I collected this rock in the summer of 2007 near the village of Ano Karyes in the Peloponessos, at a location near Mt. Lykaion Sanctuary of Zeus. I like the striking contrast between brittle failure of the chert and semi-brittle/ductile deformation in the limestone. And I like the soft hues.
The limestone (grey) was deposited in the Pindos Basin in the Neotethyan ocean in the Mediterranean region of today. During compaction and burial ground water solutions bearing dissolved silica selectively replaced some of the limestone, creating bands, layers, and nodules of chert (brown). The chert is pervasively fractured, because it is so stiff and brittle. Its mode of deformation contrasts strongly with that of the limestone, which at this scale lacks fracturing. Note that there is a vein of (white) calcite cutting through the limestone. Undoubtedly the calcite in this vein was derived from pressure dissolution of the limestone under the duress of tectonic stress. What a contrast between the deformation mechanism(s) of chert versus limestone!
Age & Formation
Grey limestone of the Flysch Transition Beds of Paleocene age, ~60 Ma, in the Pindos Group stratigraphy of the Peloponessus.