Where: Huila, Colombia (3.3° N, 75.2° W: paleocoordinates 2.6° N, 72.4° W)
• coordinate based on nearby landmark
• local area-level geographic resolution
When: Honda Group, Middle Miocene (16.0 - 11.6 Ma)
• Cerbatana Gravels and Clays
Environment/lithology: fluvial; lithified conglomerate and lithified claystone
•They occur sporadically through the section and show no definite evidence of gradational change. However, at the base of each of the five mapped lenses there is a basal concretionary sandstone.
•The conglomerates (pl. 37, a, b) are light-brown to brick-red. The darker colors usually correlate with larger detrital materials and are most abundant near the top of the unit. Individual beds vary from less than 1 meter to more than 10 meters in thickness. Most of the conglomerates in the basal part of the unit are pebble gravels, the fragments becoming progressively larger toward the top of the section, until in the beds immediately below the Monkey Unit the conglomerates are composed of large-cobble gravels. These gravels and conglomerates form prominent cliffs throughout the area and produce the headlands of many of the drainage patterns in the region. Sandstones in the Cerbatana unit are lenticular. Most of the lenses measure a few meters across (pi. 37, a), but a few can be traced for more than a kilometer. These larger masses show extensive cross-bedding of both diagonal and convex type, and are coarse- to fine-grained. Subangular to subrounded quartz makes up about 80 per cent of the mineral composition; feldspar, hornblende, micas, and metallic minerals are accessories. The sands are firmly packed but contain little or no calcareous cement. Near the base of the lenses, pebbles become more abundant and are usually oriented along the bedding planes. Finally, at the base, the sandstones grade into pebble gravels. Conversely, the upper parts of most of these strata contain thin silt and mudstone lenses and some have a concretionary upper surface (pl. 37, c; pl. 38 o,6). The interbedded clays and siltstones of the Cerbatana Gravels are more or less alike in color and mineral content. Beds vary from 10 or 15 centimeters up to about 2 meters in thickness. Rounded quartz grains make up 70 or 80 per cent of the identifiable mineral fraction. Amphiboles and metallic minerals account for the remaining determinable percentages. These sediments are relatively well indurated but weather quickly to form extensive badlands. Thin sandy beds are usually present in the siltstones. Thickness and lateral extent of the five mapped clay lenses are quite variable (fig. 2, secs. F-J). The richly fossiliferous San Nicolas Clays compose the thickest and most extensive lens within the Cerbatana unit. For the most part these clays are much like the other siltstone and mudstone lenses in the gravels. The lower part of the clays is sandy and rests upon a sandstone displaying large rounded concretions (pl. 37, c). The upper levels are progressively more silty and grade into clay near the top. The upper limit is marked by a massive, cross-bedded buff sandstone. Silt and clay beds in the San Nicolas Clays average about 25 centimeters in thickness." Description lithology taken from Fields (1959)
Size class: macrofossils
Collected by Fields
Primary reference: P. Bondesio and R. Pascual. 1977. Restos de Lepidosirenidae (Osteichthyes, Dipnoi) del Grupo Honda (Mioceno Tardío) de Colombia. Sus denotaciones paleoambientales. Asociación Geológica Argentina 17(1):34-43 [A. Cardenas /L. Mora-Rojas]more details
Purpose of describing collection: taxonomic analysis
PaleoDB collection 186805: authorized by Andrés Cárdenas, entered by Laura Mora-Rojas on 04.07.2017
Creative Commons license: CC BY (attribution)
Taxonomic list
Osteichthyes | |
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