NAME

      backtracker - Forward and Backward flowlines and hotspot tracks


SYNOPSIS

      backtracker [infile(s)] -Estage_file [ -Df|b ] [ -H[nrec] ] [ -Lf|tstep
      ] [ -Nupper_age ] [ -Tzero_age ] [ -V ] [ -: ] [ -bi[s][n] ] [ -bo[s] ]


DESCRIPTION

      backtracker reads (longitude, latitude, age) positions from infiles
      [or standard input] and computes projected (x,y,t) coordinates using
      the specified stage pole (Euler) rotations.  You can either calculate
      just final positions [Default] or create a sampled track between
      initial and final position.  The former mode allows additional data
      fields after the first 3 columns which must have
      (longitude,latitude,age).  See option -: on how to read
      (latitude,longitude,age) files.
           No space between the option flag and the associated arguments.
      Use upper case for the option flags and lower case for modifiers.

      infile(s)
           Data file(s) to be projected.  If not given, standard input is
           read.

      -E   Give file with stage poles and opening angles.  This file must
           contain one record for each stage; each record must be of the
           following format:

                lon lat tstart tstop ccw-angle

           where time is in Ma and the rest is in degrees.  Oldest stage
           must be listed first.  tstart is the time when the stage begins
           (oldest age).  Blank lines and records whose first column
           contains # will be ignored.


OPTIONS

      -D   Set the direction to go: -Df will go forward in time, while -Db
           will go backward in time [Default].

      -H   Input file(s) has Header record(s).  Number of header records can
           be changed by editing your .gmtdefaults file.  If used, GMT
           default is 1 header record.

      -L   Specify a sampled path between initial and final position: -Lf
           will draw flowlines, while -Lb will draw backtrack (hotspot
           track) paths.  Append sampling interval in km.

      -N   Set the maximum age to extend the oldest stage back in time [no
           extension].

      -T   Set the current time [0 Ma].

      -V   Selects verbose mode, which will send progress reports to stderr
           [Default runs "silently"].

      -:   Toggles between (longitude,latitude) and (latitude,longitude)
           input/output.  [Default is (longitude,latitude)].

      -bi  Selects binary input.  Append s for single precision [Default is
           double].  Append n for the number of columns in the binary
           file(s).  [Default is 3 input columns]

      -bo  Selects binary output.  Append s for single precision [Default is
           double].


EXAMPLES

      To backtrack the (x,y,t) points in the file seamounts.d to their
      origin (presumably the hotspot), using the DC85.d Euler poles, run

      backtracker seamounts.d -Db -EDC85.d > newpos.d

      To project flowlines forward from the (x,y,t) points stored in several
      3-column, binary, double precision files, run

      backtracker points.* -Df -EDC85.d -Lf25 -bo -bi3 > lines.b
      This file can then be plotted with psxy -M.


SEE ALSO

      gmt, project, mapproject, hotspotter


REFERENCES

      Wessel, P., 1999, "Hotspotting" tools released, EOS Trans. AGU, 80
      (??), p. ??.





















Man(1) output converted with man2html