Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland

1992 ◽  
Vol 29 (2) ◽  
pp. 222-235 ◽  
Author(s):  
E. H. Cumming ◽  
A. E. Aksu ◽  
P. J. Mudie
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Seismic Profiles ◽  
Ice Shelf ◽  
Acoustic Basement ◽  
Fine Grained ◽  
History Of ◽  
Lift Off ◽  
Late Wisconsinan ◽  
Basal Till

High-resolution seismic profiles and core data from Bonavista Bay, northeast Newfoundland, show that the sedimentary package above acoustic basement was deposited during the deglaciation of the Late Wisconsinan ice sheet. During the Late Wisconsinan maximum (~ 20 000 BP), Bonavista Bay was occupied by a grounded ice sheet that extended farther offshore. Deglaciation of the bay was rapid and occurred prior to ~ 13 500 BP during a time of rising sea level. A basal till was deposited beneath the grounded ice, and after lift-off an ice shelf developed over the outer basins where diamicton was deposited. The inner bay gradually deglaciated as the ice margin retreated to the present-day shoreline by ~ 13 000 BP, and fine-grained outwash sediments transported by interflows were rapidly deposited. The inner bay remained under the influence of one or more remnant ice centres until ~ 10 000 BP, with ice positioned on the Bonavista and Gander peninsulas. Normal marine conditions were established in the outer bay by ~ 13 500 BP and in the inner bay and fjords by ~ 10 000 BP.

Glacial-Marine Sedimentation and Quaternary Glacial History of Marguerite Bay, Antarctic Peninsula

1989 ◽  
Vol 31 (2) ◽  
pp. 255-276 ◽  
Author(s):  
Douglas S. Kennedy ◽  
John B. Anderson
Keyword(s):  
Antarctic Peninsula ◽  
Single Channel ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Glacial History ◽  
Ice Shelf ◽  
Seismic Reflection Data ◽  
Marguerite Bay ◽  
Marine Sedimentation ◽  
History Of

AbstractMarguerite Bay, situated between the subpolar glacial regime of the northern Antarctic Peninsula and the polar glacial regime of West Antarctica, is ideally located to test various models of glacial and glacial-marine sedimentation and specific scenarios of late Wisconsin ice sheet expansion. Piston cores and single-channel seismic reflection data were collected during the Deep Freeze 85 and 86 expeditions to determine the late Quaternary history of the area. Seismic data in the bay show a rugged seafloor, with numerous deep troughs and a very thin layer of sediment over crystalline basement or older sediments. Glacial erosion is important in modifying existing features, although the ultimate repository of the eroded material is not known; it is not found within the bay. The piston cores are topped by diatomaceous muds, which are underlain by terrigenous muds and muddy gravels that imply deposition beneath an ice shelf. Basal tills were penetrated at three sites, reflecting deposition by a grounded marine ice sheet. A reconstruction of the glacial history of Marguerite Bay since the last glacial maximum shows grounded ice filling the bay in late Wisconsin time. Rising sea level caused an uncoupling of the ice sheet and slow retreat of an ice shelf throughout the Holocene.

Quaternary stratigraphy and history, Williams Lake, British Columbia

1987 ◽  
Vol 24 (1) ◽  
pp. 147-158 ◽  
Author(s):  
John J. Clague
Keyword(s):  
British Columbia ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Stream Channels ◽  
Valley Fill ◽  
Braided Streams ◽  
History Of ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
Sand And Gravel

Thick valley-fill sediments in the vicinity of Williams Lake, British Columbia, provide a detailed record of the late Quaternary history of an area near the centre of the former Cordilleran Ice Sheet. Stratigraphic units assigned to the late Wisconsinan Fraser Glaciation, the preceding (penultimate) glaciation, and the present interglaciation are described. Especially noteworthy are (1) thick units of sand and gravel deposited by braided streams, perhaps during periods of ice-sheet growth; and (2) complex glaciolacustrine sediments that accumulated in ice-dammed lakes during periods of deglaciation.Glaciers from the Coast and Cariboo mountains coalesced and flowed north over central British Columbia during late Wisconsinan time. Fraser Glaciation advance sediments and older Pleistocene deposits were partially removed by this ice sheet, and the eroded remnants were mantled with till. At the end of the Fraser Glaciation, the Cordilleran Ice Sheet downwasted and retreated southward along an irregular front across the study area. Parts of the ice sheet stagnated and disintegrated into tongues confined to valleys. Sediment carried by melt streams flowing from decaying ice masses was deposited in glacial lakes, in stream channels, and on floodplains.

Late Quaternary sedimentation in central Flemish Pass

1992 ◽  
Vol 29 (3) ◽  
pp. 535-550 ◽  
Author(s):  
David J. W. Piper ◽  
Christopher P. G. Pereira
Keyword(s):  
Late Quaternary ◽  
Ice Sheets ◽  
Seismic Profiles ◽  
Grand Banks ◽  
The Past ◽  
Labrador Current ◽  
Lithostratigraphic Units ◽  
History Of ◽  
Quaternary History ◽  
Late Wisconsinan

Flemish Pass is a basin in 1000 m water depth on the continental slope off the Grand Banks of Newfoundland and has a Quaternary fill principally of turbidites. The late Quaternary history of the pass has been investigated using mid-range side-scan sonargraphs, high-resolution seismic profiles, and cores dated using C-14. The sequence of facies in the cores reveals six lithostratigraphic units deposited in the past 40 ka. At 15–19 ka and ?25–30 ka, sedimentation was dominated by debris-flow and turbidite deposits, together with hemipelagic deposits of similar clay-size mineralogy, derived from the Grand Banks. At other times, ice-rafting and hemipelagic sedimentation, principally of carbonate-rich sediment transported by the Labrador Current, predominated. A late Quaternary regional unconformity on the slope may reflect the effects of ice sheets reaching the shelf break, probably in the Early Wisconsinan. Late Wisconsinan resedimentation was not related to ice-marginal processes and probably resulted from iceberg impacts.

A reinterpretation of glacial and marine limits around the northwestern Laurentide Ice Sheet

1987 ◽  
Vol 24 (4) ◽  
pp. 591-601 ◽  
Author(s):  
Arthur S. Dyke
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Ice Shelf ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Banks Island ◽  
History Of ◽  
Late Wisconsinan

Seven new radiocarbon dates pertaining to deglaciation of northern Prince of Wales Island place the margin of the Laurentide Ice Sheet on the island by 11 000 BP. This requires a revision of the proposed age for the Viscount Melville Sound Ice Shelf of 10 300 – 9880 BP. A revised age of 11 300 – 11 000 BP is suggested.The new dates also require revisions of the proposed Wisconsinan and Holocene history of Banks Island. Shells thought to have been thrust onshore to an elevation of 88 m by the ice shelf on northern Banks Island after 10 600 BP are reinterpreted as undisturbed postglacial marine shells recording a relative sea level of 88 m or more. This, in turn, suggests that the East Coast Sea and Jesse Till are of Late Wisconsinan rather than Early Wisconsinan age and that the Late Wisconsinan glacial limit on Banks Island as figured on the 1968 Glacial Map of Canada, rather than on recent revisions, is essentially correct.

scholarly journals Quaternary Stratigraphy and History, Quesnel, British Columbia

2007 ◽  
Vol 42 (3) ◽  
pp. 279-288 ◽  
Author(s):  
John J. Clague
Keyword(s):  
British Columbia ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Drainage System ◽  
Glacial Lakes ◽  
Quaternary Stratigraphy ◽  
Valley Fills ◽  
History Of ◽  
Late Wisconsinan ◽  
Sand And Gravel

ABSTRACT Thick Quaternary sediments at Quesnel, British Columbia, provide a record of the late Quaternary history of an area near the centre of the former Cordilieran Ice Sheet. These sediments, in part, fill stream valleys that were cut sometime prior to the Late Wisconsinan Fraser Glaciation. Of special note are (1) fluvial or glaciofluvial sand and gravel deposited by aggrading streams, perhaps in part during early Fraser time; (2) thick glaciolacustrine mud, sand, and diamicton laid down later as glaciers advanced across central British Columbia; and (3) glaciolacustrine sediments similar to (2), but deposited in an ice-dammed lake at the end of the Fraser Glaciation. The stratigraphy is punctuated by colluvial deposits that are products of landslides from valley walls at various times during the late Quaternary; this process continues to the present. During the Fraser Glaciation, glaciers from the Coast and Cariboo Mountains coalesced and flowed north over central British Columbia. Fraser Glaciation advance sediments and older Pleistocene deposits were partially removed by this ice sheet and the eroded remnants mantled with till. At the end of this glaciation, the Cordilieran Ice Sheet downwasted and receded southward along an irregular front across the study area. Large amounts of sediment were deposited in glacial lakes dammed by the southward-retreating ice. With complete déglaciation of the interior, glacial lakes drained and the present drainage system was established. At first, valleys were partially aggraded with sand and gravel, but later, streams dissected valley fills to produce a series of terraces at successively lower levels.

scholarly journals Late Quaternary paleoenvironment of the Ross Sea continental shelf, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 275-280 ◽  
Author(s):  
Akira Nishimura ◽  
Toru Nakasone ◽  
Chikara Hiramatsu ◽  
Manabu Tanahashi
Keyword(s):  
Organic Carbon ◽  
Marine Environment ◽  
Environmental Changes ◽  
Ross Sea ◽  
Late Quaternary ◽  
Sedimentary Environment ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Accelerator Mass Spectrometer

Based on sedimenlological and micropaleontological work on three sediment cores collected at about 167° Ε in the western Ross Sea, Antarctica, and accelerator mass spectrometer l4C ages of organic carbon, we have reconstructed environmental changes in the area during the late Quaternary. Since 38 ka BP at latest, this area was a marine environment with low productivity. A grounded ice sheet advanced and loaded the sediments before about 30-25 ka BP. After 25 ka BP, the southernmost site (76°46'S) was covered by floating ice (shelf ice), preventing deposition of coarse terrigenous materials and maintaining a supply of diatom tests and organic carbon until 20 ka BP. The northernmost site (74°33'S) was in a marine environment with a moderate productivity influenced by shelf ice/ice sheet after about 20 ka BP. Since about 10 ka BP, a sedimentary environment similar to the present-day one has prevailed over this area.

Genesis of carbonate till in the lee sides of Precambrian Shield uplands, Hemlo area, Ontario

1987 ◽  
Vol 24 (10) ◽  
pp. 2004-2015 ◽  
Author(s):  
Stephen R. Hicock
Keyword(s):  
Ice Sheet ◽  
Glacial Maximum ◽  
Laurentide Ice Sheet ◽  
The South ◽  
Precambrian Shield ◽  
Basal Zone ◽  
Compressive Flow ◽  
Late Wisconsinan ◽  
Basal Till

Near Hemlo, Ontario, highly calcareous till is confined to areas located downglacier from Precambrian uplands, at least 150 km from the Paleozoic–Precambrian boundary. It comprises subglacial meltout till between lodgment tills, and the calcareous package overlies noncalcareous basal till (not studied) and underlies noncalcareous supraglacial meltout till. The tills can be distinguished by textural, carbonate, and clast compositions. Glaciotectonic deformations, stone fabrics and striae, and stone provenance from the tills, as well as erosional and depositional landforms, indicate that ice advanced to the south–southwest across bedrock contacts and over Precambrian uplands.Deposition of all five tills can be explained with one glacial event. As the Late Wisconsinan margin of the Laurentide ice sheet advanced against uplands about 20 km northeast of Hemlo it experienced compressive flow while depositing the non calcareous basal till. Upshearing of stoss-side local debris high into the ice also occurred as englacial ice overrode the slowed basal zone. Once over the upland, englacial ice assumed extending flow, and downshearing of distal debris, which was deposited as calcareous lodgment till on the lee sides of uplands. After the glacial maximum, the glacier ceased internal movement and subglacial meltout till was laid down. A late reactivation of the ice deposited the upper lodgment till and final stagnation formed the supraglacial meltout till.

Late Tertiary to late Quaternary record in the Mackenzie Mountains, Northwest Territories, Canada: stratigraphy, paleosols, paleomagnetism, and chlorine - 36

1996 ◽  
Vol 33 (6) ◽  
pp. 875-895 ◽  
Author(s):  
A. Duk-Rodkin ◽  
R. W. Barendregt ◽  
C. Tarnocai ◽  
F. M. Phillips
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Climatic Conditions ◽  
Unconsolidated Sediments ◽  
Laurentide Ice Sheet ◽  
Stratigraphic Sequence ◽  
Late Tertiary ◽  
Mackenzie Mountains ◽  
Late Wisconsinan ◽  
Stratigraphic Succession

A stratigraphic sequence of unconsolidated sediments ranging in age from Late Pliocene to Late Pleistocene is recorded in the Canyon Ranges of the Mackenzie Mountains. Three of the sections (Katherine Creek, Little Bear River, and Inlin Brook) expose bedrock and Tertiary gravel overlain by colluvium and a multiple till sequence of montane origin, separated by paleosols and capped by a till of Laurentide origin. The sections are correlated on the basis of lithology, paleosol development, paleomagnetism, and chlorine dating of surface boulder erratics. A formal stratigraphic nomenclature is proposed for the deposits of this region. The sequence of glacial tills separated by paleosols reflects a long record of glacial–interglacial cycles. Soil properties from the oldest paleosol to modern soil show a general decrease in the degree of soil development, suggesting a progressive deterioration of interglacial climatic conditions. A normal–reverse–normal sequence of remanent magnetization was determined within the stratigraphic succession and assigned to the Gauss–Matuyama–Brunhes chrons, respectively. A Gauss age was assigned to the basal colluvium, an early Matuyama age (including Olduvai) to the first two tills, and a Brunhes age to the last three tills. Laurentide deposits are of Late Wisconsinan age and are restricted to the uppermost part of the stratigraphic succession. Chlorine dates for surface boulders place the all-time limit of the Laurentide Ice Sheet at about 30 ka. The Late Wisconsinan Laurentide Ice Sheet was the only continental ice to reach the Mackenzie and Richardson mountains of the northern Cordillera.

Late Quaternary Evolution of the Northern Aegean Shelf

1989 ◽  
Vol 32 (1) ◽  
pp. 36-50 ◽  
Author(s):  
C. Perissoratis ◽  
D. Mitropoulos
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Shelf Area ◽  
Seismic Profiles ◽  
Fine Grained ◽  
Nestos River ◽  
River Bed ◽  
Ephemeral Lakes ◽  
Evros River ◽  
River Mouths

AbstractA dense network of 3.5 kHz and Uniboom seismic profiles revealed the geological evolution of the Ierissos-Alexandroupolis Shelf area of the northern Aegean during the latest sea-level rise. Near the end of the Pleistocene, ca. 14,000 yr B.P., the sea was at about − 120 m, and almost 5300 km2 of shelf was exposed to subaerial erosion. Two permanet lakes existed in the Ierissos and Kavalla Gulfs, as well as a number of ephemeral lakes scattered throughout the rest of the area. Kavalla Gulf was drained by the Nestos River which joined the Strymon River at the outer Strymonikos Plateau. On the flat Samothraki Plateau were dune fields, marshes, and a number of minor seasonal rivers, while the Evros River flowed east of the plateau. By ca. 13,000 yr B.P. the sea had risen to − 70 m and covered 30% of the previously exposed shelf. The lakes at Ierissos and Strymonikos Gulfs were shallower and the sea approached to within about 5 km of them. Kavalla Gulf and the adjacent eastern Strymonikos Plateau lay 10 m above sea level, while the sea intruded along river mouths at the Samothraki Plateau. During this transgression of the sea river-bed gravels and sands were covered by silts and clays. At the Pleistocene-Holocene transition, ca. 10,500 yr B.P., the sea lay at about − 50 m and in areas of steep slope the coast was close to its present position. At Kavalla Gulf, the sea advanced along the paleochannel of the Nestos River, and the island of Samothraki was separated from the mainland. By ca. 7500 yr B.P. the sea was only 15 m below its present level and the northeastern Aegean shelf assumed nearly its present morphology. The Nestos River changed course to the east and Thassos Island was separated from the mainland. Coarse sediment formed wedges nearshore, whereas fine-grained sediments were distributed widely by current action. In many areas, relict sediments are present.

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