The terrestrial Cr-spinels in the Maiolica Limestone: Where are they from?

A total of 33 and 65 chrome-spinel grains in the >63 and 32-63 μm fractions have been recovered from 12 beds in two stratigraphically separated groups along the 240-m-thick Monte Acuto section of the Maiolica limestone in central Italy, spanning from Berriasian to the early Hauterivian. The chemistry of these detrital spinels suggests they may represent windblown ophiolitic detritus showing the evolution of an ophiolite evolving from a MORB setting (Bosso section) to a SSZ setting including a Back Arc and an Arc setting (Monte Acuto section). The possible source of the Maiolica detrital minerals can be located in the obducting ophiolites of the Albanides and/or the Hellenides that showed a similar evolution. In this case it is particularly important to notice how the chrome-spinel detritus in the Maiolica limestone records this evolution in a relatively short period of time that lasted about 10 Ma.