Micritized skeletal grains in northern Belize Lagoon: a major source of Mg-calcite mud

Lime mud in northern Belize lagoon is composed predominantly of silt-size cryptocrystalline grains and clay-size clumps, both of which consist of anhedral, equant crystals less than 0.5 μm in size. This mud is 70-90% Mg-calcite containing 9-10 mole % MgCO₃. Detailed petrographic, morphologic and mineralogic analyses suggest that the cryptocrystalline grains are micritized skeletal grains and that the mud formed by abrasion and bioerosion of these altered grains. The abundance of cryptocrystalline grains in the Bahamas and other shallow carbonate environments suggests that micritized grains are potentially an important source of lime mud that has not previously been identified. -from Authors