geostats (version 1.6)

stereonet: stereonet

Description

Plots directional data on a Wulff or Schmidt stereonet. The Wulff equal angle polar Lambert projection preserves the shape of objects and is often used to visualise structural data. The Schmidt equal area polar Lambert projection preserves the size of objects and is more popular in mineralogy.

Usage

stereonet(
  trd,
  plg,
  coneAngle = rep(10, length(trd)),
  option = 1,
  wulff = TRUE,
  add = FALSE,
  degrees = FALSE,
  show.grid = TRUE,
  grid.col = "grey50",
  tl = 0.05,
  type = "p",
  labels = 1:length(trd),
  pch = 21,
  bg = c("black", "white"),
  lty = c(1, 2),
  ...
)

Arguments

trd

trend angle, in degrees, between 0 and 360 (if degrees=TRUE) or between 0 and \(2\pi\) (if degrees=FALSE).

plg

plunge angle, in degrees, between 0 and 90 (if degrees=TRUE) or between 0 and \(2\pi\) (if degrees=FALSE).

coneAngle

if option=4, controls the radius of a small circle around the pole with azimuth trd and dip plg.

option

scalar. If option=1 or option=4, then trd is the azimuth and plg is the dip; if option=2, then trd is the strike and plg is the dip; if option=3, then trd is the longitude and plg is the latitude.

wulff

logical. If FALSE, produces a Schmidt net.

add

logical. If TRUE, adds to an existing stereonet.

degrees

logical. If FALSE, assumes that azimuth and dip are in radians.

show.grid

logical. If TRUE, decorates the plot with a grid of great and small circles.

grid.col

colour of the grid.

tl

tick length for the N, E, S, W markers (value between 0 and 1). Set to 0 to omit the markers.

type

if option=1 or 3, coordinates can be visualsed as points (type='p'), lines (type='l') or decorated with text labels (type='t').

labels

if option=1 or 3 and type='t', specifies the text labels to be used to mark the measurements on the stereonet.

pch

plot character: see `points'.

bg

background colours of the plot characters. Vector of two colours, which are used to mark points that plot below and above the projection plane of the stereonet, respectively. Only relevant if pch falls in the range from 21:25.

lty

line type. Vector of two numbers, which are used to plot lines below and above the projection plane of the stereonet, respectively.

...

optional arguments to be passed on to the generic points function

Author

based on a MATLAB script written by Nestor Cardozo.

References

Allmendinger, R.W., Cardozo, N., and Fisher, D.M. ``Structural geology algorithms: Vectors and tensors''. Cambridge University Press, 2011.

Examples

stereonet(trd=c(120,80),plg=c(10,30),degrees=TRUE,pch=16)
stereonet(trd=c(120,80),plg=c(10,30),degrees=TRUE,
          option=4,coneAngle=c(5,10),add=TRUE)