1ORIGINATOR(1)                         GMT                        ORIGINATOR(1)
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NAME

6       originator - Associate seamounts with nearest hotspot point sources
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SYNOPSIS

9       originator [ tables ]  -E[+]rotfile
10        -F[+]hs_file  [   -Dd_km ] [  -L[flag] ] [  -Nupper_age ] [  -Qr/t ] [
11       -S[n_hs] ] [  -T ] [  -V[level] ] [  -Wmaxdist ] [  -Z ] [ -bibinary  ]
12       [ -dinodata ] [ -eregexp ] [ -hheaders ] [ -iflags ] [ -:[i|o] ]
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14       Note:  No  space  is allowed between the option flag and the associated
15       arguments.
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DESCRIPTION

18       originator reads (longitude,  latitude,  height,  radius,  crustal_age)
19       records  from  tables  [or  standard input] and uses the given Absolute
20       Plate Motion (APM) stage or total reconstruction rotation file and  the
21       list of hotspot locations to determine the most likely origin (hotspot)
22       for each seamount. It does so by calculating flowlines back in time and
23       determining  the  closest approach to all hotspots. The output consists
24       of the input records with four additional fields added for each of  the
25       n_hs  closest hotspots. The four fields are the hotspot id (e.g., HWI),
26       the stage id of the flowline segment that came closest, the  pseudo-age
27       of  the  seamount, and the closest distance to the hotspot (in km). See
28       option  -:  on  how  to  read  (latitude,   longitude,height,   radius,
29       crustal_age) files.
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REQUIRED ARGUMENTS

32       -Erotfile
33              Give  file  with rotation parameters. This file must contain one
34              record for each rotation; each record must be of  the  following
35              format:
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37              lon lat tstart [tstop] angle [ khat a b c d e f g df ]
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39              where  tstart  and  tstop  are  in  Myr and lon lat angle are in
40              degrees. tstart and tstop are the ages of the old and young ends
41              of  a  stage. If tstop is not present in the record then a total
42              reconstruction rotation is expected and tstop is implicitly  set
43              to  0  and should not be specified for any of the records in the
44              file. If a covariance matrix C for the rotation is available  it
45              must  be  specified  in  a  format using the nine optional terms
46              listed in brackets. Here, C = (g/khat)*[ a b d; b c e; d e  f  ]
47              which  shows  C  made up of three row vectors. If the degrees of
48              freedom (df) in fitting the rotation is 0 or not given it is set
49              to  10000. Blank lines and records whose first column contains #
50              will be ignored. You may prepend a leading + to the filename  to
51              indicate  you wish to invert the rotations.  Alternatively, give
52              the filename composed of two plate IDs  separated  by  a  hyphen
53              (e.g.,  PAC-MBL)  and we will instead extract that rotation from
54              the GPlates rotation database. We return an error if  the  rota‐
55              tion  cannot be found. Prepend + if you want to invert the rota‐
56              tions prior to use.
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58       -Ffile Give file with hotspot locations. This  file  must  contain  one
59              record for each hotspot to be considered; each record must be of
60              the following format:
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62              lon lat hs_abbrev hs_id r t_off t_on create fit plot name
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64              E.g., for Hawaii this may look like
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66              205 20 HWI 1 25 0 90 Y Y Y Hawaii
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68              Most applications only need the first 4 columns which thus  rep‐
69              resents  the minimal hotspot information record type. The abbre‐
70              viation may be maximum 3 characters long.  The  id  must  be  an
71              integer  from 1-32. The positional uncertainty of the hotspot is
72              given by r (in km). The t_off and t_on  variables  are  used  to
73              indicate  the  active time-span of the hotspot. The create, fit,
74              and plot indicators are either Y or N and are used by some  pro‐
75              grams  to  indicate  if  the hotspot is included in the ID-grids
76              used to determine rotations, if the hotspot chain will  be  used
77              to determine rotations, and if the hotspot should be included in
78              various plots.  The name is a 32-character maximum  text  string
79              with  the full hotspot name. Blank lines and records whose first
80              column contains # will be ignored. Prepend + if we  should  look
81              for hotspot drift tables whose name must be hs_abbrev_drift.txt.
82              Such files may be located in the  current  directory,  the  same
83              directory  as  hs_file,  or  in  the  directories  pointed to by
84              GMT_DATADIR. If found then we interpolate to get  hotspot  loca‐
85              tion as a function of time [fixed].
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OPTIONAL ARGUMENTS

88       table  One  or  more ASCII (or binary, see -bi[ncols][type]) data table
89              file(s) holding a number of data columns. If no tables are given
90              then we read from standard input.
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92       -Dd_km Sets the flowline sampling interval in km. [Default is 5].
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94       -L[flag]
95              Output  closest  approach for nearest hotspot only (ignores -S).
96              Choose -Lt for (time, dist, z) [Default], -Lw for (omega,  dist,
97              z), and -Ll for (lon, lat, time, dist, z).  Normally, dist is in
98              km; use upper case  modifiers  TWL  to  get  dist  in  spherical
99              degrees.
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101       -Nupper_age
102              Set  the maximum age to extend the oldest stage back in time [no
103              extension].
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105       -Qr/t  Input files only has (x,y,z); specify constant  values  for  r,t
106              that will be implied for each record.
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108       -S[n_hs]
109              Set the number of closest hotspots to report [Default is 1].
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111       -T     Truncate  seamount  ages exceeding the upper age set with -N [no
112              truncation].
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114       -V[level] (more ...)
115              Select verbosity level [c].
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117       -Wmaxdist
118              Only report those seamounts whose flowlines came within  maxdist
119              to any hotspot [Default reports all seamounts].
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121       -Z     Use  the  hotspot  ID  number rather than the name tag in output
122              records.
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124       -bi[ncols][t] (more ...)
125              Select native binary input. [Default is 5 input columns].
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127       -dinodata (more ...)
128              Replace input columns that equal nodata with NaN.
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130       -e[~]"pattern" | -e[~]/regexp/[i] (more ...)
131              Only accept data records that match the given pattern.
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133       -V[level] (more ...)
134              Select verbosity level [c].
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136       -icols[+l][+sscale][+ooffset][,...] (more ...)
137              Select input columns and transformations (0 is first column).
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139       -:[i|o] (more ...)
140              Swap 1st and 2nd column on input and/or output.
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142       -^ or just -
143              Print a short message about the  syntax  of  the  command,  then
144              exits (NOTE: on Windows just use -).
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146       -+ or just +
147              Print  an extensive usage (help) message, including the explana‐
148              tion of any module-specific  option  (but  not  the  GMT  common
149              options), then exits.
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151       -? or no arguments
152              Print a complete usage (help) message, including the explanation
153              of all options, then exits.
154

GEODETIC VERSUS GEOCENTRIC COORDIINATES

156       All spherical rotations are applied to  geocentric  coordinates.   This
157       means  that  incoming data points and grids are considered to represent
158       geodetic coordinates and must first be converted to geocentric  coordi‐
159       nates.  Rotations  are then applied, and the final reconstructed points
160       are converted back to geodetic coordinates.  This default behavior  can
161       be  bypassed  if  the  ellipsoid  setting  PROJ_ELLIPSOID is changed to
162       Sphere.
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EXAMPLES

165       To find the likely (hotspot) origins of the  seamounts  represented  by
166       the (x,y,z,r,tc) points in the file seamounts.d, using the DC85.d Euler
167       poles and the pac_hs.d list of possible hotspots, and report the 2 most
168       likely hotspot candidates for each seamount, run
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170              gmt originator seamounts.d -S2 -EDC85.d -Fpac_hs.d > origins.d
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172       To  determine the predicted age of a seamount, distances to the closest
173       hotspot, and echo the observed age given its  location,  observed  age,
174       and a rotation model, try
175
176              echo "1.55 -8.43 52.3" | gmt originator -FONeill_2005_hotspots.txt \
177              -EOMS2005_APM_fixed.txt -Q1/120 -Lt
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179       where 52.3 Ma is observed age. The output is 70 -95.486 52.3. To repeat
180       the same exercise with a moving hotspot model, try
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182              echo "1.55 -8.43 52.3" | gmt originator -F+ONeill_2005_hotspots.txt \
183              -EOMS2005_APM_smooth.txt -Q1/120 -Lt
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185       Now the output is 80 -213.135 52.3. Negative distances means the  clos‐
186       est approach was east of the hotspot.
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NOTES

189       GMT    distributes   the   EarthByte   rotation   model   Global_Earth‐
190       Byte_230-0Ma_GK07_AREPS.rot.  To use an alternate rotation file, create
191       an  environmental  parameters named GPLATES_ROTATIONS that points to an
192       alternate rotation file.
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SEE ALSO

195       gmt, grdrotater, grdspotter, project, mapproject, backtracker, gmtpmod‐
196       eler, grdpmodeler, grdrotater, hotspotter
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REFERENCES

199       Wessel,  P.,  1999,  "Hotspotting"  tools  released, EOS Trans. AGU, 80
200       (29), p. 319.
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203       2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
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2085.4.5                            Feb 24, 2019                    ORIGINATOR(1)
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