Middle Jurassic continental to marine transition in an extensional tectonics context: the Genna Selole Fm depositional system in the Tacchi area (central Sardinia, Italy)

Abstract

In Eastern Sardinia during the early Middle Jurassic, Alpine Tethys opening triggered the rise of a temporary tectonic high. The high collapsed rapidly, was fragmented into separate blocks, and subsequently covered by continental, transitional, and finally shallow marine deposits forming a narrow depositional system comprising the Genna Selole Fm. Present‐day exposures in the southern part of the palaeo‐high allow the sedimentological evolution of the transgressive cover sequence to be ascertained. Initial terrestrial deposits comprise alluvial fan deposits located at the mouths of palaeovalleys. These pass into braid‐deltas and in the coastal areas located between adjacent valleys mouths, palustrine and coastal plain tidally‐influenced environments developed. These environments interfingered laterally and passed seaward into a transitional, siliciclastic to carbonate tidal environment. With the collapse of the tectonic high, the continental to transitional environments were transgressed with deposition of marine carbonates. A comparison with similar coeval deposits of the W‐Mediterranean domain has been undertaken. Copyright © 2015 John Wiley & Sons, Ltd.