Authigenic Cu-carbonates in sandstones at he base of Miocene in the Logudoro Region (NW Sardinia, Italy)

Prospecting in the northern part of Sardinia, within a N-S-trending tectonic trough has led to the discovery of a number of mineralized sections in the bottom terrigenous sediments that were produced during a Miocene marine transgression. The mineralization occurs at the contact between pyroclastics and clastic sediments and consists of authigenic oxides and sulphides, suggesting fluctuations of redox conditions in a near-shore, high-pH environment. Evidence indicates that metals were transported under warm and semi-arid climatic conditions by ground waters and deposited in environments characterized by high pH and fluctuating Eh conditions. Evidence also suggests that mineralization occurred during diagenesis.