Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Sedimentology

2012

Institution
Keyword
Publication
Publication Type
File Type

Articles 1 - 30 of 42

Full-Text Articles in Physical Sciences and Mathematics

Geomorphologic Evolution Of A Rapidly Deteriorating Barrier Island System With Multiple Sediment Sources: Eastern Isles Dernieres, Louisiana, 1887 To 2006, Benjamin T. Kirkland Dec 2012

Geomorphologic Evolution Of A Rapidly Deteriorating Barrier Island System With Multiple Sediment Sources: Eastern Isles Dernieres, Louisiana, 1887 To 2006, Benjamin T. Kirkland

University of New Orleans Theses and Dissertations

Trinity, East, and Wine Islands make up the eastern half of the Isles Dernieres barrier arc in south-central Louisiana. Formed following the abandonment of the Lafourche delta complex, subsidence and storm erosion have led to rapid deterioration of the system. Since 1887, the land area of the islands has decreased seventy-seven percent, and the gulf shoreline has retreated landward more than a kilometer. Wave ravinement on the shoreface of the islands is responsible for the most sediment loss; liberated sediment travels longshore to tidal inlets. The dominant ebb tidal currents then transport the sediment to where it is deposited in …


Tempestites In A Teapot? Condensation-Generated Shell Beds In The Upper Ordovician, Cincinnati Arch, Usa, Benjamin F. Dattilo Dec 2012

Tempestites In A Teapot? Condensation-Generated Shell Beds In The Upper Ordovician, Cincinnati Arch, Usa, Benjamin F. Dattilo

Benjamin F. Dattilo

Skeletal concentrations in mudstones may represent local facies produced by storm winnowing in shallow water, or time-specific deposits related to intervals of diminished sediment supply. Upper Ordovician (Katian) of the Cincinnati region is a mixed siliciclastic-carbonate succession including meter-scale cycles containing a shelly limestone-dominated phase and a mudstone-dominated phase.

The “tempestite proximality model” asserts that shell-rich intervals originated by winnowing of mud from undifferentiated fair-weather deposits. Thus shell beds are construed as tempestites, while interbedded mudstones represent either fair-weather or bypassed mud. Meter-scale cycles are attributed to sea-level fluctuation or varying storm intensity.

Alternatively, the “episodic starvation model” argues, on …


Detrital Carbonates In A Sequence Stratigraphic Framework: An Example From The Furongian Slope Environment In The Hot Creek Range Of Central Nevada, Leon Taufani Dec 2012

Detrital Carbonates In A Sequence Stratigraphic Framework: An Example From The Furongian Slope Environment In The Hot Creek Range Of Central Nevada, Leon Taufani

UNLV Theses, Dissertations, Professional Papers, and Capstones

An integrated sedimentological study of detrital carbonates of the late Cambrian (Furongian) Hales Limestone in central Nevada was conducted in order to model facies distribution and controlling mechanisms of carbonate gravity-flow deposits. Seven closely-spaced sections and numerous traceable short sections were measured to investigate temporal and spatial changes of detrital carbonates within a high-resolution stratigraphic framework supported by biostratigraphic and carbon isotope chemostratigraphic constraints and by key physical surfaces. Polished slabs and thin section petrographic analysis were used to identify micro- and macro-scale textures and diagenesis.

Ten lithofacies are identified from the Hales Limestone. Lateral tracing of these facies reveals …


Diagenesis And Reservoir Characterization Of The Pennsylvanian Middle Atoka Formation, Sebastian And Logan Counties, West-Central Arkansas, Elvis Chekwube Bello Dec 2012

Diagenesis And Reservoir Characterization Of The Pennsylvanian Middle Atoka Formation, Sebastian And Logan Counties, West-Central Arkansas, Elvis Chekwube Bello

Graduate Theses and Dissertations

The Middle Atoka Formation evolved from a stable passive margin during the early Pennsylvanian time to a rapidly subsiding basin, with the sedimentary fill thickening greatly southward during the middle Pennsylvanian time. The basin dips in north-south direction. An east-west anticlines and synclines were observed.

The purpose of this study is to establish the stratigraphic units, reservoir geometry and distribution, and infer the depositional environments and reservoir quality. Well correlation and petrographic studies are used to achieve the goals.

Sandstone Point Count method was used. The Point Counts was divided into five categories. They include the framework grains (quartz, feldspar, …


Erosion Vulnerability In The Zarati Subwatershed And Its Impact Of Water Quality, Savanna Guelde, Alicia Mata, Troy Atchison Oct 2012

Erosion Vulnerability In The Zarati Subwatershed And Its Impact Of Water Quality, Savanna Guelde, Alicia Mata, Troy Atchison

Von Braun Symposium Student Posters

No abstract provided.


Tectonics And Sedimentary Facies Interpretation Of The Mesozoic Giron Group, Colombia, Hernando Martinez-Sacristan, Ricardo Mier-Umana, Nazrul I. Khandaker, Stanley Schleifer, Diana Lucia Leon-Martinez Oct 2012

Tectonics And Sedimentary Facies Interpretation Of The Mesozoic Giron Group, Colombia, Hernando Martinez-Sacristan, Ricardo Mier-Umana, Nazrul I. Khandaker, Stanley Schleifer, Diana Lucia Leon-Martinez

Publications and Research

Preliminary field investigations involving exposed Giron Group sediments in Colombia provided some interesting geologic information in terms of provenance, depositional environments, and development of the Mesozoic synrift sedimentary basins in Colombia. Overall, the synrift Triassic-Jurassic rift-related volcanic rocks, redbeds, and evaporites are prominent in Colombia, and a thick basin sequence of Cretaceous sandstones and shales dominates the central part of the Cordillera Oriental. These were mostly deposited in dominantly north-trending grabens. Identified sedimentary rock types were arkose, clast-and-matrix-supported conglomerate, red mudstone, variegated sandstone, siltstone and breccia. Extensive kaolinitization was noticeable in several sandstone samples. Among the notable sedimentary structures were …


Intercalibration Studies Of 210Po And 210Pb In Dissolved And Particulate Seawater Samples, Thomas Church, Sylvain Rigaud, Mark Baskaran, Anupam Kumar, Jana Friedrich, Pere Masque, Viena Puigcorbé, Guebuem Kim, Olivier Radakovitch, Gi Hong, Hui Choi, Gillian Stewart Oct 2012

Intercalibration Studies Of 210Po And 210Pb In Dissolved And Particulate Seawater Samples, Thomas Church, Sylvain Rigaud, Mark Baskaran, Anupam Kumar, Jana Friedrich, Pere Masque, Viena Puigcorbé, Guebuem Kim, Olivier Radakovitch, Gi Hong, Hui Choi, Gillian Stewart

Environmental Science and Geology Faculty Research Publications

Documented is an intercalibration (IC) exercise for both 210Po and 210Pb in seawater aliquots distributed between up to eight international laboratories that followed individual protocols. Dissolved and particulate samples were provided by GEOTRACES during two IC cruises at baseline stations in the North Atlantic and North Pacific oceans. Included were surface and/or deep dissolved and particulate samples at each site, plus complete profiles analyzed by the laboratory of the lead author. An unspecified solid phase standard was also distributed with 210Po and 210Pb in secular equilibrium to confirm spike calibrations. The 210Po activities reported n …


Late Holocene Sedimentation And Paleoenvironmental History For The Tidal Marshes Of The Potomac And Rappahannock Rivers, Tributaries To Chesapeake Bay, Neil E. Tibert, J. Bradford Hubeny, Mark Abbott, Joseph M. Kiker, Lindsay J. Walker, Shawn Mckenzie Oct 2012

Late Holocene Sedimentation And Paleoenvironmental History For The Tidal Marshes Of The Potomac And Rappahannock Rivers, Tributaries To Chesapeake Bay, Neil E. Tibert, J. Bradford Hubeny, Mark Abbott, Joseph M. Kiker, Lindsay J. Walker, Shawn Mckenzie

Virginia Journal of Science

Instrumental tide gauge records indicate that the modern rates of sea-level rise in the Chesapeake Bay more than double the global average of 1.2-1.5 mm yr-1. The primary objective for this study is to establish a relative depositional history for the tidal marshes of the Potomac and Rappahannock Rivers that will help us improve our understanding of processes that influence sedimentation in the proximal tributaries of Chesapeake Bay. Marsh cores were collected from Blandfield Point VA, Tappahannock VA, and Potomac Creek VA. The sedimentary facies include: 1) a lower unit of organic-poor, grey clay with fine sand and silt layers …


Nebraska's Wetlands: Their Wildlife And Ecology, Paul A. Johnsgard Sep 2012

Nebraska's Wetlands: Their Wildlife And Ecology, Paul A. Johnsgard

Conservation and Survey Division

1 An Overview of Nebraska's Wetlands

2 The Missouri Valley • Natural History Profiles of Some Missouri Valley Wetland Species • The Missouri Valley Wetlands

3 The Niobrara Valley Region • Natural History Profiles of Some Niobrara Valley Wetland Species • The Niobrara Valley Wetlands

4 The Platte Valley Region • Natural History Profiles of Some Platte Valley Wetland Species • The Central Platte Valley Wetlands • The North Platte Valley Wetlands

5 Other River Valley Wetlands • Natural History Profiles of Some Typical Riverine Species • The Elkhorn Valley Wetlands • The Loup Valley Wetlands • The Republican Valley …


Formation And Alteration Of Basaltic Soils On Mars, Ian Oliver Mcglynn Aug 2012

Formation And Alteration Of Basaltic Soils On Mars, Ian Oliver Mcglynn

Doctoral Dissertations

The current surface of Mars is an arid inhospitable environment, dominated by aeolian processes, composed of largely volcanic rocks that have little apparent indication of pervasive aqueous chemical weathering, and blanketed by dust. Rocks are composed of basalts and the “soil” sediments appear to be largely basaltic-derived, and are chemically similar on a global scale. If the climate was once warmer and wetter during the Noachian period, with environmental conditions favorable to the development of life, physically weathered remnants, such as large quantities of phyllosilicate minerals, should remain. Basaltic soils provide a crucial constraint on chemical and physical weathering processes, …


Outcrop Investigation Of The Reeds Spring (Boone, Mississippian) Of The Hindsville Quarry Using Terrestrial Lidar, Terryl Glenn Daniels Aug 2012

Outcrop Investigation Of The Reeds Spring (Boone, Mississippian) Of The Hindsville Quarry Using Terrestrial Lidar, Terryl Glenn Daniels

Graduate Theses and Dissertations

In northern Oklahoma and southern Kansas the Reeds Springs Formation (Boone, Mississippian) is a hydrocarbon exploration objective (Mazullo et al, 2011). The Hindsville quarry located in the northeastern portion of Washington County in Arkansas is the focus of this study. The objective of this study is to characterize the Reeds Spring at the Hindsville Quarry. The use of terrestrial light detecting and ranging(LiDAR) is used to assist in the characterization of the quarry.

The unit architecture within the Hindsville Quarry outlines varying transitional periods that give insight into the deposition of the Reeds Springs Formation. There are comparable formations within …


Reservoir Characterization And Outcrop Analog: The Osagean Reeds Spring Formation (Lower Boone), Western Osage And Eastern Kay County, Oklahoma, Taylor Friesenhahn Aug 2012

Reservoir Characterization And Outcrop Analog: The Osagean Reeds Spring Formation (Lower Boone), Western Osage And Eastern Kay County, Oklahoma, Taylor Friesenhahn

Graduate Theses and Dissertations

The Reeds Spring Formation (Osagean) is a member of the Lower Mississippian carbonate series developed on the Cherokee Platform Province of northeastern Oklahoma. On the western flank of the Ozark Dome, these rocks dip in a west-southwest direction into the subsurface where they are oil and gas reservoirs. A series of road cuts and surface exposures are cropped out in the tri-state area of northwest Arkansas, northeastern Oklahoma, and southwestern Missouri. Outcrop characteristics, including an abundant amount of nodular, anastomosing chert, generally finer-grained carbonate texture, and stratigraphic relationships provide an analog for its subsurface counterpart. Based on core description and …


Sequence Stratigraphy And Depositional Systems Of The Mansfield Sand, Upper Atoka Formation, Arkoma Basin, Arkansas, Scott Cherry Aug 2012

Sequence Stratigraphy And Depositional Systems Of The Mansfield Sand, Upper Atoka Formation, Arkoma Basin, Arkansas, Scott Cherry

Graduate Theses and Dissertations

The Mansfield sand is an informally named member of the Pennsylvanian Atoka Formation in Arkansas. Once a productive gas reservoir, the Mansfield is situated in a double plunging anticline in the southern portion of the Arkoma Basin. The formation is internally composed of sandstone units ranging in thickness from tens of feet to over a hundred feet interbedded with shale units ranging in thickness from several tens of feet to hundreds of feet. Previous studies have focused on the stratigraphy of the lower and middle Atoka. A detailed subsurface study of the stratigraphic framework of the Mansfield sand was conducted …


Reservoir Characterization And Enhanced Oil Recovery Potential In Middle Devonian Dundee Limestone Reservoirs, Michigan Basin, Usa, Abrahim Abduslam Aug 2012

Reservoir Characterization And Enhanced Oil Recovery Potential In Middle Devonian Dundee Limestone Reservoirs, Michigan Basin, Usa, Abrahim Abduslam

Masters Theses

Middle Devonian Rogers City and subjacent Dundee Limestone formations have combined oil production in excess of 375 MMBO. In general, hydrocarbon production occurs in two distinct reservoir types: 1) bottom water drive, fractured dolomite reservoirs in the Rogers City and 2) gas expansion drive, depositional facies controlled limestone reservoirs of the Dundee.

The main objective of this study is to evaluate the enhanced oil recovery (EOR) potential in Dundee Limestone reservoirs on the basis of detailed geological reservoir characterization in several fields in the Michigan Basin. Seven main depositional facies were identified from core studies in six fields. Three of …


4th International Union Of Soil Sciences Soil Classification Conference Field Tour Guidebook Jun 2012

4th International Union Of Soil Sciences Soil Classification Conference Field Tour Guidebook

Conservation and Survey Division

No abstract provided.


North Central Region Soil Survey Conference Field Tour Jun 2012

North Central Region Soil Survey Conference Field Tour

Conservation and Survey Division

No abstract provided.


Sedimentology And Allostratigraphy Of The Cardium Formation (Turonian-Coniacian) In Southern Alberta, And Equivalent Strata In Northern Montana, Joel Shank May 2012

Sedimentology And Allostratigraphy Of The Cardium Formation (Turonian-Coniacian) In Southern Alberta, And Equivalent Strata In Northern Montana, Joel Shank

Electronic Thesis and Dissertation Repository

The Turonian-Coniacian Cardium Formation of southern Alberta consists of marine sandstone and mudstone, deposited in a foreland basin over ~2.3 m.y. The formation thins from 150 m in the western foredeep to 50 m 350 km to the east. Correlation of 10 regional flooding surfaces in >1200 well logs and 25 outcrops provides an allostratigraphic framework. Mapping of two previously-unrecognized erosion surfaces (E5.2 and E5.5) reveals additional complexity within sandstone of the Raven River Member.

Facies successions coarsen upwards from thinly-bedded and bioturbated mudstone, to heterolithic facies (either bioturbated or bedded), to clean sandstone. Where conglomerate unconformably overlies this succession, …


Transitional Facies And Sequence Stratigraphic Complexity Of Shallow-Marine Star Point Formation To Coastal-Plain Blackhawk Formation Along Depositional-Strike, Wasatch Plateau, Utah, Andrew M. Ranson May 2012

Transitional Facies And Sequence Stratigraphic Complexity Of Shallow-Marine Star Point Formation To Coastal-Plain Blackhawk Formation Along Depositional-Strike, Wasatch Plateau, Utah, Andrew M. Ranson

University of New Orleans Theses and Dissertations

Facies and stratigraphic architecture right at the transition from marine to non-marine environments is poorly documented. In the Cretaceous outcrops of Utah, Star Point and Blackhawk Formations are well studied. The nature of spatio-temporal transition of these two Formations, in the deposition-strike orientation, remains undocumented. This study characterizes facies and stratigraphic complexity at the transition of the two Formations that crop out in depositional-strike orientation in the Wasatch Plateau. Data from outcrop including photomosiacs and measured sections demonstrate this complexity at a range of scales. The Star Point constitutes a shoreface environment. The Blackhawk constitutes a coastal-fluvial environment.

In the …


High-Resolution Correlation Of The Upper Cretaceous Stratigraphy Between The Book Cliffs And The Western Henry Mountains Syncline, Utah, U.S.A., Drew L. Seymour May 2012

High-Resolution Correlation Of The Upper Cretaceous Stratigraphy Between The Book Cliffs And The Western Henry Mountains Syncline, Utah, U.S.A., Drew L. Seymour

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

This study presents high-resolution correlations of the Upper Cretaceous stratigraphy between the Book Cliffs and the western Henry Mountains Syncline in Utah. The objective of this study is to understand changes in patterns of regional sediment dispersal during the Late Cretaceous on the western margin of the Cretaceous Western Interior Seaway. The intensely studied Book Cliffs consist of formations deposited in terrestrial, marginal-marine, and open-marine environments. A composite section was logged at Coal Canyon near Green River, UT. The western Henry Mountains Syncline is located in south-central Utah ~135 km S-SW of Coal Canyon. A composite section was logged at …


Characterizing Phyllosilicate Distribution, Abundance, And Origin On Mars, Christina Elizabeth Viviano May 2012

Characterizing Phyllosilicate Distribution, Abundance, And Origin On Mars, Christina Elizabeth Viviano

Doctoral Dissertations

Secondary phyllosilicates are hydrated minerals formed in the presence of liquid water. On Earth, their formation is often indicative of a neutral, water-rich environment, capable of supporting and preserving organic matter. Different phyllosilicate species may be produced in different pH levels and water-to-rock ratios. The identification of mineralogically diverse phyllosilicates in small, localized exposures on Mars provides a complex record of their formation processes. While discrete outcrops of phyllosilicates have been previously identified in high-resolution visible/near-infrared images of Mars, regional coverage of these phyllosilicate-rich areas at better resolution is limited. Furthermore, spectra of minerals in this wavelength range do not …


The Fluvial Muddy Creek Formation Near Overton, Nevada, Carl Taylor Swenberg May 2012

The Fluvial Muddy Creek Formation Near Overton, Nevada, Carl Taylor Swenberg

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Muddy Creek Formation (MCF) may represent an ancestral Colorado River deposit. To test this hypothesis, I mapped exposures of the MCF within the Virgin River Depression (VRD), a rift basin in the central Basin and Range. This is the first study to analyze fluvial MCF facies and test their viability as ancestral Colorado River deposits.

Mapping, paleocurrent analysis, conglomerate provenance, and architectural elements analysis were used in order to characterize the fluvial MCF near Overton NV. Architectural elements analysis revealed that MCF fluvial facies are most closely associated with those of a high-energy sand-bed braided river system. These results …


Muddy Creek Formation: A Record Of Late Neogene Tectonics And Sedimentation In Southern Nevada, Thomas William Muntean May 2012

Muddy Creek Formation: A Record Of Late Neogene Tectonics And Sedimentation In Southern Nevada, Thomas William Muntean

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Late Neogene Muddy Creek Formation (MCF), exposed in the vicinity of Lake Mead in southern Nevada, represents the youngest widespread Cenozoic sedimentary sequence in the region and is the focus of this study. Historically, the MCF has been largely ignored, with limited previous studies providing only regional-scale constraint on the age, stratigraphy, and mode of deposition for the formation; resulting in a data gap for our understanding of the Late Cenozoic tectonic and sedimentological evolution of southern Nevada.


Phosphate Availability During Sediment Resuspension Events In The Great Bay Estuary, Taylor Langkau Apr 2012

Phosphate Availability During Sediment Resuspension Events In The Great Bay Estuary, Taylor Langkau

Honors Theses and Capstones

Phosphate is an important nutrient to marine ecosystems such as the Great Bay Estuary. However, its bioavailability is limited due to its tendency to adsorb to marine sediments, especially iron oxides. This paper investigates phosphate dynamics during a simulated storm compared to calm conditions and aims to quantify the mechanisms of phosphate adsorption.


Stratigraphy And Paleoenvironments Of The Soeginina Beds (Paadla Formation, Lower Ludlow, Upper Silurian) On Saaremaa Island, Estonia, Richa N. Ekka Jan 2012

Stratigraphy And Paleoenvironments Of The Soeginina Beds (Paadla Formation, Lower Ludlow, Upper Silurian) On Saaremaa Island, Estonia, Richa N. Ekka

Senior Independent Study Theses

The Soeginina Beds in the Paadla Formation on the island of Saaremaa, western Estonia, are a lower Ludlow (Upper Silurian) sequence of dolostones, marls, and stromatolites. They represent rocks just above the Wenlock/Ludlow boundary, which is distinguished by a major disconformity that can be correlated to a regional regression on the paleocontinent of Baltica. The depositional environments of the Soeginina Beds include a shelfal environment, restricted shallow marine setting, intertidal mudflat and finally a hypersaline supratidal setting. The evidence includes halite crystal molds, oscillation ripples, eurypterid fragments, stromatolites, ostracods, gastropods, Chondrites trace fossils, intraclasts and oncoids. Nautiloid conchs are common, …


Exploring The Role Of Organic Matter Accumulation On Delta Evolution, Jorge Lorenzo Trueba, Vaughan Voller, Chris Paola, Robert Twilley, Azure Bevington Jan 2012

Exploring The Role Of Organic Matter Accumulation On Delta Evolution, Jorge Lorenzo Trueba, Vaughan Voller, Chris Paola, Robert Twilley, Azure Bevington

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

We explore the role of plant matter accumulation in the sediment column in determining the response of fluvial-deltas to base-level rise and simple subsidence profiles. Making the assumption that delta building processes operate to preserve the geometry of the delta plain, we model organic sedimentation in terms of the plant matter accumulation and accommodation (space made for sediment deposition) rates. A spatial integration of the organic sedimentation, added to the known river sediment input, leads to a model of delta evolution that estimates the fraction of organic sediments preserved in the delta. The model predicts that the maximum organic fraction …


Evolution With Depth From Detrital To Authigenic Smectites In Sediments From And-2a Drill Core (Mcmurdo Sound, Antarctica), Francesco Iacoviello, Giovanna Giorgetti, Fernando Nieto, Isabella Turbanti Memmi Jan 2012

Evolution With Depth From Detrital To Authigenic Smectites In Sediments From And-2a Drill Core (Mcmurdo Sound, Antarctica), Francesco Iacoviello, Giovanna Giorgetti, Fernando Nieto, Isabella Turbanti Memmi

ANDRILL Research and Publications

We have examined the nature and origin of smectites in glaciomarine sediments of the AND-2A drill core (McMurdo Sound, Antarctica) by means of X-ray diffraction (XRD) analyses on the clay fraction, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM) observations and SEM-EDS microanalyses on smectite particles. Relying on the smectite variation throughout the drill core it was possible to split the sequence into three units. Smectites throughout the core are either detrital or authigenic. Detrital smectites are close to montmorillonite-beidellite in composition while newly-formed smectites frequently have higher Fe-Mg contents and intermediate compositions between the saponite and nontronite …


Subsurface Facies Analysis Of The Late Cambrian Mt. Simon Sandstone In Western Ohio (Midcontinent, U.S.A.), James E. Evans Jan 2012

Subsurface Facies Analysis Of The Late Cambrian Mt. Simon Sandstone In Western Ohio (Midcontinent, U.S.A.), James E. Evans

James E. Evans

No abstract provided.


Evaluating Holocene Climate Change In Northern Norway Using Sediment Records From Two Contrasting Lake Systems., Nicholas L. Balascio, Raymond S. Bradley Jan 2012

Evaluating Holocene Climate Change In Northern Norway Using Sediment Records From Two Contrasting Lake Systems., Nicholas L. Balascio, Raymond S. Bradley

Raymond S Bradley

We analyzed Holocene sedimentary records from two lakes in the Lofoten Islands, northern Norway to evaluate environmental changes during the Holocene related to northern North Atlantic climate dynamics. The lakes are located in different geomorphological settings, and thus provide a contrast in their response to regional climate change. Environmental changes at both lakes were interpreted based on magnetic susceptibility, organic-matter flux, C/N, d13 Corg , Ti concentrations, and mass accumulation rates. Chronologies were established using 16 AMS radiocarbon dates, and average deposition rates in both environments are higher than 0.2 mm/year throughout the Holocene. At Vikjordvatnet, sedimentary geochemical properties define …


Biogeochemical Evidence For Prehistoric Human Impacts On The Environment In Northwestern Norway, Raymond S. Bradley, Robert D'Anjou, Nicholas L. Balascio, David B. Finkelstein Jan 2012

Biogeochemical Evidence For Prehistoric Human Impacts On The Environment In Northwestern Norway, Raymond S. Bradley, Robert D'Anjou, Nicholas L. Balascio, David B. Finkelstein

Raymond S Bradley

Disentangling the effects of climate change and anthropogenic activities on the environment is a major challenge in paleoenvironmental research. Here, we used fecal sterols and other biogeochemical compounds in lake sediments from northern Norway to identify both natural and anthropogenic signals of environmental change during the late Holocene. The area was first occupied by humans and their grazing animals at ∼2,250 ± 75 calendar years before 1950 AD (calendar years before present). The arrival of humans is indicated by an abrupt increase in coprostanol (and its epimer epicoprostanol) in the sediments and an associated increase in 5β-stigmastanol (and 5β-epistigmastanol), which …


A Mild Little Ice Age And Unprecedented Warmth In An 1800 Year Record From Svalbard, William J. D'Andrea, Raymond S. Bradley, David Vaillencourt, Nicholas L. Balascio, Al Werner, Steve Roof, Michael J. Retelle Jan 2012

A Mild Little Ice Age And Unprecedented Warmth In An 1800 Year Record From Svalbard, William J. D'Andrea, Raymond S. Bradley, David Vaillencourt, Nicholas L. Balascio, Al Werner, Steve Roof, Michael J. Retelle

Raymond S Bradley

The Arctic region is subject to a great amplitude of climate variability and is currently undergoing large-scale changes due in part to anthropogenic global warming. Accurate projections of future change depend on anticipating the response of the Arctic climate system to forcing, and understanding how the response to human forcing will interact with natural climate variations. The Svalbard Archipelago occupies an important location for studying patterns and causes of Arctic climate variability; however, available paleoclimate records from Svalbard are of restricted use due to limitations of existing climate proxies. Here we present a sub-decadal- to multidecadal-scale record of summer temperature …