bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological and Chemical Characteristics of Soil Catenas on Pinedale and Bull Lake Moraine Slopes in the Salmon River Mountains, Idaho
Authors: Berry Margaret E. 
Published: December 2004

AbstractMorphological and chemical properties of soils developed on moraines of granitic composition, and forested with lodgepole pine, in Bear Valley, Idaho, change significantly with age and slope position. Soil development on Pinedale and Bull Lake moraine slopes of similar curvature and steepness was assessed at the summits, shoulders, backslopes, and footslopes of both catenas, and at the toeslope of the Bull Lake catena. Many soil properties show trends in development with both age and slope position. These properties include clay content, clay film development, color, plagioclase weathering, and dithionite-citrate-extractable iron (Fed). The degree of development of all these properties is greater on the Bull Lake catena relative to that on the Pinedale catena. This trend reflects increased soil development with age. On both catenas, development of soil properties is commonly highest at the footslope or toeslope sites and minimum at the backslope site. Downslope changes are attributed to both colluviation and pedogenic processes, including sorting of sediments during downslope transport, greater accumulation of eolian materials transported to downslope sites by surface processes, and greater in situ weathering of mineral grains at the footslope and toeslope sites.
Postglacial Vegetation History of the Mackenzie River Basin
Authors: MacDonald Glen M. 
Published: December 2004

AbstractThree radiocarbon-dated cores from small lakes provide pollen records of postglacial vegetation change in the central Mackenzie River basin. These data are combined with previously published records to reconstruct vegetation development from central Alberta to the Mackenzie delta. The paleoecological data demonstrate that a continuous corridor of herb-and-shrub-dominated vegetation extended between Beringia and the Great Plains of North America from deglaciaiton until about 10,000 yr B.P. The initial vegetation was replaced by spruce forests between 10,000 and 8500 yr B.P. Significant vegetation change continued until approximately 500 yr B.P. when the muskeg-dominated landscape typical of the present subarctic was established. The initial herb-and-shrub vegetation was likely a reprise of conditions which existed during earlier Pleistocene deglaciations. These conditions may have provided a favorable environment for animals adapted to nonforested vegetation and promoted migration southward from Beringia and northward from the Great Plains during the last deglaciation and earlier Pleistocene deglaciations. The sequence of postglacial vegetation change in the Mackenzie basin likely reflects a combination of climatic change, edaphic change, and plant migration patterns and interactions.
Late Wisconsin History North of the Giants Range, Northern Minnesota, Inferred from Complex Stratigraphy
Authors: Björck Svante 
Published: December 2004

AbstractIn an area north of the Giants Range in northeastern Minnesota the late Wisconsin glacial and extraglacial lithostratigraphy shows that, apart from one occurrence of red clayey till, the deposits can be related to the deglaciation of the Rainy Lobe, the margin of which retreated northward, leaving debris-rich ice behind. By a combination of pollen stratigraphy, lithostratigraphy, and chronostratigraphy of lake sediments in this area, together with multivariate numerical analyses of the data set, a “hiatus” stratigraphy was set up. Combined with the glacial and extraglacial stratigraphy, it shows that the area of Glacial Lake Norwood was possibly later filled with sediments, between masses of stagnant ice, following a damming of drainge in the south by the St. Louis Sublobe. The area was drained through the Embarrass channel when the St. Louis Sublobe retreated. Then followed the drainage of Lake Koochiching through the Embarrass channel. At ca. 10,200 14C yr B.P. the area apparently became free of stagnant ice as normal lake sedimentation began in all lakes studied. A lake-level rise is indicated ca. 1000 yr later. Apart from a long-lasting phase of birch tundra parkland between ca. 12,000 (or 11,500?) and 10,600 14C yr B.P., the general pollen stratigraphy fits into the regional picture with a more or less undisturbed and gradual plant immigration from the time of the culmination of the St. Louis Sublobe.
Chronology of Lava and Associated Soils Near San Miguel, New Mexico
Authors: Gile Leland H. 
Published: December 2004

AbstractA lava flow in southern New Mexico extends into the Rio Grande Valley from the lower La Mesa geomorphic surface, a relict basin floor of middle Pleistocene age. Three buried soils occur beneath the lava at its east end. In places, the lava itself is buried by a sediment in which a soil has formed. Pedogenic carbonate was used to calculate the age of this soil, using a soil of lower La Mesa as a chronological guide. Both the latter soil and the Rio Grande Valley must be less than about 620,000 yr old according to dated volcanic ash, and are estimated to be about 500,000 yr old. Based upon this age and a total of 1200 kg/m2pedogenic carbonate in the lower La Mesa soil, the carbonate accumulated at an average rate of about 2.4 kg/m2/1000 yr. Using the same rate of carbonate accumulation, the postlava soil took about 180,000 yr to form. However, not quite all of the pedogenic carbonate in this soil has been accounted for, and a general figure of 200,000 yr is suggested for its approximate age. The geological setting indicates that the age of the lava should be very close to the age of the postlava soil, and a general figure of 200,000 yr is also suggested for approximate age of the lava. This contrasts with a new K/Ar age of 490,000 ± 30,000 yr, which is considered to be too old. However, two previously obtained K/Ar ages of 232,000 ± 80,000 and 154,000 ± 119,000 yr are much closer to the estimate based on pedogenic carbonate. The landscape of the soil that buries the lava differs from the landscape of the lower La Mesa soil that was used as a chronological guide. The rate of carbonate movement into the soils could also differ, and for this reason the age obtained by pedogenic carbonate is considered tentative.
Fission-Track Ages of Tuff Layers Related to the Pliocene-Pleistocene Boundary on the Boso Peninsula, Japan
Authors: Kasuya Masao 
Published: December 2004

AbstractFission-track ages of zircon crystals from four tuff layers in the late Cenozoic sediment sequence of the Boso Peninsula,.Japan, are 1.6 ± 0.2 myr (the Kurotaki Formation), 5.5 ± 0.6 and 5.2 ± 0.5 myr (the uppermost part of the Amatsu Formation), and 11.5 ± 0.8 myr (the middle part of the Amatsu Formation). These ages provide numerical age constraints on magneto-biostratigraphy. The normal polarity interval in the lower part of the Kiwada Formation corresponds to the Olduvai polarity subzone. The boundary between the Pliocene and Pleistocene lies slightly above the Olduvai polarity subzone.
Early Holocene Pecan, Carya Illinoensis, in the Mississippi River Valley Near Muscatine, Iowa
Authors: Bettis E. Arthur , Baker Richard G. , Nations Brenda K. , Benn David W. 
Published: December 2004

AbstractA fossil pecan, Carya illinoensis (Wang.) K. Koch, from floodplain sediments of the Mississippi River near Muscatine, Iowa, was accelerator-dated at 7280 ± 120 yr B.P. This discovery indicates that pecan was at or near its present northern limit by that time. Carya pollen profiles from the Mississippi River Trench indicate that hickory pollen percentages were much higher in the valley than at upland locations during the early Holocene. Pecan, the hickory with the most restricted riparian habitat, is the likely candidate for producing these peaks in Carya pollen percentages. Therefore, pecan may have reached its northern limit as early as 10,300 yr B.P. Its abundance in Early Archaic archaeological sites and the co-occurrence of early Holocene Carya pollen peaks with the arrival of the Dalton artifact complex in the Upper Mississippi Valley suggest that humans may have played a role in the early dispersal of pecan.
Oxygen Isotope Ratios from Tree Rings Containing Compression Wood
Authors: Luckman Brian , Gray John 
Published: December 2004

AbstractOxygen isotope determinations on the α-cellulose of tree rings cut from two leaning Picea engelmannii revealed significant differences between results from normal and compression wood radii. Nine samples (10-year periods) from the normal wood radius (1721–1953) in one tree showed good agreement with proxy climate information and maximum differences of 1.8‰ between the “warmest” and “coolest” decades sampled. Differences of equivalent magnitude were found between samples from the same decade from normal and compression wood radii. These differences are strongly related to the amount and/or density of compression wood present and suggest that sampling for paleoclimatic work should be restricted to complacent, erect trees without compression wood rings.
Holocene raised beaches at Terra Nova Bay, Victoria Land, Antarctica
Authors: Baroni Carlo , Orombelli Giuseppe 
Published: December 2004

AbstractMore than 40 14C dates for raised beaches at Terra Nova Bay ranging from the present to 7505 ± 230 yr B.P. supply minimum or maximum limiting ages that bracket a relative sea-level curve for this part of Victoria Land. Most samples consist of guano and penguin remains collected from abandoned nesting sites on beach deposits. Up to four 14C dates in stratigraphic sequence have been obtained in two soil profiles. Other samples consist of marine shells collected both within and on the surface of raised beaches. All 14C ages for organisms that lived or fed in circumantarctic waters were corrected for a large reservoir effect. The calibrated ages delimit a first relative sea-level curve for Victoria Land. Rates of uplift ranged from about 10 mm/yr following deglaciation to about 2 mm/yr in the last 3 millennia. Widespread presence of Adélie penguin nesting sites suggests that Terra Nova Bay was deglaciated before 7065 ± 250 yr B.P. (7059/6439 cal yr B.P.), when environmental conditions in the coastal area were similar to the present ones.
Holocene deltaic sequence in the Saloum estuary, Senegal
Authors: Ausseil-Badie Josiane , Barusseau J.Paul , Descamps Cyr , Salif Diop E. H. , Giresse Pierre , Pazdur Mieczyslaw 
Published: December 2004

AbstractThe 2250 km2 Saloum delta, south of Dakar, Senegal, consists of a Holocene sedimentary sequence deposited during five evolutionary stages: submerged postglacial ria, funnel-like estuary, barred estuary, cuspate delta, and reverse estuary. The passage from one stage to another was marked by the deposition of sedimentary units consisting of shelly sands, silty or sandy clays, and an extensive thick green mud. Muds in the lower strata, dating between 6130 and 3500 yr B.P., were deposited on a subtidal mudflat, while fine sands and silty clays characterize intertidal deposits. A drastic change in sedimentation patterns, resulting in the accumulation of a series of beach barriers, likely was associated with a major climatic change. The regional climate was then very dry, and silt and sand were trapped in the water behind the barriers in two stages, from 1990 to 1510 and 1020 to 600 yr B.P. Each event was accompanied by construction of shell middens that demonstrate the presence of humans who exploited newly available shallows and banks. Relative sea level did not change significantly between 6000 yr B.P. and the present. Morphological and sedimentological changes observed in the late Holocene sequences were apparently induced by a constraining climatic background.
Charophyte remains from Wadi Howar as evidence for deep mid-Holocene freshwater lakes in the eastern Sahara of Northwest Sudan
Authors: Kröpelin Stefan , Soulié-Märsche Ingeborg 
Published: December 2004

AbstractField research in the eastern Sahara (Northwest Sudan) revealed extensive early- to mid-Holocene lake marl deposits bearing gyrogonites of Charophytes (green algae, stoneworts) along the lower course of the Wadi Howar, an extinct tributary to the Nile. The Charophyte flora of a paleolake southwest of Jebel Rahib (17°31′N/26°52′E) dated prior to 4720 ± 110 yr B.P. is mainly composed of the ecologically sensitive speciesNitellopsis obtusawhich indicates permanent, relatively deep (4–12 m) and cool oligotrophic freshwater. The study ofNitellopsissites provides a new and promising approach to the reconstruction of Quaternary paleoenvironments of deserts.
Paleoecology of central Kentucky since the last glacial maximum
Authors: Wilkins Gary R. , Delcourt Paul A. , Delcourt Hazel R. , Harrison Frederick W. , Turner Manson R. 
Published: December 2004

AbstractPollen grains and spores, plant macrofossils, and sponge spicules from a 7.2-m sediment core from Jackson Pond dating back to 20,000 yr B.P. are the basis for new interpretations of vegetational, limnological, and climatic changes in central Kentucky. During the full-glacial interval (20,400 to 16,800 yr B.P.) upland vegetation was closed spruce forest with jack pine as a subdominant. Aquatic macrophyte and sponge assemblages indicate that the site was a relatively deep, open pond with low organic productivity. During late-glacial time (16,800 to 11,300 yr B.P.) spruce populations continued to dominate while jack pine declined and sedge increased as the vegetation became a more open, taiga-like boreal woodland. Between 11,300 and 10,000 yr B.P., abundances of spruce and oak pollen oscillated reciprocally, possibly reflecting the Younger Dryas oscillation as boreal taxa underwent a series of declines and increases at the southern limit of their ranges before becoming extirpated and replaced by deciduous forest. In the early Holocene (10,000 to 7300 yr B.P.) a mesic deciduous woodland developed; it was replaced by xeric oak-hickory forest during the middle Holocene between 7300 and 3900 yr B.P. Grass increased after 3900 yr B.P., indicating that the presettlement vegetation mosaic of mixed deciduous forest and prairie (the “Kentucky Barrens”) became established in central Kentucky after the Hypsithermal interval. Sponge spicules increased in number during the Holocene, reflecting reduced water depths in the pond. Sediment infilling, as well as climatic warming and the expansion of fringing shrub thickets, increased nutrient and habitat availability for freshwater sponges.
Paleoclimatic Significance of the Mineral Magnetic Record of the Chinese Loess and Paleosols
Authors: Maher Barbara A. , Thompson Roy 
Published: December 2004

AbstractThe origins of the magnetic susceptibility variations of the Chinese loess and paleosols are explored by scanning and transmission electron microscopy of magnetic extracts, and by magnetic modeling of magnetic hysteresis data, to provide quantified estimates of the major magnetic components. Microscopy identifies several distinct size and shape characteristics in the magnetic carriers. Lithogenic magnetites, intact and abraded, dominate the coarse-grained magnetic fraction. The smallest of the coarse grains is ∼ 2 μm. The remaining magnetic materal is ultrafine in size, with two types of magnetite particles present. Type A particles strongly resemble soil magnetites produced by inorganic precipitation. Type B particles, which occur rarely, are probably bacterial in origin. Quantitative modeling of these magnetic assemblages shows that over 90% of the susceptibility variations is accounted for by the superparamagnetic magnetite component. Compared to the loess units, the paleosols are richer in magnetite, particularly of superparamagnetic size, and have a threefold higher ratio of magnetite to hematite. We identify pedogenic formation of magnetite as the major contributor to the loess magnetic record. Matching this record against other paleoclimatic records, we find an extremely high correlation with the standard 18O record. The Chinese loess sequences record a very high resolution magnetic stratigraphy directly related to changing climate.
Evidence for the Dissolution of Magnetite in Recent Scottish Peats
Authors: Williams Martin 
Published: December 2004

AbstractMagnetic, hydrological, and geochemical data for 11 Scottish peat cores confirm previous reports that anthropogenic pollutants constitute the principal source of ferrimagnets to such environments, but indicate that postdepositional Fe3O4persistence may be more limited than formerly envisaged. In all cores, the lower stratigraphic limit of magnetic enrichment coincides with the water table, below which negative mV values and enhanced ratios of Fe/Mn and Cu/Zn depict an abrupt transition to a strongly anoxic regime. Dissolution of Fe3O4in the reducing, inundated zone is also signified by the more rapid down-core loss of magnetic properties in cores from topographically depressed “Sphagnum lawns” than in those from more elevated “Calluna hummocks”. As a consequence, the peak and cumulative SIRM values for cores from the former settings appear disproportionately low, and the magnetostratigraphic records from adjacent, but topographically variant sites are frequently asynchronous. In contrast to most marine and lacustrine sediments, dissolution of Fe3O4in peat induces a refinement of magnetic mineral assemblages, highlighted by declining SIRM/ARM ratios with depth and a “hardening” of remanence near the base of the magnetically enhanced strata. SEM micrographs of magnetic extracts from one Scottish core indicate that this refinement results from preferential dissolution along crystallographic weaknesses within multidomain phases, ultimately causing their disintegration and the adoption of “single domain-type” magnetic behavior. Rates of dissolution are considerably greater than those reported for marine sediments, probably due to the unusually high dissolved sulfide concentrations in mire waters.
The Mount Edgecumbe Tephra Deposits, a Marker Horizon in Southeastern Alaska Near the Pleistocene-Holocene Boundary
Authors: Riehle James R. , Mann Daniel H. , Peteet Dorothy M. , Engstrom Daniel R. , Brew David A. , Meyer Charles E. 
Published: December 2004

AbstractLate Pleistocene tephra deposits found from Sitka to Juneau and Lituya Bay are assigned to a source at the Mount Edgecumbe volcanic field, based on similarity of glass compositions to nearvent deposits and on thinning away from Kruzof Island. The sequence of near-vent layers is basaltic andesite and andesite at the base, rhyolite, and mixed dacite and rhyolite on top. The only breaks in the tephra sequence are two 1-mm-thick silt partings in a lake-sediment core, indicating a depositional interval from basaltic andesite to dacite of no more than about a millennium. Tephra deposits at sites >30 km from the vent are solely dacite and rhyolite and are 10,600 to 11,40014C yr old based on interpretation of 18 radiocarbon ages, including 5 by accelerator mass spectrometry (AMS). Basaltic andesite and andesite deposits nearer the vent are as much as 12,000 yr old.Discrepancy among radiocarbon ages of upland tephra deposits provisionally correlated as the same grainfall is resolvable within ±2 σ of analytical uncertainty. Comparison of bulk and AMS ages in one sediment core indicates a systematic bias of +600 to +1100 yr for the bulk ages; correlation of tephra deposits among upland and lacustrine sites implies an additional discrepancy of 200–400 yr between upland (relatively too young) and lacustrine ages. In any case, the Mount Edgecumbe tephra deposits are a widespread, latest Pleistocene stratigraphic marker that serves to emphasize the uncertainty in dating biogenic material from southeastern Alaska.
Late Quaternary Paleotemperatures Derived from a Speleothem from Cango Caves, Cape Province, South Africa
Authors: Talma A.S. , Vogel John C. 
Published: December 2004

AbstractAn oxygen isotope temperature record over a large part of the past 30,000 yr has been obtained for the southern Cape Province of South Africa by combining data on the isotopic composition of a stalagmite from a deep cave with that of a confined groundwater aquifer in the same region. Results show that temperatures during the last glacial maximum were on average about 6°C lower than those today, with peaks up to 7°C lower. A detailed analysis of the past 5000 yr suggests multiple fluctuations, with generally lower temperatures (1–2°C) around 4500 and 3000 yr B.P. The carbon isotopic composition of the stalagmite indicates significant vegetation changes between the late Pleistocene and today, and also during the second half of the Holocene.
Effect of acute nerve root compression on endoneurial fluid pressure and blood flow in rat dorsal root ganglia
Authors: Igarashi Tamaki , Yabuki Shoji , Kikuchi Shinichi , Myers Robert R. 
Published: December 2004

AbstractThe objective of the current study was to test the hypothesis that crush injury to nerve root increases endoneurial fluid pressure (EFP) and decreases blood flow in the associated dorsal root ganglion (DRG). A total of 21 adult, female Sprague‐Dawley rats had their left L5 nerve root and DRG exposed. The L5 nerve root was clamped for 2 s with a vascular suture clip just proximal to the DRG (compression group). Sham‐operated animals without compression were used for control (control group). EFP was recorded with a servo‐null micropipette system using a glass micropipette with tip diameter of 4 μm before and after 3 h of treatment. After the final measurement of EFP, DRG was excised and processed for histology. Blood flow in the DRG was continuously monitored by laser Doppler flow meter for 3 h. Three hours after treatment, EFP was 4.7 ± 2.7 cm H2O in the compression group and 2.2 ± 1.2 cm H2O in the control group (P < 0.05). Edema was the principal pathologic findings seen consistently in the DRG from animals in the compression group. Blood flow in the compression group was reduced 10 min after compression. This reduction was statistically significant compared with that of the control (P < 0.01). An acute compression to the nerve root increased endoneurial edema, increased EFP in the associated DRG, and reduced DRG blood flow. This combination of increased EFP and decreased blood flow in the DRG may result in neuronal ischemia and sensory dysfunction. These acute pathophysiologic changes may thus have a role in the pathogenesis of low back pain and sciatica due to disc herniation and spinal canal stenosis. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The Baryonic Tully–Fisher Relation
Authors: Gurovich Sebastián , McGaugh Stacy S. , Freeman Ken C. , Jerjen Helmut , Staveley-Smith Lister , De Blok W. J. G. 
Published: December 2004

AbstractWe validate the baryonic Tully–Fisher (TF) relation by exploring the Tully–Fisher (TF) and BTF properties of optically and Hi-selected disk galaxies. The data includes galaxies from Sakai et al. (2000) calibrator sample, McGaugh et al. (2000: M2000) I-band sample, and 18 newly acquired Hi-selected field dwarf galaxies observed with the ANU 2.3-m telescope and the ATNF Parkes telescope (Gurovich 2005a).As in M2000, we re-cast the TF and BTF relations as relationships between baryon mass and W20. First we report some numerical errors in M2000. Then, we calculate weighted bi-variate linear fits to the data, and finally we compare the fits of the intrinsically fainter dwarfs with the brighter galaxies of Sakai et al. (2000). With regards to the local calibrator disk galaxies of Sakai et al. (2000), our results suggest that the BTF relation is indeed tighter than the TF relation and that the slopes of the BTF relations are statistically flatter than the equivalent TF relations. Further, for the fainter galaxies which include the I-band M2000 and Hi-selected galaxies of Gurovich's sample, we calculate a break from a simple power law model because of what appears to be real cosmic scatter. Not withstanding this point, the BTF models are marginally better models than the equivalent TF ones with slightly smaller Χred2 values.