Correlation of sea-level curves for the Lower Silurian of the Bruce Peninsula and Lake Timiskaming District (Ontario)

1982 ◽  
Vol 19 (5) ◽  
pp. 962-974 ◽  
Author(s):  
Valerie R. Colville ◽  
Markes E. Johnson
Keyword(s):  
Great Lakes ◽  
Sea Level ◽  
Hudson Bay ◽  
Strong Correlations ◽  
The South ◽  
Upper Peninsula ◽  
Level Curves ◽  
Lower Silurian ◽  
Hudson Bay Lowlands ◽  
Open Connection

Paleobathymetric interpretation of strata from the Bruce Peninsula and Lake Timiskaming District of Ontario shows strong correlations with data from the Michigan Upper Peninsula and Ontario's Manitoulin Island. Three to four cycles of fluctuating sea level occurred during Early Silurian (Llandoverian) time throughout much of the northern Great Lakes area, and involved the highly regular replacement of ostracode–vermiform, coral–algal, and pentamerid communities by one another. Although exposure is more limited than on Manitoulin Island or the Michigan Upper Peninsula, important clues regarding Early Silurian geography are found in strata of the Bruce Peninsula and Lake Timiskaming District. Continued thinning of stratigraphic units and an increased incidence of disconformities from north to south on the Bruce Peninsula suggest the episodic rise of the Algonquin Arch farther to the south and west. Contrary to earlier paleogeographic reconstructions, the patterns of community changeovers preserved in the Silurian outlier of the Lake Timiskaming District indicate a persistent, open connection between the seas of the northern Great Lakes area and the Hudson Bay Lowlands. This interpretation is more in keeping with recent paleontologic work on faunal distributions.

Correlation of Lower Silurian strata from the Michigan Upper Peninsula to Manitoulin Island

1981 ◽  
Vol 18 (5) ◽  
pp. 869-883 ◽  
Author(s):  
Markes E. Johnson
Keyword(s):  
Sea Level ◽  
Important Application ◽  
Upper Peninsula ◽  
Boundary Area ◽  
Level Curves ◽  
Lower Silurian ◽  
Political Boundaries ◽  
Sea Level Fluctuation ◽  
Stratigraphic Nomenclature ◽  
The Relationship

The same approach in using sea-level curves to refine time-rock correlations between widely separated regions also has an important application in resolving the tangle of dual stratigraphic nomenclature that often develops in neighboring regions divided by political boundaries. A good example is the Lower Silurian of the Michigan Upper Peninsula and Manitoulin Island, Ontario. Four peaks in sea-level fluctuation are recorded in both areas by coeval pentamerid communities stratigraphically intermixed with coral–algal and ostracode–vermiform communities indicative of shallower water conditions. Despite many similarities between the rock units containing these fossil communities, most are identified by different formation names on opposite sides of the U.S.–Canadian border. This study details the eastward thinning of strata across the boundary area. The Cordell dolomite of Michigan is extended to Manitoulin Island, but not the underlying Schoolcraft dolomite, due to the pinching out of beds that define its upper and lower contacts. The Fossil Hill Formation of Manitoulin Island is accordingly reduced but retained even though it contains some of the other subformational units represented in the Schoolcraft. Facies relationships between the Michigan Hendricks dolomite and its correlative Mindemoya and St. Edmund Formations argue for their valid maintenance. The relationship between the Byron and Wingfield Formations is less clear. Probably the Dyer Bay Formation should be extended to Michigan in place of the Lime Island dolomite.

Rb–Sr contribution to the location of Churchill–Superior boundary in Manitoba

1970 ◽  
Vol 7 (3) ◽  
pp. 1017-1020
Author(s):  
A. Turek ◽  
Z. E. Peterman
Keyword(s):  
Drill Hole ◽  
Hudson Bay ◽  
The South ◽  
Lake Winnipeg ◽  
Hudson Bay Lowlands ◽  
Area North ◽  
Age Determinations

Eight whole-rock Rb–Sr age determinations on basement cores from the Hudson Bay Lowlands define an isochron of 1975 ± 45 m.y. (λRb = 1.39 × 10−11y−1) with an initial 87Sr/88Sr 0.7018 ± 0.0005. The indicated age is characteristic of the Churchill Province and on this basis Would suggest that the boundary between the Churchill and Superior provinces is to the south of the drill hole location. A similar age, 1925 ± 105 m.y. with an initial 87Sr/86Sr 0.7025 ± 0.0007, has been obtained on six whole-rock basement samples from the Minago River – Har-grave River area north of Lake Winnipeg.

Séquence de la transition Illinoien–Sangamonien : forage IAC-91 de l'île aux Coudres, estuaire moyen du Saint-Laurent, Québec

1995 ◽  
Vol 32 (11) ◽  
pp. 1950-1964 ◽  
Author(s):  
S. Occhietti ◽  
B. Long ◽  
M. Clet ◽  
X. Boespflug ◽  
N. Sabeur
Keyword(s):  
Sea Level ◽  
Saint Paul ◽  
Mixed Forest ◽  
Hudson Bay ◽  
Lawrence Estuary ◽  
Marine Invasion ◽  
Hudson Bay Lowlands ◽  
Pollen Content ◽  
St Lawrence Estuary ◽  
Glacial Complex

A series of Pleistocene deposits extending over 155 m below sea level was drilled at Aux Coudres Island, in the middle St. Lawrence Estuary, Quebec. The series, which basis is unknown, is divided into two sedimentary units: the lower Baie-Saint-Paul Glacial Complex facies (−155 to −125 m), which is correlated with the Illinoian (isotopic stage 6), and a stratified sequence referred to as the île aux Coudres Formation. The latter is subdivided into four zones: a very compact lower clay (−125 to −102 m), rhythmites with Paleozoic schist debris (−102 to −71 m), and prodeltaic silts and deltaic sandy silts with brackish water benthic foraminifera (−71 to −2 m). The spore and pollen content indicates a schrub tundra followed by an afforestation sequence of a boreal forest that changes to an Abies forest and then to an interglacial mixed forest with Betula, Jugions, Carpinus or Ostrya, Carya, and, at the top, Betula, Tsuga, Quercus, and Ulmus. The accumulation of the sediments of the Île aux Coudres Formation required approximately 3500 years, beginning with a deep marine environment (about 300 m) followed by shallowing waters during the subsequent glacioisostatic rebound phase of the regression. The sedimentation is assigned to a main postglacial marine invasion, referred to as the Guettard Sea, which occurred prior to two regional glacial episodes and was partly contemporaneous with Bell Sea invasion in the Hudson Bay lowlands. A major postglacial sedimentary influx in the Atlantic Ocean, during the Illinoian-Sangamonian transition and at the beginning of the Sangamonian (transition 6–5 and early substage 5e) is inferred from this marine event.

scholarly journals The Middle Wisconsinan History of the Laurentide Ice Sheet

2008 ◽  
Vol 41 (2) ◽  
pp. 215-235 ◽  
Author(s):  
Lynda A. Dredge ◽  
L. Harvey Thorleifson
Keyword(s):  
Great Lakes ◽  
Dynamic Instability ◽  
Ice Sheet ◽  
Ice Cover ◽  
The Arctic ◽  
Hudson Bay ◽  
Sea Level Changes ◽  
Hudson Bay Lowlands ◽  
Climate Indicators ◽  
Western Arctic

ABSTRACT Evidence for Middle Wisconsinan ice limits and climates comes from sites scattered around the periphery of the Laurentide Ice domain and from the Hudson Bay Lowlands. Interpretations are based on dated wood, peat, shell and sediment; biological climate indicators (chiefly cool-climate indicators); and stratigraphie sequences of both glacial and nonglacial units. The best evidence comes from the prairie provinces and the Great Lakes areas, both of which indicate substantial ice retreat from earlier southern glacial limits, and cool, boreal-tundra climates. The western arctic may have experienced an early warm period but both the western arctic — northwestern plains and eastern maritime areas may later have become ice accumulation areas. Three maps portray various possible ice limits. The first shows substantial ice cover in the arctic, but reduced ice cover in the prairies and Great Lakes, and expanded maritime ice caps (rather than Laurentide Ice) in the southeast and on Baffin Island. This ice mass distribution may reflect Middle Wisconsinan shifts in air masses and ocean currents. Ice volumes generated by this model are in accord with the marine oxygen isotope record and perceived global sea level changes. A modification to this model, which resolves some of the controversy in the Hudson Bay Lowlands, shows a calving bay penetrating into the heart of the ice sheet, induced by dynamic instability of the marine-based ice mass in Hudson Bay during relatively high glacial isostatic and eustatic seas. A third reconstruction portrays extensive climatically induced déglaciation and retains Laurentide ice only in parts of the northwest and Labrador-Ungava, with local ice in the Appalachian-Atlantic region. This model is based on alternative genetic interpretations of lithologic units and reassessment of age assignments.

V.—On the Cretaceous Fossils found at Moreseat, Aberdeenshire

1898 ◽  
Vol 5 (1) ◽  
pp. 21-32
Author(s):  
A. J. Jukes-Browne ◽  
John Milne
Keyword(s):  
Sea Level ◽  
The South ◽  
The North ◽  
Cretaceous Fossils

Moreseat is in the parish of Cruden, in the east of Aberdeenshire. It lies at an elevation of 300 feet above sea-level, and the surface of the ground slopes to the sea at Cruden Bay, distant five miles to the south. On the north the ground rises gradually, reaching the height of 450 feet above sea in Torhendry Ridge, which is strewn with chalk-flintsingreat abundance.

The Base and Top of the Coral-rock in Barbados

1937 ◽  
Vol 74 (8) ◽  
pp. 337-359 ◽  
Author(s):  
C. T. Trechmann
Keyword(s):  
Sea Level ◽  
The South ◽  
The West ◽  
East Part ◽  
Varying Thickness ◽  
South West ◽  
New Information ◽  
Main Portion ◽  
Coral Rock

1. The coral-rock commences nearly everywhere with a basal bed of varying thickness containing a fauna of pre-Pleistocene aspect among which the genus Haliotis (absent from these coasts at the present day), Pleurotomaria, Meiocardia, etc., are noticeable. This faunule may have lived at a depth of 700–1,000 feet.2. The supposition that the southerly anticlines are a later uplift than the main portion of Barbados is supported by the absence of ravines, and the presence of post-coral-rock beds which occur as coastal veneers at low altitudes, and in greater thickness in the south-east corner near Whitehaven.3. The south-east part of the island from Consett Point to Ragged Point has probably extended further seawards in comparatively recent times ; the series of converging faults and dislocations in the cliff sections suggest that the thrusts from the west or south-west may have been resisted by this part of the island.4. The relative claims of fault-scarping or marine erosion in production of the rising terraces is discussed ; and new information regarding the thickness of the coral-rock at sea-level from a boring is detailed.5. The finding of a faunule with Pliocene or possibly Miocene affinities at the base of the coral-rock puts the Oceanic series further back, into the Miocene.

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