Page 172 - Carbonate Platforms Facies, Sequences, and Evolution

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which
where
The
1000
0
500
analogous
have been
Sassotetto,
first
to
shallow-water
these ooids in
suggests
within the
the Pliensbachian
Monte
studied
that
depths
sediments
grainstone
Nerone,
during
and were
by Jenkyns
and
micro-oncolites,
deposited
the
not
euphotic zone.
on
The
(1972) ,
the seamount tops
the
simply
growing
packstone
at
Monte Cucco,
who
by
Pliensbachian.
presence
accretion and suggested that the ooids formed some­
few ooids are nucleated on tests of Vida/ina martana
seamount
Monte
Monte
tops after the seamounts were created contain ooids,
A
Acuto and Monte Rotondo (see Fig. 9a,b) were at
pelagic nannofossils incorporated into some of the
from the underlying Calcare Massiccio. Similar ooids
reworked
(Fig. 9b) , ensuring that these ooids were formed in
of
algal
Sibillini
seems to argue for water that is agitated on a regular
textures
found
ooids. Jenkyns (1972) considered these ooids to be
Sinemurian
tops
water
by the
200
faulting.
did
probably
mediately
fragments
deep-water
D.M. Bice and K.G. Stewart
Ma
Mountains
the
depths
after
and
presence
Instead,
waves
result
of
during
the
they
of
with
the
a
bladed to blocky cements,
were
micritic
endolithic
normal
formed
Rotondo. The grooved marginal escarpment can be seen in the photographs in Figs 6a & 7 (upper left) .
approximately
by
envelopes,
algae
Pliensbachian.
range
the
of
which
ably within the upper part of the euphotic zone.
Fig. 8. Schematic diagrams showing the formation and the approximate dimensions of the isolated seamount at Monte
not drop to great depths and drown im­
wave­
that the seamount tops were at relatively shallow­
remained at a relatively shallow-water depth, prob­
are
(Bathurst,
lengths. A similar water depth constraint is imposed
1975). These observations argue that the seamount
grading to coarser spar
Dissolved
normal
basis, which is more likely in the upper 20-30 m for
The diagenetic features of the Lower Bugarone
isopachous,
it seems that the seamount tops
sediments may also be consistent with the hypothesis
sea level
skeletal grains, syntaxial overgrowths on echinoderm