The magnetic data that were used for the Central Indian Ridge magnetic reversal
identifications in DeMets et al. (2005) consist principally of shipboard and
aeromagnetic data archived at the U.S. National Geophysical Data Center,
and several French cruises. In addition, six reversal identifications were digitized
from Project Magnet profiles shown in maps in Fisher et al. (1971), and 93 were taken
from the Ph.D. dissertation files of Jerome Dyment (Dyment 1991).
Of the 1546 reversal identifications in the file, 1457 were identified from
digital magnetic profiles.

Reversal identifications in this file are limited to those that record motion
along the Capricorn-Somalia plate boundary, located between 9 degrees S and the
Rodriguez triple junction.

Prior to identifying reversals, all of the magnetic profiles were reduced to
the pole using the local ridge azimuth and remanent and ambient field parameters
that were calculated for the location where each profile crosses the Central
Indian Ridge (or approaches it most closely). Reversal identifications were made on
a screen that displayed the phase-shifted digital files and permitted interactive
picking from those data.

The phase-shifted profiles were compared to a synthetic magnetic profile calculated
at 90N with a 0.5-km-thick magnetic source layer. For shipboard profiles,
the top of the magnetic layer was modeled to be 2.5 km below the surface.
For aeromagnetic profiles, the top of the magnetic layer was modeled to be
2.8 km below the surface since all of the aeroprofiles were flown at
a height of 1000 feet (roughly 300 m) above the ocean surface.

Readers should refer to DeMets et al. (1994) and DeMets et al. (2005) for further
details on the sources of data and data reduction methods.

References:
DeMets, C., Gordon, R. G., and Vogt, P. (1994), Location of the Africa-Australia-India
triple junction and motion between the Australian and Indian plates: Results from an
aeromagnetic investigation of the Central Indian and Carlsberg ridges
Geophys. J. Int., 119, 893-930.

DeMets, C., Gordon, R. G., and Royer, J.-Y. (2005), Motion between the Indian,
Capricorn, and Somalian plates since 20 Ma: implications for the timing and
magnitude of distributed deformation in the equatorial Indian ocean,
Geophys. J. Int., 161, 445--468.

Dyment, J. (1991), Structure et evolution de la lithosphere oceanique dans
l'ocean Indien: Apport des anomalies magnetiques, Universite de Strasbourg,
Strasbourg, These de Doctorat.

Fisher, R. L., Sclater, J. G., McKenzie, D. P. (1971), Evolution of the central
Indian Ridge, western Indian Ocean, Geol. Soc. Am. Bull., 82, 553-562.