Geology Reference
In-Depth Information
identifying the correct forcing mechanism. Third,
shallowing-upward facies successions similar
to those found at Mendola Pass can be found in
Florida Bay, the Bahamas and, to an extent, in
the Persian Gulf. By comparing the rates at which
these deposits form in modern environments, one
may better understand average cycle durations for
similar deposits in the geological past.
Recent publications offer new insights into
sea-level change during the past 20 kyr. Two com-
pilations are provided here. Table 1 summarises
Pleistocene and Holocene cyclic climatic pro-
cesses operating at sub-Milankovitch periodicit-
ies. While many types of variations are listed,
not every process is tied (observationally or oth-
erwise) to metre-scale sea-level change at these
periodicities, and none are tied to the forma-
tion of shallowing-upward depositional cycles
in modern marine carbonate sedimentary set-
tings. Table 2 compiles literature involving the
dating of Pleistocene and Holocene carbonate
shallowing-upward successions. This suggests
that in most cases, the sediments making up the
Holocene carbonate successions, most of which
are not yet complete shallowing-upward cycles,
formed over the past 5-7 kyr as the result of a
longer-term sea-level rise over the past 10-20 kyr.
While a few examples of dated shallowing-
upward facies successions from modern environ-
ments appear to have formed within the past
1000 years (see Strasser & Samankassou, 2003),
dating and analyses of Holocene and Pleistocene
carbonate successions from around the world have
not yet produced a correlatable stack of metre-
scale shallowing-upward carbonate depositional
cycles with millennial (1-2 kyr) periodicity.
Holocene and Pleistocene 'icehouse' condi-
tions, so-called because of the presence of major
land-locked ice sheets, store and release large
amounts of seawater, and allow for high-frequency
Table 1.
Compilation of dated modern and recent cyclic climatic processes and behaviours with millennial
periodicities.
Study
Cycle type
Cycle period
Roth and Reijmer (2005)
Oxygen isotope excursions in a 30 m-long core
from the leeward margin of the Great Bahama
Bank related to aragonite content
Multi-millenial
1.725 kyr
0.54 kyr
Niggemann
et al
. (2003)
Oxygen isotope excursions in 61-cm stalagmite
c
. 1.450 kyr
Bond
et al
. (1993, 1997, 2001)
Oxygen isotope excursions and ice-rafted
sediment cycles
1.5 kyr DO cycle
5-6 kyr Bond cycle
Munk
et al
. (2001)
Tidal forcing - Millennial Scale
1.795 kyr
van de Plassche
et al.
(1998)
Mean high water marks from Hammock River
marsh, Clinton, Connecticut, USA
Century scale
Table 2.
Compilation of dates of modern carbonate shallowing-upward (SU) facies successions. Most have not yet fi lled
accommodation and none of these examples exhibit stacking of shallowing-upward facies successions at millennial
periodicities.
Age of most recent SU
succession
Study
Locality
Depositional cycle type
Strasser and
Samankassou (2003)
Florida Bay, Bahamas,
Bermuda
Variable, Shoaling, tidal fl at, and
subtidal facies successions
Variable oldest 5630 BP
youngest 680 BP
Gischler (2003)
Belize platforms
Variable, Reefal, Shoaling and
subtidal facies successions
4.5 kyr
Parkinson (1989)
Southwest coast of Florida
T-R cycle, capped by red
mangrove peat
c
. 7 kyr
Tudhope (1989)
Davies Reef, central Great
Barrier Reef complex
Shallowing-up from: gravel lag;
bioturbated muddy sand; shoal
or exposure cap
Mid-cycle sediments dated
at
c
. 3 kyr. Actual cycle
must be older
Logan
et al
. (1969)
Shark Bay, Western
Australia
Shallowing-up from: grainstone;
skel. M/W; laminite cap
c
. 5 kyr
Taft
et al
. (1968)
New Providence Platform,
Bahamas
Coarsening-up from mud; skel.
P/G; grapestone GS
6.7 kyr
Note
: SU, shallowing upward; T-R, transgressive-regressive; M/W, mudstone/wackestone; P/G, packstone/grainstone; GS, grainstone.
