Ordovician stratigraphy and faunas of the Glenogle Formation, southeastern British Columbia
Authors: Norford B S , Jackson D E , Nowlan G S 
Published: July 2014

The Glenogle Formation (age: Arenig to very early Caradoc) accumulated in the White River Trough between the Purcell Platform to the west and the Bow Platform to the east. The formation is up to 851 m thick, its basal contact is conformable with the McKay
Group, and the upper contact is an unconformity below Upper Ordovician rocks that elsewhere cuts down as low as into the Precambrian. The Upper Member of the Glenogle has significant contents of quartz silt and sand within successions of shale in western outcrops and within dolomite in eastern
outcrops. The Lower Member is dominantly shale and limy shale but, in eastern outcrops, can be divided into four units (basal, cherty quartz siltstone, middle, and limestone units) by means of incursions of detrital carbonate and siliceous sediments that were swept into the White River Trough
from the Bow Platform. Debris flows within western outcrops of the Lower Member demonstrate the presence of shallow-water carbonate rocks on the Purcell Platform during early Llanvirn time. Thermal maturities are high in the Glenogle Formation (Conodont Alteration Indices mostly 4-5; Graptolite
Maximum Reflectances 7.93-11.9%).

Graptolites are prominent in the Glenogle Formation and the Pendeograptus fruticosus-Tetragraptus approximatus, Didymograptus bifidus, Isograptus victoriae maximus, Oncograptus, Cardiograptus, Paraglossograptus tentaculatus, Pseudoclimacograptus decoratus, "Glyptograptus" euglyphus and
Nemagraptus gracilis zones are recognized and can be correlated with precision with graptolite sequences in Australia, New Zealand, Newfoundland, and Spitsbergen.

The local presence of shelly fossils and recovery of conodonts from a few stratigraphic sections allow correlations between the graptolitic facies of the Glenogle Formation and the Spitsbergen sequence and with the platform facies of the North American craton. The upper part of the Ibexian Series
is correlated with the Bendigonian, Chewtonian and lower Castlemanian stages; the Orthidiella and Anomalorthis zones of the lower Whiterockian Series with the upper Castlemanian, Yapeenian and the Darriwilian stages; and the Valhallan Stage of Spitsbergen with the late Bendiognian to early
Darriwilian.

The Prioniodus elegans Conodont Zone of the Atlantic Faunal Realm and the Oepikodus communis and Jumudontus gananda-Reutterodus andinus zones of the Midcontinental Faunal Realm are at least partly correlative with the D. bifidus Zone. Conodonts of early Whiterockian age occur with graptolites of
the I. v. maximus Zone. Conodonts representing the Histiodella altifrons Zone occur in the Cardiograptus Zone and also just above the graptolites of the Oncograptus Zone. Faunas representative of the interval Lenodus variabilis Zone to Eoplacognathus suecicus Zone are present within the P.
decoratus Zone and also directly above the P. tentaculatus Zone. Faunas with Phragmodus flexuosus occur above the P. decoratus Zone and below the "G." euglyphus Zone. The Pygodus serra Zone is represented within the upper part of the "G." euglyphus Zone.