Page 214 - Carbonate Platforms Facies, Sequences, and Evolution

of
up.
this
200
have
water
(similar
opments
was
Barreiro)
relatively
bioherms
Portuguese
a
cap.
to
of
matoporoids
formed
in
structure and,
rare
A
that
the
by
the
period
were
buildups
more
of
the North Atlantic
early
only
probably
Lower
for colonization by rudists.
in this case,
component.
American
may not be reefal in origin.
able
supports
to
occurs shelfward from
significant
submarine
argillaceous
P.M.
this
the
occurring
seaboard,
reefal
Cretaceous
basin during the
Comparison
ACKNOWLEDGEMENTS
construct
of
lagoonal
was strongly controlled by faulting (such as
slightly deeper-water Tubiphytes wackestones.
lithification
with
conclusion
southeast
growth.
Ellis, R. C.L.
do not have a deeper­
'knoll-reef' type envisaged for the Demascota build­
the evidence available suggests that corals and stro­
The general lack of well-developed coral-stroma­
Stage II). This yielded coral-stromotoporoid grain­
shallow basement fault. In the larger buildup devel­
the Canadian Demascota example. Scott (1984) en­
smaller­
largely grainstone-dominated carbonate shelf edge,
Peter Ellis acknowledges the generous financial as-
the
grainstones. The grainstones exhibit no framestone
facies
of
It
an aggrading reefal structure (equivalent to Meyer's
Jurassic is
toporoid reefs within the high-energy environments
surprising in view of James's (1984) conclusion that
0336 Rhino (Fig. 24). Only one well was drilled into
Civet well in
with significant shelf-break reefal structures being a
an unusual structure being strongly influenced by a
for
shelf-break
sparse, they tend to support Jansa's (1981) idea of a
Though core data from the American buildups are
sedimentation, other than the Ota Reef, which was
reefal frameworks are not an important influence on
and
carbonate platform edges known from the area might
stones, with a possible true high-energy framestone
Ota),
reefs, when they are present, may largely be of the
interval (cores 5 and 6, Fig. 24) and was capped with
Jansa (1981) suggested that many of the steep
visaged a similar habitat for coral-stromatoporoid
appears that at least in the Atlantic Basin, corals
North
America, leaving higher-energy environments free
types of carbonate sedimentation to produce major
reef structures. Except where carbonate deposition
scale knoll-reefs in lower, energy environments such
and stromatoporoids were not able to outpace other
as those in the Portuguese Montejunto buildup and
his
a
ces
West
ancial
EuuK,
EuuK,
zone
Miguel
seismic
Econ.
Con[.
sistance
in
Massif
Richard
models
25-28.
a
summary
Canada
CREVELLO,
Wilson and R.R.
and
537-547.
(Houston).
of
L.S.
L.S.
pp. 15-19.
de
and
collaboration
a
assistance
26, 424-514.
Paleont.
support
P.D.
January
chart
statigraphiques
Carol
Hiscott,
Ramalho
reef
(1981)
&
Carbonate
(1979)
Platynota
with
et
15th
Mesozoic carbonate
(Abstract).
Royal
In: Can. Soc. Petrol.
of
Leinfelder
whilst
from
Mesozoic carbonate
shown
Mineral.,
David
1981
Whale
Montejunto
the
shelf,
Peter
building
Calgary, Alberta, Canada.
HARRIS,
in
the
Abenaki
for
Society
Canadian
working
Fig.
P.M.
Sedimentology,
Kitson,
(Kimmeridgien
shelf edge,
in
2
Abenaki update:
a Mesozoic carbonate platform. Bull.
REFERENCES
Servi'<os
update:
Ellwood,
paleontologiques.
organisms,
Grant
(Portugal):
Nova Scotia
Deutsche
Society
(1982)
Sept.
Gradstein computed the burial curves
Geol. Annual Core.
was
patiently
Nova
Foundation Res.
Miguel
of
Inferieur)
Shelf,
Upper
Portugal.
Con[.
Graham
variations
20-21
Can. Petrol.
Geobios
(through
typing
Geol6gicos
devised
dans
award of a European Postdoctoral Research Fellow­
Forschungs­
Reinhold Leinfelder acknowledges fin­
reefs of the Smackover Formation. Gul f Coast Sect. Soc.
ship) and funding from Amoco (Tulsa) and Texaco
Geol.
the
staff of the exploration department of Petrogal and
gemeinschaft (Project Le 580/1). The assistance of
Sceptre Resources in Calgary in providing well and
the Servi'<os Geol6gicos de Portugal in Lisbon, and
Geology, Baillie Carbonate Symposium, Recent Advan­
manuscript and to John Taylor and Andrew Lloyd
and Peter Skelton. The authors are grateful to Beryl
for
1, pp.
Felix
the
Ramalho
in
Exploradio de Petroleo in Lisbon. The stratigraphic
Director General of the Gabinete para a Pesquisa e
in this paper are published by kind permission of the
Hill,
depicted in
Fig. 21, using data supplied by us. Subsurface data
for drafting the figures. The authors wish to thank
19,
Schlager for the helpful comments which stimulated
Field Sample
consequences
the extensive revision of the first draft of the paper.
data is gratefully acknowledged. We thank
reviewers Paul Crevello, Franz Meyer and Wolfgang
Canada.
ATROPS, F. & MARQUES, B. (1986) Mise en evidence de Ia
1979,
Petroleum
along
le
Jurassic
variations along a
Depositional
shelf, Canada - a depositional and diagenetic model for
EuuK, L.S. (1978) The Abenaki Formation, Nova Scotia
Scotia shelf,
(Compiler, Stokes, F.A.S.),