backtracker

       backtracker  -  Forward and Backward flowlines and hotspot
       tracks

SYNOPSIS

       backtracker [infile(s)] -Estage_file [ -A[young/old]  ]  [
       -C  ] [ -Df|b ] [ -H[nrec] ] [ -Lf|tstep ] [ -Nupper_age ]
       [ -Sfilestem ] [ -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 (longi­
       tude,latitude,age).  See option -: on how to  read  (lati­
       tude,longitude,age) files.
               No  space  between the option flag and the associ­
       ated arguments. Use upper case for the  option  flags  and
       lower case for modifiers.

       infile(s)
              Data  file(s)  to be projected. If not given, stan­
              dard 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

       -A     Used in conjunction with -Lb|f to limit  the  track
              output  to  those sections whose predicted ages fit
              between the young and old limits. If -LB|F is  used
              instead  then the limits apply to the stage ids. If
              no limits are supplied then individual  limits  for
              each  seamount  are  expected  in  the input file's
              columns 4 and 5.'

       -C     Expect Total Reconstruction  Poles  (Finite  Poles)
              rather  than  Backward  Stage  Poles [Default] File
              format is similar to the stage pole  format  except
              the youngest rotation must be listed first and that
              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 .gmt­
              defaults  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  sam­
              pling  interval in km. When -LF or -LB is used, the
              third output column will contain the stage id (1 is
              youngest) [Default is along-track ages].

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

       -S     When -L is set, the tracks are normally written  to
              stdout  as  a multisegment file. Specify a filestem
              to have each track written to filestem.#,  where  #
              is  the  track  number.  The  track  number is also
              copied to the 4th output column.

       -T     Set the current time [Default is 0 Ma].

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

       -:     Toggles  between  (longitude,latitude)  and  (lati­
              tude,longitude) input/output. [Default  is  (longi­
              tude,latitude)].  Applies to geographic coordinates
              only.

       -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 preci­
              sion [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

SEE ALSO

       gmt(l),  project(l), mapproject(l), hotspotter(l) origina­
       tor(l)

REFERENCES

       Wessel, P., 1999, "Hotspotting" tools released, EOS Trans.
       AGU, 80 (29), p. 319.