Magnetic fabrics reveal Upper Mantle flow fabrics in the Troodos OphioliteComplex, Cyprus

The foliations and lineations recognized in outcrops of the Troodos mantle- sequence provide relatively few and imprecise observations of the mineral f abric. Thus, their kinematic interpretation, and any inferences about the m etamorphic Row patterns are tenuous. However. every outcrop yields the anis otropy of magnetic susceptibility (AMS) from which we may infer the combine d orientation-distribution response of silicates (pyroxene, serpentine) and magnetite. Furthermore. in many outcrops, the anisotropy of anhysteretic r emanence (AARM) isolates the contribution of magnetite to the: orientation- distribution. AMS and AARM each provide a magnitude ellipsoid whose princip al directions define the orientation-distribution of several hundred minera ls in each sample, and thus their Row fabric. Within the Troodos mantle-sequence, high-temperature. semi-cataclastic sili cate Row directions were uniform through volumes of -1 km(3) bur differ bet ween adjacent subareas. This reflects the scale of the heterogeneity of sol id-state Row. However, averaged over the entire area of similar to 100 km(2 ), the global orientation-distribution of silicate alignments were consiste nt, indicating early, silicate Row up to the west, away from a spreading ax is that lay east of the Troodos range. On the same regional scale, later ma gnetite alignments indicate flow up to the north-west. The non-horizontal a nd non-coaxial flow stages suggest that the mantle sequence was affected by diapiric rise in the solid-state, radiating from centres which may origina lly have been magma chambers. The one responsible for the recorded Row patt erns may have been approximately 30 km in diameter and located SE of Mount Troodos. (C) 2001 Elsevier Science Ltd. All rights reserved.