highly productive polar forests from the permian of antarctica abstract two stratigraphically closely spaced bedding planes exposed at lamping peak in the upper buckley formation beardmore glacier area antarctica contain abundant in situ stumps n 53 n 21 and other plant fossils that allow reconstruction of forest structure and biomass of glossopteris forests that thrived at 75 s paleolatitude in the permian mean trunk diameter is 14 and 25 cm corresponding to estimated mean maximum heights of 12 and 19 m basal areas are 65 and 80 m 2 ha 1 the above ground biomass was calculated using allometric equations for ginkgo biloba yielding biomasses of 147 and 178 mg ha 1 biomass estimates based on comparison with biomass of modern forests with equivalent basal areas are higher 225 400 mg ha 1 the amount of above ground biomass added each year annual net primary productivity based on biomass estimates and growth rings in silicified plant material from the buckley formation nearby is poorly constrained ranging from 100 2000 g m 2 yr 1 compared to modern forests at all latitudes the permian forests have high basal areas and high biomass exceeded in both only by forests of the u s pacific northwest and sequoia forests the estimated range of productivity anpp is within that of many very productive modern forests the lamping peak forests basal areas and calculated biomass are also larger than younger high paleolatitude fossil forests except for arctic cenozoic forests the presence of these highly productive fossil forests at high paleolatitude is consistent with hothouse conditions during the late permian prior to the eruption of the siberian flood basalts

fossil wood in coal forming environments of the late paleocene early eocene chickaloon formation the early cenozoic chickaloon formation is the main coal bearing sequence in south central alaska coal and associated plant macrofossils are well exposed in the eska premier and jonesville coal groups in the wishbone hill district there is a striking variation in the degree and mode of preservation of fossil trees in a vertical sequence through these coal groups we examined the wood taxonomy mineralogy and geochemistry to elucidate potential cause s for these differences the wood anatomy indicates that the wood is all assignable to the cupressaceae taxodiaceae s str and assignable to the form genus taxodioxylon hartig emend gothan however we found no significant variation in the taxonomy of the wood between stratigraphic layers the wood generally becomes better preserved in the jonesville coal group wood from the stratigraphically lower premier coal group exhibits greater plastic deformation and contains less well preserved wood anatomical features the wood from the overlying jonesville coal group retains most of its original morphology but has suffered from brittle fracture the geochemistry and mineralogy of the wood follow a pattern that corresponds to the degree of preservation the less well preserved wood tends to have a higher concentration of iron carbonate minerals e g siderite and ankerite whereas the better preserved wood contains more calcium carbonate or silica all evidence points to rapid permineralization of the original wood although the least well preserved wood shows evidence of greater organic matter decomposition than the better preserved wood the wood taxonomy and mode of preservation of wood from the upper part of the chickaloon formation is similar to wood from coeval fossil forests that developed at higher polar paleolatitudes

abrupt increase in seasonal extreme precipitation at the paleocene eocene boundary a prominent increase in atmospheric co at the paleocene eocene boundary ca 55 ma led to the warmest earth of the cenozoic for similar to 100 k y high resolution studies of continental flood plain sediment records across this boundary can provide crucial information on how the hydrological cycle responds to rapidly changing co2 here we show from continental records across the paleocene eocene boundary in the spanish pyrenees a subtropical paleosetting that during the early most intense phase of co2 rise normal semiarid coastal plains with few river channels of 10 200 m width were abruptly replaced by a vast conglomeratic braid plain covering at least 500 km 2 and most likely more than 2000 km 2 this braid plain is interpreted as the proximal parts of a megafan carbonate nodules in the megafan deposits attest to seasonally dry periods and together with megafan development imply a dramatic increase in seasonal rain and an increased intra annual humidity gradient the megafan formed over a few thousand years to similar to 10 k y directly after the paleocene eocene boundary only repeated severe floods and rainstorms could have contributed the water energy required to transport the enormous amounts of large boulders and gravel of the megafan during this short time span the findings represent evidence for considerable changes in regional hydrological cycles following greenhouse gas emissions less

palaeoecology of late cretaceous polar vegetation preserved in the hansen point volcanics nw ellesmere island canada abstract mesozoic polar forests represent an extinct biome subject to a polar light regime and elevated atmospheric co2 levels in this paper new cretaceous fossil plant assemblages are reported from nw ellesmere island canada at a paleolatitude of 75 n these occur in a campanian maastrichtian aged interval of the hansen point volcanics a unit interpreted as a coastal plain peat mire complex within an active volcanic setting studies of palynomorphs sterile and fertile foliage and wood indicate that mire environments were dominated by amber producing taxodiaceous conifers with other conifers ginkgos cycads angiosperms ferns lycopsids and bryophytes occurring in subordinate numbers leaf physiognomic studies imply that most vegetation was deciduous occurrence of traumatic rings in the woods together with a high year to year variability in ring width indicates disturbed growing conditions possibly linked to a combination of frosts volcanic eruptions and flooding abundant charcoal remains indicate that an additional important disturbance process was wildfire results of this study compare closely with those from coeval circum arctic fossil sites and augment our knowledge of the community scale ecology of the cretaceous polar biome

methanogenesis in eocene arctic soils inferred from δ13c of tree fossil carbonates we report on the carbon and oxygen stable isotope composition of fossil tree material collected at the white mountain locality of the buchanan lake formation on axel heiberg island in the high arctic of canada the fossils are middle eocene in age and have been permineralized with carbonate microscopic examination of fossils revealed them to be the remains of metasequoia stems composed of secondary carbonate calcite and original wood intermingled at the cellular level because the specimens show little compression crushing or tissue degradation we believe that carbonate permineralization occurred soon after burial and therefore provides insight into eocene carbon cycling at the locality the carbon isotope signature of the carbonate suggests that methanogenesis resulted in a 13 c enriched co2 pool that equilibrated with soil water and gave rise to unusually 13 c enriched caco3 tree fossil carbonate exhibited strikingly high d 13 c values 4 0 to 7 4x compared to published phanerozoic pedogenic carbonate d 13 c values these d 13 c values in conjunction with fractionation factors a previously determined for carbonate precipitation and methanogenic pathways indicate an eocene soil co2 pool containing 80 95 co2 produced as a by product of acetate fermentation methanogenesis because methane in the atmosphere is a powerful greenhouse gas we suggest that methane emissions from axel heiberg soils contributed to the relatively warm arctic climate during the middle eocene d 2004 elsevier b v all rights reserved

stable warm tropical climate through the eocene epoch earth s climate cooled from a period of extreme warmth in the early eocene epoch ca 50 ma to the early oligocene ca 33 ma when a large ice cap first appeared on antarctica evidence from the planktonic foraminifer oxygen isotope record in deep sea cores has suggested that tropical sea surface temperatures declined by 5 10 degrees over this interval eventually becoming much cooler than modern temperatures here we present paleotemperature estimates from foraminifer isotopes and the membrane lipids of marine crenarcheota from new drill cores in tanzania that indicate a warm and generally stable tropical climate over this period we reinterpret the previously published isotope records in the light of comparative textural analysis of the deep sea foraminifer shells which shows that in contrast to the tanzanian material they have been diagenetically recrystallized we suggest that increasingly severe alteration of the deep sea plankton shells through the eocene produced a diagenetic overprint on their oxygen isotope ratios that imparts the false appearance of a tropical sea surface cooling trend this implies that the long term eocene climatic cooling trend occurred mainly at the poles and had little effect at lower latitudes

high rates of inflation during a noneruptive episode of seismic unrest at semisopochnoi volcano alaska in 2014 2015

dike emplacement near paricutin volcano mexico in 2006 a major seismic swarm occurred near paricutin volcano between the end of may and early july 2006 more than 700 earthquakes with magnitude ml exceeding 2 4 were located paricutin located in the michoacan guanajuato volcanic field in western mexico is well known as the site of the 1943 eruption in which a new 400 m cinder cone was constructed in what had been farmland the 2006 swarm exhibits all of the characteristics typically associated with swarms of volcanic origins the earthquake rate showed the typical ramp up and ramp down over the course of several days magnitudes were evenly distributed in time with a notably high b value of 2 45 the earthquake locations cluster around a northeast striking trend extending approximately 6 km over the first two weeks hypocenters migrated steadily a few hundred meters per day rising from 9 to 5 km depth and moving northeast about 5 km on approximately june 7 the ascent of hypocenters stalled for the next three weeks hypocenters held their depth while migrating laterally back to the southwest focal mechanisms during the first part of the swarm reflected the increased stress caused by dike inflation following june 7 the stress orientation changed and became more consistent with the inflation of horizontal sill like structures though only limited information is available from the seismic swarm preceding the 1943 eruption several features including the swarm duration and magnitude relationships were comparable to those of the 2006 episode the strong indicators of a magmatic origin to the 2006 swarm suggest that at this location there are few if any traditional seismic discriminants that could be used to distinguish which seismic swarms and dike emplacement events might culminate in eruption

precursory earthquakes of the 1943 eruption of paricutin volcano michoacan mexico abstract paricutin volcano is a monogenetic volcano whose birth and growth were observed by modern volcanological techniques at the time of its birth in 1943 the seismic activity in central mexico was mainly recorded by the wiechert seismographs at the tacubaya seismic station in mexico city about 320 km east of the volcano area in this paper we aim to find any characteristics of precursory earthquakes of the monogenetic eruption though there are limits in the available information such as imprecise location of hypocenters and lack of earthquake data with magnitudes under 3 0 the available data show that the first precursory earthquake occurred on january 7 1943 with a magnitude of 4 4 subsequently 21 earthquakes ranging from 3 2 to 4 5 in magnitude occurred before the outbreak of the eruption on february 20 the s p durations of the precursory earthquakes do not show any systematic changes within the observational errors the hypocenters were rather shallow and did not migrate the precursory earthquakes had a characteristic tectonic signature which was retained through the whole period of activity however the spectra of the p waves of the paricutin earthquakes show minor differences from those of tectonic earthquakes this fact helped in the identification of paricutin earthquakes except for the first shock the maximum earthquake magnitudes show an increasing tendency with time towards the outbreak the total seismic energy released by the precursory earthquakes amounted to 2 10 19 ergs considering that statistically there is a threshold of cumulative seismic energy release 10 17 18 ergs by precursory earthquakes in polygenetic volcanoes erupting after long quiescence the above cumulative energy is exceptionally large this suggests that a monogenetic volcano may need much more energy to clear the way of magma passage to the earth surface than a polygenetic one the magma ascent before the outbreak of paricutin volcano is interpretable by a model of magma filled crack formation proposed by weertman based on seismic data and other field observations

using repeating volcano tectonic earthquakes to track post eruptive activity in the conduit system at redoubt volcano alaska in the year following the end of the 2009 eruption of redoubt volcano alaska four signifi cant swarms of low frequency lowmagnitude m l 0 1 earthquakes occurred at shallow depths beneath the summit because swarms of low frequency lf earthquakes preceded eruptions in 1989 and 2009 the posteruption swarms caused considerable concern and prompted the alaska volcano observatory to raise the monitoring levels on three occasions none of these swarms led to eruptions however and most observers including us initially concluded that the swarms had been caused by minor stress adjustments in the new lava dome or in the surrounding summit glaciers new observations reveal that the shallow lf swarms were accompanied by 2 families of repeating earthquakes at depths between 3 km and 6 km below sea level where the magma storage region is thought to be these mid crustal volcano tectonic vt type earthquakes were identical to earthquakes recorded during the 2009 redoubt eruption more than 6 months earlier focal mechanisms demonstrate that these earthquakes have thrust mechanisms inconsistent with the strike slip nature of regional faulting based on these observations we conclude that they are generated through processes occurring within the magma storage region the concurrence of the repeating vt earthquakes with the shallow lf swarms indicates that the shallow lf earthquakes were also magmatically driven our results emphasize that even brief episodes of low amplitude earthquake activity such as the lf swarms observed at redoubt following the 2009 eruption can be indicative of magmatic activity perhaps more signifi cant however is the demonstration that the conduit system at redoubt remained active intact and capable of transporting heat and fl uids to the surface months after the eruption was considered over

multiplets their behavior and utility at dacitic and andesitic volcanic centers 1 multiplets or groups of earthquakes with similar waveforms are commonly observed at volcanoes particularly those exhibiting unrest using triggered seismic data from the 1980 1986 mount st helens msh eruption we have constructed a catalog of multiplet occurrence our analysis reveals that the occurrence of multiplets is related at least in part to the viscosity of the magma we also constructed catalogs of multiplet occurrence using continuous seismic data from the 2004 eruption at msh and 2007 eruption at bezymianny volcano russia prior to explosions at msh in 2004 and bezymianny in 2007 the multiplet proportion of total seismicity mpts declined while the average amplitudes and standard deviations of the average amplitude increased the life spans of multiplets time between the first and last event were also shorter prior to explosions than during passive lava extrusion dome forming eruptions that include a partially solidified plug like msh 1983 1986 and 2004 2008 often possess multiplets with longer life spans and mpts values exceeding 50 conceptually the relatively unstable environment prior to explosions is characterized by large and variable stress gradients brought about by rapidly changing overpressures within the conduit we infer that such complex stress fields affect the number of concurrent families mpts average amplitude and standard deviation of the amplitude of the multiplets we also argue that multiplet detection may be an important new monitoring tool for determining the timing of explosions and in forecasting the type of eruption

high latitude meteoric δ18o compositions paleosol siderite in the middle cretaceous nanushuk formation north slope alaska siderite bearing pedogenic horizons of the nanushuk formation of the north slope alaska provide a critical high paleolatitude oxygen isotopic proxy record of paleoprecipitation supplying important empirical data needed for paleoclimatic reconstructions and models of greenhouse world precipitation rates siderite 18 o values were determined from four paleosol horizons in the national petroleum reserve alaska npr a grandstand 1 core and the values range between 17 6 and 14 3 peedee belemnite pdb with standard deviations generally less than 0 6 within individual horizons the 13 c values are much more variable ranging from 4 6 to 10 8 pdb a covariant 18 o versus 13 c trend in one horizon probably resulted from mixing between modified marine and meteoric phreatic fluids during siderite precipitation groundwater values calculated from siderite oxygen isotopic values and paleobotanical temperature estimates range from 23 0 to 19 5 standard mean ocean water smow minor element analyses show that the siderites are impure having enrichments in ca mg mn and sr minor element substitutions and mg fe and mg ca mg ratios also suggest the influence of marine fluids upon siderite precipitation the pedogenic horizons are characterized by gleyed colors rare root traces abundant siderite abundant organic matter rare clay and silty clay coatings and infillings some preservation of primary sedimentary stratification and a lack of ferruginous oxides and mottles the pedogenic features suggest that these were poorly drained reducing hydromorphic soils that developed in coal bearing delta plain facies and are similar to modern inceptisols model derived estimates of precipitation rates for the late albian of the north slope alaska 485 626 mm yr are consistent with precipitation rates necessary to maintain modern peat forming environments this information reinforces the mutual consistency between empirical paleotemperature estimates and isotope mass balance models of the hydrologic cycle and can be used in future global circulation modeling gcm experiments of greenhouse world climates to constrain high latitude precipitation rates in simulations of ancient worlds with decreased equator to pole temperature gradients

plant and mammal diversity in the paleocene to early eocene of the bighorn basin abstract abundant plant and vertebrate fossils have been recovered from fluvial sediments deposited in the bighorn basin wyoming during the first 13 m y of the tertiary here we outline and discuss changes in the composition and diversity of floras and faunas during this period which includes the recovery of terrestrial ecosystems from the k t boundary extinctions and later during the paleocene eocene transition the greatest global warming of the cenozoic floral diversity has been studied at three levels of spatial resolution sub local at individual collecting sites local along a single bed or stratigraphic horizon and basin wide regional sub local diversity shows a moderate increase from the early to late paleocene followed by a decrease across the paleocene eocene boundary then an increase into the later early eocene local heterogeneity was lower in paleocene backswamp floras although distinct groups of species dominated in different local fluvial settings such as backswamps and alluvial ridges heterogeneity of backswamp forests increased by about 65 from the early to late wasatchian early eocene the number of plant species inferred from the bighorn basin dataset rose gradually from the puercan to an early clarkforkian peak of about 40 species declined sharply to about 25 species by the clarkforkian wasatchian boundary then rose through the wasatchian to about 50 species a regional analysis of mammalian genera shows high turnover and a rapidly increasing number of genera within a million years of the k t boundary 10 50 genera a slight decline to 40 genera by the early clarkforkian then an increase from 40 to 75 genera by the late wasatchian our analyses found no major extinctions in mammals during the paleocene and early eocene in the bighorn basin but a one third decrease in the number of plant species at about the paleocene eocene boundary rates of taxonomic turnover were much higher for mammals than plants the diversity trends for plants and mammals show little congruence implying that the two groups responded in a very different manner to post k t extinction opportunities there is also little congruence between plant diversity levels and change in mean annual temperature mat as inferred from foliar physiognomy

tectonic implications of paleomagnetic poles from lower tertiary volcanic rocks south central alaska we have determined the paleolatitude of lower tertiary volcanic rocks in southern alaska to measure possible poleward translation of the wrangellia and the peninsular terranes after 50 m y ago previous paleomagnetic studies have shown that in triassic and jurassic time these terranes were located near the equator and have moved at least 3000 km poleward relative to the north american craton our sample localities are in the northern talkeetna mountains in mildly deformed andesite and dacite flows 50 4 51 3 53 9 and 56 3 m y by k ar that overlap lower cretaceous flysch lower permian volcanic rocks of wrangellia and upper triassic pillow basalt of the susitna terrane results from 26 cooling units 23 of reversed polarity and 3 of normal polarity give a mean paleomagnetic pole at 69 5 n 179 6 e 95 12 2 stratigraphic sections from opposite limbs of a syncline yield directional paths that pass the fold test satisfying a necessary condition for primary origin of the magnetization the corresponding mean paleolatitude 76 n of the northern talkeetna mountains is 8 10 higher than the latitude predicted from the eocene reference pole for north america therefore northward drift of the talkeetna superterrane which is the amalgamation of the wrangellia and peninsular terranes during and after middle jurassic time was probably complete by 50 m y ago our results are consistent with paleomagnetic poles from uppermost cretaceous and paleocene volcanic sequences in denali national park the lake clark region northern bristol bay region and near mcgrath these poles generally lie south of the cratonic poles suggesting that the region between the kaltag bruin bay and castle mountain faults has rotated counterclockwise relative to north america since the early eocene

precursory seismicity associated with frequent large ice avalanches on iliamna volcano alaska usa since 1994 at least six major volume 10 6 m 3 ice and rock avalanches have occurred on iliamna volcano alaska usa each of the avalanches was preceded by up to 2 hours of seismicity believed to represent the initial stages of failure each seismic sequence begins with a series of repeating earthquakes thought to represent slip on an ice rock interface or between layers of ice this stage is followed by a prolonged period of continuous ground shaking that reflects constant slip accommodated by deformation at the glacier base finally the glacier fails in a large avalanche some of the events appear to have entrained large amounts of rock while others comprise mostly snow and ice several avalanches initiated from the same source region suggesting that this part of the volcano is particularly susceptible to failure possibly due to the presence of nearby fumaroles although thermal conditions at the time of failure are not well constrained it is likely that geothermal energy causes melting at the glacier base promoting slip and culminating in failure the frequent nature and predictable failure sequence of iliamna avalanches makes the volcano an excellent laboratory for the study of ice avalanches the prolonged nature of the seismic signal suggests that warning may one day be given for similar events occurring in populated regions

temporal spatial variations of stress at redoubt volcano alaska inferred from inversion of fault plane solutions abstract we inverted fault plane solutions fps of 420 earthquakes with a largest magnitude of 3 1 mostly occupying a 4 4 10 km 3 volume beneath redoubt volcano for principal stress directions during 1989 1998 on average fpss were computed with 8 p wave readings inversions performed with 48 fps yielding misfits of 7 and the size of the 95 confidence regions of the stress directions is 30 during the 1989 1990 eruptions stresses were typically sub horizontal 1 and 2 striking ese wnw and nne ssw respectively and near vertical 3 whereas during july 1991 january 1998 we found near vertical 1 and sub horizontal 2 and 3 striking sse nnw and ene wsw respectively we found differences in plunge of 1 up to 60 between 1990 and 1991 and sub volumes with different stress at the 99 confidence level evaluated with the z test based on the changes in stress directions from the eruptive to the inactive period we infer that the magnitudes of principal stresses increased progressively during the eruptions and had subsequently decreased by the post eruption period the observations can be explained by expansion and contraction of a plexus like magma body together with changes in physical properties of the magmas involved we estimate that the absolute values of principal stresses are similar to each other and are in the range 182 187 mpa

the organic geochemistry of coal from plant materials to coal coalification is a process that transforms plant remains under the influence of time temperature and possibly pressure to a black generally lustrous solid organic fossil fuel having a very complex chemistry although much has been learned in the past two centuries on coal chemistry we still have little knowledge of the way plant materials undergo these transformations the problem has been the existence of adequate characterization tools the advent of some new tools for structural elucidation of macromolecules has led to some revised thinking on coalification originally thought to be a process involving the full degradation of plant remains and subsequent reconstitution of these remains the general consensus today is that the process involves a selective preservation of certain resistant plant components followed by some minor reorganization of the biopolymers that survive the major components of plants do degrade and the resistant ones often constitute only a small fraction of the original mass of the plant materials this paper examines the most recent literature concerning coalification and focuses on the chemistry associated with coalification of certain recognizable plant remains that have been at the center of research activity for the past two decades thus we examine the recent knowledge of the chemistry of resistant biopolymers in extant and fossil wood cuticles resins spores and algae knowledge that has been assembled to establish the reaction pathways towards coal macromolecules

radiometric age of the chickaloon formation of south central alaska location of the paleocene eocene boundary k ar and fission track ages from two volcanic ash partings in upper chickaloon formation coals range from 53 3 1 5 m y to 55 8 1 7 m y these ages establish that the paleocene eocene boundary 55 m y occurs within the dated upper part of this formation

diagenetic siderite and other ferroan carbonates in a modern subsiding marsh sequence abstract mineralogical and carbon and oxygen stable isotope compositions in siderite rich concretions from a marsh within the mississippi river deltaic plain are highly variable the concretions have sideritic interiors and become more calcitic and dolomitic ankeritic near their margins 13c values of these concretions range from 10 0 to 7 4 pdb and 1 o values range from 2 4 to 8 9 pdb the stable isotope compositions exhibit two general trends one is a growth trend that shows 13c an 18o depletion from the centers to the margins of the nodules and bands the other is a progressive burial trend that shows 13c enrichments and 18o depletions at the centers of the concretions with depth a zonal model for carbonate precipitation with emphasis on an early fresh water non sulfidic methanic phase followed by a sulfidic stage associated with marine inundation of the marsh explains much of the observed carbon isotopic variations mixing of fluids plus precipitation in a partially closed chemical microsystem accounts for most of the oxygen isotope fractionations documented between growth layers and casts doubt on the utility of change in 18o shifts as an indicator of depth or relative temperature of concretion formation for concretions that form in coastal environments

high resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at redoubt volcano alaska abstract a combination of satellite and airborne high resolution visible and thermal infrared tir image data detected and measured changes at redoubt volcano during the 2008 2009 unrest and eruption the tir sensors detected persistent elevated temperatures at summit ice melt holes as seismicity and gas emissions increased in late 2008 to march 2009 a phreatic explosion on 15 march was followed by more than 19 magmatic explosive events from 23 march to 4 april that produced high altitude ash clouds and large lahars two or three lava domes extruded and were destroyed between 23 march and 4 april after 4 april the eruption extruded a large lava dome that continued to grow until at least early july 2009

assessment of depositional ash loadings from the 2009 eruption of mt redoubt abstract volcanic ash deposited onto ice and snow in the arctic has the potential to perturb the regional radiation balance by altering the surface reflectivity in order to determine changes in surface albedo loading fields of deposits must be quantified loading fields are defined as the total mass of ash deposited over an area we assessed the areal extent and loading of ash deposits from the 2009 eruption of mt redoubt using an eulerian volcanic ash transport and dispersion model fall3d combined with satellite and deposit observations because direct observations are often limited in remote arctic regions we devised a novel method for modeling ash deposit loading fields for the entire eruption based on best fit parameters of a well studied eruptive event the major land depositing eruptive events events 2 6 on march 23 24 were chosen for analyses realistic ranges of model parameters were selected based on the well described event 5 march 23 and were estimated for other events the model results were validated against nasa a train satellite data and field measurements reported by the alaska volcano observatory overall good to moderate agreement was found a total cumulative deposit area of 3 7 106 km2 was produced and loadings ranged from 7000 3000 g m 2 near the vent to

repeating volcano tectonic earthquakes at mt etna volcano sicily italy during 1999 2009 abstract repeating volcano tectonic vt earthquakes taking place at mt etna during 1999 2009 were detected and analyzed to investigate their behavior we found 735 families amounting to 2479 vt earthquakes representing 38 of all the analyzed vt earthquakes the number of vt earthquakes making up the families ranges from 2 to 23 over 70 of the families comprise 2 or 3 vt earthquakes and only 20 families by more than 10 events the occurrence lifetime is also highly variable ranging from some minutes to ten years in particular more than half of the families have a lifetime shorter than 0 5 day and only 10 longer than 1 year on the basis of these results most of the detected families were considered burst type i e show swarm like occurrence and hence their origin cannot be explained by a temporally constant tectonic loading indeed since the analyzed earthquakes take place in a volcanic area the rocks are affected not only by tectonic stresses related to the fairly steady regional stress field but also by local stresses caused by the volcano such as magma batch intrusions movements and gravitational loading we focused on the five groups of families characterized by the longest repeatability over time namely high number of events and long lifetime located in the north eastern eastern and southern flanks of the volcano unlike the first four groups which similarly to most of the detected families show swarm like vt occurrences group v located in the north eastern sector exhibits a more tectonic behavior with the events making up such a group spread over almost the entire analyzed period it is clear how both occurrence and slip rates do not remain constant but vary over time and such changes are time related to the occurrence of the 2002 2003 eruption finally by fpfit algorithm a good agreement between directions identified by nodal planes and the earthquake epicentral distribution was generally found

paleoenvironmental reconstruction of a middle miocene forest from the western canadian arctic abstract abundant fossil plant remains are preserved in deposits of middle miocene age of the ballast brook formation on banks island northwest territories canada intact seed cones logs and stumps are preserved in situ as mummified remains and present an opportunity to reconstruct the composition structure and productivity of a pinaceae dominated forest that once grew north of the arctic circle paleolatitude ca 74 n we mapped and measured 78 tree stumps exposed in three dimensions on a 0 12 ha peat layer an analysis of the wood anatomy and seed cones indicates that a haploxylon pine dominated this lowland forest although species of both picea and glyptostrobus were growing in the swamp as well stump diameters ranged from 7 cm to 108 cm average 42 cm we utilized allometric relationships to predict tree heights based on the stump diameters in the fossil forest our results indicate that the average tree height of this miocene forest may have been as large as 21 m we used stump diameter data and predicted tree height to calculate the parabolic stem volume and stem biomass for the exposed area of fossil forest stem biomass assuming an average wood density of 410 kg m 3 may have been as great as 259 mg ha 1 or as little at 202 mg ha 1 the annual ring width of the stem wood sampled in the field was 1 26 mm for pinus 1 20 mm for picea and 0 21 mm for glyptostrobus based on these growth rates our estimate of biomass sequestered aboveground as wood is at most 3 8 mg ha 1 y 1 based on our estimates these lowland forest communities were of moderate biomass and productivity typical of modern cool temperate forests in north america

origin and diagenetic evolution of ca mg fe carbonates in some coalfields of japan carbonate concretions lenses and bands in the pleistocene palaeogene and upper triassic coalfields of japan consist of various carbonate minerals with varied chemical compositions authigenic carbonates in freshwater sediments are siderite calcite ankerite dolomite ferroan magnesite in brackish water to marine sediments in the coal measures calcite dolomite ankerite siderite ferroan magnesite and in the overlying marine deposits calcite dolomite siderite most carbonates were formed progressively during burial within a range of depths between the sediment water interface and approximately 3 km the mineral species and the chemical composition of the carbonates are controlled primarily by the initial sedimentary facies of the host sediments and secondarily by the diagenetic evolution of pore water during burial based on the regular sequence and burial depth of precipitation of authigenic carbonates in a specific sedimentary facies three diagenetic stages of carbonates are proposed carbonates formed during stage i 2000 m are fe calcite and extremely high ca mg siderite the latter is exclusively in marine mudstones the supply of ca is partly from the alteration of silicates in the sediments at elevated burial temperatures after uplift calcite with low mg content precipitates from percolating groundwater and fills extensional cracks

paleoenvironment and paleoecology of a late paleocene high latitude terrestrial succession arkose ridge formation at box canyon southern talkeetna mountains alaska abstract paleogene sedimentary rocks of the arkose ridge formation talkeetna mountains alaska preserve a record of a fluvial lacustrine depositional environment and its forested ecosystem in an active basin among the convergent margin tectonic processes that shaped southern alaska an 800 m measured succession at box canyon indicates braid plain deposition with predominantly gravelly deposits low in the exposure to sandy and muddy facies associations below an overlying lava flow sequence u pb geochronology on zircons from a tuff and a sandstone within the measured section as well as an ar ar date from the overlying lava constrain the age of the sedimentary succession to between 59 ma and 48 ma fossil plant remains occur throughout the arkose ridge formation as poorly preserved coalified woody debris and fragmentary leaf impressions at box canyon however a thin lacustrine depositional lens of rhythmically laminated mudrocks yielded fish fossils and a well preserved floral assemblage including foliage and reproductive organs representing conifers sphenopsids monocots and dicots leaf physiognomic methods to estimate paleoclimate were applied to the dicot leaf collection and indicate warm temperate paleotemperatures 11 15 4 c mat and elevated paleoprecipitation 120 cm yr map estimates as compared to modern conditions results that are parallel with previously published estimates from the partly coeval chickaloon formation deposited in more distal depositional environments in the same basin the low abundance of leaf herbivory in the box canyon dicot assemblage 9 of leaves damaged is also similar to the results from assemblages in the meander plain depositional systems of the chickaloon this new suite of data informs models of the tectonostratigraphic evolution of southern alaska and the developing understanding of terrestrial paleoecology and paleoclimate at high latitudes during the late paleocene early eocene greenhouse climate phase

evolution of the december 14 1989 precursory long period event swarm at redoubt volcano alaska abstract the intermittency pattern and evolution in waveforms of long period lp seismic events during the intense 23 h swarm that preceded the december 14 1989 eruption of redoubt volcano are investigated utilizing cross correlation to exploit the high degree of similarity among waveforms a substantially more complete event catalog is generated than was available from near realtime detection based on short term long term amplitude ratios which was saturated by the high rate of activity the temporal magnitude distribution of the predominant lp events is found to have an unusual banded structure in which the average magnitude of each band slowly increases and then decreases through time a bifurcation that appears in the uppermost band shortly after the peak in magnitudes is characterized by a quasi periodicity in intermittency and magnitude that is reminiscent of one of the classic routes to chaotic behavior in some non linear systems the waveforms of the predominant events evolve slowly but unsteadily through time these gradual changes appear to result from variations in the relative amplitudes of spectral peaks that remain stable in frequency which suggests that they are due to differential excitation of a single resonant source two other previously unrecognized repetitive waveforms are also identified but the signals from these secondary events are not clearly recorded at distances beyond the closest station similarities among the spectra of the predominant and secondary events suggest that the signals from these events also could represent different modes of exciting the same source significant changes in the rates and the sizes of the largest of these secondary events appear to coincide with the peak in the size distribution of the predominant lps at least some of the non repetitive lp waveforms in the swarm appear to be the result of the superposition of signals from the rapid repetition of predominant lp source thus placing a constraint on the repeat time of the triggering mechanism for this source a lone hybrid event which has a waveform character intermediate between the predominant lp events and high frequency volcano tectonic events was also identified in the swarm the occurrence of this event provides important evidence that the low frequency character of the lp events is a source rather than a path or site effect

life at the top of the greenhouse eocene world a review of the eocene flora and vertebrate fauna from canada s high arctic early middle eocene ca 53 38 ma sediments of the eureka sound group in canada s arctic archipelago preserve evidence of lush mixed conifer broadleaf rain forests inhabited at times by alligators turtles and diverse mammals including primates tapirs brontotheres and hippo like coryphodon this biota reflects a greenhouse world offering a climatic and ecologic deep time analog of a mild ice free arctic that may be our best means to predict what is in store for the future arctic if current climate change goes unchecked in our review of the early middle eocene arctic flora and vertebrate fauna we place the arctic fossil localities in historic geographic and stratigraphic context and we provide an integrated synthesis and discussion of the paleobiology and paleoecology of these eocene arctic forests and their vertebrate inhabitants the abundance and diversity of tapirs and plagiomenids both rare elements in midlatitude faunas and the absence of artiodactyls early horses and the hyopsodontid condylarth hyopsodus well represented at midlatitude localities are peculiar to the eocene arctic the eocene arctic macrofloras reveal a forested landscape analogous to the swamp cypress and broadleaf floodplain forests of the modern southeastern united states multiple climate proxies indicate a mild temperate early middle eocene arctic with winter temperatures at or just above freezing and summer temperatures of 20 c or higher and high precipitation at times this high precipitation resulted in freshwater discharge into a nearly enclosed arctic ocean basin sufficient to cause surface freshening of the arctic ocean supporting mats of the floating fern azolla fluctuating arctic ocean sea level due to freshwater inputs as well as tectonics produced temporary land bridges allowing land plants and animals to disperse between north america and both europe and asia

seismological evidence for long term and rapidly accelerating magma pressurization preceding the 2009 eruption of redoubt volcano alaska abstract successful eruption forecasts are heavily dependent on the recognition of well established patterns in volcano monitoring data therefore it is critical to develop in retrospect an understanding of the physical basis for cases of abnormal precursory behavior as the basis for a a complete understanding of the range of precursory signals that may be expected at a particular volcano and b development of new monitoring approaches to detect more subtle signals of the underlying processes responsible for common patterns of seismic unrest here using a hybrid analysis of shear wave splitting sws and double couple fault plane solutions fps we document the timing and nature of local stress field changes in the months to days preceding the 2009 eruption of redoubt volcano alaska which was characterized by an abnormally long period of precursory low frequency seismicity reflected in multiple escalations of alert levels prior to the eruption we find that an approximately 90 change in the polarization of fast s wavelets accompanied the earliest signs of seismic unrest in 2008 and continued through the eruption before diminishing in 2009 a similar change in the orientation of vt fps occurred 18 48 h prior to the eruption onset on march 23 2009 but almost two months after a strong increase in the rate of shallow vt earthquakes combined our sws and fps results show the earliest and latest known changes in seismic monitoring data respectively and are suggestive of a protracted period of slow magma ascent followed by a short period of rapidly increasing magma pressurization beneath the volcano these results demonstrate the power of a combined stress field analysis for clarifying the processes driving ambiguous seismic unrest at active volcanoes

high precision relative locations of earthquakes at mount st helens washington several earthquake sequences have occurred at mount st helens as clusters of shallow events with nearly identical waveforms multiplets we present a technique that allows the relative relocation of events within a multiplet to at least an order of magnitude higher precision than is typically possible with traditional techniques a multiplet is studied in pairs of events called doublets each doublet is made up of a reference event and one other event from the multiplet the cross spectrum of a short window beginning just before the p arrival is used to compute differences in arrival times between seismograms from the same station for each doublet these time differences computed with a precision of 1 2 ms are then used to locate each earthquake relative to the reference event engineering explosions with well known locations are used to test the relocation technique explosions can be relocated with accuracy better than 20 m for events within 250 m of the reference explosion the relocation technique is applied to earthquakes preceding the september 10 1984 and the may june 1985 dome building eruptions of mount st helens forty events that occurred during a 12 hour period in september 1984 are located in a volume approximately 30 m in diameter beneath the lava dome the earthquakes following the extrusion do not occur in multiplets and appear to be distributed over a much larger volume in the may june 1985 eruption we recognize three multiplet sets that took place successively in time the multiplets are interpreted as repeated failure or slip within a relatively small volume due to high strain rates around the magma supply conduit

delineation of the distinctive nature of tertiary coal beds abstract floral character in mires has changed progressively through time in the carboniferous pteridophytes sphenophytes and lycophytes were dominant but by the permian gymnosperms were an important component of mire flora during the early mesozoic gymnosperms remained the characteristic mire vegetation together with pteridophytes and conifers became dominant during the jurassic cretaceous and paleocene vegetation are similar with taxodiaceous flora being important in mire vegetation from the eocene onwards however angiosperms were increasingly dominant in mire communities and in the miocene herbaceous vegetation began to play a significant role together with these changes in floral character at least three aspects of coal character also appear to vary sequentially with time and are distinctive in the tertiary 1 proportions and thickness of vitrain banding 2 coal bed thickness and 3 proportions of carbonised material a compilation has been made of data from the coal literature comparing older coals with those of the tertiary in order to give a perspective in which to examine tertiary coals it was found that only tertiary coals contain significant proportions of coal devoid of vitrain bands in addition tertiary coals are the thickest recorded coal beds and generally contain low percentages of carbonised material many less than 5 as compared to older coals it is interesting to note that paleocene coal beds are similar to cretaceous coals in that they tend to be thinner and contain higher proportions of carbonised material than do younger tertiary coals the absence of vitrain bands in some tertiary coal beds is thought to result from the floras dominated by angiosperms which are relatively easily degraded as compared to gymnosperms the thickness of tertiary coals may be related to an increase in biomass production from the carboniferous through to the tertiary as plants made less investment in producing lignin an energy intensive process in addition with less lignin in plants easier degradation of biomass may have facilitated nutrient recycling which in turn led to greater biomass production increased biomass production may have also diluted the carbonised material present in some tertiary peats leading to lower proportions in the coal another possible cause of decreased carbonised components in tertiary coal is that decreasing lignin content resulted in decreased charring during fires as lignin is particularly prone to charring a third possibility is that the carbonised component of peat may be concentrated during coalification so that tertiary coals generally of lower rank than mesozoic or paleozoic coals contain a smaller fraction of carbonised plant material it is not at present clear which of these mechanisms may have affected carbonised material in peat and coal but it is clear that lignin type and content has had an important role in determining peat and coal character since the paleozoic

mechanism of the 1996 97 non eruptive volcano tectonic earthquake swarm at iliamna volcano alaska a significant number of volcano tectonic vt earthquake swarms some of which are accompanied by ground deformation and or volcanic gas emissions do not culminate in an eruption these swarms are often thought to represent stalled intrusions of magma into the mid or shallow level crust real time assessment of the likelihood that a vt swarm will culminate in an eruption is one of the key challenges of volcano monitoring and retrospective analysis of non eruptive swarms provides an important framework for future assessments here we explore models for a non eruptive vt earthquake swarm located beneath iliamna volcano alaska in may 1996 june 1997 through calculation and inversion of fault plane solutions for swarm and background periods and through coulomb stress modeling of faulting types and hypocenter locations observed during the swarm through a comparison of models of deep and shallow intrusions to swarm observations we aim to test the hypothesis that the 1996 97 swarm represented a shallow intrusion or failed eruption observations of the 1996 97 swarm are found to be consistent with several scenarios including both shallow and deep intrusion most likely involving a relatively small volume of intruded magma and or a low degree of magma pressurization corresponding to a relatively low likelihood of eruption

temporal change of upper crustal vp vs ratios with volcanic evolution in redoubt volcano abstract volcanic activities accompany changes in the physical and chemical properties of the medium the ratio between p and s wave velocities v p v s is sensitive to the medium property changes we investigate temporal variations of the v p v s ratios in the upper crust around redoubt volcano in the 1989 2014 time period using the traveltimes of local earthquakes the v p v s ratios reached 2 0 immediately prior to the 1989 1990 and 2009 eruptions these high v p v s ratios may be associated with partial melts in the edifice the v p v s ratios rapidly decreased to 1 7 during the 1989 1990 and 2009 eruptions due to decreasing temperatures fluids and pore pressures and increasing effective stresses after melt eruptions and gas emission the change rates of the v p v s ratios showed evident spatial distributions the v p v s ratios increased at a rate of 0 025 0 003 yr 1 below the 2009 vent during the inter eruption period between the 1989 1990 and 2009 eruptions due to an increase in the temperature which may be associated with the recharge of the magma in the lower crust the increase rate of the v p v s ratios was as low as 0 005 0 001 yr 1 in the regions located away from the eruption site the v p v s ratios appear to have increased consistently at a rate of 0 017 0 004 yr 1 since the 2009 eruption

an analysis of neogene climates in beringia abstract a newly developed multivariate analysis of foliar physiognomy provides accurate valid and precise repeatable data for nonmarine climates in beringia during the mid miocene thermal maximum both summers and especially winters were warmer than now a temperature decline at about 12 13 ma involved decreases in both summer and winter temperatures but summer temperatures appear to have decreased more than winter temperatures during the interval from about 12 ma to about 8 ma winter temperatures fluctuated resulting in two apparent increases in mean annual temperature when the counter clockwise rotation of north america during this interval is factored in overall mean annual temperature declined decrease in summer and winter temperatures at about 12 13 ma can also be documented in the west beringian northeast siberian region although small size of known beringian leaf assemblages younger than about 7 or 8 ma precludes multivariate physiognomic analysis general floristic analyses concomitant with inferences based on the sedimentary record suggest that whereas summer temperatures had approximately reached their present day levels by 5 6 ma winter temperatures continued to decline during the pliocene

atmospheric carbon dioxide linked with mesozoic and early cenozoic climate change carbon isotopes of fossil plants and model simulations suggest that atmospheric carbon dioxide levels were variable during the period 200 to 60 million years ago the large decreases in the partial pressure of co2 coincide with glaciations providing evidence against climate co2 decoupling during the mesozoic

seismic evolution of the 1989 1990 eruption sequence of redoubt volcano alaska abstract redoubt volcano in south central alaska erupted between december 1989 and june 1990 in a sequence of events characterized by large tephra eruptions pyroclastic flows lahars and debris flows and episodes of dome growth the eruption was monitored by a network of five to nine seismic stations located 1 to 22 km from the summit crater notable features of the eruption seismicity include 1 small long period events beginning in september 1989 which increased slowly in number during november and early december 2 an intense swarm of long period events which preceded the initial eruptions on december 14 by 23 hours 3 shallow swarms 0 to 3 km of volcano tectonic events following each eruption on december 15 4 a persistent cluster of deep 6 to 10 km volcano tectonic earthquakes initiated by the eruptions on december 15 which continued throughout and beyond the eruption 5 an intense swarm of long period events which preceded the eruptions on january 2 and 6 nine additional intervals of increased long period seismicity each of which preceded a tephra eruption hypocenters of volcano tectonic earthquakes suggest the presence of a magma source region at 6 10 km depth earthquakes at these depths were initiated by the tephra eruptions on december 15 and likely represent the readjustment of stresses in the country rock associated with the removal of magma from these depths the locations and time history of these earthquakes coupled with the eruptive behavior of the volcano suggest this region was the source of most of the erupted material during the 1989 1990 eruption this source region appears to be connected to the surface by a narrow pipe like conduit as inferred from the hypocenters of volcano tectonic earthquakes concentrations of shallow volcano tectonic earthquakes followed each of the tephra eruptions on december 15 these shocks may represent stress readjustment in the wall rock related to the removal of magma and volatiles at these depths this shallow zone was the source area of the majority of long period seismicity through the remainder of the eruption the long period seismicity likely reflects the pressurization of the shallow portions of the magmatic system

paleomagnetism of eocene plutonic rocks matanuska valley alaska paleomagnetic analysis of 88 samples from 14 sites in four eocene sills in the matanuska valley south central alaska yields a paleomagnetic pole at lat 72 9 n long 281 1 e precision parameter k 15 4 the paleolatitude of this result suggests that this part of the alaskan crust was at or near its present position relative to north america in the middle tertiary this pole also indicates that the region has been rotated clockwise by approximately 50 these results can be explained by local block rotations of fault bounded blocks in response to regional right lateral shear along both the castle mountain and border ranges faults

seismic observations of redoubt volcano alaska 1989 2010 and a conceptual model of the redoubt magmatic system abstract seismic activity at redoubt volcano alaska has been closely monitored since 1989 by a network of five to ten seismometers within 22 km of the volcano s summit major eruptions occurred in 1989 1990 and 2009 and were characterized by large volcanic explosions episodes of lava dome growth and failure pyroclastic flows and lahars seismic features of the 1989 1990 eruption were 1 weak precursory tremor and a short 23 hour long intense swarm of repetitive shallow long period lp events centered 1 4 km below the crater floor 2 shallow volcano tectonic vt and hybrid earthquakes that separated early episodes of dome growth 3 13 additional swarms of lp events at shallow depths precursory to many of the 25 explosions that occurred over the more than 128 day duration of eruptive activity and 4 a persistent cluster of vt earthquakes at 6 to 9 km depth in contrast the 2009 eruption was preceded by a pronounced increase in deep lp dlp events at lower crustal depths 25 to 38 km that began in mid december 2008 two months of discontinuous shallow volcanic tremor that started on january 23 2009 a strong phreatic explosion on march 15 and a 58 hour long swarm of repetitive shallow lp events the 2009 eruption consisted of at least 23 major explosions between march 23 and april 5 again accompanied by shallow vt earthquakes several episodes of shallow repetitive lp events and dome growth continuing until mid july increased vt earthquakes at 4 to 9 km depth began slowly in early april possibly defining a mid crustal magma source zone magmatic processes associated with the 2009 eruption seismically activated the same portions of the redoubt magmatic system as the 1989 1990 eruption although the time scales and intensity vary considerably among the two eruptions the occurrence of precursory dlp events suggests that the 2009 eruption may have involved the rise of magma from lower crustal depths based on the evolution of seismicity during the 1989 1990 and 2009 eruptions the redoubt magmatic system is envisioned to consist of a shallow system of cracks extending 1 to 2 km below the crater floor a magma storage or source region at roughly 3 to 9 km depth and a diffuse magma source region at 25 to 38 km depth close tracking of seismic activity allowed the alaska volcano observatory to successfully issue warnings prior to many of the hazardous explosive events that occurred in 2009

the seismicity of the 2009 redoubt eruption article redoubt volcano erupted in march 2009 following 6 months of precursory seismic activity the 4 5 month long eruptive sequence was accompanied by phreatic and magmatic explosions periods of steady dome growth lahars seismic swarms extended episodes of volcanic tremor and changes in the background seismicity rate this study presents a seismic chronology of the eruption and places it in context with the variety of other geological and geophysical data that were recorded during the eruptive period we highlight 6 notable seismic swarms 3 of which preceded large explosions the swarms varied from an hour to several days in duration and contained tens to over 7000 earthquakes many of the swarms were dominated by low frequency type earthquakes that contained families of repeating events seismic tremor varied considerably in frequency amplitude and duration during the eruption with distinct characteristics accompanying different types of volcanic activity the explosion signals during march 23 24 were the most energetic and the explosions on march 26 29 contained proportionally more low frequency energy 0 033 0 3 hz two seismic stations were particularly well suited to recording lahars that flowed down the drift river valley data from these stations showed that lahars were generated by the majority of the explosion events as well as during the continuous eruptive activity on march 29 when no large explosions occurred we also examine the seismicity which occurred outside of the explosion and swarm episodes and find several families of repeating vt earthquakes which begin shortly before the april 4 explosion and that continue

earthquake classification location and error analysis in a volcanic environment implications for the magmatic system of the 1989 1990 eruptions at redoubt volcano alaska abstract determination of the precise locations of seismic events associated with the 1989 1990 eruptions of redoubt volcano posed a number of problems including poorly known crustal velocities a sparse station distribution and an abundance of events with emergent phase onsets in addition the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm this algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations the velocity model was calibrated on the basis of a posteruptive seismic survey in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice the model consists of a stack of homogeneous horizontal layers setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice detailed analysis of hypocentral errors shows that the long period lp events constituting the vigorous 23 hour swarm that preceded the initial eruption on december 14 could have originated from a point 1 4 km below the crater floor a similar analysis of lp events in the swarm preceding the major eruption on january 2 shows they also could have originated from a point the location of which is shifted 0 8 km northwest and 0 7 km deeper than the source of the initial swarm we suggest this shift in lp activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of december volcano tectonic vt earthquakes did not occur until after the initial 23 hour long swarm they began slowly just below the lp source and their rate of occurrence increased after the eruption of 01 52 ast on december 15 when they shifted to depths of 6 to 10 km after january 2 the vt activity migrated gradually northward this migration suggests northward propagating withdrawal of magma from a plexus of dikes and or sills located in the 6 to 10 km depth range precise relocations of selected events prior to january 2 clearly resolve a narrow steeply dipping pencil shaped concentration of activity in the depth range of 1 7 km which illuminates the conduit along which magma was transported to the surface a third event type named hybrid which blends the characteristics of both vt and lp events originates just below the lp source and may reflect brittle failure along a zone intersecting a fluid filled crack the distribution of hybrid events is elongated 0 2 0 4 km in an east west direction this distribution may offer constraints on the orientation and size of the fluid filled crack inferred to be the source of the lp events

growth ring analysis of early tertiary conifer woods from the canadian high arctic and its paleoclimatic interpretation abstract fossil forests where petrified stumps were preserved in growth position have been found within early tertiary sediments near strathcona fiord ellesmere island canadian arctic archipelago these fossil forests are obvious evidence for early tertiary climate much warmer than that of today we analyzed the growth rings of petrified woods from two fossil forest sites one in middle paleocene and the other in late early eocene to extract information on climate change the woods consist most abundantly of metasequoia and cf glyptostrobus suggesting that these forests grew in similar environments of warm to cool temperate climates mean ring width mean sensitivity and power spectrum were calculated for ring width sequences although significant difference in the mean ring width between the two forests was found a comparison with living trees suggests that the difference can be attributed to the specific difference between the forests so that a significant climate change may not necessarily be invoked we found little significant difference in the mean sensitivity and power spectrum between the forests neither did we find any strong indication of periodicities consideration of all features suggests that there was no significant difference in climate of middle paleocene and late early eocene time in the high arctic however the mean ring widths of these forests were significantly smaller than that reported for mid cretaceous high arctic fossil forest

extreme warming of mid latitude coastal ocean during the paleocene eocene thermal maximum inferences from tex86 and isotope data changes in sea surface temperature sst during the paleocene eocene thermal max imum petm have been estimated primarily from oxygen isotope and mg ca records generated from deep sea cores here we present a record of sea surface temperature change across the paleocene eocene boundary for a nearshore shallow marine section located on the eastern margin of north america the sst record as inferred from tex86 data indicates a minimum of 8 c of warming with peak temperatures in excess of 33 c similar ssts are estimated from planktonic foraminifer oxygen isotope records al though the excursion is slightly larger the slight offset in the oxygen isotope record may reflect on seasonally higher runoff and lower salinity

sedimentology facies architecture and chemostratigraphy of a continental high latitude paleocene eocene succession the chickaloon formation alaska abstract the paleocene eocene chickaloon formation of southern alaska represents rapid deposition in a floodbasin setting contains abundant and diverse fossil plant material and spans the paleocene eocene thermal maximum petm sedimentologic lithofacies and chemostratigraphic analyses of exposures of the chickaloon formation were conducted in order to provide a contextual framework for this late paleocene early eocene high latitude sedimentary succession and to test if hyperthermal conditions are recorded in the unit at the main study area in the evan jones coal mine strata represent an alluvial sequence dominated by floodplain channel sandstone crevasse lobe crevasse channel and mire deposition floodplain environments are represented by medium gray commonly nodular and or carbonate cemented shaly siltstone and centimeter scale thick sheet sandstone interbeds most channel sandstone deposits are interpreted to be crevasse channels and are generally small 2 5 m thick rarely coarser than medium grained sandstone and sand grains are commonly coated with fe oxides carbonaceous shale and coal are localized and indicate a high rate of organic carbon accumulation in the area 13c analyses of bulk organic carbon from the succession at the evan jones mine are internally consistent with this interpretation they yield uniformly negative values that are typical of continental organic matter 21 7 to 28 5 x 25 4 fossil plant material is also very common and includes leaves wood seeds and resins from broad leaf angiosperms conifers ferns and sphenopsids considered together lithologic and paleontologic data suggest that these strata represent a floodbasin environment the observed crevasse channels probably originate from a main channel located within several kilometers of the depocenter ash fall tuffs punctuate the studied sequence and contain abundant reworked or recycled zircons indicating that the depocenter was proximal to a volcanic source across all of these chickaloon depositional environments a significant negative isotopic shift 5 8 occurs which we hypothesize to represent a short lived perturbation associated with a global hyperthermal event

tree growth at polar latitudes based on fossil tree ring analysis permineralized trunks and mature wood samples with well preserved growth rings are described and analyzed from the upper permian and middle triassic of the central transantarctic mountains this fossil wood is unique in that the plants lived in an environment with no modern analogue and exhibited luxuriant tree growth above 75 s paleolatitude ring width averages 1 69 2 3 mm with maximum width of 6 83 9 9 mm an order of magnitude larger than ring widths produced at near polar latitudes today tree rings in both the permian and triassic woods show similar structure consisting almost entirely of earlywood spring wood with between 0 12 of each ring classified as latewood summer wood the small amount of latewood 0 6 cells indicates a very rapid transition to seasonal dormancy probably in response to decreasing light levels at these paleolatitudes in order to accurately delimit the earlywood latewood boundary a comparison was done of classical dendroclimatological techniques and alternative techniques utilized primarily by paleobotanists analyzing fossil woods we found that classical wood anatomy techniques provided a more accurate explanation of wood development and tree growth for these high latitude samples the suggested cool temperate late permian glossopteris flora from this area differs substantially from the warm temperate middle triassic corystosperm flora leaf type dicroidium and very different paleoclimates have been reconstructed for these two time periods ring structure and wood growth from both sites however are very similar indicating that these plants were responding to the environment in very similar ways the structure of the tree rings including a large number of earlywood tracheids and a very low number of latewood cells provides evidence that growth at these polar latitudes was limited by light levels rather than water and temperature as occurs in modern high latitude forests these fossil tree rings have important implications for understanding woody shoot growth and cambial function at high latitudes during periods of global warmth 2007 elsevier b v all rights reserved