This succession includes dark grey shales of the Sembar Formation, hemi pelagic nodular limestones, marls and shales of the Goru Formation (Shah, 1977) and
biomicrite sand marls of the Parh Limestone.
Allochems were bioclasts (foraminifera test and microshell fragments) embedded in a fine-grained calcite matrix (foram
biomicrite; Figures 2b, c).
Biomicrite is the most characteristic lithol ogy of this facies, showing intense and well developed bacterial and cyanobacterial laminar textures coating the plant remains (Hernandez et al., 1998).
The fossil specimens were collected from a glauconitic
biomicrite bed exposed in the North Sulphur River channel in Fannin County.
The topmost part of the upper Ballysteen Limestone contains lenses of Waulsortian
biomicrite with associated calcarenites and argillites and two tuff horizons also occur.
The textural type recognized in this microfacies is wacke-packstone fabric according to Dunham (1962) and poorly- washed
biomicrite according to Folk (1959).
Biomicrite is the most characteristic lithology of this facies, showing intense and well developed bacterial and cyanobacterial laminar textures coating the plant remains (Hernandez et al., 1998).
The Roxton Limestone is unusual among carbonates, being a fragmental glauconitic
biomicrite with large fragments (indicative of a high energy environment) within a micritic matrix (typical of a low energy situation).
The samples from La Luna Formation (Turonian-Coniacian) were taken from Quebrada La Sorda, Santander, where they are characterized by the dominance of foraminifera
biomicrites with partial silicification, pseudospar and siliciclastic sediments of silt and sand sizes, mainly towards the top of the unit (Sarmiento et al.
In thin section the rocks from either side of the volcanogenic layer are sparse foraminiferal
biomicrites with heterohelicids as the dominant group.