Storm-deposited sandstones (tempestites) and related ichnofossils of the Late Ordovician Georgian Bay Formation, southern Ontario, Canada

1991 ◽  
Vol 28 (2) ◽  
pp. 266-282 ◽  
Author(s):  
Michael Kerr ◽  
Nicholas Eyles
Keyword(s):  
Foreland Basin ◽  
Detailed Examination ◽  
Middle Part ◽  
Late Ordovician ◽  
Southern Ontario ◽  
Georgian Bay ◽  
Fine Grained ◽  
Delta Plain ◽  
Niagara Escarpment ◽  
Taconic Orogeny

The Late Ordovician Geogian Bay Formation of southern Ontario, Canada, comprises up to 250 m of grey to blue–grey shales interbedded with highly fossiliferous calcareous sandstones. These strata were deposited in equatorial paleolatitudes after 448 Ma in a shallow foreland basin created by overthrusting along the eastern margin of North America (the Taconic orogeny). The Georgian Bay Formation comprises the middle part of an upward-shallowing progradational sequence from deep-water transgressive shales of the underlying Whitby Formation to muddy tidal-flat sequences of the overlying Queenston Formation. Exposures in brickyard and river cuts near Toronto, and northwards along a narrow outcrop belt along the foot of the Niagara Escarpment, show laterally extensive (100 m+), sharp-based sheets of sandstone up to 1 m thick, with gutter casts and washed-out (hypichnial) trace fossils (dominantly Planolites and Paleophycus) on their lower bedding surfaces. Detailed examination of sandstone beds in outcrop and in three boreholes that penetrate the formation shows that the beds are composed internally of a basal fossil hash layer overlain by flat, hummocky, and wave-rippled divisions. Bed tops show a variety of wave-ripple forms and are heavily bioturbated (dominantly Bifungites, Conostichus, Diplocraterion, Didymaulichnus, Teichichnus). Sandstone sheets are interpreted as storm deposits (tempestites) resulting from tropical storms (hurricanes) transporting fine-grained suspended sediment from a delta plain onto a muddy shelf to the west.

scholarly journals Systematic ichnology of the Late Ordovician Georgian Bay formation of southern Ontario, eastern Canada /

1998 ◽  
Author(s):  
D. Christopher A. Stanley ◽  
R. K. Pickerill ◽  
Keyword(s):  
Late Ordovician ◽  
Eastern Canada ◽  
Southern Ontario ◽  
Georgian Bay

Revision of the position of the Ordovician–Silurian boundary in southern Ontario: regional chronostratigraphic implications of δ13C chemostratigraphy of the Manitoulin Formation and associated strata

2011 ◽  
Vol 48 (11) ◽  
pp. 1447-1470 ◽  
Author(s):  
Stig M. Bergström ◽  
Mark Kleffner ◽  
Birger Schmitz ◽  
Bradley D. Cramer
Keyword(s):  
Middle Part ◽  
Adjacent Region ◽  
Geologic History ◽  
Southern Ontario ◽  
Georgian Bay ◽  
The North ◽  
Head Formation ◽  
Depositional Patterns ◽  
Baseline Values ◽  
Anticosti Island

δ13C values of 142 samples from the Manitoulin Formation and subjacent strata collected from 14 exposures and two drill-cores on Manitoulin Island, Bruce Peninsula, and the region south of Georgian Bay suggest that the Manitoulin Formation is latest Ordovician (Hirnantian) rather than earliest Silurian in age. A δ13C excursion identified as the Hirnantian isotope carbon excursion (HICE), which has a magnitude of nearly 2.5‰ above baseline values, is present in an interval from the upper Queenston Formation to the lower to middle part of the Manitoulin Formation in most of Bruce Peninsula and in the area south of Georgian Bay, whereas on Manitoulin Island the HICE appears to be absent. This indicates that a significant part of the Manitoulin Formation is older on the Bruce Peninsula and in its adjacent region than on Manitoulin Island. The chemostratigraphically based conclusions are consistent with biostratigraphic data from conodonts and brachiopods. The Hirnantian δ13C curve from Anticosti Island, Quebec is closely similar to those of southern Ontario. Traditionally, the Ordovician–Silurian boundary has been placed at the base of the Manitoulin Formation, but the new results suggest that it is more likely to be at, or near, the base of the overlying Cabot Head Formation. These new results have major implications for the interpretation of the geologic history and marine depositional patterns of the latest Ordovician of a large part of the North American Midcontinent.

Nature and origin of sediments infilling poorly defined buried bedrock valleys adjacent to the Niagara Escarpment, southern Ontario, Canada

2007 ◽  
Vol 44 (1) ◽  
pp. 89-105 ◽  
Author(s):  
Patricia A Meyer ◽  
Carolyn H Eyles
Keyword(s):  
Late Quaternary ◽  
Groundwater Exploration ◽  
Interconnected System ◽  
Southern Ontario ◽  
Fine Grained ◽  
Niagara Escarpment ◽  
Vertical Changes ◽  
Facies Types ◽  
Surficial Deposits ◽  
Tentative Correlation

The buried Paleozoic bedrock surface of southern Ontario is dissected by an interconnected system of valleys. These buried valleys are infilled with thick successions of glacial, interglacial, and fluvial sediments that contain a lengthy record of changing environmental conditions during the late Quaternary. Detailed logging of over 500 m of sediment recovered from 11 continuously cored boreholes provides the basis for this study. The boreholes were drilled within two poorly defined bedrock valleys located east of the Niagara Escarpment in southern Ontario as part of a groundwater exploration program. Six distinct facies types were identified within the cores: sand, gravel, fine-grained sediment, and sand-rich, mud-rich, and clast-rich diamict. Textural characteristics of the cored sediments and vertical changes in facies types were used to identify six stratigraphic units (SU I through SU VI) within the valley-infill deposits. These units are interpreted to record fluvial or colluvial (SU I), lacustrine (SU II), fluvial, glaciofluvial or deltaic (SU III), subglacial (SU IV), glaciofluvial (SU V) and subglacial or ice marginal (SU VI) conditions. Sediment characteristics and stratigraphic relationships allow tentative correlation with known surficial deposits. Analysis of the subsurface characteristics and geometries of this stacked succession of coarse- and fine-grained stratigraphic units also allows identification of the geometry of potential aquifers.

A new scleritomous metazoan from the Late Ordovician Georgian Bay Formation, southern Ontario

1998 ◽  
Vol 35 (7) ◽  
pp. 827-831 ◽  
Author(s):  
David M Rudkin
Keyword(s):  
New Genus ◽  
Late Ordovician ◽  
New Genus And Species ◽  
Southern Ontario ◽  
Georgian Bay ◽  
Early Ordovician ◽  
Primary Composition ◽  
Level Group

A new genus and species of articulated scleritomous metazoan, Curviconophorus andersoni, is described on the basis of a unique specimen from the Late Ordovician Georgian Bay Formation of southern Ontario. The affinities of the organism remain obscure, although the overall morphology of component sclerites suggests a possible relationship with the Agmata, an extinct phylum-level group so far known with certainty only from the Cambrian. Curved, conical elements of the scleritome are preserved as internal moulds and yield no details of ultrastructure or primary composition, precluding detailed comparisons with the aggultinated, internally laminated sclerites of agmatans. Curviconophorus gen.nov. has a scleritome architecture similar to that of the Early Ordovician putative agmatan Dimorphoconus granulatus, though it has fewer elements that are strictly monomorphic.

Provenance and depositional environment of organic-rich calcareous black shale of the Late Ordovician Macasty Formation, western Anticosti Basin, eastern Canada

2019 ◽  
Vol 56 (3) ◽  
pp. 321-334 ◽  
Author(s):  
Keiko Hattori ◽  
André Desrochers ◽  
Janice Pedro
Keyword(s):  
Depositional Environment ◽  
Pore Space ◽  
Bulk Composition ◽  
Explosive Volcanism ◽  
Late Ordovician ◽  
Source Rocks ◽  
Eastern Canada ◽  
Fine Grained ◽  
Taconic Orogeny ◽  
Calcite Cement

The organic-rich Macasty shale in the Gulf of St. Lawrence was deposited in the Late Ordovician during the Taconic orogeny. The orogeny involved explosive volcanism and thrusting of allochthonous rocks in the eastern margin of North America. Neodymium isotope compositions of the shale show that the provenance is predominantly Grenvillian granite–gneissic rocks, which were widely exposed north of the basin, with little contribution from Taconic igneous rocks. The bulk composition and the presence of detrital kaolinite suggest that the Grenvillian source rocks underwent intense weathering before erosion. Fine-grained detritus was deposited in the Anticosti Basin, where abundant organic activity kept the sediment–water interface under anoxic conditions. This proposed interpretation is supported by the enrichment of redox-sensitive elements, such as As, V, and U, and by high δ34S for pyrite. Calcite cement formed in the pore space of sediments during the diagenesis at temperatures below 60 °C. The low-temperature diagenetic conditions are consistent with the preservation of abundant organic matter in the shale.

Darriwilian graptolites of the Hamburg succession (Dauphin Formation), Pennsylvania, and their geologic significance

2005 ◽  
Vol 42 (5) ◽  
pp. 791-813 ◽  
Author(s):  
G Robert Ganis
Keyword(s):  
Foreland Basin ◽  
Late Ordovician ◽  
Middle Ordovician ◽  
Taconic Orogeny ◽  
Age Range

Graptolites from the Dauphin Formation in the allochthonous Hamburg succession of the Appalachians in Pennsylvania, USA, are late Darriwilian (Da) 3 to early Da 4 age (Middle Ordovician); this age range constrains the timing of the latest depositional episode before the terrane was tectonically mobilized. These rocks were emplaced into the Martinsburg foreland basin of Laurentia during the Taconic orogeny in the early Caradoc (Late Ordovician). Nineteen taxa are described defining a narrow biostratigraphic interval. Among the characteristic fauna collected from of the Da 4 Zone are Pterograptus elegans Holm, Cryptograptus schaeferi Lapworth, Hustedograptus teretiusculus (Hisinger) ?, Haddingograptus oliveri (Bouček), Glossograptus hincksii (Hopkinson), Pseudophyllograptus angustifolius s.l. (J. Hall), and Archiclimacograptus cf. riddellensis (Harris). Tetragraptus cf. erectus Mu et al. found with the above suggests a level low in the Da 4 Zone and a limited occurrence of Bergstromograptus crawfordi (Harris) may indicate some strata within the Da 3 Zone. Proposed new forms include Pseudotrigonograptus ? ricardo sp. nov., and at least two reteograptids. Four examples of Kalpinograptus and Kalpinograptus ? may be new.

Buried bedrock valleys and glacial and subglacial meltwater erosion in southern Ontario, Canada

2011 ◽  
Vol 48 (5) ◽  
pp. 801-818 ◽  
Author(s):  
Cunhai Gao
Keyword(s):  
Drainage System ◽  
Geological Mapping ◽  
Glacial Erosion ◽  
Diagnostic Features ◽  
Simple Modification ◽  
Southern Ontario ◽  
Georgian Bay ◽  
Niagara Escarpment ◽  
Mechanical Weathering ◽  
Subglacial Meltwater

Morphometric features from a recently compiled bedrock topography map by the Ontario Geological Survey suggest a glacial erosion origin for the buried large bedrock valleys and troughs in southern Ontario. The bedrock valleys at Milverton, Wingham and Mount Forest are tunnel valleys, resulting from subglacial meltwater erosion beneath the Huron ice lobe, probably during or shortly after the Late-Wisconsinan glacial maximum. Diagnostic features for this interpretation include abrupt valley beginning and termination, uneven longitudinal valley profiles and up-slope gradients. The Dundas bedrock valley is the western extension of the Lake Ontario Basin. No comparable bedrock valleys were found to connect it to the Milverton valley for a joint drainage system as previously suggested. The Laurentian bedrock trough is the southeastward extension of the Georgian Bay Basin, both developed along shale bedrock between the Precambrian shield highlands and the Niagara Escarpment, resulting from long-term mechanical weathering associated with Pleistocene glacial erosion. This bedrock low has a floor that exceeds 50 km in width and is 26 m and more below the current water level of Georgian Bay. It could drain Georgian Bay should the drift cover be removed. There is no evidence to suggest that a preglacial river channel, if it existed, is still preserved in the floor of the Laurentian trough as previously suggested. The framework for an intensely glacially sculpted bedrock surface differs from the previous view for simple modification of a preglacial landscape and is, therefore, important in regional subsurface geological mapping and groundwater studies.

Planolites constriannulatusisp. nov. from the Late Ordovician Georgian Bay Formation of southern Ontario, eastern Canada

Ichnos ◽  
1994 ◽  
Vol 3 (2) ◽  
pp. 119-123 ◽  
Author(s):  
D. Christopher ◽  
A. Stanley ◽  
Ron K. Pickerill
Keyword(s):  
Late Ordovician ◽  
Eastern Canada ◽  
Southern Ontario ◽  
Georgian Bay
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