HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by PLINT, A. G. Articles by RYLAARSDAM, J. R. Search for Related Content GeoRef GeoRef Citation

A HIGH-LATITUDE EPILITHOZOAN FAUNA ON QUARTZITE CLASTS AND THE PROBLEM OF COBBLE TRANSPORT ACROSS A COASTAL PLAIN: MIDDLE TURONIAN KASKAPAU FORMATION, BRITISH COLUMBIA, CANADA

¹ Department of Earth Sciences, University of Western Ontario, London, Ontario, N6A 5B7, Canada
² Imperial Oil Resources, Fifth Avenue Place, 237 4^th Ave. SW, Calgary, Alberta, T2P 3M9, Canada gplint{at}uwo.ca

The Middle Turonian Kaskapau Formation in the Rocky Mountain Foothills of northeastern British Columbia comprises up to 950 m of shallow marine sandstones cyclically interstratified with marine mudstones and minor lagoonal deposits. Transgressive surfaces are commonly mantled by thin pebble lags. A transgressive pebble lag exposed in Quality Creek near Tumbler Ridge town site includes rare, well-rounded quartzite cobbles and a quartzite boulder, which were deposited at a paleolatitude of about 67°N. Encrusting organisms are unevenly distributed over five of the largest clasts. Disciniscid brachiopods are abundant on one cobble but are otherwise rare. A conical-shelled lingulate brachiopod with concentric growth lamellae occurs sparsely, and a weakly ribbed lingulate brachiopod is represented by one shell. Serpulid worm tubes, encrusting bryozoans, and possible basal attachments of corals are also present. Attached foraminifera are abundant and distributed over several clasts. Generic diversity and taxic dominance values are moderate. The fauna includes many elements typical of Cretaceous lower-latitude hard substrates but is unusual in lacking bivalves; their absence might be due to a combination of abundant clastic supply, high turbidity, possibly lowered salinity in the nearshore zone, and relatively low water temperature (10°C).

The gradient of rivers that supplied gravel to the Kaskapau shoreline was estimated from clast size (typically <30 mm) and bed thickness in coeval fluvial conglomerate. Results suggest river gradients of about 0.3–0.4 m/km close to the shoreline. Calculations based on the encrusted cobbles suggest an unreasonably steep river gradient of about 1.9 m/km. The most likely alternative transport mechanism is rafting in the roots of trees, although the high paleolatitude might not preclude rafting by winter river ice.