Abstract
Abstract Deep-tow vector magnetic data have been acquired across the fast-spreading southern East Pacific Rise 18°S and inverted to magnetization intensity variations. Vector magnetic data are used to determine continuous magnetic intensity within intervals of constant polarity over the Matuyama and Brunhes periods up to the Cobb Mountain event at 1.19 Ma. A comparison of our deep-tow vector data and a sediment core-derived geomagnetic paleointensity timescale suggests that the short-wavelength magnetic anomaly signal is indeed of geomagnetic origin and can be used to date the seafloor with a high resolution. The crustal age determined from our date reveals a highly asymmetric spreading rate for the recent period (since 0.3 Ma).
Highlights
Geomagnetic polarity reversals generate parallel magnetic lineations in the oceanic crust, which has been utilized for answering various questions about the science of the Earth
We demonstrate good correlation between the magnetization and the sediment-derived paleointensity timescale, which indicates that paleointensity variations have a major effect on the tiny wiggles of a magnetic anomaly
The whole magnetized 2A layer could be a wrong assumption only for the narrow axis region
Summary
Geomagnetic polarity reversals generate parallel magnetic lineations in the oceanic crust, which has been utilized for answering various questions about the science of the Earth. Sea-surface magnetic surveys cover most of the world’s ocean basin and are used, together with the geomagnetic polarity timescale, as a means to characterize the age and spreading geometry of the oceanic crust Such studies have proven essential for our current understanding of plate motion and tectonic evolution of the mid-ocean ridge system. Paleointensity variations published in the 1990s (Meynadier et al, 1992; Valet and Meynadier, 1993; Guyodo and Valet, 1996, 1999; Valet et al, 1999; Yamazaki, 1999) show great advances in better age control and in accuracy as the number of records increases This leads to a better continuity in time coverage, good enough to compare with the high-resolution magnetic anomaly data across or near the ocean ridge axis. YAMAMOTO et al.: GEOMAGNETIC PALEOINTENSITY FROM DEEP-TOW VECTOR MAGNETIC DATA bathymetry(m) magnetization
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