Magnetic fabrics reveal Upper Mantle Flow fabrics in the Troodos Ophiolite Complex, Cyprus

The foliations and lineations recognized in outcrops of the Troodos mantle-sequence provide relatively few and imprecise observations of the mineral fabric. Thus, their kinematic interpretation, and any inferences about the metamorphic flow patterns are tenuous. However, every outcrop yields the anisotropy of magnetic susceptibility (AMS) from which we may infer the combined orientation–distribution response of silicates (pyroxene, serpentine) and magnetite. Furthermore, in many outcrops, the anisotropy of anhysteretic remanence (AARM) isolates the contribution of magnetite to the orientation–distribution. AMS and AARM each provide a magnitude ellipsoid whose principal directions define the orientation–distribution of several hundred minerals in each sample, and thus their flow fabric. the Troodos mantle-sequence, high-temperature, semi-cataclastic silicate flow directions were uniform through volumes of ∼1 km3 but differ between adjacent subareas. This reflects the scale of the heterogeneity of solid-state flow. However, averaged over the entire area of ∼100 km2, the global orientation–distribution of silicate alignments were consistent, indicating early, silicate flow up to the west, away from a spreading axis that lay east of the Troodos range. On the same regional scale, later magnetite alignments indicate flow up to the north-west. The non-horizontal and non-coaxial flow stages suggest that the mantle sequence was affected by diapiric rise in the solid-state, radiating from centres which may originally have been magma chambers. The one responsible for the recorded flow patterns may have been approximately 30 km in diameter and located SE of Mount Troodos.