A geomagnetic record over the last 3.5 million years from deep-tow magnetic anomaly profiles across the Central Indian Ridge

High-resolution records of the geomagnetic field intensity over the last 4 Myr provided by paleomagnetic analyses of marine sediments have shown the o ccurrence of short-lived low field intensity features associated with excur sions or short polarity intervals. In order to evaluate the ability of mari ne magnetic anomalies to record the same geomagnetic events, we have collec ted six deep-tow (similar to 500 m above the seafloor) and several sea surf ace magnetic anomaly profiles from the Central Indian Ridge across the Brun hes, Matuyama, and Gauss chrons (i.e., from the ridge axis to anomaly 2A). After removal of topography, latitude, and azimuth effects, we converted di stances into time sequences using well-dated polarity reversal anomalies as tie points. We calculated the average signal to test the robustness of the short-wavelength anomalies. The resulting stacked profile is very similar to stacked sea surface and downward continued profiles from the Central Ind ian Ridge, the East Pacific Rise, and the Pacific-Antarctic Ridge. Our resu lts suggest that in addition to polarity reversals, to previously suggested geomagnetic events (subchrons or excursions) within the Brunhes and Matuya ma chrons. A new small-scale magnetic anomaly, likely generated by several closely spaced geomagnetic field intensity variations represent the major c ontributor to the detailed shape of recent marine magnetic anomalies in inv estigated areas. We observe a dense succession of microanomalies that are c orrelated excursions (Ontong Java 1 and 2, and Gilsa), is found after the O lduvai chron. The near-bottom results support the existence of three geomag netic features between the Gauss-Matuyama boundary and Olduvai. They also s uggest three geomagnetic events during the C2A.ln subchron within the Gauss chron. This study emphasizes the potential of deep-tow magnetic surveys in detecting fluctuations in geomagnetic field intensity and, in particular, short-lived excursions, a poorly constrained part of the geomagnetic field temporal variation spectrum.