1ORIGINATOR(1) GMT ORIGINATOR(1)
2
6 originator - Associate seamounts with nearest hotspot point sources
7
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] ]
13 Note: No space is allowed between the option flag and the associated
15 arguments.
16
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.
30
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:
36 lon lat tstart [tstop] angle [ khat a b c d e f g df ]
38 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.
57 -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:
61 lon lat hs_abbrev hs_id r t_off t_on create fit plot name
63 E.g., for Hawaii this may look like
65 205 20 HWI 1 25 0 90 Y Y Y Hawaii
67 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].
86
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.
91 -Dd_km Sets the flowline sampling interval in km. [Default is 5].
93 -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.
100 -Nupper_age
102 Set the maximum age to extend the oldest stage back in time [no
103 extension].
104 -Qr/t Input files only has (x,y,z); specify constant values for r,t
106 that will be implied for each record.
107 -S[n_hs]
109 Set the number of closest hotspots to report [Default is 1].
110 -T Truncate seamount ages exceeding the upper age set with -N [no
112 truncation].
113 -V[level] (more ...)
115 Select verbosity level [c].
116 -Wmaxdist
118 Only report those seamounts whose flowlines came within maxdist
119 to any hotspot [Default reports all seamounts].
120 -Z Use the hotspot ID number rather than the name tag in output
122 records.
123 -bi[ncols][t] (more ...)
125 Select native binary input. [Default is 5 input columns].
126 -dinodata (more ...)
128 Replace input columns that equal nodata with NaN.
129 -e[~]"pattern" | -e[~]/regexp/[i] (more ...)
131 Only accept data records that match the given pattern.
132 -V[level] (more ...)
134 Select verbosity level [c].
135 -icols[+l][+sscale][+ooffset][,...] (more ...)
137 Select input columns and transformations (0 is first column).
138 -:[i|o] (more ...)
140 Swap 1st and 2nd column on input and/or output.
141 -^ or just -
143 Print a short message about the syntax of the command, then
144 exits (NOTE: on Windows just use -).
145 -+ 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.
150 -? or no arguments
152 Print a complete usage (help) message, including the explanation
153 of all options, then exits.
154
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.
163
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
169 gmt originator seamounts.d -S2 -EDC85.d -Fpac_hs.d > origins.d
171 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 echo "1.55 -8.43 52.3" | gmt originator -FONeill_2005_hotspots.txt \
177 -EOMS2005_APM_fixed.txt -Q1/120 -Lt
178 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
181 echo "1.55 -8.43 52.3" | gmt originator -F+ONeill_2005_hotspots.txt \
183 -EOMS2005_APM_smooth.txt -Q1/120 -Lt
184 Now the output is 80 -213.135 52.3. Negative distances means the clos‐
186 est approach was east of the hotspot.
187
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.
193
195 gmt, grdrotater, grdspotter, project, mapproject, backtracker, gmtpmod‐
196 eler, grdpmodeler, grdrotater, hotspotter
197
199 Wessel, P., 1999, "Hotspotting" tools released, EOS Trans. AGU, 80
200 (29), p. 319.
201
203 2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
2045.4.5 Feb 24, 2019 ORIGINATOR(1)