The C.H. Kindle Collection : Middle Cambrian To Lower Ordovician Trilobites From the Cow Head Group, western Newfoundland

The Cow Head Group is an allochthonous sequence of Middle Cambrian to late Arenig sedimentary breccias, limestones and shales deposited in a deep lower slope environment close to a continental margin. Imbricate thrusting has resulted in repeated exposure of laterally equivalent "proximal" to "distal" facies which may be correlated using graptolitic control in the interbeds. "Proximal" sections are characterised by massive, coarse breccias with interbedded limestones and green/dark grey shales. More distal exposures have fewer and thinner breccias and limestones, while the green/grey shales are replaced progressively by red, non-graptolitic ones. Although the succession is by no mean unbroken or complete, it furnishes one of the best and most continuously graptolitic sections through the Arenig. A new zonal scheme is erected for the Cow Head Group, which could prove suitable as a new North American standard. Furthermore, several limestones and siliceous shales have yielded exquisitely preserved isolated material, permitting integration of fine growth detail with complete flattened specimens. With the exception of the uppermost Arenig U. austrodentatus Zone, Arenig graptoloids possess a prosicular origin for thl1• The earliest graptoloids with a metasicular origin for the first theca appear in this zone, including Undulograptus, Cryptograptus and Paraglossograptus. This interval, equivalent to Dai of the Australasian scheme, therefore represents a hitherto unrecorded major evolutionary step in graptolite evolution.

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Middle Ordovician Table Head Group of western Newfoundland: a revised stratigraphy

Canadian Journal of Earth Sciences ◽

10.1139/e80-101 ◽

1980 ◽

Vol 17 (8) ◽

pp. 1007-1019 ◽

Cited By ~ 16

Author(s):

Colin F. Klappa ◽

Paul R. Opalinski ◽

Noel P. James

Keyword(s):

Carbonate Platform ◽

Head Group ◽

Group Status ◽

Middle Ordovician ◽

Iapetus Ocean ◽

Lower Ordovician ◽

Head Formation ◽

New Formation

Lithostratigraphic nomenclature of early Middle Ordovician strata from western Newfound land is formally revised. The present Table Head Formation is raised to group status and extended to include overlying interbedded terrigenoclastic-rich calcarenites and shales with lime megabreccias. Four new formation names are proposed: Table Point Formation (previously lower Table Head); Table Cove Formation (previously middle Table Head); Black Cove Formation (previously upper Table Head); and Cape Cormorant Formation (previously Caribou Brook formation). The Table Point Formation comprises bioturbated, fossiliferous grey, hackly limestones and minor dolostones; the Table Cove Formation comprises interbedded lime mudstones and grey–black calcareous shales; the Black Cove Formation comprises black graptolitic shales; and the Cape Cormorant Formation comprises interbedded terrigenoclastic and calcareous sandstones, siltstones, and shales, punctuated by massive or thick-bedded lime megabreccias. The newly defined Table Head Group rests conformably or disconformably on dolostones of the Lower Ordovician St. George Group (an upward-migrating diagenetic dolomitization front commonly obscures the contact) and is overlain concordantly by easterly-derived flysch deposits. Upward-varying lithologic characteristics within the Table Head Group result from fragmentation and subsidence of the Cambro-Ordovician carbonate platform and margin during closure of a proto-Atlantic (Iapetus) Ocean.

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Lithostratigraphic and allostratigraphic framework of the Cambrian–Ordovician Potsdam Group and correlations across Early Paleozoic southern Laurentia

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2016-0151 ◽

2017 ◽

Vol 54 (5) ◽

pp. 550-585 ◽

Cited By ~ 8

Author(s):

David G. Lowe ◽

R.W.C. Arnott ◽

Godfrey S. Nowlan ◽

A.D. McCracken

Keyword(s):

Climate Change ◽

Early Paleozoic ◽

Middle Cambrian ◽

Shallow Marine ◽

Upper Cambrian ◽

Subaerial Exposure ◽

Marine Sedimentation ◽

Lower Ordovician ◽

Fluvial Sedimentation ◽

Mixed Carbonate

The Potsdam Group is a Cambrian to Lower Ordovician siliciclastic unit that crops out along the southeastern margins of the Ottawa graben. From its base upward, the Potsdam consists of the Ausable, Hannawa Falls, and Keeseville formations. In addition, the Potsdam is subdivided into three allounits: allounit 1 comprises the Ausable and Hannawa Falls, and allounits 2 and 3, respectively, the lower and upper parts of the Keeseville. Allounit 1 records Early to Middle Cambrian syn-rift arkosic fluvial sedimentation (Ausable Formation) with interfingering mudstone, arkose, and dolostone of the marine Altona Member recording transgression of the easternmost part of the Ottawa graben. Rift sedimentation was followed by a Middle Cambrian climate change resulting in local quartzose aeolian sedimentation (Hannawa Falls Formation). Allounit 1 sedimentation termination coincided with latest(?) Middle Cambrian tectonic reactivation of parts of the Ottawa graben. Allounit 2 (lower Keeseville) records mainly Upper Cambrian quartzose fluvial sedimentation, with transgression of the northern Ottawa graben resulting in deposition of mixed carbonate–siliciclastic strata of the marine Rivière Aux Outardes Member. Sedimentation was then terminated by an earliest Ordovician regression and unconformity development. Allounit 3 (upper Keeseville) records diachronous transgression across the Ottawa graben that by the Arenigian culminated in mixed carbonate–siliciclastic, shallow marine sedimentation (Theresa Formation). The contact separating the Potsdam Group and Theresa Formation is conformable, except locally in parts of the northern Ottawa graben where the presence of localized islands and (or) coastal salients resulted in subaerial exposure and erosion of the uppermost Potsdam strata, and accordingly unconformity development.

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Cambrian and Ordovician linguliform brachiopods from the Shallow Bay Formation (Cow Head Group), western Newfoundland

Journal of Paleontology ◽

10.1017/s0022336000018060 ◽

2001 ◽

Vol 75 (2) ◽

pp. 241-260 ◽

Cited By ~ 4

Author(s):

Sean P. Robson ◽

Brian R. Pratt

Keyword(s):

New Species ◽

Continental Slope ◽

Head Group ◽

Lower Paleozoic ◽

Middle Cambrian ◽

Middle Ordovician ◽

Upper Cambrian ◽

Three New Species ◽

Brachiopod Fauna ◽

Shallow Bay

Linguliform brachiopods were recovered from the Upper Cambrian Downes Point Member (lower Sunwaptan) and from the Middle Ordovician Factory Cove Member (Arenig) of the Shallow Bay Formation, Cow Head Group, of western Newfoundland. These rocks are a series of Middle Cambrian to Middle Ordovician conglomerates, lime mudstones, and shales that formed a sediment apron at the base of the lower Paleozoic continental slope of Laurentia. The linguliform brachiopod fauna consists of sixteen species assigned to twelve genera. Three new species are described: Picnotreta lophocracenta, Neotreta humberensis, and Siphonotretella parvaducta.

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Stratigraphy and geochemical composition of the Cambrian Alum Shale Formation in the Porsgrunn core, Skien–Langesund district, southern Norway.

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2018-66-01 ◽

2018 ◽

Vol 66 ◽

pp. 1-20

Author(s):

Niels Hemmingsen Schovsbo ◽

Arne Thorshøj Nielsen ◽

Andreas Olaus Harstad ◽

David L. Bruton

Keyword(s):

Gamma Ray ◽

Geochemical Composition ◽

Middle Cambrian ◽

Alum Shale ◽

Carbon Isotope Excursion ◽

Lower Ordovician ◽

Shale Formation ◽

Sedimentary Succession ◽

Southern Norway ◽

Spice Event

The fully cored BHD-03-99 borehole (hereafter referred to as the Porsgrunn borehole and core) penetrated Ordovician and Cambrian strata in the Skien–Langesund district, southern part of the Oslo region in Norway. Hand-held X-ray fluorescence (HH-XRF) measurements combined with spectral gamma ray and density core scanning of the Middle Cambrian – Furongian Alum Shale Formation have been made and compared with similar measurements obtained on Alum Shale cores from Scania (southernmost Sweden) and Bornholm (Denmark). The Porsgrunn drill site is located in an area that was only mildly overprinted by Caledonian tectonics and represents one of the few sites in the Oslo area where a nearly untectonised sedimentary succession can be studied in terms of thickness and geochemistry. The Alum Shale Formation is 28.8 m thick in the Porsgrunn core, excluding the thickness of five 0.9–5.5 m thick dolerite sills of assumed Permian age. In the Alum Shale Formation the bulk densities are around 2.7 g/cm3 with a slightly decreasing trend up through the formation. The shale has total organic carbon (TOC) values up to 14 wt%, which is comparable to the TOC levels for the Alum Shale elsewhere in the Oslo area and for dry gas matured Alum Shale in Scania and Bornholm. The basal Furongian is characterised by a gamma ray low and an increase in Mo interpreted to reflect the Steptoean Positive Carbon Isotope Excursion (SPICE) event. The Porsgrunn core data suggest that the Mo concentration remained high also after the SPICE event. Characteristic, readily identified features in the gamma log motif are named the Andrarum gamma low (AGL), base Furongian gamma low (BFGL), Olenus triple gamma spike (OTGS) and the Peltura gamma spike (PGS). No Lower Ordovician Alum Shale is present. The 14.8 m thick Furongian part of the Alum Shale represents the Olenus, Parabolina, Leptoplastus, Protopeltura and Peltura trilobite superzones judging from log-stratigraphic correlations to Scania and Bornholm. The Middle Cambrian interval is 14.0 m thick and includes the Exsulans Limestone Bed and 1.4 m of quartz sandstone. A 0.3 m thick primary limestone bed may be an equivalent to the Andrarum Limestone Bed. The succession represents the Paradoxides paradoxissimus and P. forchhammeri superzones. The Alum Shale Formation rests atop the 13.0 m thick Lower Cambrian Stokkevannet sandstone (new informal name) that in turn directly overlies the basement. Overall, the stratigraphic development of the comparatively thin Alum Shale Formation resembles the condensed sequence seen on Bornholm.

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Cambrian–Lower Ordovician of SW Quebec–NE New York

GSA in the Field in 2020 ◽

10.1130/2021.0060(01) ◽

2021 ◽

pp. 1-32

Author(s):

Osman Salad Hersi ◽

Ed Landing ◽

David Franzi ◽

James Hagadorn

Keyword(s):

New York ◽

Sediment Accumulation ◽

Early Cambrian ◽

Geological History ◽

Middle Cambrian ◽

Early Ordovician ◽

Lower Ordovician ◽

History Of ◽

Rodinia Supercontinent ◽

Stratigraphic Nomenclature

ABSTRACT The Ottawa aulacogen/graben on the NE US—Canadian (SW Quebec and eastern Ontario) border is a long ENE-trending structure formed with initial late Neo proterozoic rifting of the Rodinia supercontinent. This rifting formed the active spreading arms (New York Promontory and Quebec Reentrant) along the (presently) NE margin of the new Laurentia paleocontinent, with the Ottawa aulacogen commonly regarded as a failed arm of the rifting. However, no sediment accumulation in the aulacogen is recorded until the late early Cambrian subsidence of a SE- trending belt that includes the aulacogen and its extension, the Franklin Basin, in NW Vermont. Late early Cambrian marine onlap (Altona Formation) followed by more rapid late middle Cambrian subsidence and deposition of fluviatile arkoses (Covey Hill Formation of SW Quebec and Ausable Formation/Member of eastern New York) record rapid foundering of this “failed arm.” Subsequent deposition (latest middle Cambrian–Early Ordovician) in the Ottawa aulacogen produced a vertical succession of lithofacies that are fully comparable with those of the shelf of the New York Promontory. One of the greatest challenges in summarizing the geological history of the Ottawa aulacogen is the presence of a duplicate stratigraphic nomenclature with lithostratigraphic names changing as state and provincial borders are crossed.

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The proposed Cambrian–Ordovician global Boundary stratotype and point (GSSP) in Western Newfoundland, Canada

Geological Magazine ◽

10.1017/s0016756800013042 ◽

1988 ◽

Vol 125 (4) ◽

pp. 381-414 ◽

Cited By ~ 53

Author(s):

C. R. Barnes

Keyword(s):

New Species ◽

Shallow Water ◽

Head Group ◽

Middle Cambrian ◽

Middle Ordovician ◽

Green Point ◽

Group A ◽

Conodont Fauna ◽

Three New Species

AbstractSections exposing the Cambrian–Ordovician Boundary interval at Broom Point in western Newfoundland have been proposed earlier for a global systemic boundary stratotype. These lie within the Cow Head Group, a late Middle Cambrian to early Middle Ordovician allochthonous unit of limestone, shale, and conglomerate deposited at the toe of the ancient continental slope and on the adjacent continental rise. Several recent studies have further investigated the stratigraphy, sedimentology, and palaeontology of the Cow Head Group and others are under way on magnetostratigraphy and chemostratigraphy. These aspects are reviewed for six key boundary sections representing proximal to distal facies: Cow Head Ledge, Broom Point South, Broom Point North, St Pauls Inlet Quarry, Martin Point, and Green Point. In particular, new data are presented from 260 conodont samples that yielded 15500 conodonts. This intense sampling has allowed the discrimination of minor hiatuses in the proximal to intermediate facies where conglomerates have eroded and cannibalized underlying strata. New conodont data from Broom Point North have lowered the base of the C. lindstromi Zone into unit 74 conglomerates, thereby making this section unsuitable as a boundary stratotype. New collections from Green Point have yielded abundant conodonts and over 9400 conodonts have been recovered from 77 samples.The conodont, graptolite, and trilobite biostratigraphy through the boundary interval is documented allowing accurate correlation between sections and more precisely revealing small hiatuses in the proximal and intermediate facies. The sequence of conodont zones is: Eoconodontus notchpeakensis, Cordylodus proavus, C. caboti, C. intermedius, C. lindstromi and C. angulatus. These can be correlated with trilobite zones established from both in situ and clast faunas from the proximal to intermediate facies and with graptolite assemblages (of Cooper 1979) especially in the intermediate to distal facies. Three new species of Cordylodus are described (C. andresi, C. hastatus and C. tortus) and the full apparatus of Iapetognathus preaengensis is illustrated.The criteria for selecting a global boundary stratotype and point (GSSP) are reviewed in terms of the Cow Head sections. The Green Point section is shown to meet, and largely surpass, the prerequisites required of a stratotype. The Green Point section is proposed to be the global boundary stratotype with the base of the Ordovician System defined at the base of unit 23, which is the base of the Broom Point Member, Green Point Formation, at a level coincident with the base of the Cordylodus lindstromi Zone. In addition to an abundant and superbly preserved conodont fauna, this section preserves the best sequence of earliest planktic graptolites through a 40 m interval; the first nematophorous graptolites (of Assemblage 1) occur in unit 25, 6.9 m above the base of the C. lindstromi Zone. This level can be readily correlated into the proximal facies where both deep and shallow water trilobites (in situ and in clasts, respectively) show the base of the C. lindstromi Zone to lie within the Symphysurina brevispicata trilobite Subzone.

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Fauna of the lower Beauharnois Formation (Beekmantown Group, Lower Ordovician), Grande-Île, Quebec

Canadian Journal of Earth Sciences ◽

10.1139/e96-086 ◽

1996 ◽

Vol 33 (8) ◽

pp. 1132-1153 ◽

Cited By ~ 9

Author(s):

Sylvain Desbiens ◽

Thomas E. Bolton ◽

Alexander D. McCracken

Keyword(s):

New York ◽

Head Group ◽

Faunal Assemblage ◽

Lower Ordovician ◽

Assemblage Zone

Lenses of bioclastic packstone and grainstone within the lower dolomite sequence of the Ogdensburg Member, Beauharnois Formation (Beekmantown Group, Lower Ordovician), in the Valleyfield region, Quebec, bear a distinct diverse faunal assemblage. This Isoteloides–Goniotelina–Ribeiria assemblage is characterized by brachiopods Finkelnburgia armanda (Billings) and Finkelnburgia cullisoni Ulrich and Cooper, molluscs Ribeiria calcifera Billings, "Maclurites" affinis (Billings), and Ceratopea canadensis (Billings), and trilobites Isoteloides canalis (Whitfield), Isoteloides peri Fortey, Bolbocephalus convexus (Billings), Goniotelina subrectus (Bradley), Strigigenalis caudata (Billings), and Hystricurus conicus (Billings). Precise correlation of this lower Beauharnois megafauna is with the Strigigenalis caudata Zone of the Catoche Formation, Cassinian Stage, of western Newfoundland, the Oxford Formation of southeastern Ontario, the Fort Cassin Formation, Cassinian Stage, Canadian Series of New York–Vermont, and the Ross–Hintze trilobite Zone G2 of Utah, Upper Ibexian Series (Tulean Stage). Conodonts include Acodus comptus (Branson and Mehl), Acodus delicatus (Branson and Mehl), Colaptoconus emarginatus (Barnes and Tuke), Colaptoconus quadraplicatus (Branson and Mehl), Scolopodus subrex Ji and Barnes, Drepanoistodus angulensis (Harris), and Oepikodus communis (Ethington and Clark). This fauna corresponds to the Oepikodus communis–"Microzarkodina" marathonensis Zone, which has its lowest limit above the middle of Zone G2 in the Ibex area of Utah. In western Newfoundland, the fauna correlates with the Oepikodus communis – Protoprioniodus simplicissimus Assemblage Zone of the Catoche Formation, and the Prioniodus elegans and Oepikodus evae zones in the Cow Head Group.

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3D geological models from combined interpretation of airborne-TEM and geological data- Two examples from Sweden

10.5194/egusphere-egu2020-7204 ◽

2020 ◽

Author(s):

Mehrdad Bastani ◽

Lena Persson ◽

Peter Dahlqvist ◽

Eva Wendelin ◽

Johan Daniels

Keyword(s):

Groundwater Resources ◽

Geophysical Data ◽

Saline Groundwater ◽

Middle Cambrian ◽

3D Geological Modeling ◽

Rock Types ◽

Transient Electromagnetic ◽

Lower Ordovician ◽

Geological Models ◽

Resistivity Image

The geological survey of Sweden (SGU) has carried out several detailed airborne TEM (Transient Electromagnetic) surveys in recent years. The data collected in these surveys were inverted to provide models of the resistivity of the subsurface, down to a few hundred meters depth. These resistivity models together with the data from existing boreholes and ground observations offer an excellent basis for further 3D geological modeling.&#160; The airborne TEM data presented in this study were collected between 2013 and 2016, covering large areas of the islands of &#214;land and Gotland, in Sweden. Both islands face problems with water supply due to limited groundwater resources. The aim of the surveys was to identify new groundwater resources, specify the depth to saline groundwater and to improve the understanding of the geology of the islands. On &#214;land, the Paleozoic sedimentary succession reaches thicknesses of approximately 250 m and is composed of Lower Cambrian sandstone, Middle Cambrian siltstone, and claystone followed by the Alum Shales of Upper Cambrian and Lower Ordovician age. Above this lies an up to 40 m thick Lower Ordovician limestone succession, which forms the bedrock at the surface across much of the island. The entire sedimentary sequence rests on Precambrian crystalline rocks. On the Island of Gotland, Silurian bedrock represents the upper part of a 250-800 m thick Paleozoic sequence overlying the crystalline basement. The Silurian bedrock is dominated by interbedded layers of limestone and marlstone, where the interface between limestone and marlstone is often the primary hydraulic conductor.After acquisition, these data were processed and inverted (1D inversions with lateral constraints), to provide a series of large airborne datasets, providing a resistivity image down to depths of about 250 m in some areas. The considerable resistivity contrast between lithologies, e.g. limestone and marlstone on Gotland, provided an excellent opportunity to resolve boundaries between the different rock types. Borehole information, geological maps, ground geophysical data and the inversion results were incorporated in a 3D geological modelling software. On comparison of the airborne models, ground geophysical data and borehole information it was clear that the airborne resistivity models correlated well with the other available data. Hence, the resistivity models were used as the basis for constructing the 3D hydrogeological and geological models over significant parts of the islands. In this study we present the 3D geological models over the islands of &#214;land and Gotland which were constructed from the integrated interpretation of all the available data. The models are composed of voxels, each representing a certain lithology classified using a statistical approach. The classification is based on the resistivity range, distance to the neighboring wells/boreholes and the geological observations at the surface. The 3D voxel models will be/have been utilized in hydrological modelling, societal planning, and groundwater management.

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The Atlas-Meseta Red Beds basin (Morocco) and the Lower Ordovician rifting of NW-Gondwana

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.187.3.155 ◽

2016 ◽

Vol 187 (3) ◽

pp. 155-168 ◽

Cited By ~ 13

Author(s):

Hassan Ouanaimi ◽

Abderrahmane Soulaimani ◽

Christian Hoepffner ◽

André Michard ◽

Lahssen Baidder

Keyword(s):

Debris Flows ◽

The South ◽

Red Beds ◽

The West ◽

Middle Cambrian ◽

Shallow Marine ◽

Marine Deposits ◽

Magmatic Rocks ◽

Lower Ordovician ◽

Nw Gondwana

AbstractThe transition from the Cambrian to Ordovician in Morocco is known to be characterized by a frequent Furongian hiatus, restricted extension of the Tremadocian marine deposits, and frequent unconformities at the base of the transgressive upper Floian deposits. In the present work, we first highlight the occurrence of Fe- and mica-rich, red silty/sandy formations in the Central and Eastern High Atlas between the Middle Cambrian and Upper Floian sequences. In the Tislyt type-locality, a synsedimentary hemigraben structure is defined, within which the red beds show frequent slump folds, debris flows and internal unconformities. The correlation with several coeval series of the Meseta domain allows us to define a shallow marine, ferruginous clastic Atlas-Meseta Red Beds (AMRB) basin during the Tremadocian-early Floian. The AMRB basin extended between the Meseta coastal block and the Anti-Atlas domain, being limited by the fault zones that became the West Meseta shear zone and the South Meseta fault, respectively, in the Variscan orogen. The AMRB basin compares with the coeval rifted basins of the central Iberian and Armorican massifs. The red beds were likely sourced from the east, from both the Precambrian basement and Early Ordovician magmatic rocks, contrary to the Ordovician deposits of the Sahara platform sourced from the south. Subsidence of the AMRB and central Iberian-Armorican basins of the NW-Gondwana border aborted during the Floian, whereas the opening of the Rheic ocean went on more to the west.

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