ORIGINATOR

originator − Associate seamounts with hotspot point sources

originator [infile(s)] −Estage_file −Fhs_file [ −C ] [ −Dd_km ] [ −H[i][nrec] ] [ −Nupper_age ] [ −S[n_hs] ] [ −T ] [ −V ] −Wmaxdist ] [ −:[i|o] ] [ −bi[s|S|d|D][ncol] ]

originator reads (longitude, latitude, height, radius, crustal_age) records from infiles [or standard input] and uses the given Absolute Plate Motion (APM) stage poles and the list of hotspot locations to determine the most likely origin (hotspot) for each seamount. It does so by calculating flowlines back in time and determining the closest approach to all hotspots. The output consists of the input records with four additional fields added for each of the n_hs closest hotspots. The four fields are the hotspot id (e.g., HWI), the stage id of the flowline segment that came closest, the pseudo-age of the seamount, and the closest distance to the hotspot (in km). See option −: on how to read (latitude, longitude,height, radius, crustal_ag) 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)

Seamount data file(s) to be analyzed. 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 tstart and tstop are in Ma and the rest is in degrees. The oldest stage must be listed first. tstart (tstop) is the age of the old (young) end of the stage. Blank lines and records whose first column contains # will be ignored.

−F

Give file with hotspot locations. This file must contain one record for each hotspot to be considered; each record must be of the following format:

lon lat hs_id hs_name

E.g., for Hawaii this may look like

205

20

HWI

Hawaii

Blank lines and records whose first column contains # will be ignored.

−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 the tstart column is optional (assumed to be 0 Ma).

−D

Sets the flowline sampling interval in km. [Default is 5].

−H

Input file(s) has Header record(s). Number of header records can be changed by editing your .gmtdefaults4 file. If used, GMT default is 1 header record. Use −Hi if only input data should have header records [Default will write out header records if the input data have them].

−N

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

−S

Set the number of closest hotspots to report [Default is 1].

−T

Truncate seamount ages exceeding the upper age set with −N [no truncation].

−V

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

−W

Only report those seamounts whose flowlines came within maxdist to any hotspot [Default reports all seamounts].

−:

Toggles between (longitude,latitude) and (latitude,longitude) input and/or output. [Default is (longitude,latitude)]. Append i to select input only or o to select output only. [Default affects both].

−bi

Selects binary input. Append s for single precision [Default is d (double)]. Uppercase S (or D) will force byte-swapping. Optionally, append ncol, the number of columns in your binary file if it exceeds the columns needed by the program. [Default is 5 input columns].

To find the likely (hotspot) origins of the seamounts represented by the (x,y,z,r,tc) points in the file seamounts.d, using the DC85.d Euler poles and the pac_hs.d list of possible hotspots, and report the 2 most likely hotspot candidates for each seamount, run

originator seamounts.d −S2 −EDC85.d −Fpac_hs.d > origins.d

GMT(l), project(l), mapproject(l), backtracker(l) hotspotter(l)

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