strata-class {SDAR}

Class "strata"

Description

The SDAR package introduces a new S4 object class called strata to define the representation of stratigraphy and sedimentological data. This S4 class gives a rigorous definition of a stratigraphy object; a valid object of this S4 class must meet all the requirements specified in the class definition (e.g., the names of the columns must be called: bed_number, base, top, rock_type, prim_litho, and grain_size. Also, the base and top must be numeric). This class automatically validates the inputted dataset and returns a stratigraphy class object.

Usage

strata(x, datum="top")

Arguments

x

an object (e.g, data.frame) with stratigraphic and sedimentological information to be validated; in the Slots section below, see the requirements of this class.

datum

string; either 'base' or 'top', case sensitive. 'base' is the case when thickness is measured up from the bottom of, e.g., an outcrop section; 'top' is the case when depths are measured down from the surface, e.g., boreholes and cores.

Objects from the Class

Objects of this class represents basic stratigraphic and sedimentological information for the standardization and construction of a comprehensive graphic log (Johnson, 1992).

Slots

.Data:

object of class data.frame, which holds the minimum required data to draw a lithological profile in SDAR.
bed_number: numeric; it is useful to give a unique index to each bed/layer to facilitate later reference; numbering should begin at the stratigraphically lowest bed.
base: numeric; stratigraphic position measured at the bottom of the layer.
top: numeric; stratigraphic position measured at the top of the layer. Base and top defines the thickness of each bed/layer, overlapping between layers is not allowed.
rock_type: string; must include only one of these values: sedimentary, volcaniclastic or covered.
prim_litho: string; description of the primary (i.e., predominant) lithology; must include only one of the values listed in table 2 (see Primary lithology in vignettes). (e.g., claystone, siltstone, mudstone, shale, sandstone, conglomerate), more lithology patterns will be provided at next SDAR version.
grain_size: string; description of the grain size dominant in the layer; must include only one of the values listed in table 3 (see Grain size in vignettes). (e.g., clay, silt; very fine sand, fine sand, medium sand, coarse sand, and very coarse sand). 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), and it is represented by the width of the lithological profile (x-axis) (Miall 1999, Fig. 2.25). In graphic logs generated by SDAR, grain size is indicated by the graphic scale at the header of the lithological profile.

Extends

Class "data.frame", directly.
Class "list", by class "data.frame", distance 2.

Methods

plot

signature(object = "strata")

summary

signature(object = "strata")

Author(s)

John Ortiz

References

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

Miall, A.D., 1999. Principles of Sedimentary Basin Analysis, third edition, Springer, New York, 616 pp.

Johnson, M.R. 1992. A proposed format for general-purpose comprehensive graphic logs. Sedimentary Geology, Volume 81, Issues 3-4, Pages 289-298, ISSN 0037-0738.
https://www.sciencedirect.com/science/article/pii/0037073892900764

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)
saltarin_val <- strata(saltarin_beds, datum="top")
class(saltarin_val)