saltarin_beds {SDAR}

Lithological description of borehole SaltarinST-1A
dataset (beds/layers)

Description

This dataset gives a lithologic description for borehole Saltarin 1A, located in the Llanos Basin in eastern Colombia (4.612 N, 70.495 W). The stratigraphic well Saltarin 1A drilled 671 meters of the Miocene succession of the eastern Llanos basin, corresponding to the Carbonera (124.1 m; 407.1 ft), Leon (105.1 m; 344.8 ft), and Guayabo Formations (441.8 m; 1449.5 ft) (Bayona, et al. 2008). The Saltarin core was described at a scale of 1:50 for identification of grain-size trends, sedimentary structures, clast composition, thickness of lamination, bioturbation patterns, and macrofossil identification, all of which are used for identify individual lithofacies and for sedimentological and stratigraphic analyses.

Usage

data(saltarin_beds)

Format

The Saltarin dataset provided by this package is a dataset comprising the lithological description of 686 rock layers described along of 671 meters of the Saltarin 1A borehole; it is a data.frame object with 686 layers (rows), including thickness, composition and texture description of each layer, stored following the suggested format by SDAR (22 columns).

bed_number

numeric; it is useful to give each bed/layer a number to facilitate later reference; numbering begins at the stratigraphically lowest bed (Tucker 2011)

base

numeric; stratigraphic position measured at the bottom of each layer, in meters.

top

numeric; stratigraphic position measured at the top of each layer, in meters.

rock_type

string; rock type class following this clasification: sedimentary, volcaniclastic, or covered.

prim_litho

string; description of the primary (i.e. major) lithology class, (e.g., claystone, mudstone, siltstone, shale, sandstone, conglomerate, breccia, limestone, coal).

grain_size

string; description of the grain size dominant in layer. For siliciclastic rocks, it is based on the Wentworth (1922) classification system, for carbonate rocks it is based on Dunham (1962), and for classification of pyroclastic rocks it is based on Wentworth and Williams (1932). (e.g., clay, silt; very fine sand, fine sand, medium sand, coarse sand, and very coarse sand); see all the grain-size options in table 3 at SDAR data model vignettes.

prim_litho_percent

numeric; percent of primary lithology.

sec_litho

string; using same categories described for prim_litho.

grain_size_sec_litho

string; description of the grain size for the secondary lithology in layer; using same categories described for grain_size

sec_litho_percent

numeric; percent of secondary lithology.

base_contact

string; description of the boundary at the base of the layer (geological contact): sharp planar, gradational, faulted, covered.

grading

string; description of the vertical variations in grain size; normal (beds that show gradation from coarser particles at the base to finer particles at the top), inverse (reverse or inverse grading, gradation from finer at the base to coarser at the top), (Boggs, 2011).

grain_size_base

string; grain size at the base of the layer using same categories described for grain_size.

grain_size_top

string; grain size at the top of the layer using same categories described for grain_size.

sorting

string; description of the degree of uniformity of grain size: very well sorted, well sorted, moderately sorted, poorly sorted, very poorly sorted.

roundness

string; measurement of roundness of sedimentary particles (Krumbein 1941): very angular, angular, sub angular, sub rounded, rounded, well rounded.

matrix

string; composition of material wherein larger grains, crystals or clasts are embedded: muddy, sandy, ashy, micrite, not recognizable.

cement

string; composition of the crystalline material precipitated around the edges of grains: siliceous, ferruginous, calcite, dolomite, kaolinitic, sparite, not recognizable.

fabric

string; grain fabric (packing). For sedimentary rocks: clast supported, matrix supported.

munsell_color

string; color description based on the Munsell chart codes from the Geological Society of America Rock Color Chart (Committee 1991)

Rcolor

string; R colors can be specified either by name (e.g col = "red") or as a hexadecimal RGB triplet (such as col = "#FFCC00").

notes

string; additional description in a free text format ('Comments/Remarks').

Author(s)

Lithological description: Bayona, et al. 2008
Sedimentological and Stratigraphic Interpretation: Bayona, G. and Duarte, E.

Source

Access to the well core was provided by Alejandro Mora and Andres Fajardo of HOCOL S.A. (core description: 2007)

References

Bayona, G., Valencia, A., Mora, A., Rueda, M., Ortiz, J., Montenegro, O. 2008. Estratigrafia y procedencia de las rocas del Mioceno en la parte distal de la cuenca antepais de los Llanos de Colombia. Geologia Colombiana, 33, 23-46.

Bogs, S. 2011. Principles of Sedimentology and Stratigraphy. Prentice Hall, fifth edition.

Dunham, R. 1962. American Association of Petroleum Geologists Memoir. Classification of carbonate rocks according to depositional texture. In Ham, W.E. Classification of carbonate rocks, 1, 108-121

Krumbein, W. C. 1941. The effects of abrasion on the size, shape and roundness of rock fragments. The Journal of Geology 49(5), 482-520.

Munsell Geological Rock-Color Chart With Genuine Munsell Color Chips. Munsell Color, 2009.

Tucker, M. E. 2011. Sedimentary Rocks in the Field: A Practical Guide. Geological Field Guide. Wiley

Wentworth, C. K. 1922. A scale of grade and class terms for clastic sediments. Journal of Geology, 30, 377-392.

Wentworth, C. K. and Williams, H. 1932. Classification and terminology of pyroclastic rocks. National Research Council Bulletin, 89, 19-53.

Examples

data(saltarin_beds)
names(saltarin_beds)