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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 50 (1966)

Issue: 3. (March)

First Page: 628

Last Page: 628

Title: Previous HitUnconformitiesNext Hit in Phanerozoic Succession of Northern Jasper National Park, Alberta: ABSTRACT

Author(s): Eric W. Mountjoy

Article Type: Meeting abstract


Several Previous HitunconformitiesNext Hit occur in the Paleozoic and Mesozoic shelf sequences of the Alberta Rocky Mountains. The stratigraphic succession is repeated several times because of thrust faulting. This repetition, combined with excellent exposures, permits a study of the lateral variations in the stratigraphic units and of the contacts of these units. Most of the stratigraphic breaks are disconformities in local outcrops, but regionally some are important angular Previous HitunconformitiesNext Hit.

The stratigraphic, sedimentologic, and paleontologic evidence is reviewed for the following Previous HitunconformitiesNext Hit: (1) Precambrian-Cambrian and Lipalian interval, (2) Cambrian-Ordovician, (3) sub-Devonian, (4) Late Devonian Frasnian-Famennian, (5) Devonian-Mississippian, (6) Carboniferous-Triassic, and (7) Triassic-Jurassic boundary and gaps in the Jurassic sequence.

The important criteria for recognition of these breaks in the stratigraphic succession are, in order of importance: (1) regional stratigraphy, (2) paleontology, and (3) sedimentary phenomena. Of the sedimentary phenomena, eroded surfaces or truncations and residual concentrations of quartz and chert are very useful. Fossils also are useful for locating stratigraphic breaks. Other features, including phosphates and abrupt changes of lithology, also are associated with some Previous HitunconformitiesTop. In several cases it is impossible without paleontologic evidence to determine the position of a particular stratigraphic break even with complete exposure and closely spaced stratigraphic sections.

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Copyright 1997 American Association of Petroleum Geologists