scholarly journals Chrono-, litho- and conodont bio-stratigraphy of the Rauchkofel Boden Section (Upper Ordovician – Lower Devonian), Carnic Alps, Austria

2017 ◽  
Vol 50 (4) ◽  
pp. 445-469 ◽  
Author(s):  
Hans Peter Schönlaub ◽  
Carlo Corradini ◽  
Maria G. Corriga ◽  
Annalisa Ferretti
Keyword(s):  
Lower Devonian ◽  
Upper Ordovician ◽  
Carnic Alps

Chronometric calibration of mid-Ordovician to Tournaisian conodont zones: a compilation from recent graphic-correlation and isotope studies

1992 ◽  
Vol 129 (6) ◽  
pp. 709-721 ◽  
Author(s):  
Barry G. Fordham
Keyword(s):  
High Resolution ◽  
High Precision ◽  
Time Scale ◽  
Lower Devonian ◽  
New South ◽  
Upper Ordovician ◽  
South Wales ◽  
Isotope Studies ◽  
Stratotype Section ◽  
Upper Silurian

AbstractThree available graphic-correlation analyses are used to calibrate mid-Palaeozoic conodont zonations: Sweet's scheme for the mid- to Upper Ordovician; Kleffner's for the mid- to Upper Silurian; and Murphy & Berry's for the lower and middle Lower Devonian. The scheme of Sweet is scaled by applying the high-precision U-Pb zircon date of Tucker and others for the Rocklandian and linked with that of Kleffner by scaling the graptolite sequence of the Ordovician-Silurian global stratotype section to fit two similarly derived dates from this sequence. The top of Kleffner's scheme, all of Murphy & Berry's, as well as standard zones to the Frasnian are calibrated by using tie-points of the latest Cambridge-BP time-scale (GTS 89). However, the recent microbeam zircon date by Claoué-Long and others for the Hasselbachtal Devonian-Carboniferous auxiliary stratotype is used to calibrate the standard Famennian zones. Also the similarly derived but preliminary determination reported by Roberts and others from the Isismurra Formation of New South Wales is tentatively taken as the top of the Tournaisian and so used to calibrate Tournaisian zones. Despite the considerable extrapolation required to compile these schemes and their inherent errors, the resultant time-scale closely agrees with other dates of Tucker and others from the Llanvirn as well as the GTS 89 Homerian-Gorstian tie-point. This suggests that stratigraphic methods can be usefully applied to geochronometry. The Llandovery appears to have lasted longer (16 m. y.) than usually envisaged and the Ordovician-Silurian boundary may need to be lowered to approximately 443.5 Ma. Certainly, chrons varied widely in duration and further stratigraphic studies to estimate their relative durations as well as high-resolution dating for their calibration will be crucial to more accurate biochronometries.

Upper Ordovician and Lower Devonian stratigraphy and paleontology of Perce, Quebec; Part II (cont.)

1930 ◽  
Vol s5-20 (119) ◽  
pp. 365-392 ◽  
Author(s):  
C. Schuchert ◽  
G. A. Cooper
Keyword(s):  
Lower Devonian ◽  
Upper Ordovician

Biostratigraphic significance of lower Paleozoic microfaunas from eastern Canada

2004 ◽  
Vol 41 (5) ◽  
pp. 489-505 ◽  
Author(s):  
Esther Asselin ◽  
Aïcha Achab ◽  
Azzedine Soufiane
Keyword(s):  
New Brunswick ◽  
Lower Devonian ◽  
Head Group ◽  
Upper Ordovician ◽  
Eastern Canada ◽  
Lower Paleozoic ◽  
Anticosti Island ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula ◽  
Mapping Program

Chitinozoan studies recently carried out in the “Appalachian Forelands and St. Lawrence Platform” National Geoscience Mapping Program (NATMAP) project have confirmed the regional biostratigraphic value of a number of chitinozoan species and led to a better documentation of their stratigraphic and geographic distribution in eastern Canada. The typical Darriwilian microfaunas first described from the Table Head Group of western Newfoundland and containing Conochitina chydaea are now recognised in the Rivière Ouelle Formation at Les Méchins, Gaspé Peninsula. In the Upper Ordovician successions of the St. Lawrence Platform at Neuville and in the Charlevoix area, Quebec, Conochitina primitiva is indicative of the multidens–pre-americanus graptolite zonal range, Hercochitina duplicitas of the americanus Zone, and Hercochitina spinetum and Acanthochitina cancellata characterize the ruedemanni – lower spiniferus zonal interval. The occurrence of Cyathochitina vaurealensis and Hercochitina crickmayi in turbidite deposits of the Grog Brook Group of northwestern New Brunswick confirms the minimal facies dependence of these two Richmondian index species. Eisenackitina dolioliformis, characteristic of the late Aeronian and Telychian successions of Arctic Canada, Gaspé Peninsula, and Anticosti Island, is now recognised in samples from the Upsalquitch Formation of northwestern New Brunswick and the Cabano Formation of the Rimouski area in Quebec. The palynological data from Devonian successions of the Matapedia Valley, the Rimouski area, and the Beauce – Eastern Townships region show that the succession of Lower Devonian chitinozoan assemblages of the Forillon Peninsula based on short-ranging species can be used in establishing regional correlations in the Gaspé Belt.

XI.—The Evolution of the Scottish Caledonides in Relation to their Isotopic Age Pattern

1970 ◽  
Vol 68 (11) ◽  
pp. 361-389 ◽  
Author(s):  
J. F. Dewey ◽  
R. J. Pankhurst
Keyword(s):  
Lower Devonian ◽  
Benioff Zone ◽  
Isotopic Age ◽  
Upper Ordovician ◽  
Geological Evidence ◽  
Continental Rise ◽  
Early Ordovician ◽  
The Third ◽  
Third Stage ◽  
Uplift And Erosion

SynopsisThree main stages are recognized in the evolution of the Scottish Caledonian orogen. Firstly, the development of the depositional framework from late Pre-Cambrian to early Ordovician times is outlined, The thick Moine and Dalradian sediments, accumulating on a continental rise, are shown to be equivalent to the shelf sequence of the foreland, and likely correlations are suggested. Secondly, the events comprising the Caledonian deformation and metamorphism of these sediments are reviewed and related to the development of a Benioff zone and coupled oceanic trench along the southern margin of the orogen through the Ballantrae complex. Comparison of stratigraphic and isotopic evidence for the age of these events leads to the conclusion that all major deformation and metamorphism occurred during a relatively short climactic episode 480–510 m.y. ago, within the Arenigian stage of the Ordovician. The third factor in the evolution of the orogen is post-climactic uplift and erosion continuing throughout Upper Ordovician, Silurian and Lower Devonian times. Contours of K–Ar mica ages are presented and related to the geological evidence for this prolonged period of isostatic recovery and thermal adjustment. The style and timing of granitic plutonism, which is closely associated with this third stage, may be indicative of crustal behaviour during uplift rather than continued metamorphism at depth.

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