Petrography and Geochemistry of the Leucocratic Rocks in the Ophiolites from the Pollino Massif (Southern Italy)

In the Tethyan realm, leucocratic rocks were recognized as dikes and layers outcropping
in the ophiolitic rocks of the Western Alps, in Corsica, and in the Northern Apennines. Several
authors have suggested that the origin of leucocratic rocks is associated with partial melting of
cumulate gabbro. Major and trace elements composition and paragenesis provided information
about the leucocratic rocks genetic processes. This research aims at disclosing, for the first time,
the petrographical and geochemical features of Timpa delle Murge leucocratic rocks, Pollino Massif
(southern Italy), in order to discuss their origin and geodynamic significance through a comparison
with other Tethyan leucocratic rocks. These rocks are characterized by high amounts of silica
with moderate alumina and iron-magnesium contents showing higher potassium contents than
plagiogranites, due to plagioclase alteration to sericite. Plagioclase fractionation reflects negative
Eu anomalies indicating its derivation from gabbroic crystal mushes. The chondrite normalized
REEs patterns suggest the participation of partial melts derived from a metasomatized mantle in a
subduction environment. The results reveal some similarities in composition with other Tethyan
leucocratic rocks, especially those concerning Corsica and the Northern Alps. These new data provide
further clues on the origin of these leucocratic rocks and the Tethyan area geodynamic evolution.