Sediment composition, provenance, and Holocene paleoenvironmental evolution of the Southern Po River coastal plain (Italy)

Abstract

Geochemistry, sediment provenance, and the Holocene paleoenvironmental evolution of the Southern Po River coastal plain (Italy) were examined based on the geochemical analysis of 279 sediment samples from 35 cores. The Holocene succession is subdivided into four major facies associations: back‐barrier, transgressive barrier, shallow‐marine, and beach‐ridge deposits. Bulk chemical composition shows remarkable differences between facies associations, and the poly‐modal behavior in the related frequency curves suggests distinct sources of sediment. Using MgO and Ni as geochemical tracers, changes in sediment provenance were assessed with the aim to reconstruct the Holocene paleoenvironmental evolution of the area. The Po River and the Apenninic rivers represented the main sources of sediment during the early stages of transgression and highstand sea‐level conditions, whereas transgressive barrier and early shallow‐marine facies associations exhibit a clear North Adriatic river (eastern Alpine) provenance. The Holocene paleoenvironmental evolution of the study area, between about 10 ky and the present, indicates the presence of a bypass zone in front of the Po River mouth between 9 and 6 ky BP. At that time, sediment supplied by the North Adriatic rivers was transported southward by the longshore drift, bypassed the weak Po River influx and accumulated close to the Apennines. Comparison between Holocene facies associations and current back‐barrier and shallow‐marine sediments confirms that the present‐day basin circulation is similar to the one that acted during the last episode of sea‐level rise.

Three‐fold nature of coastal progradation during the Holocene eustatic highstand, Po Plain, Italy – close correspondence of stratal character with distribution patterns

“…The original provenance signal can be confounded by changes in grain size, but alumina is effective as a normalization factor (Covelli & Fontolan, ; Menon et al ., ; Liaghati et al ., ): Cr/Al 2 O 3 , in particular, has been tested successfully in Po Plain sediments for discriminating mafic/ultramafic from non‐mafic/ultramafic provenances (Amorosi et al ., , 2014b; Curzi et al ., ; Amorosi, ; Di Giuseppe et al ., ). The best proxy for carbonate (dolostone) versus siliciclastic contribution based on single ratios was MgO/Al 2 O 3 (Amorosi et al ., , ; Curzi et al ., ; Greggio et al ., ), which in this area closely reflects the abundance of dolomite in the sediment (Marchesini et al ., ).…”

Tracing clinothem geometry and sediment pathways in the prograding Holocene Po Delta system through integrated core stratigraphy

“…A total of 166 core samples were analysed for bulk‐sediment geochemistry. Samples were collected at depths <30 m from 12 cores (Figure b): P13N, P14N, P10N, P8N, P4N, CB and 205S10 (Greggio, Giambastiani, Campo, Dinelli, & Amorosi, ), core 187S1 (Amorosi, Colalongo, Dinelli, Lucchini, & Vaiani, ), Barr (Core1 in Amorosi, Dinelli, Rossi, Vaiani, & Sacchetto, ), EM7, EM12 and 187S3 (this study). The dataset includes 51 additional modern river sediment samples that were used as reference samples for the geochemical characterization of source areas (Figure ).…”

“…Mafic and ultramafic rocks crop out extensively in the western Alps and at the northwestern tip of the Apennines, and represent exclusive catchment lithologies that were adopted to delineate basin-wide markers of sediment provenance. These ophiolite successions consist primarily of peridotite, gabbro, basalt and ophiolitic breccia and deliver large volumes of Cr-rich (and Ni-rich) detritus to the alluvial and coastal systems (Amorosi, Centineo, Dinelli, Lucchini, & Tateo, 2002;Amorosi & Sammartino, 2018;Curzi, Dinelli, Ricci Lucchi, & Vaiani, 2006;Greggio et al, 2018).…”

“…Therefore, major elements, such as Mg and Ca (and their oxides MgO and CaO), can be used to discriminate these source areas. Calibration with mineralogical data (Marchesini et al, 2000) has shown that Mg enrichments in modern coastal deposits reflect erosion and transport of detrital dolomite from the North Adriatic river catchments, which acted as sources of particular detritus to the Po coastal plain (Amorosi et al, 2002(Amorosi et al, , 2007Amorosi & Sammartino, 2018;Curzi et al, 2006;Greggio et al, 2018).…”

Major and Trace Elements Geochemistry of Đồng Ho Sediments (Quảng Ninh, Viet Nam): Imlication for Paleoenvironmental Condition

“…Việc xác định nguồn cấp vật liệu và điều kiện hình thành trầm tích vụn cơ học có ý nghĩa quan trọng trong nghiên cứu và khôi phục điều kiện cổ môi trường thành tạo trầm tích [1][2][3]. Điều này đặc biệt có ý nghĩa đối với nghiên cứu sự biến đổi của môi trường trầm tích, vùng nguồn xâm thực và điều kiện khí hậu trong quá khứ địa chất.…”