rotconverter

Manipulate total reconstruction and stage rotations

Synopsis

gmt rotconverter [ ± ] rotA [ ± rotB ] [ ± rotC ] … [ -A ] [ -D ] [ -Fout ] [ -G ] [ -M[fact] ] [ -N ] [ -S ] [ -T ] [ -W ] [ -V[level] ] [ -hheaders ] [ --PAR=value ]

Note: No space is allowed between the option flag and the associated arguments.

Description

rotconverter reads one or more plate motion models (stage or total reconstruction rotations) stored in the given files. If more than one plate motion model is given we will add or subtract them in the order they were listed. The minus sign means we should first transpose the rotation and then add it to the previous rotation. If a file cannot be opened we will attempt to decode the file name as a single rotation whose parameters are separated by slashes.

Required Arguments

rotX
Name of a file with a plate motion model. Separate several files with desired operator (+ or -). The very first file may also have a leading minus operator to imply a transpose. We also recognize filenames of the form A-B, where both A and B are uppercase plate abbreviations as used by GPlates, to indicate we should look up the rotation between the two plates in the GPlates rotation file (e.g., PAC-MBL). If any of the specified rotation models cannot be opened as a file, we will try to decode the file name as lon/lat/tstart[/tstop]/angle for a single rotation given on the command line. The tstop argument is required for stage poles only. For a single total reconstruction rotation without any time information, give lon/lat/angle only.

Optional Arguments

-A
Indicate that times are actually just opening angles [times in Myr].
-D
Report longitudes use the -180/+180 range [Default is 0/360].
-Fout
Specify the output format for rotations. The out flag must be either t or s for total reconstruction or stage rotations, respectively. [Default is -Ft (output contains total reconstruction rotations)].
-G
Output final rotations in the Plates4 format used by GPlates [Default is spotter format].
-M[fact]
Scale opening angles by fact on output [0.5]. Typically used to get half-rates needed for flowlines. Requires stage pole output (see -F).
-N
Place all output poles in the northern hemisphere [Default reports positive rotation angles].
-S
Place all output poles in the southern hemisphere [Default reports positive rotation angles].
-T
Transpose the final result, i.e., change the sign of the rotation angles.
-W
Ensure all output rotations have negative opening angles [Default reports positive rotation angles].
-V[level] (more …)
Select verbosity level [c]. Report statistics of extracted rotations.
-^ or just -
Print a short message about the syntax of the command, then exits (NOTE: on Windows just use -).
-+ or just +
Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exits.
-? or no arguments
Print a complete usage (help) message, including the explanation of all options, then exits.
--PAR=value
Temporarily override a GMT default setting; repeatable. See gmt.conf for parameters.

Limitations

Note that only one of -N, -S, and -W can be used at the same time.

Examples

To convert the total reconstruction rotations in the file model_total_reconstruction.APM to stage poles, run

gmt rotconverter model_total_reconstruction.APM -Fs > model_stages.APM

To obtain Nazca motion relative to Pacific hotspots by adding the motion of Nazca relative to a fixed Pacific to the Pacific-Hotspot reference model DC85_stages.d, and report the result as total reconstruction reconstruction poles in the northern hemisphere, try

gmt rotconverter DC85_stages.APM + Pac_Naz_stages.RPM -N -Ft > \
                 Naz_HS_total reconstruction.APM

To add the final rotations ROT(150.1, 70.5, -20.3) and ROT (145.0, 40.0, 11.4), try

gmt rotconverter 150.1/70.5/-20.3 + 145/40/11.4

which prints out 157.32, -80.44, 11.97.

To make stage rotations suitable for generating flowlines (fracture zones) from a model of relative plate motions PL1-PL2.RPM, assuming symmetric spreading, try

gmt rotconverter PL1-PL2.RPM -M -Fs > PL1-PL2_half.RPM
gmt rotconverter - PL1-PL2.RPM -M -Fs > PL2-PL1_half.RPM

To compute rotations for India relative to a fixed Africa using the plate circuit India-Central Indian Basin-Antarctica-Africa, based on the GPlates rotations database, try

gmt rotconverter IND-CIB CIB-ANT ANT-AFR > India_Africa.RPM

Notes

GMT distributes the EarthByte rotation model Global_EarthByte_230-0Ma_GK07_AREPS.rot. To use an alternate rotation file, create an environmental parameters named GPLATES_ROTATIONS that points to an alternate rotation file.