Section 19
Chapter 18,370

Possible high-frequency geomagnetic polarity changes in Lower-Middle Jurassic carbonates in Iraq

Hijab, B.R.; Tarling, D.H.

Physics of the Earth and Planetary Interiors: -4: 342-347


DOI: 10.1016/0031-9201(90)90047-2
Accession: 018369010

Palaeomagnetic results from Iraqi standard 2.5-cm Jurassic limestone specimens show weak intensities and directions of remanence that are initially randomly scattered, other than an absence of high inclinations. When these are sliced parallel to the bedding in 1-cm discs, their intensity increases and their directions show greater stratigraphic consistency. The age of the remanence appears to be primary (early diagenetic) on the basis of their sedimentological properties. The magnetization is unrelated to mineralogy and is interpreted as normal and reversely magnetized components within standard sized samples. This suggests that, at this time, frequent polarity changes took place resulting in similar polarities within stratigraphic zones < 2–3 cm thick, corresponding to at least five polarity transitions per million years.

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