Karst-Determined Facies Patterns in British Honduras: Holocene Carbonate Sedimentation Model

Abstract

The distribution of Holocene sediment types on the British Honduras shelf is correlated broadly with bathymetry as a result of the modifications in water circulation and turbulence imposed by bathymetric relief. Subsurface information demonstrates that this relief has been inherited in large part from an underlying, pre-Holocene limestone erosion surface. On the northern shelf the relatively subdued pre-Holocene relief is symptomatic of temperate or doline karst; on the southern shelf the considerable relief on the same surface is suggestive of tropical or conical karst. This difference in offshore-relief expression is consistent with parallel changes in the mainland limestone topography and with differences in the presumably causal factor of rainfall distribution. In both karst regimes, however, solution morphology has been directed in its expression by underlying structure. Significantly, Holocene carbonate sedimentation has accentuated the drowned topographic relief through an accelerated rate of carbonate deposition on the highs. Thus the climatically and structurally determined variations in karst topography not only control the distribution of Holocene sediments but also their three-dimensional geometry. The same relation should apply to the geologic record.