Major controls on architecture, sequence stratigraphy and paleosols of middle Pleistocene continental sediments ("Qc Unit"), eastern central Italy

Abstract

Middle Pleistocene continental sediments in central Italy ("Qc Unit") record the oldest fluvial accumulation along the uplifting margin of the Peri-Adriatic basin. The architecture of the sediment body can be divided into two unconformity-bounded, fining-upward cycles interpreted as genetically related depositional sequences. These sequences highlight the systematic adjustment of the fluvial systemto changes in the ratio between accommodation space and sediment supply (A/S ratio) and, from base to top, comprise the following surfaces and stratal components: (i) a regionally correlative sequence boundary resulting from an A/S ratio ≤ 0; (ii) a low-accommodation systems tract characterized by conglomerate-rich, amalgamated channel fills and recording an A/S ratio b 1; (iii) an expansion surface marking the turnaround point from low-accommodation systems tract to high-accommodation systems tract deposits; (iv) a high-accommodation systems tract dominated by floodplain fines encasing lens-like, fluvial channel deposits and denoting an A/S ratio N 1; and (v) amature red argillic paleosol. To constrain the climatic signal for paleosols formation, the two sequence-capping mature paleosols have been investigated. The results of these studies suggest that they were developed under humid and warm climatic conditions associated with interglacial phases, which have been correlatively attributed to Marine Oxygen Isotope\ud Stages 11 and 9

Long-term landscape evolution of the Molise sector of the central-southern Apennines, Italy

“…This palaeosurface coincides with the top of the palaeosol that closes up the Qc2 sequence, the second sedimentary cycle of the Campomarino Conglomerates (Bracone et al 2012a), and, therefore, is Middle Pleistocene in age. A palaeosol, correlated to the previous one, is present immediately north of the Molise area, in the Abruzzo and Marche foothills, and dated to MIS 9 (Di Celma et al 2015), confirming the Middle Pleistocene age of the III order palaeosurface.…”

A late Quaternary multiple paleovalley system from the Adriatic coastal plain (Biferno River, Southern Italy)

“…A prominent, laterally extensive reddish paleosol developed under warm and humid climate (interglacial) conditions marks the top of sequence Qc2 (Bracone et al, 2012a). Close to the study area, this paleosol correlates with marine isotope stage (MIS) 9 (Di Celma et al, 2015).…”

“…Based on the MIS 9 age assignment of the mature red argillic paleosol identified at the Apenninic margin (Di Celma et al, 2015), we infer that Biferno River excavated a deep incision in the bedrock after ca. 350 ky BP.…”

Fossil forests in the Austral Basin (Argentina) marking a Cenomanian heterogeneous forced regressive surface

“…Furthermore, the presence of vertic features, such as slickensides, and wedge-shaped peds, allows a further classification of this type of soils as vertic Alfisols (Soil Survey Staff, 1975Varela et al, 2012a). In thin-section the presence of cross striated b-fabric also indicates shrinking and swelling processes related to seasonal contrast (Hussein & Adey, 1998;Driese et al, 2003;Kovda & Mermut, 2010;Di Celma et al, 2015). In thin-section the presence of cross striated b-fabric also indicates shrinking and swelling processes related to seasonal contrast (Hussein & Adey, 1998;Driese et al, 2003;Kovda & Mermut, 2010;Di Celma et al, 2015).…”

“…Slickensides and microslickensides are formed in soils by periodic expansion and contraction of expansive clay minerals associated with strongly seasonal precipitation (White, 1997;Retallack, 2001;Driese et al, 2003). In thin-section the presence of cross striated b-fabric also indicates shrinking and swelling processes related to seasonal contrast (Hussein & Adey, 1998;Driese et al, 2003;Kovda & Mermut, 2010;Di Celma et al, 2015). The Alfisols from the Mata Amarilla fossil forests also have hydromorphic features, such as the presence of gley colours, mottles and nodules in the Bg and E horizons.…”