WATERFALL TUFAS AND CARBONATE GROWTH ON JUTE SNAILS (PACHYCHILIS) AT CHECHEM HA CAVE (BELIZE, CENTRAL AMERICA)

Chechem Ha Cave (Cayo District, Western Belize) exhibits thick accumulations of waterfall tufa along emergent stream escarpments and layered calcite growth on living and recently dead Pachychilus “jute” snails. The geology of the region consists predominantly of steeply dipping Santa Rosa metasedimentary slate and phyllite (Late Pz) unconformably overlain by Cobban-Barton Creek carbonates (K) with well-developed karst. The emergent stream erodes through these carbonates becoming supersaturated with carbonate and producing stepped temporary base level waterfalls. Chechem Ha water fall is over 60m high with additional small (up to 1m) stepped escarpments continuing down the Vaca Escarpment. Water chemistry parameters were surveyed at twenty locations over a 150m stream reach from above the falls and over the falls. Water samples were analyzed for pH using a bench-top electrode and a photometer and calcium ion concentration using a photometer. Results indicate a distinct correlation between pH levels and calcium ion concentration. Each escarpment displayed a sharp rise in pH and a steep drop in calcium ion concentration. Chechem Ha waterfall has highly banded travertine accumulations several meters thick and displays the greatest increase in pH and drop in calcium ion concentration. Jute snails above and below the waterfall exhibit carbonate growth 3 to 5 times the thickness of the shell. Layered waterfall tufa and carbonate overgrowths on modern and Mayan jute snails may preserve a geochemical signature that could offer insights into seasonal rainfall and climate change in Western Belize and the decline of the Maya.