar to those of the river therefore we recommend caution when applying the mbt cbt proxy it should only be used in sediment cores that were under high river influence the influence of riverine derived isoprenoid gdgt isogdgt on the isogdgt based tex86 temperature proxy was also examined in marine spm and sediments an input of riverine isogdgts from the amazon river was apparent but its influence on the marine tex86 was minor since the tex86 of spm in the amazon river was similar to that in the marine spm and sediments

what does a mean mean the temporal evolution of detrital cosmogenic denudation rates in a transient landscape in equilibrium landscapes 10 be concentrations within detrital quartz grains are expected to quantitatively refl ect basin wide denudation rates in transient landscapes though detrital quartz is derived from both the incising adjusting lowland and the unadjusted relict upland the integrated 10 be concentrations still provide a denudation rate averaged across the two domains because fi eld samples can provide only a snapshot of the current upstream averaged erosion rate we employ a numerical landscape evolution model to explore how 10 be derived denudation rates vary over time and space during transient adjustment model results suggest that the longitudinal pattern of mean denudation rates is generated by the river s progressive dilution of low volume high concentration detritus from relict uplands by the integration of high volume low concentration detritus from adjusting lowlands the proportion of these materials in any detrital sample depends on what fraction of the upstream area remains unadjusted because the boundary of the adjusting part of the landscape changes over time the longitudinal trend in cosmogenic nuclide derived erosion rates changes over time these insights are then used to guide our interpretation of geomorphic and longitudinal cosmogenic nuclide data from the south fork eel river sfer in the california coast range united states the northward propagating crustal thickening and rock uplift associated with the passage of the mendocino triple junction generates a mobile wave of uplift that progressively sweeps longitudinally down the sfer the consequences of this forcing can be both replicated in the model environment and observed in the fi eld the sfer contains transient landforms including knickpoints and river terraces along mainstem and tributary channels that defi ne a clear boundary between an incised adjusting lowland and an unadjusted relict upland we report nine nested basin wide denudation rates in the mainstem of the sfer using terrestrial cosmogenic 10 be in river borne sediment we fi nd that denudation rates increase in the downstream direction from 0 2 mm yr in the upper catchment to 0 5 mm yr at the outlet using comparisons to the modeled landscape we show that this pattern of denudation rates paired with the distribution of relict topography throughout the watershed refl ect the immaturity of the landscape s transient adjustment later in this modeled transient the predicted erosion rates decrease downstream before they become uniform this interpretation of our data has potentially far reaching implications for quantifying the uplift history and response time of transient landscapes using cosmogenic nuclides

fluvial sediment flux to the arctic ocean the paper presents an overview of recent publications on the fluvial suspended sediment flux to the arctic ocean the total suspended matter exported from the russian territory is 102 10 6 t year and from the canadian arctic is 125 10 6 t year the total suspended matter tsm flux to the arctic 227 10 6 t year is very low only about 1 of the global flux mean concentrations of suspended matter and specific sediment discharge are approximately one order of magnitude lower than the global concentration an analysis of the trends in the sediment loads based on records of up to 62 years in length shows decreases yenisey increases kolyma and stability ob among the reasons for the very low concentrations and fluxes of suspended sediment in the arctic rivers are thin weathering crusts on the arctic watersheds low precipitation extensive permafrost low temperatures for most of the year large areas of swamps and lakes and a low level of human activity a stochastic sediment transport model by morehead et al morehead m d syvitski j p hutton e w peckham s d 2003 modeling the temporal variability in the flux of sediment from ungauged river basins glob planet change 39 95 110 is applied to the arctic rivers to estimate the sediment load increase should the surface temperature of the drainage basin increase for every 2 c of warming a 30 increase in the sediment flux could result and for each 20 increase in water discharge a 10 increase in sediment load could follow based on this model an increase of the sediment flux of six largest arctic rivers yenisey lena ob pechora kolyma and severnaya dvina is predicted to range from 30 to 122 by 2100

drastic changes in the distribution of branched tetraether lipids in suspended matter and sediments from the yenisei river and kara sea siberia implications for the use of brgdgt based proxies in coastal marine sediments abstract the distribution of branched glycerol dialkyl glycerol tetraethers brgdgts in soils has been shown to correlate with ph and mean annual air temperature because of this dependence brgdgts have found an application as palaeoclimate proxies in coastal marine sediments based on the assumption that their distribution is not altered during the transport from soils to marine systems by rivers to study the processes acting on the brgdgt distributions we analysed the full suite of brgdgts including the recently described 6 me brgdgts in both the suspended particulate matter spm of the siberian yenisei river and the spm and sediments of its outflow in the kara sea the brgdgt distribution in the spm of the yenisei river was fairly constant and characterized by high abundances of the 6 me brgdgts reflecting their production at the neutral ph of the river water however the brgdgt distribution showed marked shifts in the marine system firstly in the yenisei river mouth the fractional abundance of the 6 me brgdgts decreases sharply the brgdgt signature in the yenisei river mouth possibly reflects brgdgts delivered during the spring floods that may carry a different distribution also coastal cliffs were shown to contain brgdgts and to influence especially those sites without major river inputs e g khalmyer bay further removed from the river mouth in situ production of brgdgts in the marine system influences the distribution however also the fractional abundance of the tetramethylated brgdgt ia increases resulting in a distribution that is distinct from in situ produced signals at similar latitudes svalbard we suggest that this shift may be caused by preferential degradation of labile riverine in situ produced brgdgts and the subsequent enrichment in less labile soil material the offshore distribution indeed agrees with the brgdgt distribution encountered in a lowland peat this implies that the offshore kara sea sediments possibly carry a soil dominated signal indicating potential for palaeoclimate reconstructions at this site both in the river system and coastal cliffs brgdgts were much more abundant than crenarchaeol an archaeal isoprenoid gdgt resulting in high 0 93 branched and isoprenoid tetraether bit index values moving downstream in the marine sediments a decrease in brgdgt concentrations coeval with an increase in crenarchaeol resulted in decreasing bit index values this decrease correlates with changes in bulk proxies for terrigenous input 13corg c n confirming the use of the bit index to trace the delivery of river transported and coastal cliff derived terrigenous organic matter

distribution of branched gdgts in surface sediments from the colville river alaska implications for the mbt cbt paleothermometer in arctic marine sediments significant climate fluctuations in the arctic over the recent past and additional predicted future temperature changes highlight the need for high resolution arctic paleoclimate records arctic coastal environments supplied with terrigenous sediment from arctic rivers have the potential to provide annual to subdecadal resolution records of climate variability over the last few millennia a potential tool for paleotemperature reconstructions in these marine sediments is the revised methylation index of branched tetraethers mbt cyclization ratio of branched tetraethers cbt proxy based on branched glycerol dialkyl glycerol tetraethers brgdgts in this study we examine the source of brgdgts in the colville river alaska and the adjacent simpson lagoon and reconstruct temperatures from simpson lagoon sediments to evaluate the applicability of this proxy in arctic estuarine environments the colville catchment soils fluvial sediments and estuarine sediments contain statistically similar brgdgt distributions indicating that the brgdgts throughout the system are soil derived with little alteration from in situ brgdgt production in the river or coastal waters temperatures reconstructed from the mbt cbt indices for surface samples show good agreement with regional summer june through september temperatures suggesting a seasonal bias in arctic temperature reconstructions from the colville system in addition we reconstruct paleotemperatures from an estuarine sediment core that spans the last 75 years revealing an overall warming trend in the twentieth century that is consistent with trends observed in regional instrumental records these results support the application of this brgdgt based paleotemperature proxy for subdecadal scale summer temperature reconstructions in arctic estuaries containing organic material derived from sediment laden episodic rivers

contrasting lipid biomarker composition of terrestrial organic matter exported from across the eurasian arctic by the five great russian arctic rivers contrasting lipid biomarker composition of terrestrial organic matter exported from across the eurasian arctic by the five great russian arctic rivers

distinguishing eustatic and epeirogenic controls on lower middle cambrian boundary successions in west gondwana morocco and iberia major eustatic fall has been invoked to explain lower middle cambrian boundary sandstones and faunal replacements on a number of cambrian palaeocontinents this proposal has been tested on the moroccan and spanish margins of west gondwana and found to be inadequate to explain stratigraphical developments in these regions sandstone intervals long presumed to be regressive and late early cambrian in age are now shown to be early middle cambrian and composed of a lower regressive and an overlying transgressive sandstone separated by a regional unconformity only the lower tidalites i e tazlaft formation in morocco and lower daroca sandstones in spain record the hawke bay eustatic regression in west gondwana the tazlaft is overlain by a newly recognized unconformably overlying sandstone talelt formation that onlapped southern morocco with reactivation of a pull apart or transcurrent regime up to 150 m of erosion on uplifted blocks in the high atlas range and foundering of the souss basin to the south preceded onlap and deposition of the volcanic rich tatelt the correlative and depositional analogue of the upper daroca and lower valdemides formations in northern spain with folding and erosion a type 1 depositional sequence boundary also caps the tatelt at its contact with an overlying lower middle cambrian mudstone dominated succession this unconformity probably occurs in spain within the valdemiedes formation and corresponds to a faunal discontinuity called the valdemiedes geoevent the iberian daroca regression and moroccan asrir regression are misnomers as the sandstones on which they are based are composite units with a lower regressive interval that records eustatic fall and an upper transgressive unit that records epeirogenically driven onlap

sources of terrigenous inputs to surface sediments of the colville river delta and simpson s lagoon beaufort sea alaska 1 the provenance of sediments and particulate organic carbon poc in the colville river delta and adjacent simpson s lagoon in the alaskan beaufort sea was investigated using a variety of bulk and molecular techniques including stable and radiocarbon isotopes neodymium isotopes algal pigments and lignin phenols additionally stable carbon isotopes and lignin phenols were analyzed on four different density fractions from sediments the colville river the largest river in north america with a watershed exclusively located in the high arctic tundra was an important source of terrestrial poc to the western edge of the lagoon shown by extremely old radiocarbon ages fraction modern of 0 165 0 001 close to the river mouth up to 0 418 0 002 farther away stations without northern protective barrier islands had large amounts of marine poc input and evidence of benthic microalgae was found in one area of the lagoon chlorophyll a concentration 35 0 g goc 1 in the high algal biomass area compared to 1 to 7 g goc 1 outside of it stations in the middle and eastern end of the lagoon showed significant sediment input from coastal erosion input of peat indicating non lignin phenols 0 079 mg 100mgoc 1 in the eastern lagoon compared to 0 022 mg 100mgoc 1 near the colville delta and on the eastern end of the lagoon there was evidence of input of mackenzie river poc shown with neodymium isotopes and also cop poc inputs derived from rivers coastal erosion and marine productivity were quantified using a ternary mixing model and showed that fluvial supply and coastal erosion were the dominant carbon sources to the lagoon this constitutes the first study of poc delivery by the colville river into a nearshore region and illustrates that continued warming of the high arctic tundra will likely lead to increased riverine poc delivery to this region of the world

selective preservation of soil organic matter in oxidized marine sediments madeira abyssal plain in ocean margin sediments both marine and terrestrial organic matter om are buried but the factors governing their relative preservation and degradation are not well understood in this study we analysed the degree of preservation of marine isoprenoidal and soil derived branched glycerol dialkyl glycerol tetraethers gdgts upon long term oxygen exposure in om rich turbidites from the madeira abyssal plain by analyzing gdgt concentrations across oxidation fronts relative to the anoxic part of the turbidites ca 7 20 of the soil derived branched gdgts were preserved in the oxidized part while only 0 2 3 of the marine isoprenoid gdgt crenarchaeol was preserved due to these different preservation factors the branched isoprenoid tetraether bit index a ratio between crenarchaeol and the major branched gdgts that is used as a tracer for soil derived organic matter substantially increases from 0 02 to 0 4 split flow thin cell splitt separation of turbidite sediments showed that the enhanced preservation of soil derived carbon was a general phenomenon across the fine particle size ranges 38 m calculations reveal that despite their relatively similar chemical structures degradation rates of crenarchaeol are 2 fold higher than those of soil derived branched gdgts suggesting preferential soil om preservation possibly due to matrix protection

trilobite diversity patterns in the middle cambrian of southwestern europe a comparative study abstract this paper describes the pattern of trilobite diversity throughout the middle cambrian in two fossiliferous basins of the western gondwana margin the iberian chains northeastern spain and the montagne noire southern france the documented fluctuations of species diversity allow us to recognize 1 a substantial extinction event recorded in latest early cambrian times named valdemiedes event which separates the culmination of a widespread decline of trilobites and the stepwise immigration of cosmopolitan invaders 2 a major trilobite radiation occurring in the earliest leonian and culminating across the caesaraugustian languedocian transition in which a peak in diversity of trilobites and carpoids was close to a major flooding surface 3 a major reduction of trilobite taxa across the early middle languedocian transition related to a well documented regressional trend and 4 a second immigration of trilobite fauna in the late languedocian which coincided with trangressional pulses and the establishment of suitable shaly substrates in addition we summarize the known trilobite occurrences from the middle cambrian of southwestern europe maps of the distribution of some relevant taxa genera and species over the western gondwana margin are documented

soil organic matter transport along an sub arctic river sea transect bacteriohopanepolyols bhps and glycerol dialkyl glycerol tetraethers gdgts have potential as soil tracing biomarkers for the extensive shelves of the arctic ocean in this work these biomarkers

branched glycerol dialkyl glycerol tetraethers and crenarchaeol record post glacial sea level rise and shift in source of terrigenous brgdgts in the kara sea arctic ocean this study evaluates the glycerol dialkyl glycerol tetraether gdgt distribution and provenance in sediments spanning a minimum of 13 3 ka from the st anna trough northern kara sea the site has experienced extensive fluctuation in the delivery of river derived organic matter om caused by a eustatic change in sea level this is in line with the record of the concentration of the isoprenoid gdgt crenarchaeol produced by marine thaumarchaota which was low at the bottom of the core increasing gradually in the most shallow unit the concentration of branched br gdgts showed an opposite trend and a marked shift in distribution the deepest sediments 10 ka with a distribution currently encountered in surface sediments in front of the yenisei river are characterized by terrigenous brgdgts whereas the distribution in the shallowest unit 10 ka is strongly influenced by marine in situ brgdgts during the shift from terrigenous to marine sourced brgdgts there was one horizon where a pronounced shift in the brgdgt distribution was observed and the brgdgt concentration significantly decreased as the brgdgts delivered to the current kara sea system are derived from several sources we postulate that a temporary change in the relative importance of the brgdgt sources happened during this interval both in situ production and changing brgdgt provenance have implications for paleoclimate reconstruction using brgdgts in situ production of marine brgdgts results in a higher reconstructed ph however these in situ produced brgdgts did not influence the reconstructed mean annual air temperature mat when the matmrs calibration was used changes in the relative contribution of brgdgt sub pools were shown however to influence both soil ph reconstruction and mat reconstruction

late holocene glaciation and twentieth century retreat northeastern brooks range alaska lichenometric dating of moraines deposited by eight glaciers in the northeastern brooks range suggests major glacial advances or stillstands at about 2600 1000 450 and 60 lichenometric l years bp the latter two advances of the early middle and latest part of the little ice age respectively formed promi nent moraines at all glaciers studied in response to overall twentieth century warming these glaciers have retreated at average rates of 2 to 19 m yr 1 from the distinct ridges formed in ad 1890 glacier thinning at rates of 0 7 to 0 9 m yr 1 accounts for over 90 of the ice loss

a review of the late cambrian furongian palaeogeography in the western mediterranean region nw gondwana abstract the cambrian ordovician transition of the western mediterranean region nw gondwana is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series the hiatii are diachronous and involved progressively younger strata along the gondwanan margin from sw morocco to ne montagne noire they can be related to development of a multi stage rifting further north currently connected to the opening of the rheic ocean and concomitant erosion on southern rift shoulders the platforms of this margin of gondwana occupied temperate water mid latitudes and were dominated by siliciclastic sedimentation while carbonate factories were only episodically active in the montagne noire platform the upper cambrian is devoid of significant gaps in the southern montagne noire and the iberian chains there the sedimentation took place in a transgressive dominated depositional system with common offshore deposits and clayey substrates and was bracketed by two major regressive trends the late cambrian is also associated with the record of volcanic activity e g in the cantabrian and ossa morena zones and the northern montagne noire and widespread development of a tectonic instability that led to the episodic establishment of palaeotopographies and record of slope related facies associations several immigration events are recognized throughout the latest middle cambrian late cambrian and tremadocian the trilobites show a stepwise replacement of acado baltic type families e g the conocoryphid paradoxidid solenopleurid assemblage characterized by i a late languedocian latest middle cambrian co occurrence of middle cambrian trilobite families with the first anomocarid dorypygid and proasaphiscid invaders ii a late cambrian immigration replacing previous faunas composed of trilobites aphelaspidids catillicephalids ceratopygids damesellids eulomids idahoiids linchakephalids lisariids onchonotinids and pagodiids linguliformean brachiopods acrotretids obolids scaphelasmatids siphonotretids and zhanatellids echinoderms mitrates glyptocystitid cystoids and stromatocystoids and conodonts belonging to the lower peltura zone and iii the subsequent input of new trilobites asaphids calymenids catillicephalids nileids and remopleurids which marks the base of the proteuloma geinitzi zone associated with pelmatozoan holdfasts oryctoconus and a distinct input of late tremadocian conodonts paltodus deltifer zone the biogeographic distribution of latest middle and late cambrian trilobites supports brachiopod data indicating strong affinities between the western mediterranean region east gondwana north china korea south china australia and antarctica and kazakhstania during the late languedocian which became significantly stronger during the late cambrian this major shift may suggest modification in oceanic circulation patterns throughout gondwana across the middle late cambrian transition

comparison of instrumental and gdgt based estimates of sea surface and air temperatures from the skagerrak sea surface temperatures ssts and annual mean air temperatures mats are estimated for the last 200 years from glycerol dialkyl glycerol tetraethers gdgts proxies in a marine sediment core from the skagerrak off southern norway the reconstructed values compare well with annual ssts and summer air temperatures obtained from composite regional instrumental records the results provide further confidence in the application of proxies based on gdgts to estimate past temperatures

multiple δ13c excursions spanning the cambrian explosion to the botomian crisis in siberia new high resolution 13 c data through the lower cambrian of siberia reveal multiple positive excursions coincident with phases in the explosion of invertebrate phyla nemakit daldynian to middle botomian stages comparison of the 18 o and trace element mg fe mu sr chemistry indicate that six new 13 c cycles are primary rather than diagenetic features with potential for global correlation positive 13 c excursions up to 3 indicate that fractional organic carbon burial rates were high but variable through the cambrian explosion values for 13 c dropped sharply from around 2 2 to 1 6 in botomian time coincident with mass extinction of the archaeocyathan reef biota the rapid fluctuation of the 13 c signal and the temporal coincidence of the pronounced negative shift with the extinction event hint that the 13 c record may record productivity variations during the early cambrian radiation

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

coastal erosion vs riverine sediment discharge in the arctic shelf seas this article presents a comparison of sediment input by rivers and by coastal erosion into both the laptev sea and the canadian beaufort sea cbs new data on coastal erosion in the laptev sea which are based on field measurements and remote sensing information and existing data on coastal erosion in the cbs as well as riverine sediment discharge into both the laptev sea and the cbs are included strong regional differences in the percentages of coastal erosion and riverine sediment supply are observed the cbs is dominated by the riverine sediment discharge 64 45 106 t a 1 mainly of the mackenzie river which is the largest single source of sediments in the arctic riverine sediment discharge into the laptev sea amounts to 24 10 106 t a 1 more than 70 of which are related to the lena river in comparison with the cbs the laptev sea coast on average delivers approximately twice as much sediment mass per kilometer a result of higher erosion rates due to higher cliffs and seasonal ice melting in the laptev sea sediment input by coastal erosion 58 4 106 t a 1 is therefore more important than in the cbs and the ratio between riverine and coastal sediment input amounts to 0 4 coastal erosion supplying 5 6 106 t a 1 is less significant for the sediment budget of the cbs where riverine sediment discharge exceeds coastal sediment input by a factor of ca 10

distributions and temperature dependence of branched glycerol dialkyl glycerol tetraethers in recent lacustrine sediments from china and nepal 1 glycerol dialkyl glycerol tetraether gdgt membrane lipids in surface sediments from 24 lakes in china and nepal were analyzed the result shows that branched gdgt lipids occur widely in the studied lake sediments the different distribution of branched gdgts between the chinese soils from weijers et al 2007b and the chinese lake sediments indicates that the branched gdgts in the lacustrine sediment are the mixture of allochthonous and autochthonous branched gdgts our result supports the suggestion that temperature is the principal factor affecting the distribution of gdgts seasonality sources and precipitation increase the uncertainty of the correlation between the methylation index of branched tetraethers mbt cyclization ratio of branched tetraethers cbt proxy and the temperature the correlations of the mbt cbt index with mean annual air temperature t for the global lakes are t 6 803 7 062 cbt 37 090 mbt n 139 p 0 0001 r2 0 62 and rmse 5 24 c for the global lakes with ph 8 5 t 3 949 5 593 cbt 38 213 mbt n 100 p 0 0001 r2 0 73 and rmse 4 27 c the significant correlation suggests that the mbt cbt proxy might be used as a potential paleotemperature proxy in the limnic environment the mbt cbt proxy provides an independent way to evaluate and verify the sensitivities of the different proxies for paleotemperature reconstruction from lacustrine sediments

neogene non marine sedimentation and tectonics in small pull apart basins of the san andreas fault system sonoma county california the san andreas fault system in northern california forms an 80 90 km wide zone of right lateral shear extensional tectonism within this broad shear zone is indicated by both neogene silicic volcanic rocks that gradually young in the direction of shear propagation to the north west and by numerous neogene faultbounded structural basins filled with thick non marine sequences the little sulphur creek basins three well exposed 1 5 2 km wide pull apart basins within this shear system have sedimentation patterns analogous to those of much larger pull apart basins they were formed and subsequently deformed by east west extension and by north west to south east orientated right slip concurrently with basin filling palaeocurrent and maximum clast size data indicate both lateral sediment transport from fault bounded basin margins and longitudinal transport down the basin axes the basins are filled primarily with coarse alluvial fan and streamflow deposits derived from a surrounding igneous sedimentary and metamorphic provenance two of the basins contain basin plain type lacustrine turbidites that grade laterally into distal alluvial fan fan delta and sublacustrine delta deposits talus deposits along the south west margin of the basins contain megabreccia indicative of active uplift structures indicative of dewatering liquefaction and slumping suggest penecontemporaneous tectonism

the earliest species of burlingia walcott 1908 trilobita from south china biostratigraphical and palaeogeographical significance burlingia balangensis sp nov from the lower cambrian of south china represents the earliest species of this genus and suggests that the genus may have originated in south china a revision of the genus shows that b primitiva and b obscura can be used in order to indentify the base of the cambrian stage 5 when other trilobites are absent because their last appearance datum lad coincides with the first appearance datum fad of oryctocephalus indicus available palaeogeographic and palaeoclimatic models suggest five major palaeocurrents during cambrian times which could control the migration patterns of the burlingia clade from south china to baltica