CARBONATE FACIES OF THE DEEP-WATER TOLEDO FORMATION OF THE BELIZE BASIN, SOUTHERN BELIZE, CENTRAL AMERICA

The Toledo formation in the Belize Basin is an informal Paleogene unit consisting of interbedded sandstone-mudstone, sandstones, conglomerates, and limestones, which are exposed in southern Belize. We examined the petrology and syndepositional environments of the carbonates in the Toledo formation, which have relatively minor occurrences. The tan to buff carbonates within the Toledo formation are generally tabular and laterally extensive with thicknesses of 0.20 to 2.5 m and occur within sequences of thin interbedded sandstone-mudstone units. Two major facies are identified: a carbonate breccia and wackestone/packstone. The carbonate breccia is clast-supported and shows reverse and normal grading. The base of the unit is marked by a 0.47 m thick carbonate gravel bed with fossil fragments and chert. The main breccia is 2.34 m thick and is dominated by cobble- to boulder-size clasts of limestone with some sandstone/mudstone rip-up clasts. This main breccia grades into a 0.19 m thick skeletal wackestone-packstone. The wackestone-packstone facies displays vertical burrows close to bases. Skeletal grains are generally abundant and consist of an open-marine assemblage of crinoids and echinoids and a restricted marine assemblage of gastropods, foraminifera, and algae. Non-skeletal grains are generally rare to common and consist of oöids, peloids, and terrigenous grains. Cementation and porosity occlusion are the main carbonate diagenetic features present. The patterns of cementation are consistent with marine phreatic and meteoric phreatic zones.