Page 173 - Carbonate Platforms Facies, Sequences, and Evolution

(/)
Q)
-�
(/)
(.)
Qi
E
Q;
til
turbidites
towards
features
sea-level
northern
1000
500
0
sediments
Deposition of
the
Fig. 8. (Cont.)
curve
of the
composed
Cecca et al., 1981).
centres
of
(Haq
'Marmarone
et
al.,
beds'
of pores
Cretaceous)
-
are
shallow water
Apennines appear to have
1987),
all
seems
probably never too far below sea-level.
to
Times of exposure have been postulated
which
detritus
coarse-grained
require
to be volumetrically significant in the basinal sedi-
period of subaerial exposure of the seamount tops.
diagenetic features of the fresh-water phreatic zone
The ooids from the seamount tops do not appear
it seems quite likely that the seamount tops were
workers on the basis of independent evidence (see
Colacicchi et at., 1970; Farinacci et al., 1981; and
mainly low-amplitude fluctuations during this time,
Given the most recent Jurassic
characteristic
from any landmass, the presence of these diagenetic
shows
(and their absence from overlying pelagic
by other
a
(Longman, 1980). Since all of the seamounts in the
been isolated
Sibillini
to
size
ments.
up < 20%
water
The
Mountains
Isolated carbonate seamounts, Italy
PLIENSBACHIAN
that described
by
carbonate
1 km of reworked ooids.
Marmarone
particles
beds
Bosellini et al.
seldom
Formation of ooids and other shallow
(1981).
of most of the seamount tops relative to
exceed
the
imagine that the basins would have been completely
total sediment budget, which may have prevented
paucity of ooids in the basinal sediments is the small
159
and more efficient producers of sediment, one can
sizes of the basins. If the seamount tops were larger
filled with shallow-water detritus in a manner similar
ooids to fill the adjacent Belluno trough with nearly
They
platform (see Fig. 1), produced and exported enough
somewhat larger fault bounded platform, the Friuli
described a situation in the southern Alps where a
20-30 m in thickness, and the ooids generally make
of these beds. Part of the reason for the
the northern Apennines had been completely filled,
there would have been a substantial increase in the
If the small sub-basins of
sea level