--> Abstract: Past High Sea-Stands and Platform Stability: Evidence from Conch Bar Cave, Middle Caicos, by Peter Smart, Gina Moseley, David Richards, and Fiona Whitaker; #90078 (2008)

Datapages, Inc.Print this page

Past High Sea-Stands and Platform Stability: Evidence from Conch Bar Cave, Middle Caicos

Peter Smart1, Gina Moseley1, David Richards1, and Fiona Whitaker2
1Geography, University of Bristol, Bristol, United Kingdom
2Earth Sciences, University of Bristol, Bristol, United Kingdom

Conch Bar Cave comprises a series of large phreatic chambers open to the surface along the southern margin of an aeolianite ridge. From these phreatic passages run to terminate abruptly in the interior of the ridge, continuing in most cases only as cm sized tubes. The simplest passages are elliptical tubes, with relatively horizontal floors and ceilings punctuated by domes. Most passage sections are more complex, with remnants of former roof and floor levels. Some of these are bedding concordant and lithologically controlled. But overall, there are strong modes present in the passage ceiling elevations, which suggest they indicate past positions of the formative mixing zone or water table. The highest level present in the cave is more than 17 m above present sea level, and suggests either that there has been uplift of the platform, or that past sea levels have been above this elevation. The eastern parts of the cave show submergence, whilst the western parts are dry. This suggests that there may have been tilting of the platform to the east, also the direction of the open platform margin.

Despite the size and antiquity of the cave (>195 ka U series date on speleothem at sea level), its preservation potential in the geological record is low. The cave has been intercepted by surface lowering and back wasting of the ridge, and the low mechanical strength of poorly cemented carbonates limits roof stability. Such caves may therefore be only rarely preserved as paleokarst cavities, more normally being represented by residual cliffed embayments and breccia bodies, if at all. Under ice house conditions with frequent sea level changes, it is unlikely that any clear association between past sea level still-stands and cave or enhanced porosity zones could be established from the rock record.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas