Facies character and skeletal composition of heterozoan carbonates in a high-energy confined embayment (Miocene, Finale Ligure Limestone, NW Italy)

• Published in: Sedimentary Geology
• Main Authors: Della Porta, G, Nembrini, M, Berra, F, Vertino, A
• Other Authors: G. Della Porta, M. Nembrini, F. Berra, A. Vertino
• Format: Article in Journal/Newspaper
• Language: English
• Published: ELSEVIER 2022
• Subjects: Miocene; Finale Ligure; Heterozoan carbonate; Embayment; Subaqueous dune; Stylasterid corals; Settore GEO/02 - Geologia Stratigrafica e Sedimentologica; Planktonic foraminifera
• Online Access: https://hdl.handle.net/2434/945874; https://doi.org/10.1016/j.sedgeo.2022.106209

During the early and middle Miocene, diverse photozoan to heterozoan carbonate and mixed carbonatesiliciclastic depositional systems characterized the Mediterranean region at palaeo-latitudes of 30-40 degrees N, during a time of warm climate. These systems ranged from carbonate ramp to rimmed platforms to current-swept flooded incised palaeo-valleys, seaways and straits. This study focuses on the facies character, skeletal biota composition, diagenesis and stable carbon and oxygen isotope signature of a mixed carbonate-siliciclastic succession (lower-middle Miocene Finale Ligure Limestone and underlying Oligocene-lower Miocene siliciclastic deposits) accumulated in a high-energy coastal setting (Finale Ligure, NW Italy) to improve the knowledge on the variety and controlling factors of Miocene heterozoan skeletal carbonates.The 3D reconstruction of the geometry of the early-middleMiocene Finale Ligure basin identifies an embayment, about 35 km2wide, limited by uplifted and eroded Alpine tectonic units and connected to the open sea through a strait. The Oligocene-Miocene sedimentary succession unconformably overlying the Alpine deformed substrate consists of 14 lithofacies (L1-L14). Besides pockets of karstic breccias (L1) preceding the marine transgression, discontinuous outcrops of glaucony-bearing litharenite, siltstone, conglomerate and wackestone/packstone with planktonic foraminifera (L2-L4) represent the preserved remnants of an eroded marine shelf affected by tectonic uplift and subsequent erosion, approximately in the Aquitanian-Burdigalian, overlain through an angular unconformity by transgressive conglomerates and bioturbated litharenites (L5-L7). The onset of carbonate skeletal production characterizes the overlying compositionally mixed carbonate-siliciclastic LanghianSerravallian Finale Ligure Limestone succession (up to 100-150 m thick, L8-L14). These cross-bedded skeletal packstone and grainstone/rudstone are composed of barnacles, echinoderms, bryozoans, bivalves, scleractinian and stylasterid ...