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Ministry of Energy Mines and Responsible for Core Review

Correlation of Lower Cretaceous Coal Measures,
Peace River Coalfield, British Columbia

Paper 1981 - 3

by P.McL.D. Duff and R.D. Gilchrist

View Entire Paper (PDF, 64MB)

 

The 1970's saw the beginning of one of the most ambitious exploration programs ever undertaken
in British Columbia when various companies decided to define the coal potential of the
northeast part of the province. During a very short period of time an unprecedented number of cored
boreholes were drilled in what is now termed the Peace River Coalfield, an area that extends 290
kilometres from the Alberta border to Williston Lake. In addition, rotary holes and geophysical logs of
both these and the cored holes have provided a wealth of new information on the Lower Cretaceous
rocks containing the coal.


In 1975 the Geological Division of the British Columbia Ministry of Mines and Petroleum
Resources decided that an attempt should be made to collate this information in order to: (a)
summarize the improvement in our knowledge of the stratigraphy of a structurally complex and poorly
exposed area, (b) provide a useful framework for further exploration work, (c) assist in the meaningful
assessment of coal resources and reserves, and (d) add to the sum of geological knowledge of the
area and point to important areas of geological research.


As a preliminary to such studies it was decided to expand the petroleum core storage facility at
Charlie Lake near Fort St. John, so as to be able to accept cores from coal exploration holes as well.
There, the cores are available, under suitable restrictions, for examination by geologists.
This publication presents progress on the efforts made between 1975 and 1978 to improve
methods of correlation in the coalfield and to amplify the excellent stratigraphic framework established
by Stott (1968) which expedited coalfield exploration.


Coal-bearing portions of the succession formed in alluvial-deltaic environments. Lateral facies
changes in both the coal seams and the associated sedimentary rocks are the norm. Consequently,
correlation is difficult, particularly in structurally complex areas. Early correlation attempts with a
heavy reliance on geophysical logs often proved unsatisfactory. In some areas it was decided that
coal seams were simply a series of disconnected lenses; in other areas correlations of individual beds
were 'forced' because lateral continuity was assumed. As in most geological situations neither
extreme is correct. To establish the detailed stratigraphy on any property thorough examination of drill
core is essential and much information may be missed if the core is examined hastily or if the
importance of certain sedimentary features is not recognized.


The correlation charts presented in this publication are a first attempt at an overview of the
stratigraphy of the coalfield. The detailed logs show geophysical and geological features which are
presently considered to be the most significant aids to correlation from the point of view of the
exploration geologist. As in coal-bearing sequences of other ages in other countries, macrofossils, as
well as the normal rock types, and sedimentary and other structures in the cores, play an essential
part in correlation. In addition, recognition of volcanic ash horizons provide valuable stratigraphic
markers and it is hoped that this publication will stimulate the search for them by geologists in the
field. In due course, detailed palynological, paleobotanical, paleontological, geochemical, mineralogical,
and other studies will undoubtedly modify details of the stratigraphy presented here.


The Carbon Creek basin originally was included in this study. A number of cores from it were
examined but the macrofauna found were generally fresh with some brackish water nonmarine
species. The stratigraphy was a problem because no Gething/Moosebar contact was found in the
basin and there were no satisfactory Cadomin rocks. We have not included the Carbon Creek basin in
our interpretations but we have given the fossil list for the holes examined in Appendix I as a reference
for future workers.
 

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