Acoustic interpretation of Quaternary sedimentation and erosion on the channelled upper Laurentian Fan, Atlantic margin of Canada

1982 ◽  
Vol 19 (10) ◽  
pp. 1974-1984 ◽  
Author(s):  
David J. W. Piper ◽  
William R. Normark
Keyword(s):  
Single Channel ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Survey Area ◽  
Overbank Sediments ◽  
Abandoned Channel ◽  
Acoustic Facies ◽  
Seismic Reflection Profiles ◽  
Atlantic Margin ◽  
To Receive

About 1000 km of single-channel seismic-reflection profiles from a 50 km × 100 km area on the upper Laurentian Fan shows no evidence of the large slumps interpreted by previous workers in this area. Our detailed profile grid indicates that slump-like masses are commonly in depositional continuity with definite autochthonous sediments, and surfaces previously interpreted as slide planes are either facies changes or the result of valley-wall erosion. Only a few small slump blocks of relatively consolidated sediment are found on the uppermost fan. Acoustic-facies distribution shows a single Early (?) Pleistocene fan valley crossing the northeast part of the survey area with thick overbank sediments to the southwest. In the middle (?) Pleistocene this valley became incised. Its upper reaches then ceased to receive sediment, and a new valley was cut extending southward from the upper slope and intercepting the lower reaches of the old fan valley. This channel diversion was probably related either to the glacial excavation of the Laurentian Channel or to a major slump scar that formed east of the survey area. Most of the old abandoned channel was plugged by overbank deposits from the new master channel. Two other valleys farther west also developed at this time or somewhat earlier. In Late Pleistocene time, all three valleys were incised and more than 1 km of sedimentary material was stripped from much of the uppermost part of the fan, probably as a result of headward erosion of submarine canyons and general thalweg lowering.

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.

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.

Bayesian analysis of sea-level sensitivity to CO2 forcing across the mid-Pleistocene transition: possible implications for early-Pleistocene ice-sheet extent

2021 ◽  
Author(s):  
Parker Liautaud ◽  
Peter Huybers
Keyword(s):  
Energy Balance ◽  
Bayesian Analysis ◽  
Sea Level ◽  
Late Pleistocene ◽  
Radiative Forcing ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Model Parameters

<p><span>Foregoing studies have found that sea-level transitioned to becoming approximately twice as sensitive to CO</span><span><sub>2</sub></span><span> radiative forcing between the early and late Pleistocene (Chalk et al., 2017; Dyez et al., 2018). In this study we analyze the relationships among sea-level, orbital variations, and CO</span><span><sub>2</sub></span><span> observations in a time-dependent, zonally-averaged energy balance model having a simple ice sheet. Probability distributions for model parameters are inferred using a hierarchical Bayesian method representing model and data uncertainties, including those arising from uncertain geological age models. We find that well-established nonlinearities in the climate system can explain sea-level becoming 2.5x (2.1x - 4.5x) more sensitive to radiative forcing between 2 and 0 Ma. Denial-of-mechanism experiments show that the increase in sensitivity is diminished by 36% (31% - 39%) if omitting geometric effects associated with thickening of a larger ice sheet, by 81% (73% - 92%) if omitting the ice-albedo feedback, and by more than 96% (93% - 98%) if omitting both. We also show that prescribing a fixed sea-level age model leads to different inferences of ice-sheet dimension, planetary albedo, and lags in the response to radiative forcing than if using a more complete approach in which sea-level ages are jointly inferred with model physics. Consistency of the model ice-sheet with geologic constraints on the southern terminus of the Laurentide ice sheet can be obtained by prescribing lower basal shear stress during the early Pleistocene, but such more-expansive ice sheets imply lower CO</span><span><sub>2</sub></span><span> levels than would an ice-sheet having the same aspect ratio as in the late Pleistocene, exacerbating disagreements with </span><span>𝛿</span><span><sup>11</sup></span><span>B-derived CO</span><span><sub>2</sub></span><span> estimates. These results raise a number of possibilities, including that (1) geologic evidence for expansive early-Pleistocene ice sheets represents only intermittent and spatially-limited ice-margin advances, (2) </span><span>𝛿</span><span><sup>11</sup></span><span>B-derived CO</span><span><sub>2</sub></span><span> reconstructions are biased high, or (3) that another component of the global energy balance system, such as the average ice albedo or a process not included in our model, also changed through the middle Pleistocene. Future work will seek to better constrain early-Pleistocene CO</span><span><sub>2</sub></span><span> levels by way of a more complete incorporation of proxy uncertainties and biases into the Bayesian analysis.</span></p>

The Acheulean Technocomplex of the Iberian Atlantic Margin as an Example of Technology Continuity Through the Middle Pleistocene

2020 ◽  
Author(s):  
Eduardo Méndez-Quintas ◽  
Manuel Santonja ◽  
Lee J. Arnold ◽  
João Pedro Cunha-Ribeiro ◽  
Pedro Xavier da Silva ◽  
...  
Keyword(s):  
Middle Pleistocene ◽  
Atlantic Margin

An Anvilian (Early Pleistocene) Marine Fauna from Western Seward Peninsula, Alaska

1974 ◽  
Vol 4 (4) ◽  
pp. 441-470 ◽  
Author(s):  
D.M. Hopkins ◽  
R.W. Rowland ◽  
R.E. Echols ◽  
P.C. Valentine
Keyword(s):  
North Atlantic ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Northwestern Pacific ◽  
River Terrace ◽  
Bering Strait ◽  
Land Bridge ◽  
Marine Fauna ◽  
Seward Peninsula ◽  
Bering Shelf

Cover sediments of the York Terrace exposed near the California River, western Seward Peninsula, Alaska, yield mollusks, ostracodes, and foraminifera that lived during the Anvilian transgression of early Pleistocene age. The fossiliferous sediments lie at the inner edge of the York Terrace, a deformed wave-cut platform that extends eastward from Bering Strait along much of the southern coast of Seward Peninsula. The seaward margin is truncated by the little-deformed Lost River Terrace, carved during the Pelukian (Sangamonian) transgression. The early Pleistocene sediments seem to have been deposited between the first and second of four glaciations for which evidence can be found in the California River area.The California River fauna includes several extinct species and several species now confined to areas as remote as the northwestern Pacific and north Atlantic. The fauna probably lived in water temperatures much like those of the present time but deeper water on the Bering Shelf is suggested.The presence of an early Pleistocene fauna at the inner edge of the York Terrace at California River shows that the terrace was largely carved before and during early Pleistocene time. However, a marine fauna apparently of middle Pleistocene age is found on the York Terrace near Cassiterite Peak, and this seems to indicate that the terrace remained low until middle Pleistocene time. Uplift of the York Terrace probably was accompanied by uplift of Bering Strait. The strait may have been deeper, and there may have been no land bridge between the Seward Peninsula of Alaksa and the Chukotka Peninsula of Siberia during most of early and middle Pleistocene time.

The Olduvai buffaloPelorovisand the origin ofBos

2007 ◽  
Vol 68 (2) ◽  
pp. 220-226 ◽  
Author(s):  
Bienvenido Martínez-Navarro ◽  
Juan Antonio Pérez-Claros ◽  
Maria Rita Palombo ◽  
Lorenzo Rook ◽  
Paul Palmqvist
Keyword(s):  
Western Europe ◽  
Sensu Stricto ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Morphometric Study ◽  
Large Size ◽  
Morphological Differences ◽  
Mammal Assemblages ◽  
Tool Technology ◽  
Different Origin

AbstractThe origin of the genusBosis a debated issue. From ∼ 0.5 Ma until historic times, the genus is well known in the Eurasian large mammal assemblages, where it is represented byBos primigenius. This species has a highly derived cranial anatomy that shows important morphological differences from other Plio-Pleistocene Eurasian genera of the tribe Bovini such asLeptobos,Bison,Proamphibos-Hemibos, andBubalus. The oldest clear evidence ofBosis the skull fragment ASB-198-1 from the middle Pleistocene (∼ 0.6–0.8 Ma) site of Asbole (Lower Awash Valley, Ethiopia). The first appearance ofBosin Europe is at the site of Venosa-Notarchirico, Italy (∼ 0.5–0.6 Ma). Although the origin ofBoshas traditionally been connected withLeptobosandBison, after a detailed anatomical and morphometric study we propose here a different origin, connecting the middle Pleistocene Eurasian forms ofB. primigeniuswith the African Late Pliocene and early Pleistocene large size member of the tribe BoviniPelorovis sensu stricto. The dispersal of theBoslineage in Western Europe during middle Pleistocene times seems to coincide with the arrival of the Acheulean tool technology in this continent.

Unravelling basin shoulder dynamics through detrital apatite fission-track signature: the case of the Quaternary Mugello Basin, Italy

2017 ◽  
Vol 155 (7) ◽  
pp. 1413-1426
Author(s):  
MARIA LAURA BALESTRIERI ◽  
MARCO BENVENUTI ◽  
RITA CATANZARITI
Keyword(s):  
Fission Track ◽  
Age Distribution ◽  
Northern Apennines ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Apatite Fission Track ◽  
Fan Delta ◽  
Lower Pleistocene ◽  
Intermontane Basins ◽  
Delta Sediments

AbstractDetrital apatite fission-track (AFT) thermochronology has been applied to lower Pleistocene lacustrine fan-delta sediments of the NE shoulder of the Mugello Basin, the youngest and closest to the main watershed among the Northern Apennines intermontane basins. The aim was to decode the shoulder uplift dynamics during the development of the basin through the analysis of the Quaternary fluvio-lacustrine deposits. Bedrock shoulder analysis, performed to match the detrital AFT data with their source, revealed the presence of a unexpected only partially annealed portion of a turbidite foredeep unit (AFT ages >7–5 Ma) belonging to the structural complex that constitutes the shoulder bedrock. These data disagree with the AFT age distribution pattern of the well-studied Northern Apennines chain, suggesting a segmentation of the foredeep basin. The latter may have been related to the presence of a tectonically induced topographic high (pre-late Langhian) in the area limiting the thickness of the overriding Ligurian lid. On the other hand, detrital AFT data provided arguments for understanding the dynamics of Mugello Basin shoulder uplift and rotation. The proportion in the different stratigraphic units of the fan-delta sediments of single grains showing young (reset) and old (non-reset) ages points to late Early Pleistocene timing of the development of the SW-verging backthrust that characterizes the study area. These data confirm and detail the picture of an early Quaternary development of the Mugello Basin under a compressional setting, only later (middle Pleistocene to present) superimposed by normal faultings.

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