Middle Ordovician (late Dapingian–Darriwilian) conodonts from the Cow Head Group and Lower Head Formation, western Newfoundland, Canada1This article is one of a series of papers published in CJES Special Issue: In honour of Ward Neale on the theme of Appalachian and Grenvillian geology.

2012 ◽  
Vol 49 (1) ◽  
pp. 59-90 ◽  
Author(s):  
Svend Stouge
Keyword(s):  
National Park ◽  
New Genus ◽  
Head Group ◽  
Middle Ordovician ◽  
Green Point ◽  
Global Correlation ◽  
Head Formation ◽  
Lower Head ◽  
Lowermost Part ◽  
Shallow Bay

Middle Ordovician (late Dapingian–Darriwilian) conodonts from the Shallow Bay and Green Point formations, Cow Head Group, and the Lower Head Formation are recorded from three sections in Gros Morne National Park. The collection was investigated to clarify local age relationships between the uppermost part of the Cow Head Group and the interbedded to overlying sediments of the Lower Head Formation. Conodonts from St. Pauls Inlet North section indicate a middle Dapingian age for the upper lower Bed 13, latest Dapingian to early Darriwilian age for the upper Bed 13, an early Darriwilian (Dw 1) age for the top beds or Bed 15 of the Shallow Bay Formation at Lower Head, and the Lower Head Formation is referred to the Darriwilian. The uppermost part of the lower Bed 13 contains Periodon hankensis n. sp., Gothodus sp. A , and Diaphorodus delicatus followed by Periodon macrodentatus , Ansella longicuspica , Erraticodon n. sp. A , and Spinodus wardi n. sp. in the lowermost part of upper Bed 13. The fauna with P. macrodentatus is referred to the newly established Periodon macrodentatus conodont (phylo-)Zone, which is used for global correlation. The uppermost fauna in the Cow Head Group, i.e., Bed 15, includes Histiodella holodentata , Nealeodus martinpointensis , Oistodella pulchra , Dzikodus peavyi , and Yangtzeplacognathus n. sp. A , which are included in the Histiodella holodentata conodont (Bio-)Subzone of the Periodon macrodentatus Zone. Nealeodus is a new genus introduced here; Periodon hankensis n. sp. and Spinodus wardi n. sp. are new species described from the beds 13 and 15, respectively, in the Cow Head Group; Drepanodus aff. D. giganteus , Drepanodus aff. D. robustus , Erraticodon n. sp. A, Protopanderodus cf. P. cooperi , P. cf. P. varicostatus , and Yangtzeplacognathus n. sp. A are taxa referred to in open nomenclature.

Carbon-isotope stratigraphy of the SPICE event (Upper Cambrian) in eastern Laurentia: implications for global correlation and a potential reference section

2018 ◽  
Vol 156 (08) ◽  
pp. 1311-1322 ◽  
Author(s):  
Karem Azmy
Keyword(s):  
Carbon Isotope ◽  
Head Group ◽  
Upper Cambrian ◽  
Green Point ◽  
Global Correlation ◽  
Isotope Profile ◽  
Isotope Stratigraphy ◽  
Lowermost Part ◽  
Spice Event ◽  
Shallow Bay

AbstractThe δ13C profile from the lower interval of the Martin Point section in western Newfoundland (Canada) spans the Upper Cambrian (uppermost Franconian – lowermost Trempealeauan). The investigated interval (∼110 m) is a part of the Green Point Formation of the Cow Head Group and consists of the upper part of the Tucker Cove Member (topmost part of the Shallow Bay Formation) and the lowermost part of the Martin Point Member (bottom of the Green Point Formation). It is formed of rhythmites of marine carbonates alternating with shales and minor conglomeratic interbeds. Multiscreening petrographic and geochemical techniques have been utilized to evaluate the preservation of the investigated lime mudstones. The δ13C and δ18O values of the sampled micrites (−4.8 ‰ to +1.0 ‰ VPDB and −8.2 ‰ to −5.3 ‰ VPDB, respectively) have insignificant correlation (R2= 0.01), as similarly do the δ13C values with their Sr counterparts (R2= 0.07), which supports the preservation of at least near-primary δ13C signatures that can be utilized to construct a reliable high-resolution carbon-isotope profile for global correlations. The δ13C profile exhibits two main negative excursions: a lower excursion (∼4 ‰) that reaches its maximum at the bottom of the section and an upper narrow excursion (∼6 ‰) immediately above the boundary of the Tucker Cove/Martin Point members (Shallow Bay Formation – Green Point Formation boundary). The lower excursion may be correlated with the global SPICE event, whereas the upper excursion may match with a post-SPICE event that has been also recognized in profiles of equivalent sections on different palaeocontinents.

Early development and flysch sedimentation in Ordovician Taconic foreland basin, west-central Newfoundland

1990 ◽  
Vol 27 (9) ◽  
pp. 1247-1257
Author(s):  
Gustavo González-Bonorino
Keyword(s):  
Foreland Basin ◽  
Passive Margin ◽  
Shallow Marine ◽  
Submarine Fans ◽  
Green Point ◽  
West Central ◽  
Head Formation ◽  
Lower Head ◽  
North American Craton ◽  
Shallow Bay

During the Early to Late Ordovician the Taconic foredeep in west-central Newfoundland evolved from an underfilled to an overfilled state in response to cratonward advance, thickening, and erosion of the Taconic Orogen. Early orogen-derived sediment in the foreland basin consisted of middle(?) to lake Arenigian deep-water mudstones that accumulated on an inner (craton-facing) slope prism (uppermost parts of Shallow Bay and Green Point formations and correlative units). These deposits are interbedded with and overlie passive-margin slope sediments. In the middle Arenigian to early Llanvirnian, sand from the orogen formed several small, sand-rich submarine fans (Lower Head Formation and correlative units) on the lower reaches of the inner slope and basin plain. The fans may have been fed by closely spaced rivers draining the orogen, as presently occurs in western South America. Only proximal portions of these fans are now exposed. The flysch basin was narrow, constricted by the inner slope and the passive-margin slope, and located a short distance seaward from the buried hingeline of the proto-North American craton. As the orogen thickened sufficiently to override the crustal ramp, the carbonate shelf on the craton drowned, clastic depocentres migrated onto the foundered craton, and a thicker flysch (Mainland Sandstone) accumulated in Llanvirnian-Llandeilian time. In the Caradocian the foreland basin was overfilled with shallow-marine terrigenous sediments (Long Point Formation). Regional flysch dispersal was from a St. Lawrence promontory to a Quebec reentrant.

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

1980 ◽  
Vol 17 (8) ◽  
pp. 1007-1019 ◽  
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.

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

2001 ◽  
Vol 75 (2) ◽  
pp. 241-260 ◽  
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.

The trilobite fauna of the Middle Ordovician Doularg Formation of the Girvan district, Scotland, and its palaeoenvironmental significance

1991 ◽  
Vol 82 (1) ◽  
pp. 27-54 ◽  
Author(s):  
J. K. Ingham ◽  
R. P. Tripp
Keyword(s):  
New Species ◽  
New Genus ◽  
Silty Mudstone ◽  
Middle Ordovician ◽  
Ecological Control ◽  
The North ◽  
Head Formation ◽  
The Rich

ABSTRACTThe Doularg Formation is defined within the Albany Group (Tappins Complex); the formation consists of the unfossiliferous Fence Member at the base, succeeded by the Gorse Member (formerly the “Albany mudstones with nodular limestones”), the Separation Sandstone and the Jubilation Member, a bedded, calcareous, silty mudstone. The last named has yielded the rich assemblage of trilobites described, representing thirty genera and including one new genus and seven new species—Bronteopsis matutina, Bumastoides? rivulus, Agerina laurentica, Tretaspis eximia, Ampyxina medici, Stiktocybele (gen. nov.) bathytera, Platycalymene metoeca: Nileus is the most common trilobite. The trilobite fauna indicates that the Doularg Formation should be correlated with some part of the Benan Conglomerate, the uppermost formation of the Barr Group to the north of the Stinchar Valley, and is probably of Llandeilo age. The trilobite association is most closely allied to that of the slightly older basal Superstes Mudstone, reflecting the strong ecological control affecting deeper water faunas. The affinity of the Jubilation Member trilobites with those of the middle Table Head Formation (Llanvirn) of western Newfoundland, is evidenced by the presence in both of Nileus, Cybelurus, Peraspis, and Bronteopsis. These are the four most common genera in the Jubilation Member, comprising over half the total trilobite specimens, and provide striking evidence of the longevity of deeper water genera.

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

1988 ◽  
Vol 125 (4) ◽  
pp. 381-414 ◽  
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.

Middle Ordovician (Whiterockian) gastropods of western Newfoundland: Macluritoidea and Euomphaloidea

2001 ◽  
Vol 75 (2) ◽  
pp. 284-294 ◽  
Author(s):  
David M. Rohr ◽  
E. A. Measures
Keyword(s):  
Head Group ◽  
Middle Ordovician ◽  
First Time ◽  
Shallow Bay

Gastropods that occur in the Anomalorthis brachiopod zone in the Spring Inlet Member of the Table Point Formation and in the Orthidiella brachiopod zone of the Shallow Bay Formation of the Cow Head Group are documented. Gastropods from western Newfoundland comprise part of the Toquima-Table Head fauna, and six of the seven genera described here are also found in Whiterockian strata of Nevada. Four species assigned to Monitorella Rohr, 1994, Maclurites Le Sueur, 1818, and Malayaspira Kobayashi, 1958, originally described by E. Billings in 1865 from Middle Ordovician (Whiterockian) strata of Newfoundland are revised. Five species of Helicotoma Salter, 1859, Malayaspira Kobayashi, 1958; Lytospira Koken, 1896; Rossospira Rohr, 1994; and Pachystrophia Perner, 1903, not previously reported from Newfoundland are also described. The probable opercula of Monitorella crenulata (Billings, 1865), and Maclurites emmonsi (Billings, 1865), are also illustrated for the first time.

Late Cambrian radiolarian faunas and biostratigraphy of the Cow Head Group, western Newfoundland

2002 ◽  
Vol 76 (1) ◽  
pp. 1-33 ◽  
Author(s):  
Mun-Zu Won ◽  
William J. Iams
Keyword(s):  
Carbonate Rocks ◽  
National Park ◽  
The Other ◽  
Taxonomic Position ◽  
Head Group ◽  
New Genera ◽  
Faunal Assemblages ◽  
Green Point ◽  
Late Cambrian ◽  
The Difference

Well-preserved Late Cambrian radiolarian faunas were recovered from carbonate rocks of the Cow Head Group of the Great Northern Peninsula of the island of Newfoundland, Canada. Several different faunal assemblages were recognized from three strata at Green Point, one from a stratum at Martin Point, and three from strata at Broom Point South in Gros Morne National Park. The faunas contain nine genera, five of which are new, and 33 species, all but two of which are new. The five new genera are Curvechidnina, Grosmorneus, Pararcheoentactinia, Ramuspiculum, and Subechidnina. Most of the genera belong to the families Archeoentactinidae, Echidninidae, Palaeospiculumidae, and Protoentactiniidae; a few taxa have an uncertain taxonomic position. Echidnina, whose taxonomic identity was uncertain, is shown to be a radiolarian.The diversity of each of these faunas is similar, but the difference in faunal compositions among the faunas examined is distinct. From this analysis, the Late Cambrian strata between Martin Point and Green Point can be more precisely correlated, and the previous correlation has been revised. With the recovery of the conodonts in this study, the provisionally placed boundary between the Franconian and Trempealeauan at Martin Point by earlier researchers is revised and positioned between unit 30 and unit 31.The biostratigraphic range of the co-occurring conodonts indicates that the youngest fauna described in this paper belongs to the Eoconodontus notchpeakensis Zone of late Trempealeauan age and that the other faunas (from Martin Point and Green Point) are of Franconian age.

Carbon-isotope stratigraphy of the uppermost Cambrian in eastern Laurentia: implications for global correlation

2018 ◽  
Vol 156 (5) ◽  
pp. 759-771 ◽  
Author(s):  
KAREM AZMY
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Screening Tools ◽  
Head Group ◽  
Green Point ◽  
Global Correlation ◽  
Marine Carbonates ◽  
Isotope Profile ◽  
Isotope Stratigraphy ◽  
Insignificant Correlation

AbstractThe δ13C profile from an interval of the Martin Point section in western Newfoundland (Canada) spans the upper Furongian (uppermost Cambrian). The interval (~90 m) is a part of the Green Point Formation of the Cow Head Group and consists of the Martin Point (lower) and the Broom Point (upper) members. It is formed of slope marine carbonates alternating with shales (rhythmites) and conglomeratic interbeds. The preservation of the investigated micritic carbonates was meticulously evaluated by multiple petrographic and geochemical screening tools. The δ13C and δ18O values (−0.5 ± 0.8 ‰VPDB and −7.1 ± 0.3 ‰VPDB, respectively) exhibit insignificant correlation (R2= 0.002) and similarly the correlation of δ13C values with their Sr and Mn counterparts, which supports the preservation of at least near-primary δ13C signatures that can be utilized to construct a reliable high-resolution carbon-isotope profile for global correlations.The δ13C profile exhibits two main negative excursions, a lower broad excursion (~3 ‰) that reaches its maximum at ~70 m below the Martin Point / Broom Point members boundary and an upper narrow excursion (~2.5 ‰) immediately below the same boundary. The lower excursion can be correlated with the global latest Furongian HERB event (TOCE), which is also recognized in the C-isotope profile of the GSSP boundary section at Green Point whereas the upper excursion matches with that of the Cambrian‒Ordovician boundary in the same section. The peak of the HERB δ13C excursion is correlated with positive shifts on the Th/U and Ni profiles (redox and productivity proxies).

Allochthonous slope sequence at Lobster Cove Head: evidence for a complex Middle Ordovician platform margin in western Newfoundland

1987 ◽  
Vol 24 (6) ◽  
pp. 1199-1211 ◽  
Author(s):  
Noel P. James ◽  
Jack W. Botsford ◽  
S. Henry Williams
Keyword(s):  
Deep Water ◽  
Carbonate Platform ◽  
Head Group ◽  
Middle Ordovician ◽  
The North ◽  
Platform Margin ◽  
Taconic Orogeny ◽  
Group Contact ◽  
Carbonate Platform Margin ◽  
Shallow Bay

The upper part of an intact sequence of Lower to Middle Ordovician deep-water sediments, which now form a large, disrupted raft within the Rocky Harbour Mélange at Lobster Cove Head, is interpreted as having been deposited downslope from a drowned carbonate platform margin. The entire 50 m thick section is Arenig (late Canadian or Ibexian to early Whiterock) in age; graptolite biostratigraphy demonstrates a correlation with upper parts of the Cow Head Group to the north. The basal part of the section is a proximal facies of the Cow Head Group (Shallow Bay Formation, Factory Cove Member, Beds 9, 10, and part of Bed 11). The upper part of the section consists of interbedded dolostone and shale and is unlike any other sequence in the Cow Head Group. This upper sedimentary sequence is defined as the Lobster Cove Head Member of the Shallow Bay Formation, Cow Head Group. Contact between the two sedimentary packages is also marked by a faunal break and coincides with emplacement of megaconglomerate Bed 12 at Cow Head.This break marks the change from a uniform to complex carbonate platform margin configuration and is here interpreted as the result of synsedimentary faulting. The margin upslope from Cow Head remained in shallow water during the final stages of Cow Head Group deposition, whereas that upslope from Lobster Cove Head was drowned and shed little sediment into deep water. The synsedimentary faulting, which led to rapid subsidence and platform-margin drowning upslope from Lobster Cove Head and possibly the deposition of megaconglomerate Bed 12 at Cow Head, coincides with the onset of the Taconic Orogeny in western Newfoundland.

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