27/07/2009 Greece VI: The IGME Ophiolitics

Well, today we had to go into IGME to deposit our 100s of kilograms of rock samples collected so far, and to let Annie do some work. Before returning to Grevena, we decided to take a look at a small ophiolitic mass between IGME and Argilos. Only around 20m thick, the unit comprised lavas, sheared at the base, with sands and a lateritic surface. Not an ophiolite by any stretch of the imagination. Given the lack of shearing in the underlying sediments (which look identical to many of those found in the Zavordhas region), my guess is that the unit may be an olistolith. Certainly it is difficult to believe that the shearing was due to thrusting, given the thickness of the unit and lack of shearing in the upper sections of the unit.

We then returned to the conglomerate we visited a few days ago. Looking at the southern end of the outcrop, it became clear that we had missed more vital clues to the history of the outcrop; isoclinal folding in the Cretaceous carbonates above the ophiolitic conglomerates which look extremely similar to mass flow deposits I have seen in Spain. Before leaving, we checked the conglomerate. Every pebble was polished and striated, and many were faceted. Looking at literature in the evening, I failed completely to find any reference to striation and facetting in mass flow deposits. I still think this is more likely then the fault alternative, but this will need a more detailed study than we have time for here.

Spot the soft sediment fold...