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sea-level oscillations with amplitudes of several
tens of metres. As an example, dating of coral
reef terraces in Barbados by Bloom
et al
. (1974)
suggests that six major sea-level oscillations
have occurred over the past 130 kyr, with
amplitudes of 20-100 m (Bloom
et al
., 1974;
Chappell & Shackleton, 1986). Shallow-marine
carbonate cycles produced by sea-level oscilla-
tions of these magnitudes are also comparably
thicker than those found in the Alpine Triassic
(Goldhammer
et al
., 1990). Pleistocene depo-
sitional cycles identifi ed in Florida and the
Bahamas are of the order of 5-15 m thick, and con-
sist of subtidal carbonate capped by laterally cor-
relative red soil crusts (Goldhammer & Kaufman,
1995). Both modern carbonate shallowing-upward
successions as well as the record of Pleistocene
and Holocene sea-level oscillations operate at
cyclic frequencies that are in tune with known
orbital periodicities (Table 2; Logan
et al
., 1969;
Bloom
et al
., 1974; Tudhope, 1989; Parkinson,
1989; Goldhammer & Kaufman, 1995; Strasser &
Samankassou, 2003).
The Early to Mid-Triassic is generally con-
sidered to have been a period of greenhouse
(or possibly transitional icehouse-greenhouse)
climate, lacking major continental ice sheets, and
is therefore thought to have been characterized by
comparably low-amplitude (10 m or less), high-
frequency sea-level oscillations (Vail
et al
., 1977;
Goldhammer
et al
., 1990; Wright, 1992; Read,
1995). Consequently, shallowing-upward depo-
sitional cycles are relatively thin (1-2 m), but in
many cases still form stacks that seem to refl ect
orbitally driven composite eustasy. Many workers
have suggested that Triassic depositional cycles
formed as the result of Milankovitch-band high-
frequency-low-amplitude eustatic oscillations
related to rhythmic orbital perturbations that
affected the spatial and temporal distribution of
solar energy at the Earth's surface (Fischer, 1964;
Schwarzacher, 1975, 1993, 2005; Goldhammer
et al
., 1990; Goldhammer & Kaufman, 1995; Yang &
Lehrmann, 2003; Maurer
et al
., 2004; Zühlke,
2004; Cozzi
et al
., 2005).
The geo-climatic conditions of the Holocene
and Pleistocene stand in contrast to those of the
Early to Mid-Triassic. However, observations
from modern sediments suggest that cyclic cli-
matic perturbations with millennial periodicit-
ies are not being recorded as shallowing-upward
carbonate depositional allocycles, even in areas
where carbonate sediments have infi lled avail-
able accommodation space (e.g. tidal fl ats of
Andros Island). Instead, most shallowing-upward
facies successions dated from the Holocene and
Pleistocene seem to have formed with period-
icities that are commensurate with Milankovitch
and/or other multimillennial processes. It is cer-
tainly possible that the processes driving Triassic
depositional cycles were unique to that period
of geological time and that comparison between
modern and ancient records is not warranted.
However, the presence of Triassic allocycles that
have an apparent statistical profi le that is consist-
ent with Milankovitch orbital parameters, a link
that is temporally justifi ed through comparative
rate studies of Holocene facies successions, leaves
two main options regarding their origin discussed
in the following sections.
The successions of carbonate depositional cycles
at Latemar and Mendola Pass sections record
periodic, allogenic processes directly linked to
Milankovitch cycle driven composite eustasy
The case for Milankovitch cycle driven compos-
ite eustasy forcing the deposition of either fun-
damental cycles and/or megacycles at Latemar
and Mendola Pass sections is substantial, and is
based on extensive sedimentological and statis-
tical analyses. While the two main models sup-
porting the presence of Milankovitch composite
eustasy involve different timescales (see Fig. 1),
both studies strongly argue for the presence of
multimillennial astroclimatic forcing in the devel-
opment of carbonate depositional cycles. Here, it
is recognized that both the models of Goldhammer
et al
. (1987) and Zühlke
et al
. (2003) argue that
the development of Latemar cyclicity is linked to
orbital forcing.
From a comparative sedimentological stand-
point, Latemar and Mendola cyclic stratigraphy
agrees with known parameters of Milankovitch
band driven sedimentation. Dating of shallow-
ing-upward successions from modern carbonate
settings indicates that most have formed (most
of which are not yet complete 'cycles') over the
past 5-7 kyr in response to Holocene sea-level rise
(Table 2). The fact that many platforms have not yet
aggraded to sea level and/or formed exposure caps
suggests that the periodicity associated with the
cyclic driver is longer than the time in which the
depositional cycle actually forms. Additionally,
sea-level oscillations inferred from coral reefs
and deep-sea sediments confi rm that fi ve oscil-
lations with amplitudes of 20-100 m occurred
over the past 100 kyr (Broecker
et al
., 1968; Bloom
