Download or read book Paleoenvironmental Analyses of an Organic Deposit from an Erosional Landscape Remnant Arctic Coastal Plain of Alaska written by and published by . This book was released on 2005 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dominant landscape process on the Arctic Coastal Plain of northern Alaska is the formation and drainage of thaw lakes. Lakes and drained thaw lake basins account for approximately 75% of the modern surface expression of the Barrow Peninsula. The thaw lake cycle usually obliterates lacustrine or peat sediments from previous cycles which could otherwise be used for paleoecological reconstruction of long-term landscape and vegetation changes. Several possible erosional remnants of a former topographic surface that predates the formation of the thaw lakes have been tentatively identified. These remnants are characterized by a higher elevation, a thick organic layer with very high ground ice content in the upper permafrost, and a plant community somewhat atypical of the region. Ten soil cores were collected from one site, and one core was intensively sampled for soil organic carbon content, pollen analysis, and 14C dating. The lowest level of the organic sediments represents the earliest phase of plant growth and dates to ca. 9000 cal BP. Palynological evidence indicates the presence of mesic shrub tundra (including sedge, birch, willow, and heath vegetation); and microfossil indicators point to wetter eutrophic conditions during this period. Carbon accumulation was rapid due to high net primary productivity in a relatively nutrient-rich environment. These results are interpreted as the local response to ameliorating climate during the early Holocene. The middle Holocene portion of the record contains an unconformity, indicating that between 8200 and 4200 cal BP sediments were eroded from the site, presumably in response to wind activity during a drier period centered around 4500 cal BP. The modern vegetation community of the erosional remnant was established after 4200 cal BP, and peat growth resumed. During the late Holocene, carbon accumulation rates were greatly reduced in response to the combined effects of declining productivity associated with climatic cooling, and increased nutrient stress as paludification and permafrost aggradation sequestered mineral nutrients.
Download or read book Encyclopedia of Quaternary Science written by and published by Elsevier. This book was released on 2006-11-24 with total page 7184 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quaternary sciences constitute a dynamic, multidisciplinary field of research that has been growing in scientific and societal importance in recent years. This branch of the Earth sciences links ancient prehistory to modern environments. Quaternary terrestrial sediments contain the fossil remains of existing species of flora and fauna, and their immediate predecessors. Quaternary science plays an integral part in such important issues for modern society as groundwater resources and contamination, sea level change, geologic hazards (earthquakes, volcanic eruptions, tsunamis), and soil erosion. With over 360 articles and 2,600 pages, many in full-color, the Encyclopedia of Quaternary Science provides broad ranging, up-to-date articles on all of the major topics in the field. Written by a team of leading experts and under the guidance of an international editorial board, the articles are at a level that allows undergraduate students to understand the material, while providing active researchers with the latest information in the field. Also available online via ScienceDirect (2006) – featuring extensive browsing, searching, and internal cross-referencing between articles in the work, plus dynamic linking to journal articles and abstract databases, making navigation flexible and easy. For more information, pricing options and availability visit www.info.sciencedirect.com. 360 individual articles written by prominent international authorities, encompassing all important aspects of quaternary science Each entry provides comprehensive, in-depth treatment of an overview topic and presented in a functional, clear and uniform layout Reference section provides guidence for further research on the topic Article text supported by full-color photos, drawings, tables, and other visual material Writing level is suited to both the expert and non-expert
Download or read book Eolian Sand and Interbedded Organic Horizons at Kealok Creek on the Arctic Coastal Plain of Alaska written by L. David Carter and published by . This book was released on 1978 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoenvironmental Analysis of the Bear Lake Formation Alaska Peninsula Alaska written by Richard McGhee Wisehart and published by . This book was released on 1971 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Mesa Site written by U.S. Department of the Interior and published by Createspace Independent Publishing Platform. This book was released on 2014-02-20 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Between 1978 and 1999, excavations in arctic and western Alaska have revealed the presence of Paleoindians during terminal Pleistocene/early Holocene times, ca. 12,000 to 9500 years BP (Before Present). The Type Site for this cultural manifestation, the Mesa Site, is located on the northern flank of the central Brooks Range at N68° 24.72 W155° 48.02, amid rolling foothills that extend northward 40 miles to the Colville River. The site lies atop a mesa-like ridge that rises 180 feet above the floor of the Iteriak Creek valley, offering an unobstructed 360° view of the surrounding treeless countryside. Excavation at the site has produced the remains of more than 450 formal flaked stone tools and over 120,000 pieces of lithic debitage, which comprise an assemblage typical of the “classic” Paleoindian cultures of the North American High Plains. More than 150 of the artifacts are the complete or fragmentary remains of lanceolate projectile points, many of which have been recovered from within the charcoal/soil matrix of discrete hearths which are the central features of numerous activity areas. The age of the occupation is constrained by 44 uncalibrated AMS radiocarbon dates covering the interval 11,700 to 9700 years BP. The site lacks evidence of any widespread postdepositional disturbance and, except for a small, discrete manifestation in Locality A, contains no remains of more recent cultures. The composition of the Mesa artifact assemblage and its obvious technological relationship with the Paleoindian cultures of mid-continent North America mark it as distinctly different from other ancient arctic cultures. The presence of the Mesa Complex demonstrates a previously undocumented cultural diversity in Eastern Beringia at the Pleistocene/Holocene boundary. This is an interim report. The amount of data generated by the Mesa project is immense. Although we engaged in some analysis and compilation of data as we progressed through the field work, we are not in a position to present this information in its totality. Therefore, limits have necessarily been placed upon the scope of this report so that it can be completed in a reasonable amount of time. While some primary analysis has not been completed, we have enough information to present a report that is more descriptive and introspective than a raw data monograph. In this report, we address the scope of research, order and describe the data analyzed so far, and interpret and summarize the findings to date. This will be accomplished by discussing the following subjects: the culture history of the region and the place of the Mesa Complex within that culture history framework; the natural setting of the site region; the excavation and data collection methods; the description of the site including the natural and cultural stratigraphy, cultural features, localities and activity areas; the flaked stone industry including artifact typology, tool-stone variety, and tool use; the regional Pleistocene faunal assemblage; the regional Pleistocene climate and ecology; and site use.
Download or read book A Multi proxy Record of Holocene Paleoenvironmental and Paleoclimate Change at Lake Tokun South central Alaska written by Jonathan Gilbert Griffith and published by . This book was released on 2014 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sediment cores from Lake Tokun were used to reconstruct paleoenvironmental and paleoclimate changes in the Copper River delta area, Alaska. A 4.2-m-long sediment sequence was analyzed for organic matter, chlorophyll-a, magnetic susceptibility, and bulk density. The chronology was based on radiocarbon ages and short-lived isotopes. Distinct changes in the sedimentary succession record major paleoenvironmental changes during the Holocene. Prior to 8.8 ka, Lake Tokun received meltwater from the Martin River Glacier at a time when sea level had transgressed at least 6 km inland of the present shoreline likely due to isostatic depression upon deglaciation. From 8.8 to 0.7 ka, Lake Tokun was a shallow lake receiving sporadic pulses of rock flour when Martin River overtopped its channels. At 735-1215 AD, rock flour deposited in Lake Tokun represents an aggrading outwash plain as the Martin River Glacier expanded and then deposited its terminal moraine. The proximal end of the associated outwash plain dammed Lake Tokun, deepening the lake and enhancing sediment deposition. The lake attained its present depth about 1215 AD and rock flour has not reentered the lake since then. The uppermost sedimentary unit (150 cm thick) was analyzed at 0.5 cm resolution (average of 3 year per sample) using VNIR reflectance spectroscopy to infer the concentration of chlorophyll-a (chl-a). Instrumental weather data from Cordova (1917 to 2009) show a strong inverse correlation (r2 = 0.49; p = 0.03) between August precipitation and sedimentary chl-a content in Lake Tokun. Storms beginning in the late summer and persisting through the fall are important in controlling peak discharges and the subsequent transport of allochthonous material into Lake Tokun. Winter (DJF) temperature is also inversely correlated with chl-a content (r2 = 0.33; p = 0.04), indicating that warm winters, which tend to be wet, also lead to enhanced runoff, which carries mineral matter that dilutes the chl-a content of the lake sediment. Decreased chl-a values suggest increased runoff during the early to middle Little Ice Age (LIA; 1215-1650 AD). Increased chl-a values during the late LIA (1650-1850 AD) are suggestive of decreased runoff. This study demonstrates that multi-proxy analysis of lake sediments is an effective method for inferring past paleoenvironmental and paleoclimate change.
Download or read book Archaeal and Bacterial Communities Across a Chronosequence of Drained Lake Basins in Arctic Alaska written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We examined patterns in soil microbial community composition across a successional gradient of drained lake basins in the Arctic Coastal Plain. Analysis of 16S rRNA gene sequences revealed that methanogens closely related to Candidatus 'Methanoflorens stordalenmirensis' were the dominant archaea, comprising>50% of the total archaea at most sites, with particularly high levels in the oldest basins and in the top 57 cm of soil (active and transition layers). Bacterial community composition was more diverse, with lineages from OP11, Actinobacteria, Bacteroidetes, and Proteobacteria found in high relative abundance across all sites. Notably, microbial composition appeared to converge in the active layer, but transition and permafrost layer communities across the sites were significantly different to one another. Microbial biomass using fatty acid-based analysis indicated that the youngest basins had increased abundances of gram-positive bacteria and saprotrophic fungi at higher soil organic carbon levels, while the oldest basins displayed an increase in only the gram-positive bacteria. While this study showed differences in microbial populations across the sites relevant to basin age, the dominance of Candidatus 'M. stordalenmirensis' across the chronosequence indicates the potential for changes in local carbon cycling, depending on how these methanogens and associated microbial communities respond to warming temperatures.
Download or read book Fractionation of Organic Matter from Arctic Soils in Alaska written by Wendy Marie Loya and published by . This book was released on 1996 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoenvironments of deposition paleocurrent directions and the provenance of tertiary deposits along Kachemak Bay Kenai Peninsula Alaska written by S. E. Rawlinson and published by . This book was released on 1979 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Whole rock and Geochemical Analyses Part of Unca and Popof Islands Alaska written by Alaska. Division of Geological and Geophysical Surveys and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Total Organic Carbon and Rock eval Pyrolysis Data of Cutting from the Following Alaska Northslope Wells written by Alaska Geologic Materials Center and published by . This book was released on 2000 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marine continental Transitions in a Greenhouse World written by Dolores A. Van der Kolk and published by . This book was released on 2016 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Near horizontal (6° dipping) outcrop exposures of Upper Cretaceous (Santonian-Campanian) strata at Shivugak Bluffs in northern Alaska preserve an extensive record of a clinoform-topset system. These strata are subdivided lithostratigraphically into proximal shelf, deltaic, and shallow marine deposits of the Schrader Bluff Formation and lower delta plain, coastal plain, and fluvial deposits of the continental Prince Creek Formation. Shivugak Bluffs includes 400 m of continuous marine deposits overlain by 140 m of strata containing the marine–continental transition between the lower Schrader Bluff and Prince Creek formations. The marine-continental transition is one of the few outcrop expressions of an ancient, muddy, prograding river-dominated deltaic system that contains interdistributary bays that shoal upward into floodbasins with pedogenic modification. The lowermost 400 m of the lower Schrader Bluff Formation is divided into the Rogers Creek, Barrow Trail, and Sentinel Hill members interpreted as recurring deposits of river-dominated deltas comprising distributary mouth bars (DMBs), subaqueous terminal distributary channels (TDCs), interdistributary bays, medial delta front deposits, distal delta front deposits, and prodelta deposits interbedded with proximal shelf deposits. One interval within the Rogers Creek Member comprising the most hummocky cross-stratified (HCS) interval at Shivugak Bluffs is interpreted as wave-reworked DMB-TDC complexes or storm sheets. The Schrader Bluff (West Sak and Tabasco equivalent in the subsurface) and Prince Creek (Ugnu equivalent in the subsurface) formations are relevant to industry as outcrop analogs for numerous shallow, viscous- to heavy-oil reservoirs on the central North Slope, Alaska. From a reservoir perspective, a 36-m-thick subset of the Alaska succession within the Rogers Creek Member is compared to 36- and 34-m-thick wave-dominated successions of the Kenilworth and Grassy Members of the Blackhawk Formation in the Book Cliffs in eastern Utah. The Rogers Creek Member includes amalgamated DMB-TDC complexes (54%) with minor HCS wave-reworked deposits (46%). This succession is compared with the Kenilworth and Grassy members that exhibit predominantly swaley and HCS intervals (75–81%) with minor channel complexes (14–25%). The Blackhawk Formation, based on this analysis, is a poor reservoir analog for the lower Schrader Bluff Formation of Arctic Alaska.
Download or read book Paleoenvironmental Reconstruction of the Late Cretaceous Maastrichtian Prince Creek Formation Near the Kikaktegoseak Dinosaur Quarry North Slope Alaska written by Erik Brandlen and published by . This book was released on 2008 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: "During 2005, sedimentological fieldwork was conducted, and bulk sediment samples were taken for paleopedological, paleopalynological and paleoenvironmental analysis of the Prince Creek Formation, near the Kikak-Tegoseak dinosaur quarry, North Slope, Alaska. This work is a detailed description of those outcrops. The outcrops are interpreted as an anastomosed crevasse-splay complex similar to the modem Cumberland Marshes area, Saskatchewan River, Canada and the Cretaceous Dakota Formation, Wyoming. Frequent avulsions and flooding of the splay channels reflect a history of rapid sedimentation that inhibited paleosol development and may have contributed to the preservation and fossilization of large numbers of dinosaur bones. Drab paleosol colors indicate gleyed conditions related to soil saturation. However, micromorphological features, microenvironments related to vegetation and the abundance of charcoal, indicate periods of drier conditions. The paleoenvironment was one of a seasonally wet splay complex, with small, shallow, anastomosed splay channels, aggrading levees, incipient soils, wetlands and ephemeral ponds. Taxodiaceae, Pinaceae, ferns and tree ferns dominated the vegetation, but angiosperms were rare. The paleoclimate was cool temperate, with a seasonal precipitation regime. No evidence of freezing conditions was found despite the paleogeographic location high above the Cretaceous Arctic Circle"--Leaf iii.
Download or read book Quantitative Analysis of a Late Quaternary Cave Deposit Porcupine River Alaska written by Robert A. Sattler and published by . This book was released on 1989 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoenvironment and Post depositional Changes Recorded in the Chemical Composition of Marine Sediments from the Gulf of Alaska written by Mark Sebastian Zindorf and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gubik Formation of Quaternary Age in Northern Alaska written by Robert Foster Black and published by . This book was released on 1964 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoenvironments of the Chignik Formation Alaska Peninsula written by Drena Katherine Theresa Fairchild and published by . This book was released on 1977 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
