Pleistocene volcanic damming of Yukon River and the maximum age of the Reid Glaciation, west-central Yukon

2004 ◽  
Vol 41 (2) ◽  
pp. 151-164 ◽  
Author(s):  
Crystal A Huscroft ◽  
Brent C Ward ◽  
René W Barendregt ◽  
Lionel E Jackson Jr. ◽  
Neil D Opdyke
Keyword(s):  
Flood Plain ◽  
Yukon Territory ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Pillow Basalt ◽  
Oxygen Isotope Stage ◽  
Yukon River ◽  
River Flood ◽  
Normal Magnetization ◽  
Eruptive Period

Stratigraphic, paleomagnetic, and radioisotope investigations of the Selkirk Volcanic Group have identified a new eruptive period and constrained the age of the Reid Glaciation, the most extensive middle Pleistocene cordilleran advance recognized in central Yukon. Downstream from Fort Selkirk, a complex of valley-filling compound pahoehoe basalt flows and pillow basalt is exposed for 10 km along the Yukon River and is overlain by outwash deposited during the Reid Glaciation. The flows have an 40Ar/39Ar age of 311 ± 32 ka. This age is consistent with the normal magnetization of the flows and their termination below the level of the contemporary Yukon River flood plain. Taken with the ca. 190 ka Sheep Creek tephra, which overlies Reid drift elsewhere in Yukon Territory, the Reid Glaciation is constrained to oxygen isotope stage 8, not stage 6 as previously thought. The presence of thick foreset-bedded pillow breccia units intercalated with the subaerial flows indicates that this eruption caused damming of the Yukon River. Reevaluation of the stratigraphy of early Pleistocene basalt flows and pillow lavas in the Fort Selkirk area indicates that volcanic damming of the Yukon River has occurred at least once previously.

Age of some Pleistocene interglacial beds and associated fossils in eastern Beringia defined by fission tracks in glass shards of Chester Bluff tephra

2017 ◽  
Vol 88 (1) ◽  
pp. 152-159 ◽  
Author(s):  
John A. Westgate ◽  
Nicholas J.G. Pearce
Keyword(s):  
Fission Track ◽  
Yukon Territory ◽  
East Central ◽  
Oxygen Isotope Stage ◽  
Yukon River ◽  
Dating Method ◽  
The Mean ◽  
Loess Deposits ◽  
The Rich

AbstractApplication of the glass fission-track dating method to Chester Bluff tephra (CBt), exposed in loess deposits at Chester Bluff along the Yukon River in east-central Alaska, has clarified the age of the immediately underlying fossiliferous interglacial bed. Surprise Creek tephra (SZt), at site CRH47 in the northern Old Crow basin of the Yukon Territory, is a correlative of CBt so that the new age information on CBt can also be applied to the interglacial sediments below SZt. Two independent age determinations were obtained on CBt, 243±28 ka and 249±26 ka, giving a weighted mean age and error of 246±19 ka. Therefore, the closely associated interglacial bed belongs to the early part of Marine Oxygen Isotope Stage (MIS) 7. The stratigraphy and paleoenvironmental setting of SZt show that deposition of the tephra occurred soon after interglacial conditions, when the climate became colder, probably between MIS 7.5 and 7.4, that is, slightly younger than the mean fission-track age, but within the 1σ uncertainty. This result tightly constrains the age of the rich mammalian faunal assemblage found at and just below SZt at the CRH47 site.

Chronology of newly-discovered Paleolithic artifact assemblages in Lantian (Shaanxi province), central China

2016 ◽  
Vol 86 (3) ◽  
pp. 316-325 ◽  
Author(s):  
Haixin Zhuo ◽  
Huayu Lu ◽  
Shejiang Wang ◽  
Khobaib Ahmad ◽  
Wenfeng Sun ◽  
...  
Keyword(s):  
Technology Development ◽  
Homo Erectus ◽  
Central China ◽  
Shaanxi Province ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Stratigraphic Correlation ◽  
Oxygen Isotope Stage ◽  
Lithic Artifacts ◽  
The 1960S

AbstractThe Homo erectus cranium, mandible and hundreds of associated lithic artifacts found in Lantian (central China) in the 1960s demonstrate that the area was important for hominin habitation during the early to middle Pleistocene. However, the region, which was not adequately researched until the early 2000s, still poses several questions regarding hominin behavior and lithic technology development. In this study, three loess-paleosol sequences (the Jijiawan, Ganyu and Diaozhai sites), from which in situ stone artifacts were recovered, are investigated and dated by optically stimulated luminescence (OSL), magnetostratigraphy and stratigraphic correlation. The results demonstrate that the artifacts are located within paleosol layers S4 (correlative with marine oxygen isotope stage (MIS) 11), S3 (MIS 9), S2 (MIS 7), and S1 (MIS 5); and within loess layer L1 (MIS 2-4). The main stone-knapping technique used was direct hard hammer percussion. In addition, the technological features of the stone tools found at these sites exhibit little variation, indicating the presence of a long-established, stable technology in the Lantian area. Our observations show that the ancient humans lived episodically on the terraces of the Bahe River from the early Pleistocene, indicating a long history of hominin occupation of the region.

Sedimentology, faunal content and pollen record of Middle Pleistocene palustrine and lagoonal sediments from the Peri-Adriatic basin, Abruzzi, eastern central Italy

2016 ◽  
Vol 86 (3) ◽  
pp. 359-372 ◽  
Author(s):  
Pierluigi Pieruccini ◽  
Claudio Di Celma ◽  
Federico Di Rita ◽  
Donatella Magri ◽  
Giorgio Carnevale ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Central Italy ◽  
Freshwater Wetlands ◽  
Middle Pleistocene ◽  
Pollen Record ◽  
Vegetation Development ◽  
Oxygen Isotope Stage ◽  
Open Forest ◽  
Facies Succession

AbstractA 25 m-thick outcrop section exposed at Torre Mucchia, on the sea-cliff north of Ortona, eastern central Italy, comprises a rare Middle Pleistocene succession of shallow-water and paralic sediments along the western Adriatic Sea. An integrated study of the section, including facies and microfacies analyses, and characterization of paleobiological associations (mollusks, fishes, ostracods, foraminifers and pollen), enable a detailed reconstruction of the paleoenvironmental and paleoclimatic conditions during deposition. The shallow-water deposits include a transgressive, deepening- and fining-upward shoreface to offshore-transition facies succession overlain by a regressive shoreface-foreshore sandstone body with an erosive base and a rooted and pedogenically altered horizon at the top that imply deposition during sea-level fall. This forced regressive unit is overlain by paralic strata forming a transgressive succession comprising palustrine carbonates and back-barrier lagoonal mudstones. The palustrine carbonates exhibit some of the typical features encountered in palustrine limestones deposited within seasonal freshwater wetlands (marl prairies). Following the sea-level rising trend, the freshwater marshes were abruptly replaced by a barrier-lagoon system that allowed deposition of the overlying mud-rich unit. Within these deposits, the faunal assemblages are consistent with a low-energy brackish environment characterized by a relatively high degree of confinement. The pollen record documents the development of open forest vegetation dominated by Pinus and accompanied by a number of mesophilous and thermophilous tree taxa, whose composition supports a tentative correlation with Marine Oxygen Isotope Stage 17. The new pollen record from Torre Mucchia improves our understanding of the vegetation development in the Italian Peninsula during the Middle Pleistocene and sheds new light on the role played by the most marked glacial periods in determining the history of tree taxa.

Flood vulnerability assessment in the light of rice cultivation characteristics in Mekong River flood plain in Cambodia

2013 ◽  
Vol 12 (S2) ◽  
pp. 275-286 ◽  
Author(s):  
Toshio Okazumi ◽  
Shigenobu Tanaka ◽  
Youngjoo Kwak ◽  
Badri Bhakta Shrestha ◽  
Ai Sugiura
Keyword(s):  
Vulnerability Assessment ◽  
Flood Plain ◽  
Rice Cultivation ◽  
Mekong River ◽  
Flood Vulnerability ◽  
River Flood ◽  
Flood Vulnerability Assessment

Aeolian influx and related environmental conditions on Gran Canaria during the early Pleistocene

2018 ◽  
Vol 91 (1) ◽  
pp. 35-50 ◽  
Author(s):  
Inmaculada Menéndez ◽  
José Mangas ◽  
Esperança Tauler ◽  
Vidal Barrón ◽  
José Torrent ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Textural Analysis ◽  
Climatic Conditions ◽  
Saharan Dust ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Quartz Content ◽  
Gran Canaria ◽  
Climatic Oscillations ◽  
Climatic Variations

AbstractThe island of Gran Canaria is regularly affected by dust falls due to its proximity to the Saharan desert. Climatic oscillations may affect the Saharan dust input to the island. Geochemical, mineralogical, and textural analysis was performed on a well-developed and representative early Pleistocene paleosol to examine Saharan dust contribution to Gran Canaria. Significant and variable Saharan dust content was identified in addition to weathering products such as iron oxides and clay minerals. Variations in quartz and iron oxide concentrations in the paleosol likely reflect different Saharan dust input in more/less-contrasted rhexistasic/biostatic climatic conditions. Linking the quartz content in Canarian soils, the Ingenio paleosol, and two Canarian loess-like deposits to different ages from the Quaternary, we hypothesized that the dust input should be lower (about 33–38%) throughout the early to middle Pleistocene than during the late Quaternary. The Saharan dust input to the Gran Canaria profile in the Pleistocene persisted in spite of climatic variations.

137Cs contamination of Techa river flood plain in Brodokalmak settlement

1999 ◽  
Vol 50 (6) ◽  
pp. 1121-1129 ◽  
Author(s):  
A.V. Chesnokov ◽  
A.P. Govorun ◽  
M.V. Ivanitskaya ◽  
V.I. Liksonov ◽  
S.B. Shcherbak
Keyword(s):  
Flood Plain ◽  
Techa River ◽  
River Flood ◽  
137Cs Contamination

scholarly journals Cosmogenic burial dating of in cave-deposited alluvium: unravelling long-term incision rates and complex speleogenesis in multi-level cave systems

2020 ◽  
Author(s):  
Gilles Rixhon ◽  
Didier L. Bourlès ◽  
Régis Braucher ◽  
Alexandre Peeters ◽  
Alain Demoulin
Keyword(s):  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Fluvial Terrace ◽  
Base Level ◽  
Cave System ◽  
River Incision ◽  
Order Of Magnitude ◽  
History Of ◽  
Multi Level

<p>Multi-level cave systems record the history of regional river incision in abandoned alluvium-filled phreatic passages which, mimicking fluvial terrace sequences, represent former phases of fluvial base-level stability. In this respect, cosmogenic burial dating of in cave-deposited alluvium (usually via the nuclide pair <sup>26</sup>Al/<sup>10</sup>Be) represents a suitable method to quantify the pace of long-term river incision. Here, we present a dataset of fifteen <sup>26</sup>Al/<sup>10</sup>Be burial ages measured in fluvial pebbles washed into a multi-level cave system developed in Devonian limestone of the uplifted Ardenne massif (eastern Belgium). The large and well-documented Chawresse system is located along the lower Ourthe valley (i.e. the main Ardennian tributary of the Meuse river) and spans altogether an elevation difference exceeding 120 m.</p><p>The depleted <sup>26</sup>Al/<sup>10</sup>Be ratios measured in four individual caves show two main outcomes. Firstly, computed burial ages ranging from ~0.2 to 3.3 Ma allows highlighting an acceleration by almost one order of magnitude of the incision rates during the first half of the Middle Pleistocene (from ~25 to ~160 m/Ma). Secondly, according to the relative elevation above the present-day floodplain of the sampled material in the Manants cave (<35 m), the four internally-consistent Early Pleistocene burial ages highlight an “anomalous” old speleogenesis in the framework of a gradual base-level lowering. They instead point to intra-karsting reworking of the sampled material in the topographically complex Manants cave. This in turn suggests an independent, long-lasting speleogenetic evolution of this specific cave, which differs from the <em>per descensum</em> model of speleogenesis generally acknowledged for the regional multi-level cave systems and their abandoned phreatic galleries. In addition to its classical use for inferring long-term incision rates, cosmogenic burial dating can thus contribute to better understand specific and complex speleogenetic evolution.</p>

scholarly journals GEOLOGICAL AND MAGNETIC SUSCEPTIBILITY MAPPING OF MOUNT GIOUCHTA (CENTRAL CRETE)

2017 ◽  
Vol 43 (1) ◽  
pp. 289 ◽  
Author(s):  
E. Kokinou ◽  
E. Kamberis ◽  
A. Sarris ◽  
I. Tzanaki
Keyword(s):  
Magnetic Susceptibility ◽  
Spatial Distribution ◽  
Stress Field ◽  
Magnetic Measurements ◽  
Strain Analysis ◽  
Geological Structure ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Western Slope ◽  
Strain Pattern

Giouchta Mt. is located south of Heraklion city, in Crete. It is an N-S trending morphological asymmetric ridge, with steep western slope whilst the eastern slope represents a smoother relief, composed of Mesozoic limestone and Eocene- lower Oligocene flysch sediments of the Gavrovo -Tripolis zone. The present study focuses on the geological structure of Mt. Giouchta. Field mapping and tectonic analysis is performed for this purpose. The dominant structures are contractional in nature, deformed by normal faulting related to the extensional episodes initiated in Serravallian times. The strain pattern in the area is revealed from strain analysis. It is inferred that the orientation of the stress field in the area has changed several times: the N-S, stress field which was dominant during Late Serravallian times changed to NE-SW (in Late Serravallian? - Early Tortonian) and subsequently to WNW-ESE (Early to Middle Tortonian) to become NW-SE in Late Tortonian. This orientation changed also during the Quaternary times trending from NW-SE (Early Pleistocene) to ENE-WSW (Middle Pleistocene-Holocene). In addition to the above, surface soil samples were collected in the wider area of mount Giouchta and they were analyzed in order to determine the magnetic susceptibility. GIS techniques were used for mapping the spatial distribution of the geological features and the magnetic measurements on the topographic relief of the area. Statistical analysis techniques were also applied in order to investigate the relation of faulting and magnetic susceptibility. Maps representing the spatial distribution of the above measurements were created by using appropriate interpolation algorithms.

scholarly journals Elephant bones for the Middle Pleistocene toolmaker

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256090
Author(s):  
Paola Villa ◽  
Giovanni Boschian ◽  
Luca Pollarolo ◽  
Daniela Saccà ◽  
Fabrizio Marra ◽  
...  
Keyword(s):  
Upper Paleolithic ◽  
Raw Material ◽  
General Idea ◽  
Early Pleistocene ◽  
Stone Tool ◽  
Middle Pleistocene ◽  
Medium Size ◽  
Bone Tools ◽  
Lithic Industry ◽  
Taphonomic Analysis

The use of bone as raw material for implements is documented since the Early Pleistocene. Throughout the Early and Middle Pleistocene bone tool shaping was done by percussion flaking, the same technique used for knapping stone artifacts, although bone shaping was rare compared to stone tool flaking. Until recently the generally accepted idea was that early bone technology was essentially immediate and expedient, based on single-stage operations, using available bone fragments of large to medium size animals. Only Upper Paleolithic bone tools would involve several stages of manufacture with clear evidence of primary flaking or breaking of bone to produce the kind of fragments required for different kinds of tools. Our technological and taphonomic analysis of the bone assemblage of Castel di Guido, a Middle Pleistocene site in Italy, now dated by 40Ar/39Ar to about 400 ka, shows that this general idea is inexact. In spite of the fact that the number of bone bifaces at the site had been largely overestimated in previous publications, the number of verified, human-made bone tools is 98. This is the highest number of flaked bone tools made by pre-modern hominids published so far. Moreover the Castel di Guido bone assemblage is characterized by systematic production of standardized blanks (elephant diaphysis fragments) and clear diversity of tool types. Bone smoothers and intermediate pieces prove that some features of Aurignacian technology have roots that go beyond the late Mousterian, back to the Middle Pleistocene. Clearly the Castel di Guido hominids had done the first step in the process of increasing complexity of bone technology. We discuss the reasons why this innovation was not developed. The analysis of the lithic industry is done for comparison with the bone industry.

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