scholarly journals Evidence for a hardwater radiocarbon dating effect, Wonder Lake, Denali national park and preserve, Alaska, U.S.A.

2002 ◽  
Vol 53 (3) ◽  
pp. 407-411 ◽  
Author(s):  
Jonathan K. Child ◽  
Al Werner
Keyword(s):  
National Park ◽  
Sediment Cores ◽  
Pollen Record ◽  
Lake Area ◽  
Alaska Range ◽  
Radiocarbon Age ◽  
The North ◽  
Late Wisconsinan ◽  
Denali National Park ◽  
Age Estimates

Abstract Anderson et al. (1994) present a late Pleistocene/Holocene pollen record for lacustrine sediment cores retrieved from the north end of Wonder Lake, Denali National Park and Preserve, Alaska. Bulk radiocarbon age estimates obtained during their study suggest that either a Picea refugium persisted in the foothills of the north Alaska Range near Wonder Lake during the Late Wisconsinan, or that bulk radiocarbon age estimates are inaccurate. Subsequent cores recovered from Wonder Lake (and a near-by kettle pond) have been correlated to the Anderson et al. core and age dated using Atomic Mass Spectrometry (AMS) radiocarbon age estimates. AMS radiocarbon ages suggest that bulk radiocarbon ages from Anderson et al. (1994) are affected by hardwater conditions in Wonder Lake causing them to appear greater than 2000 14 C years too old. The corrected core chronology is consistent with documented regional vegetation changes during the glacial/interglacial transition and does not require a local Picea refugium in the Wonder Lake area during the Late Wisconsinan.

Progress in mineralogical quantitative analysis of rock samples: application to quartzites from Denali National Park, Alaska Range (USA)

2016 ◽  
Vol 31 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Mărgărit M. Nistor ◽  
Nicolae Har ◽  
Simona Marchetti Dori ◽  
Simona Bigi ◽  
Alessandro F. Gualtieri
Keyword(s):  
National Park ◽  
Mineralogical Composition ◽  
Alaska Range ◽  
X Ray ◽  
Rock Samples ◽  
The North ◽  
Chemistry Calculation ◽  
Denali National Park ◽  
Bulk Chemistry

This work deals with the determination of the mineralogical composition of three quartzite samples, selected as case study to verify the viability and accuracy of various experimental techniques commonly used in geometallurgy and petrography for the determination of the mineralogical composition of rock samples. The investigated samples are from the North-Eastern side of the Denali National Park (Alaska Range, USA). The mineralogical phase abundance of the samples was determined by digitally assisted optical modal point counting, scanning electron microscopy (SEM) + energy dispersive spectroscopy (EDS) modal and digital image analysis, normative calculation from bulk chemistry calculation, and modal Rietveld X-ray powder diffraction. The results of our study indicate that the results provided by modal optical and SEM digitalized counting seem less accurate than the others. The determination with EDS mapping was found to be inaccurate only for one sample. Agreement was found between the X-ray diffraction estimates and bulk chemistry calculation. For both modal optical and SEM digitalized counting, the statistics was probably insufficient to provide accurate results. The estimates obtained from the various methods are compared with each other in the attempt to attain general indications on the precision, accuracy, advantages/disadvantages of each method.

scholarly journals A pterosaur manus track from Denali National Park, Alaska Range, Alaska, United States

Palaios ◽  
2009 ◽  
Vol 24 (7) ◽  
pp. 466-472 ◽  
Author(s):  
A. R. Fiorillo ◽  
S. T. Hasiotis ◽  
Y. Kobayashi ◽  
C. S. Tomsich
Keyword(s):  
United States ◽  
National Park ◽  
Alaska Range ◽  
Denali National Park

scholarly journals A new 30 000-year chronology for rapidly deposited sediments on the Lomonosov Ridge using bulk radiocarbon dating and probabilistic stratigraphic alignment

Geochronology ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 81-91
Author(s):  
Francesco Muschitiello ◽  
Matt O'Regan ◽  
Jannik Martens ◽  
Gabriel West ◽  
Örjan Gustafsson ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Sediment Cores ◽  
Monte Carlo Algorithm ◽  
Stratigraphic Correlation ◽  
Lomonosov Ridge ◽  
14C Dating ◽  
High Accumulation ◽  
Radiocarbon Age ◽  
Age Estimates

Abstract. We present a new marine chronostratigraphy from a high-accumulation rate Arctic Ocean core at the intersection of the Lomonosov Ridge and the Siberian margin, spanning the last ∼ 30 kyr. The chronology was derived using a combination of bulk 14C dating and stratigraphic correlation to Greenland ice-core records. This was achieved by applying an appositely developed Markov chain Monte Carlo algorithm for Bayesian probabilistic alignment of proxy records. The algorithm simulates depositionally realistic alignments that are consistent with the available radiocarbon age estimates and allows deriving uncertainty bands associated with the inferred alignment. Current composite chronologies from this region are reasonably consistent with our age model during the Holocene and the later part of deglaciation. However, prior to ∼ 14 kyr BP they yield too old age estimates with offsets that linearly increase up to ∼ 40 kyr near the onset of Marine Isotope Stage (MIS) 2. Our results challenge the robustness of previous regional chronostratigraphies and provide a new stratotype for correlation of sediment cores from this sector of the Lomonosov Ridge and East Siberian slope. In particular, they call for a re-interpretation of events in recent sea-ice proxy reconstructions (Xiao et al., 2015) inaccurately attributed to MIS 3 and the Last Glacial Maximum.

Heinrich event-0 (DC-0) in sediment cores from the northwest Labrador Sea: recording events in Cumberland Sound?

1998 ◽  
Vol 35 (5) ◽  
pp. 510-519 ◽  
Author(s):  
Matthew E Kirby
Keyword(s):  
Sediment Cores ◽  
Ice Sheet ◽  
Transport Processes ◽  
Labrador Sea ◽  
Sediment Layer ◽  
Strong Constraint ◽  
The North ◽  
Cumberland Sound ◽  
Late Wisconsinan ◽  
Detrital Carbonate

Layers of ice-rafted, limestone debris rich sediment were deposited in the northwest Labrador Sea and the North Atlantic during the last glacial period (10-80 ka); these sediments were deposited by Heinrich events (H), events which record catastrophic collapses of the Laurentide Ice Sheet in the region of the Hudson Strait. These intervals of detrital carbonate rich sediments are referred to as detrital carbonate layers (DC) in the northwest Labrador Sea. Accelerator mass spectrometry (AMS) 14C dates provide a strong constraint on the timing for these events; H-1 = DC-1 and H-2 = DC-2. DC-0, also known as H-0, correlative to the Younger Dryas cooling event, is not as distinct a sediment unit in the northwest Labrador Sea as DC-1 and DC-2. An analysis of sediments from two cores (HU75009-IV-055 and HU75009-IV-056) off the mouth of the Hudson Strait in the northwest Labrador Sea basin sheds new light on the "missing" DC-0 sediment unit. Timing for the DC-0 event in cores 055 and 056 is bracketed between 11.3 ka ± 105 years and 10.4 ka ± 185 years based on AMS 14C dates. Sedimentology of the DC-0 unit reveals a sediment layer rich in ice-rafted debris with an increase in percentage of dolomite (representative material <2 mm), clay-size dolomite, and kaolinite; it is significantly different from DC-1 and DC-2 in the same analyzed cores. For example, the percent carbonate increase in DC-1 and DC-2 is approximately three to four times higher than that in DC-0. In addition, DC-1 and DC-2 show clear evidence for mass sediment transport processes which are not observed in DC-0. From these data, the DC-0 sediment unit in the northwest Labrador Sea records Cumberland Sound ice margin change and, for reasons addressed in this paper, the Hudson Strait does not play a major role in the deposition of DC-0 sediments at these core sites. Provenance indicators, such as kaolinite and dolomite, from the core study sediments corroborate this hypothesis. These results provide strong evidence for Cumberland Sound ice margin activity and sediment contribution during DC events, specifically DC-0, and additional evidence for multiple and synchronous ice margin change along the eastern Laurentide ice margin during the Late Wisconsinan, thus further supporting an atmospheric forcing mechanism for Late Wisconsinan ice sheet change.

Quaternary events in the Elkwater Lake area of southeastern Alberta

1986 ◽  
Vol 23 (12) ◽  
pp. 2024-2038 ◽  
Author(s):  
Willem J. Vreeken
Keyword(s):  
Volcanic Eruption ◽  
Middle Miocene ◽  
Lake Area ◽  
Present Level ◽  
Maximum Extent ◽  
The North ◽  
Green Lake ◽  
South Saskatchewan River ◽  
Late Wisconsinan ◽  
North And South

New data necessitate revisions in the Quaternary chronology of the Elkwater Lake area. Relicts of post-Middle Miocene preglacial erosion surfaces descend to the north and south from the Middle Miocene depositional surface on the Cypress Hills plateau. Both sets of surfaces are marked by oxidized weathering zones, locally culminating in relicts of preglacial paleosols. Both surfaces are overlain by a loess replete with cryogenic imprints. Deposition of this loess with cryogenic imprints shortly predates arrival of the Green Lake glacier at its terminus.The Green Lake end moraine marks the maximum extent of Laurentide ice in this area. Features previously attributed to the older Elkwater glacier can be explained with reference to proglacial meltwater action associated with the Green Lake glacier. The concept of Elkwater drift is no longer valid.Younger loesses, called upper loess, mantle nonglaciated terrain and the Green Lake end moraine and began accumulating just before Glacier Peak tephra was deposited (ca. 12 000 years ago). Because there is no evidence of weathering on the Green Lake end moraine beneath the upper loess, Green Lake drift dates from the late Wisconsinan. Most of the upper loess was deposited during the early Holocene and some since the Mazama volcanic eruption, 6600 years ago.Elkwater Lake reached its highest postglacial level, i.e., at least 6.6 m above the present level, well after the Mazama eruption, before spilling across the Green Lake end moraine into the Ross Creek system. This event irrevocably changed the regimen of Ross Creek, probably to its confluence with the South Saskatchewan River, at Medicine Hat.

scholarly journals Supplemental Material: Lithologic, geomorphic, and permafrost controls on recent landsliding in the Alaska Range

2020 ◽  
Author(s):  
A.I. Patton ◽  
et al.
Keyword(s):  
National Park ◽  
Initiation Site ◽  
Landslide Inventory ◽  
Inventory Data ◽  
Alaska Range ◽  
Surficial Geology ◽  
Park Road ◽  
Denali National Park

Plate S1: 1:24,000 scale map of the surficial geology of the Denali National Park road corridor. Table S1: Landslide inventory data, including coordinates of the initiation site and slope characteristics of the landslides evaluated.

scholarly journals Late Holocene tephrostratigraphy from Cajas National Park, southern Ecuador

2020 ◽  
Vol 47 (3) ◽  
pp. 508
Author(s):  
Stephanie H. Arcusa ◽  
Tobias Schneider ◽  
Pablo V. Mosquera ◽  
Hendrik Vogel ◽  
Darrell Kaufman ◽  
...  
Keyword(s):  
National Park ◽  
Sediment Cores ◽  
Grain Morphology ◽  
Radiocarbon Age ◽  
Sedimentary Sequences ◽  
Plant Remains ◽  
Southern Ecuador ◽  
History Of ◽  
Tephra Layers ◽  
Active Volcanoes

Lakes located downwind of active volcanoes serve as a natural repository for volcanic ash (tephra) produced during eruptive events. In this study, sediment cores from four lakes in Cajas National Park, southern Ecuador, situated approximately 200 km downwind of active volcanoes in the Northern Andes Volcanic Zone, were analysed to document the regional history of tephra fall extending back around 3,000 a cal BP. The ages of the lacustrine sedimentary sequences were constrained using a total of 20 AMS radiocarbon ages on plant remains. The tephra layers were correlated among the lakes based on their radiocarbon age, elemental composition, colour, and grain morphology. We found five unique tephra layers, each at least 0.2 cm thick, and further constrained their ages by combining the results from two age-depth modelling approaches (clam and rbacon). The tephra layers were deposited 3,034±621, 2,027±41, 1,557±177, 733±112, and 450±70 a cal BP. The ages of all but the youngest tephra layer overlap with those of known eruptions from Tungurahua. Some tephra layers are missing as macroscopic layers in several cores, with only two of the five tephra layers visible in the sediment of three lakes. Likewise, previous studies of lake sediment cores from the region are missing the four youngest tephra layers, further highlighting the need to sample multiple lakes to reconstruct a comprehensive history of fallout events. The newly documented stratigraphic marker layers will benefit future studies of lake sediments in Cajas National Park.

scholarly journals A new 30,000 year chronology for rapidly deposited sediments on the Lomonosov Ridge using bulk radiocarbon dating and probabilistic stratigraphic alignment

2019 ◽  
Author(s):  
Francesco Muschitiello ◽  
Matt O'Regan ◽  
Jannik Martens ◽  
Gabriel West ◽  
Örjan Gustafsson ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Sediment Cores ◽  
Monte Carlo Algorithm ◽  
Stratigraphic Correlation ◽  
Lomonosov Ridge ◽  
14C Dating ◽  
High Accumulation ◽  
Radiocarbon Age ◽  
Age Estimates

Abstract. We present a new marine chronostratigraphy from a high-accumulation rate Arctic Ocean core at the intersection of the Lomonosov Ridge and the Siberian margin, spanning the last ∼30 kyr. The chronology was derived using a combination of bulk 14C dating and stratigraphic correlation to Greenland ice-core records. This was achieved by applying an appositely developed Markov chain Monte Carlo algorithm for Bayesian probabilistic alignment of proxy records. The algorithm simulates depositionally realistic alignments that are consistent with the available radiocarbon age estimates and allows deriving uncertainty bands associated with the inferred alignment. Current composite chronologies from this region are reasonably consistent with our age model during the Holocene and the latter part of deglaciation. However, prior to ∼14 kyr BP they yield too old age estimates with offsets that linearly increase up to ∼40 kyr near the onset of Marine Isotope Stage (MIS) 2. Our results challenge the robustness of previous regional chronostratigraphies and provide a new stratotype for correlation of sediment cores from this sector of the Lomonosov Ridge and East Siberian slope. In particular, they call for a re-interpretation of events in recent sea-ice proxy reconstructions (Xiao et al., 2015) inaccurately attributed to MIS-3 and the Last Glacial Maximum.

Sign in / Sign up

Export Citation Format

Share Document