2003; Gischler, 2006b). Holocene reef lagoon development is ideally characterized by a succession of Pleistocene
bedrock, dark soil, mangrove peat, shell bed (coquina),
Halimeda-rich packstone, and mollusk-Halimeda-foramrich wackestone and packstone, from bottom to top
(Gischler, 2003). This succession is an expression of
Holocene inundation by the rising sea and subsequent
deepening. There is an ongoing controversy regarding
the nature of the reef foundations. Based on coring, the
basement of Holocene reefs on the offshore atolls and
the barrier reef is Pleistocene limestone. Ferro et al.
(1999) suggested that parts of the barrier reef platform
were underlain by prograding siliciclastics, based on seismic investigations. The increase in reef thickness from
north to south is thought to be an expression of both an
increase in karst dissolution during Pleistocene sea-level
lowstands and stronger subsidence in the same direction
(Purdy, 1974; Gischler and Hudson, 2004). Holocene reefs
on the Belize shelf are located both over Pleistocene limestone and siliciclastics (Purdy, 1974; Choi and Ginsburg,
1982). The former position of channel and river bars as
well as incised valleys apparently was decisive for shaping
antecedent topography and Holocene reef initiation (Esker
et al., 1998; Ferro et al., 1999). Indeed, the rhomboid
shape of some of the shelf reefs is reminescent of channel
bars. In addition, Lara (1993) and Purdy (1998) showed
that faulting and folding was of importance for the formation of topographic highs and the subsequent initiation of
reefs on the southern Belize shelf and southern barrier reef,
respectively.
Summary
The Belize reef system includes fringing, barrier, and
atolls reefs as well as lagoonal patch reefs and lagoon
atolls (faroes). The reefs, which are predominantly composed of corals (Acropora sp., Montastraea sp.) exhibit
clear zonations. The Belize shelf is a classic example of
a mixed carbonate–siliciclastic system, like many other
large barrier reefs. Eleven modern sediment facies may
be distinguished. The reef system of Belize is located on
a passive continental margin with tilted fault blocks
forming the basement. Both differential subsidence and
variation in karst dissolution of underlying Pleistocene
limestone determined patterns of late Quaternary reef
accretion. Postglacial reef growth was extensive with
thicknesses of >20 m and average accretion rates of
3 m/kyr.
Bibliography
Aronson, R. B., and Precht, W. F., 1997. Stasis, biological disturbance, and community structure of a Holocene coral reef. Paleobiology, 23, 326–346.
Choi, D. R., and Ginsburg, R. N., 1982. Siliciclastic foundations of
Quaternary reefs in the southernmost Belize lagoon, British
Honduras. Geological Society of America Bulletin, 93, 116–126.
Droxler, A., Alley, R. B., Howard, W. R., Poore, R. Z., and Burckle,
L. H., 2003. Unique and exceptionally long interglacial isotope
stage 11: window into earth warm future climate. Geophysical
Monograph, 137, 1–14.
Esker, D., Eberli, G. P., and McNeill, D. F., 1998. The structural and
sedimentological controls on the reoccupation of Quaternary
Belize Barrier and Atoll Reefs, Figure 7 Late Quaternary cores taken along Belize Barrier Reef, from north to south (from Gischler,
2008).
BELIZE BARRIER AND ATOLL REEFS
117
bedrock, dark soil, mangrove peat, shell bed (coquina),
Halimeda-rich packstone, and mollusk-Halimeda-foramrich wackestone and packstone, from bottom to top
(Gischler, 2003). This succession is an expression of
Holocene inundation by the rising sea and subsequent
deepening. There is an ongoing controversy regarding
the nature of the reef foundations. Based on coring, the
basement of Holocene reefs on the offshore atolls and
the barrier reef is Pleistocene limestone. Ferro et al.
(1999) suggested that parts of the barrier reef platform
were underlain by prograding siliciclastics, based on seismic investigations. The increase in reef thickness from
north to south is thought to be an expression of both an
increase in karst dissolution during Pleistocene sea-level
lowstands and stronger subsidence in the same direction
(Purdy, 1974; Gischler and Hudson, 2004). Holocene reefs
on the Belize shelf are located both over Pleistocene limestone and siliciclastics (Purdy, 1974; Choi and Ginsburg,
1982). The former position of channel and river bars as
well as incised valleys apparently was decisive for shaping
antecedent topography and Holocene reef initiation (Esker
et al., 1998; Ferro et al., 1999). Indeed, the rhomboid
shape of some of the shelf reefs is reminescent of channel
bars. In addition, Lara (1993) and Purdy (1998) showed
that faulting and folding was of importance for the formation of topographic highs and the subsequent initiation of
reefs on the southern Belize shelf and southern barrier reef,
respectively.
Summary
The Belize reef system includes fringing, barrier, and
atolls reefs as well as lagoonal patch reefs and lagoon
atolls (faroes). The reefs, which are predominantly composed of corals (Acropora sp., Montastraea sp.) exhibit
clear zonations. The Belize shelf is a classic example of
a mixed carbonate–siliciclastic system, like many other
large barrier reefs. Eleven modern sediment facies may
be distinguished. The reef system of Belize is located on
a passive continental margin with tilted fault blocks
forming the basement. Both differential subsidence and
variation in karst dissolution of underlying Pleistocene
limestone determined patterns of late Quaternary reef
accretion. Postglacial reef growth was extensive with
thicknesses of >20 m and average accretion rates of
3 m/kyr.
Bibliography
Aronson, R. B., and Precht, W. F., 1997. Stasis, biological disturbance, and community structure of a Holocene coral reef. Paleobiology, 23, 326–346.
Choi, D. R., and Ginsburg, R. N., 1982. Siliciclastic foundations of
Quaternary reefs in the southernmost Belize lagoon, British
Honduras. Geological Society of America Bulletin, 93, 116–126.
Droxler, A., Alley, R. B., Howard, W. R., Poore, R. Z., and Burckle,
L. H., 2003. Unique and exceptionally long interglacial isotope
stage 11: window into earth warm future climate. Geophysical
Monograph, 137, 1–14.
Esker, D., Eberli, G. P., and McNeill, D. F., 1998. The structural and
sedimentological controls on the reoccupation of Quaternary
Belize Barrier and Atoll Reefs, Figure 7 Late Quaternary cores taken along Belize Barrier Reef, from north to south (from Gischler,
2008).
BELIZE BARRIER AND ATOLL REEFS
117