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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 68 (1984)

Issue: 12. (December)

First Page: 1923

Last Page: 1924

Title: Upper Jurassic and Lower Cretaceous Sedimentary Sequence, Baltimore Canyon Trough, United States Atlantic Margin: ABSTRACT

Author(s): Jan Libby-French


The extent and character of Upper Jurassic and Lower Cretaceous rock units in the Baltimore Canyon Trough are revealed by geologic data from 29 exploratory wells. These data, released to the public in 1982, have been used previously to define regional rock-stratigraphic units. In this study, four detailed stratigraphic cross sections were constructed to show rock-unit correlations based on lithology and electric logs. Thin-section photo-micrographs document the mineralogic composition of these units. The stratigraphic terminology used herein is informally adopted from the nomenclature used on the Scotian Shelf.

Most of the Upper Jurassic section consists primarily of "Mic Mac" gray shale and siltstone with minor amounts of very fine to medium-grained quartzarenite, red-brown shale, and lignite. This interval also

End_Page 1923------------------------------

contains some anomalously thick sandstones and siltstones, which are generally limited to the north and have been tentatively assigned to the "Mohawk"(?) unit. These sandstones are mostly medium to coarse-grained, calcite-cemented quartzarenites. Upper Jurassic "Abenaki" limestone as much as 2,210 ft (675 m) thick was penetrated by most of the eastern wells. The limestone is mostly wackestone to grainstone, with varying amounts of oolites and fossils. Thick-bedded sandstones characterize the Lower Cretaceous "Mississauga" unit. These sandstones are mostly fine to medium-grained, calcite-cemented quartzarenites. The overlying "Naskapi" unit consists of calcareous shale. Thick sandstone beds dominate the uppermost "Logan Canyon" unit, which consists mostly of fine to coarse-grained, cal ite-cemented quartz arenite.

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