SUBMARINE FAN COMPLEX FACIES OF THE PALEOGENE TOLEDO FORMATION IN SOUTHERN BELIZE

The Toledo formation of Belize is a thick sequence of clastic deep water facies developed within a succession of submarine fan complexes adjacent to the Maya Mountains, along the northern margin of the Belize basin. The Toledo formation ranges in thickness from 100 – 10,000 ft (30 – 3,000 m) and is underlain by the “KT” boundary interval and/or the Upper Cretaceous Campur formation. The Toledo formation crops out over a wide belt in the Toledo District of southern Belize and has been drilled in a small number of exploratory wells. Facies analysis of outcrops has delineated several deep water facies including channel and lobe/inter-channel deposits. Channel deposits are characterized by thick, medium to coarse grained, amalgamated, channelized sandstones, pebbly sandstones, conglomerates and pebbly mudstones and generally exhibits a thinning upward sequence. Lobe/inter-channel deposits are dominated by laterally extensive, interbedded sheet-like sandstone-mudstone beds which develop at or near submarine fan channels. Lobe/inter-channel deposits are generally thickening upward sequences. Localized slumping is common in sandstone-mudstone beds. These sand-rich channel and lobe deposits are interpreted as middle to lower fan (suprafan) environments. Based on calcareous nannofossil biostratigraphy the age of the Toledo formation is middle Paleocene (Selandian). This age postdates the convergence of the North American and Caribbean Plates (Late Cretaceous) and predates tectonic activity in the Motagua fault zone (Eocene).