SCIENCE REVIEW 1987 - Bedford Institute of Oceanography

Research
Fig. 1 Sedimentary basins of eastern Canada Separate Mesozoic - Cenozoic basins in the offshore
are not identified
10
The Grand Banks of Newfoundland
are bounded by a variety of types of
margins formed through different
geological processes - normally
rifted, transform, and substantially
stretched, as examples.
The eastern margin of the Banks has
been separated from a substantial
source of sediment, so that the nature
of the ocean-continent transition can
be studied without the hindrance of
thick sediments.
The potential for hydrocarbons in
several deep marginal sedimentary
basins on the Banks is significant.
Newfoundland and the adjacent offshore,
is the primary location of the
Lithoprobe East studies. This is an
important component of the National
Lithoprobe Program sponsored by the
National Scientific and Engineering
Research Council and the Department
of Energy, Mines and Resources, with
participants from industry, university
and government laboratories.
In addition, the Gulf of St. Lawrence
provides a water-covered window from
which to study the Paleozoic basins of the
Gulf of St. Lawrence and the tectonic
development of the Appalachian system
formed during an earlier closing of the
Atlantic Ocean. These Paleozoic basins can
then be compared with the Mesozoic-
Cenozoic basins of the present passive
margin formed during the early phases of
seafloor spreading in the present Atlantic
Ocean 100-200 million years ago.
A total of 4200 kms of deep seismic
reflection data (20 second two-way travel
time) has been obtained so far across the
Appalachian terrains, the sedimentary
basins of the Grand Banks, the Gulf of St.
Lawrence, and the ocean margin of the
eastern Grand Banks (Figure 2). While
conventional exploration seismic data
provides information on typically the
upper 10-12 kilometres of the earth’s crust,
these data have imaged the crust all the
way to the Moho, the boundary between
the Earth’s crust and mantle, 30 km and
more below the surface of the earth. The
results have provided important new
insights into the deeper structure of the
sedimentary basins which in turn has led to
new models for the processes of development
and the tectonic history of these
basins and the potential for hydrocarbon
resources that they may contain.
The Frontier Geoscience Program also
provided an opportunity to develop and
build ocean bottom seismometers (OBS).
The OBS are deployed on the seafloor and
record seismic events for refraction studies,
providing information on the bulk nature
of crustal layers and so complementing the
reflection studies which map the depth and
variations of interfaces between layers. The
development, construction and maintenance
of these OBS has been an excellent
example of technology transfer between a
government laboratory and the private
sector. Originally designed by AGC staff,
these units have been further developed by
industry and are now maintained and
operated very successfully for users in
Canada and the United States, by a Halifax
engineering company, Seastar Instruments
Ltd.
Fig. 2 Deep seismic reflection lines and
aeromagnetic coverage of the Grand Banks and
margins collected under the Frontier Geoscience
Program.