Outline of the Jurassic System in Canada

1963 ◽  
Author(s):  
H Frebold
Keyword(s):  
1994 ◽  
Vol 131 (2) ◽  
pp. 191-200 ◽  
Author(s):  
G. Warrington ◽  
J. C. W. Cope ◽  
H. C. Ivimey-Cook

AbstractIn 1967 the Somerset coastline near Watchet was proposed as the type area of the basal (Planorbis) chronozone of the Hettangian Stage and thus of the Jurassic System. Neither at that time nor subsequently, however, has a type locality and section been nominated from those available in the area. There is urgent need to select a Global Stratotype Section and Point (GSSP) for the base of the Hettangian, and of the Jurassic System. The cliff forming the headland at the west side of St Audrie's Bay, three kilometres east of Watchet, Somerset, is here proposed as the type locality and section, with the base of the Hettangian Stage, at the base of the Planorbis Chronozone, being placed at the horizon currently recognized as that at which ammonites of the genus Psiloceras appear. In this section the base of the Planorbis Chronozone corresponds with the base of the Psiloceras planorbis Biozone. The proposal of this section is conditioned by the availability of comprehensive litho- and biostratigraphic information, and the ability of the section to fulfil International Commission on Stratigraphy (ICS) requirements for a candidate GSSP.


1885 ◽  
Vol 2 (5) ◽  
pp. 239-240
Author(s):  
W. T Blanford
Keyword(s):  

1885 ◽  
Vol 2 (1) ◽  
pp. 47-48
Author(s):  
W. T. Blanford
Keyword(s):  

1998 ◽  
Vol 43 (22) ◽  
pp. 1898-1901 ◽  
Author(s):  
Zhaojie Guo ◽  
Zhicheng Zhang ◽  
Fangang Zeng
Keyword(s):  

1996 ◽  
Vol 33 (3) ◽  
pp. 418-428 ◽  
Author(s):  
Carlos M. González-León ◽  
David G. Taylor ◽  
George D. Stanley Jr

The Antimonio Formation furnishes a record of sedimentation across the Triassic–Jurassic system boundary and is one of a few stratigraphic sections globally that preserves latest Triassic to Hettangian ammonoids in stratigraphic succession. The boundary falls near the middle of the formation, within a 155 m thick stratigraphic section, which is divided into five distinct sedimentary packages. The laminated shales and siltstones in the middle of package 4 represent deposition in an anoxic or disaerobic setting. Although shales of package 4 themselves are poorly fossiliferous, they are bounded below and above by Triassic and Jurassic biotas, respectively. The Triassic–Jurassic system boundary should fall within or stratigraphically close to the laminated beds. The transgressive–regressive signature from the Antimonio Formation corresponds closely to that of the Gabbs and Sunrise formations in Nevada and jointly shows eustatic regressive events at or near the beginning of the latest Triassic Crickmayi Zone and another near the top of the Hettangian. The beds from package 4 indicate a transgression closely associated with the Triassic–Jurassic system boundary.


1979 ◽  
Vol 116 (4) ◽  
pp. 303-311 ◽  
Author(s):  
E. G. Poole

SummaryIt was recently proposed that the base of the Jurassic system be taken at the base of the Blue Lias in the Watchet area of Somerset thus including the underlying White Lias in the Triassic System. The mapped base of the Blue Lias however is a diachronous horizon ranging from pre-planorbis Beds age in Somerset to Schlotheimia angulata Zone age in Warwickshire. No certain chronological correlation is possible between the base of the Blue Lias in the Watchet area and any limestone or other horizon in the pre-planorbis Beds elsewhere nor is there even a palaeontological separation associated with this horizon. This paper reiterates established Geological Survey practice of taking the Triassic-Jurassic boundary in Great Britain at the top of the Cotham Beds and thus including the White Lias limestones in the Lower Lias. The White Lias limestones are regarded as a local shallow-water facies of the pre-planorbis Beds since they both contain similar non-ammonitiferous marine macrofossil assemblages;the Cotham Beds provide palaeontological separation since they divide theseassemblages from the different marine macrofossil assemblages found in the Lower Rhaetic Westbury Beds and also contain the boundary between the Rhaetipollis and Heliosporites miospore zones. The lacustrine or lagoonal Cotham Beds are similar in lithology to the Tea Green Marl and also include reddened beds of mudstone like those of the Keuper Marl; they are therefore better contained in the continental Triassic system rather than the marine Jurassic system.


2010 ◽  
Vol 18 (3) ◽  
pp. 349-352
Author(s):  
V. A. Zakharov ◽  
A. Yu. Guzhikov ◽  
M. A. Rogov ◽  
V. B. Sel’tser ◽  
O. P. Goncharenko
Keyword(s):  

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