scholarly journals Seismostratigraphy of the Middle St. Lawrence Esturary: A Late Quaternary Glacial Marine to Estuarine Depositional/Erosional Record

2007 ◽  
Vol 46 (2) ◽  
pp. 133-150 ◽  
Author(s):  
Dan Praeg ◽  
Bruno d’Anglejan ◽  
James P. M. Syvitski
Keyword(s):  
Late Quaternary ◽  
Coarse Grained ◽  
Glacial Ice ◽  
Sea Levels ◽  
The North ◽  
Deep Waters ◽  
Saguenay Fjord ◽  
Mass Displacement ◽  
Unconformity Surface ◽  
Middle Estuary

ABSTRACTA buried bedrock trough 350 m deep extends 100 km above Saguenay Fjord beneath the North Channel of the middle estuary. Four of five regional seismostratigraphic units are recognized in and adjacent to the trough; unit 1 (glacial ice-contact) and older sediments might also be present beneath the largely unpenetrated trough axis. Units 2 and 3 represent thick glacial marine sediments deposited in the >550 m deep waters of the Goldthwait Sea after glacial withdrawal ca. 13 ka BP: lower draped muds 10-20 m thick (unit 2) suggest deposition proximal to a retreating ice margin, while upper onlapping muds > 290 m thick (unit 3) record distal basin-filling; lateral transition to a coarse-grained proximal wedge 5*260 m thick (unit 2) is indicated by unit 3 reflectors rising and strengthening towards the Saguenay entrance, where a stable ice-margin ca. 13-11 ka BP supplied sediment to the lower and middle estuary. Unit 4 corresponds to lobes over 30 m thick on both sides of the upper North Channel, recording marginal input from glacial fluvio-deltaic sources. Unit 5 (estuarine sands, gravels and muds =£30 m thick) unconformably overlies glacial units. A smooth unconformity surface records erosion (at least 15 m, to axial depths >150m) by strong currents; irregular relief above depths of 25-50 m might relate to relative sea levels below present ca. 7-6 ka BP. Sand bedforms (apparently inactive) occur at the estuary floor, and possibly buried beneath estuarine muds; buried bedforms would imply an early Holocene genesis. Greatest thicknesses of estuarine mud coincide with adjacent fluvial discharges. Sandy/gravelly veneers form the estuary floor in most places. Mass displacement has disturbed units 3 and 5 along the northern, and locally southern, walls of the North Channel.

Origin of glacial ridges (OIS 6) in the Kaskaskia Sublobe, southwestern Illinois, USA

2012 ◽  
Vol 78 (2) ◽  
pp. 341-352 ◽  
Author(s):  
Nathan D. Webb ◽  
David A. Grimley ◽  
Andrew C. Phillips ◽  
Bruce W. Fouke
Keyword(s):  
Debris Flows ◽  
Spatial Arrangement ◽  
Coarse Grained ◽  
Ice Flow ◽  
Glacial Ice ◽  
Distinctive Features ◽  
Fine Grained ◽  
The North ◽  
Till Fabric ◽  
Glacial Landforms

AbstractThe origin of Illinois Episode (OIS 6) glacial ridges (formerly: ‘Ridged Drift’) in the Kaskaskia Basin of southwestern Illinois is controversial despite a century of research. Two studied ridges, containing mostly fluvial sand (OSL ages: ~ 150 ± 19 ka), with associated debris flows and high-angle reverse faults, are interpreted as ice-walled channels. A third studied ridge, containing mostly fine-grained till, is arcuate and morainal. The spatial arrangement of various ridge types can be explained by a glacial sublobe in the Kaskaskia Basin, with mainly fine-grained ridges along the sublobe margins and coarse-grained glaciofluvial ridges in a paleodrainage network within the sublobe interior. Illinois Episode till fabric and striation data demonstrate southwesterly ice flow that may diverge near the sublobe terminus. The sublobe likely formed as glacial ice thinned and receded from its maximum extent. The Kaskaskia Basin contains some of the best-preserved Illinois Episode constructional glacial landforms in the North American midcontinent. Such distinctive features probably result from ice flow and sedimentation into this former lowland, in addition to minimal postglacial erosion. Other similar OIS 6 glacial landforms may exist in association with previously unrecognized sublobes in the midcontinent, where paleo-lowlands might also have focused glacial sedimentation.

The late Quaternary geology of the Chalk River region, Ontario and Quebec

1982 ◽  
Vol 19 (6) ◽  
pp. 1218-1231 ◽  
Author(s):  
N. R. Catto ◽  
R. J. Patterson ◽  
W. A. Gorman
Keyword(s):  
Forest Fires ◽  
Late Quaternary ◽  
Glacial Ice ◽  
Ottawa River ◽  
The North ◽  
Discharge Rates ◽  
Aeolian Activity ◽  
River Region ◽  
Ice Retreat ◽  
Time Changes

Glacial ice covered the Chalk River area through most of the Wisconsin Stage. About 11 300 years ago, an ice retreat was followed immediately by a short incursion of Champlain Sea waters, which deposited at least 2.5 m of clay, silt, and sand. A local readvance, probably associated with the St. Narcisse event, deposited till on the marine sediments. Following the final retreat of the ice from the area, lacustrine and aeolian deposition occurred locally for a short time.About 10 500 years ago, the North Bay drainage route opened, greatly increasing the discharge of the Ottawa River. A faint terrace at a present elevation of 209 m probably formed at this time. Changes in the drainage routes of proglacial lakes and in the rate of ice retreat caused a general decrease in discharge rates, and resulted in the formation of pronounced terraces, now at 180, 160, and 129 m, and fainter terraces at 170, 141, and 137 m. By about 5000 years BP, the North Bay outlet closed, and the river fell to approximately 111 m, its present elevation at Chalk River.During the whole period of terrace formation, alluvial sands were being deposited and, as river levels fell, exposed sands were reworked by the wind until anchored by vegetation. Charcoal horizons within the aeolian sequences indicate that forest fires occasionally destroyed the vegetation cover, re-initiating aeolian activity. Locally, active dunes are present near Chalk River, but most of the area has been stabilized by vegetation.

scholarly journals Late Quaternary paleoseismic sedimentary archive from deep central Gulf of Corinth: time distribution of inferred earthquake-induced layers

2014 ◽  
Vol 56 (6) ◽  
Author(s):  
Corina Campos ◽  
Christian Beck ◽  
Christian Crouzet ◽  
Eduardo Carrillo ◽  
Aurélien Van Welden ◽  
...  
Keyword(s):  
Time Distribution ◽  
Late Quaternary ◽  
Coarse Grained ◽  
Lower Term ◽  
Piston Core ◽  
Magnetic Susceptibility Anisotropy ◽  
North Central ◽  
Fine Grained ◽  
The North ◽  
Gulf Of Corinth

<p>A sedimentary archive corresponding to the last 17 cal kyr BP has been studied by means of a giant piston core retrieved on board R/V MARION-DUFRESNE in the North Central Gulf of Corinth. Based on previous methodological improvements, grain-size distribution and Magnetic Susceptibility Anisotropy (MSA) have been analysed in order to detect earthquake-induced deposits. We indentified 36 specific layers -Homogenites+Turbidites (HmTu) - intercalated within continuous hemipelagictype sediments (biogenic or bio-induced fraction and fine-grained siliciclastic fraction). The whole succession is divided into a non-marine lower half and a marine upper half. The “events” are distributed through the entire core and they are composed of two terms: a coarse-grained lower term and an upper homogeneous fine-grained term, sharply separated. Their average time recurrence interval could be estimated for the entire MD01-2477 core. The non-marine and the marine sections yielded close estimated values for event recurrence times of around 400 yrs to 500 yrs.</p>

Late quaternary mangrove distribution in northern Australia

1996 ◽  
Vol 9 (2) ◽  
pp. 219 ◽  
Author(s):  
GM Crowley
Keyword(s):  
Sea Level ◽  
River Flow ◽  
Late Quaternary ◽  
Gradual Change ◽  
Mangrove Forests ◽  
Northern Australia ◽  
Sea Levels ◽  
The North ◽  
Wet Tropics ◽  
Australian Coastline

Although mangroves have long graced the north Australian coastline, stable sea levels required for the formation of extensive mangrove swamp forests have occurred only intermittently over the late Quaternary. Most ancestral mangrove swamps are likely to have been formed below present sea level. The only well-preserved deposits that have been described, developed on the present continental surface as sea level reached its present position in the early Holocene. Gradual upstream shifting of mangrove communities from about 8400 BP is recorded in sediments from the wet tropics, followed by the establishment of extensive Rhizophora forests over the newly drowned estuaries. More extensive Rhizophora swamps developed in the monsoon tropics where an earlier transitional phase has not been preserved. These 'big swamps' infilled over the next 1500–4500 years as sediments accumulated above the now stable sea level. The present mangrove estate, though more restricted, is fairly stable, with maintenance of mangrove forests in protected prograding bays and in estuaries kept open by adequate river flow. In the short term, mangroves may be threatened by human influences, but any change in climate leading to a gradual change in sea level should again provide conditions for expansion of mangrove habitats across northern Australia.

Late Quaternary steady deformation of the Minle Fault in the north Qilian Shan, NE Tibet

2021 ◽  
pp. 228775
Author(s):  
Qingri Liu ◽  
Youli Li ◽  
Jianguo Xiong ◽  
Huiping Zhang ◽  
Weipeng Ge ◽  
...  
Keyword(s):  
Late Quaternary ◽  
The North ◽  
North Qilian

scholarly journals A Prospective Study for the Mitigation of the Climate Change Effects: The Case of the North Aegean Region of Greece

2020 ◽  
Vol 12 (24) ◽  
pp. 10420
Author(s):  
Ioannis Chatziioannou ◽  
Efthimios Bakogiannis ◽  
Charalampos Kyriakidis ◽  
Luis Alvarez-Icaza
Keyword(s):  
Climate Change ◽  
Prospective Study ◽  
Adaptation To Climate Change ◽  
Water Shortages ◽  
Sea Levels ◽  
Aegean Region ◽  
Climate Change Effects ◽  
The North ◽  
North Aegean ◽  
A Prospective Study

One of the biggest challenges of our time is climate change. Every day, at different places of the world, the planet sends alarming messages about the enormous transformations it is experiencing due to human-based activities. The latter are responsible for changing weather patterns that threaten food production, energy production and energy consumption, the desertification of land, the displacement of people and animals because of food and water shortages due to the reductions in rainfall, natural disasters and rising sea levels. The effects of climate change affect us all, and if drastic measures are not considered in a timely manner, it will be more difficult and costly to adapt to the aforementioned effects in the future. Considering this context, the aim of this work is to implement a prospective study/structural analysis to the identified sectors of a regional plan of adaptation to climate change so as to promote the resilience of the region against the negative phenomena generated by the climate crisis. This was achieved in two steps: first, we identified the relationships between the strategic sectors of the plan and organized them in order of importance. Second, we assessed the effectiveness of several public policies oriented towards a city’s resilience according to their impact upon the strategic sectors of the plan and the co-benefits generated by their implementation for society. The results highlight that the most essential sectors for the mitigation of climate change are flood risk management, built environment, forest ecosystem management, human health, tourism and rise in sea level. As a consequence, the most important measures for the resilience of the North Aegean Region against climate change are the ones related to the preparation of strategic master plans for flood protection projects.

OSL ages and origin of Late Quaternary sediments in the North Transdanubian Hills (Hungary): timing of neotectonic activity

2010 ◽  
Vol 222 (1-2) ◽  
pp. 209-220 ◽  
Author(s):  
Edit Thamó-Bozsó ◽  
Árpád Magyari ◽  
Balázs Musitz ◽  
Attila Nagy
Keyword(s):  
Late Quaternary ◽  
Quaternary Sediments ◽  
Neotectonic Activity ◽  
The North

Late Quaternary change in the mountains of New Guinea

Antiquity ◽  
1995 ◽  
Vol 69 (265) ◽  
pp. 818-830 ◽  
Author(s):  
Geoff Hope ◽  
Jack Golson
Keyword(s):  
Late Quaternary ◽  
New Guinea ◽  
Mountainous Areas ◽  
The South ◽  
Environmental Sequence ◽  
The North ◽  
Australian Continent

At the south and north limits of our region are mountainous areas very different from the open arid spaces of the Australian continent between. In the north, the high country of New Guinea offers a complex and well-studied environmental sequence as the arena for early and puzzling human adaptations, precursor of the extraordinary societies of the island today.

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