| Location : | Australia | North America | Europe |
| Server : | www.es.usyd.edu.au | disconnected | ftp-sdt.univ-brest.fr |
| Directory : | /pub/agegrid | Agegrid |
You may obtain the grid and other related files using your web browser (click on
one of the high-lighted address above) or by anonymous ftp as follow (expected inputs are in bold characters):
(if unsure about how
to use the ftp protocol contact your system administrator)
| age_1.x.grd.gz | a GMT netcdf grd file of ocean ages |
| Version 1.6: December 2001 | |
| Version 1.5: October 2001 | |
| Version 1.3: Replaced Pacific-Nazca isochrons based on
new mag. anom. picks in French Polynesia from
Munschy et al. (1996). Carmen Gaina helped with
constructing new isochrons. The ref. is:
Munschy, M., Antoine, C., and Gachon, A., Evolution tectonique de la region des Tuamotu, ocean Pacifique Central, C.R. Acad. Sci. Paris, t. 323, serie II a, 941-948, 1996. The COB off western Australia has been updated based on Mihut, D. and Mueller, R.D., in press, Volcanic margin formation and Mesozoic rift propagators in the Cuvier abyssal plain off Western Australia, JGR. In this version, continental crust is coded with values=300, and oceanic areas not presently covered with gridded data is set to 999. This allows you to use different colors (or grays) in your color pallette file for differentiating these features in a plot. (December 1997) | |
| Version 1.2: correct a timescale conversion error for an 5, and include the area north of 72 deg N (June 1997) | |
| Version 1.1: Update to Cande and Kent (1995) and Gradstein et al. (1994) timescales. The two timescales overlap at an 34, and we have chosen Gradstein et al's age (83.5 m.y.) for an 34 (May 1996). | |
| age_1.x.bint.gz | a short integer binary file of ocean ages, without
header ages are multiplied by 100 |
| rate_1.x.grd.gz | a GMT netcdf grid of spreading rates |
| asym_1.x.grd.gz | a GMT netcdf grid of asymmetry of spreading |
| dirx_1.x.grd.gz | a GMT netcdf grid of direction of spreading |
| diry_1.y.grd.gz | a GMT netcdf grid of direction of spreading |
| age.cpt.gz | a GMT color palette for ages |
THE FOLLOWING FILES HAVE NOT BEEN UPDATED SINCE VERSION 1.1 (i.e. as published in JGR 1997)
| age_errors_1.1.grd.gz | a GMT netcdf grd file of age errors |
| age_errors_1.1.i2.gz | a short integer binary file of age errors,
without header age errors are multiplied by 100 |
| age_error_1.1.ps.gz | an A4 postscript file of the age and error grids |
We provide a C-program named grdage_cor.c which can be used to update the agegrid using different timescales. A Makefile is included to compile the program (it depends on the GMT and NETCDF libraries which you need to have installed). The program reads a grid file in default GMT grd-format and a table which includes the mapping of old to new ages (see example age_conv.tab).
The file age.cpt is a GMT color pallette file which can be used to plot the agegrid using the GMT software.
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Optional files:
The file isochrons.dat contains the seafloor spreading isochrons the age agrid is based on. The data are stored in "PALEOMAP" format. Each data "string" starts with a 2 line "header". The 1st line contains 3 integer numbers you can ignore, and a geographic description of the data. The 2nd line contains a 3 digit plate ID (e.g. 301 = Eurasia), the age of the isochron, another age (default = 999.0), a data type descriptor (e.g. IS 5 = isochron at magnetic anomaly 5 time), the plate ID of the conjugate plate and a few other numbers you can ignore. A list of plate ID integers can be found in the file globalage_pid.lst.
The files platebound.dat and platebound_xr.dat contain present day plate boundaries and the location of extinct ridges, respectively, in the same format as above. Neither file is necessarily complete or correct. In case you have more up-to-date data for either present day or extinct plate boundaries which you may wish to share with us, please let us know.
In order to plot these data with the GMT software system, an awk script can be used to strip off the headers and create an mutliple segment GMT lat/lon file:
awk ' NF==3 && $1 != 99.0000 {
if ($2 < 0) $2 = $2 + 360;
if ($3 == 3) printf("> new string\n%s\t%s\n", $1, $2);
else printf("%s %s\n",$1,$2);
}' file_name.dat
Two tar files contain closed right-handed polygons of the major plates (plate_polygons.tar) and of the boundaries between oceanic and continental crust (cob_polygons.tar). All polygons are lat/lon ascii files without headers.
COB POLYGONS
"cont" in the filename indicates that the polygon encloses continental crust while "ocean" in the filename indicates that the polygon encloses ocean crust within continental crust. The cob_polygons are (lat/lon format):
| afr_cont_cob.yx | African |
| ant_cont_cob.yx | Antarctica |
| arctic_ocean_cob.yx | Arctic Ocean |
| aus_cont_cob.yx | Australia |
| car_ocean_cob.yx | Caribbean |
| cayman_ocean_cob.yx | Caribbean (Cayman Trough) |
| eur_cont_cob.yx | Eurasia |
| gulfmex_ocean_cob.yx | Gulf of Mexico |
| janmay_cont_cob.yx | Jan Mayen |
| madagas_cont_cob.yx | Madagascar |
| nam_cont_cob.yx | North America |
| nzealand_cont_cob.yx | New Zealand |
| s_georgia_cont_cob.yx | South Georgia Microcontinent |
| sam_cont_cob.yx | South America |
| seychel_cont_cob.yx | Seychelles |
PLATE POLYGONS
| afr_plate.yx | Africa |
| ant_plate.yx | Antarctica |
| arab_plate.yx | Arabia |
| aus_plate.yx | Australia |
| car_plate.yx | Caribbean |
| coco_plate.yx | Cocos Plate |
| east_plate.yx | Easter Microplate |
| eur_plate.yx | Eurasia |
| ind_plate.yx | India |
| juan_plate.yx | Juan de Fuca Plate |
| nam_plate.yx | North America |
| naz_plate.yx | Nazca Plate |
| pac_plate.yx | Pacific Plate |
| sam_plate.yx | South America |
The University of Sydney
Department of Geology and Geophysics
Edgeworth David Building F05
N.S.W. 2006
AUSTRALIA