About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

CSPG Bulletin

Abstract


Bulletin of Canadian Petroleum Geology
Vol. 38 (1990), No. 1. (March), Pages 175-175

C.S.P.G. 1990 Convention, "Basin Perspectives"

Diagenesis of the Charlie Lake Formation, Northwest Alberta [Abstract]

Nunez-Betelu, L.1, Shawa, M.S.2

ABSTRACT

The Charlie Lake Formation (Carnian) of the Peace River Arch area has a complex depositional and diagenetic history. The Charlie Lake sediments were deposited in tidal and associated environments in a nearshore setting. Lithofacies commonly consist of shallowing-upward sequences of subtidal, intertidal, and supratidal sediments. These sediments are predominantly dolomite, stromatolitic carbonate, reddish fine-grained sandstone and siltstone, and massive and interbedded anhydrite.

Porosity development in the Charlie Lake sediments ranges from 0 to 20 per cent. The best porosities and permeabilities are often associated with relatively large crystal sizes in dolomites and algal mats. Fracturing and faulting also played a major role in porosity development by serving as conduits for undersaturated ground water solutions.

Good porosity and permeability are also associated with the fine grained sandstone restricted mainly to the upper half of the Charlie Lake Formation. Sandstone porosity is commonly patchy and formed as a result of the dissolution of feldspar and other unstable mineral grains, as well as cements.

Diagenetic modifications of the Charlie Lake sediments include dolomitization, minor silica replacement and cementation, carbonate and anhydrite cementation, and dedolomitization. Gypsum ghosts in anhydrite indicate that at least part of the anhydrite was deposited subaqueously. Dedolomitization fabrics include 1) incomplete replacement of dolomite crystals by calcite; 2) polycrystalline rhombic pseudomorphs of calcite after dolomite; 3) rhombohedral pores; and 4) calcite zones in dolomite crystals.

End_of_Record - Last_Page 175-------

ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES

1 (Koldo), University of Calgary, Calgary T2N 1N4

2 Shawa Geoconsultants Ltd., Calgary T2P 3N3

Copyright © 2003 by The Society of Canadian Petroleum Geologists. All Rights Reserved.