Abstract

The age of radiolarites covering the Balagne ophiolite is reassessed based on new and revised radiolarian fossil evidence. The oldest radiolarian cherts are dated as upper Bathonian-lower Callovian in two tectonic units: San Colombano and Novella. These are amongst the oldest ages available so far from ophiolites of the Ligurian ocean. An important stratigraphic gap, spanning the Callovian-early Kimmeridgian interval, is specified between radiolarites and the overlying (and locally gullying) San Colombano shallow-water limestones (sub-unit I). We can now specify that radiolarian ooze accumulated until the late Kimmeridgian in the distal parts of the Balagne margin (sub-unit SC III and Novella unit), while fragments of Hercynian basement fell into the Balagne basin during the late Kimmeridgian-Tithonian.

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