Day 1, Locality 7
Pinewoods of the High Troodos, near Mt Olympos:
Parking near Troodos army base we walk through pinewoods, with many mature native species and inspect mantle harzburgite and mantle fabrics, deformation, diapirism and mantle melting features; dunite pods and chromite segregations. Finally we reach the old Kannoures mine, with massive chromites and magma diapirism.
During this walk Pinus nigra will be the dominant species seen, but Pinus brutia can also be seen, rare at this altitude. Cedrus libani and Juniperus foetidissima, with possibly Pinus halapensis, make up the remaining tall species. Quercus sp., Arbutus, and Teucrium form a lower storey, often occurring in clumps. In April numerous carpeting species should also be flowering, enjoying the moisture from the recently melted snows.
A detour will be made a short way into the walk, to examine the harzburgitic mantle sequence. On the crest of a small rise, an exposure of harzburgite is seen criss-crossed by numerous veins and dykelets. These represent minor episodes of intrusion into the mantle, from adjacent magma bodies as they collect near the top of the mantle. Vein composition suggests a range of fractionation levels and evolution of the magma bodies. Ultramafic veins of dunite (orange-brown), more generally as small pods, orthopyroxenite (bronze colour), clinopyroxenite (pale green), wehrlite (green and black), and websterite (green and bronze), can be found. Also, mafic veins of lighter coloured gabbro can be identified. The veins are either straight or wavy, and many cross-cut each other. One explanation for these veins is that they formed as either residual melt bodies, or later melts generated after the main phase of melt generation which fuelled the spreading system. Intrusion of these immediately off-axis bodies would be controlled by availability and composition of remaining magma, and by the temperature of the mantle as it spreads away from the axis and cools. Many of the dunite veins represent melt channels, where fresh magma has leached CPX and OPX from the harzburgite during ascent, leaving a residue of olivine-rich dunite. During leaching, some melts would become charged with both CPX, and later OPX. Subsequent crystallisation of these enriched melt bodies are thought to have produced some of the pyroxenite veins observed (Buchl et al., 2002). Other foliation structures may also be seen in the harzburgites at this locality, and are of mantle flow origin.
A couple of short videos are available: MPG-1 WMV-1 ; MPG-2 WMV-2 . The sound is a bit variable but at least there's not too much wind!
As we continue our walk along the track, we proceed over mantle harzburgite, which in places is cut by very significant ultramafic and mafic veins. In some pyroxenite veins, pyroxene crystals up to 5-10 cm can be found.
Sometimes deep snow can lie on the northern slopes until April, making the chromite mine inaccessible.
The track continues to the remains of the Kannoures chromite mine. In this area the dunite pods within the mantle contain abundant chromite layers and disseminated grains, as chrome spinel joins olivine, crystallising as small magma bodies rise to the base of the crust. The chromite occurs as grains of black shiny chrome spinel within orangeweathering dunite, or as segregation veins within the dunite, and also as more massive bands in dunite-free chromitite bodies. Specimens of all three types should be accessible in the exposures, and the spoil heaps.
Note the rust-coloured Dunite rocks.
The ground all around the derelict mine workings is littered with sheets of galvanised metal, some of it still in remarkably good condition!
