Integrated micropaleontological study of the Messinian diatomaceous deposits of the Monferrato Arc (Piedmont basin, NW Italy): New insights into the paleoceanographic evolution of the northernmost Mediterranean region

Pellegrino, Luca; Abe, Kenta; Gennari, Rocco; Lozar, Francesca; Pierre, Francesco Dela; Natalicchio, Marcello; Mikami, Yuta; Jordan, Richard W.; Carnevale, Giorgio

doi:10.1016/j.marmicro.2020.101910

Cited by 7 publications

(4 citation statements)

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“…Similarly, low TOC contents of the diatomaceous shales in spite of high biosiliceous productivity agree with the notion that organic matter was mostly degraded aerobically, as hypothesized for other Neogene Mediterranean (e.g. Pérez‐Folgado et al ., 2003; Pellegrino et al ., 2020a,b) and global (e.g. White et al ., 1992; Koizumi & Yamamoto, 2018) diatomaceous deposits.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the Thalassionemataceae probably thrived in the upper layer of the water column, following a nutrient pulse provided by riverine input in accord with the scattered occurrence of reworked chrysophycean cysts and benthic diatoms (cf. Pellegrino et al ., 2020a) or water column mixing, forming large aggregates. Once nutrients were exhausted, diatom aggregates rapidly sank towards the seafloor.…”

Section: Discussionmentioning

confidence: 99%

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From biogenic silica and organic matter to authigenic clays and dolomite: Insights from Messinian (upper Miocene) sediments of the Northern Mediterranean

et al. 2022

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The biogeochemical cycles of carbon and silicon are tightly coupled in modern marine environments due to the pivotal role of planktonic diatoms. Once diatoms are sedimented, the fate of organic matter and biogenic silica is initially governed by bottom water oxygen levels and bacterial communities involved in remineralization processes. The early diagenesis of biosiliceous sediments may result in drastic changes in composition, sometimes hampering palaeoenvironmental reconstruction. Sedimentary successions deposited in the Mediterranean region during the Messinian salinity crisis (5.97–5.33 Ma) allow to explore the early diagenetic transformation of organic matter and biogenic silica in a restricted basin experiencing a severe palaeoceanographic turnover. Sedimentological and petrographic observations coupled to elemental, mineralogical, inorganic and organic geochemical analyses were carried out on biosiliceous (diatomaceous shales and diatom‐bearing mudstones) and associated clay‐rich and dolomite‐rich sediments (dolomitic mudstones) interbedded with primary gypsum layers in the Piedmont Basin (north‐west Italy). The state of preservation of biogenic silica was governed by different pathways of organic matter remineralization, depending on bottom and pore water redox conditions, which were controlled by the structure of the water column. Aerobic respiration of organic matter in a mixed water column and an oxygenated seafloor promoted biogenic silica preservation. In contrast, bottom water anoxia induced by permanent stratification of the water column favoured the concomitant formation of dolomite and authigenic clays. In particular, organic matter degradation through bacterial sulphate reduction increased pore water alkalinity, promoting the precipitation of dolomite. At the same time, the rise in pH promoted the dissolution of biogenic silica which, reacting with pore water cations, ultimately caused the formation of authigenic clays. This study suggests that the apparent annihilation of Mediterranean marine biota during the Messinian salinity crisis partially reflects an early diagenetic bias produced by interactions of the carbon, silicon and sulphur biogeochemical cycles in a restricted basin.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

From biogenic silica and organic matter to authigenic clays and dolomite: Insights from Messinian (upper Miocene) sediments of the Northern Mediterranean

et al. 2022

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“…For this reason, these organisms are often used to monitor aquatic systems [10]. Moreover, the analysis of fossil diatom assemblages in paleontological studies allows one to trace past environmental changes in aquatic systems [11,12]. The European Water Framework Directive (WFD 2000/60/EC, European Commission 2000), transposed by Italian legislation with the D.Lgs.…”

Section: Introductionmentioning

confidence: 99%

“…These diatoms potentially acquire particular relevance in the assessment of temporary high-elevation lakes' ecological status [5]. In fact, such isolated ecosystems are particularly vulnerable to biodiversity loss, as a consequence of the negative effects of various anthropogenic pressures, including intensive summer tourism and climate changes [12]. The composition of diatomic communities, based on the different tolerance of species to water chemistry, and their ability to respond promptly to multiple stressors, can provide important ecological information on these unstable environments, the survival of which is strongly linked to hydrological and climatic processes.…”

Section: Introductionmentioning

confidence: 99%

The Diatomic Diversity of Two Mediterranean High-Elevation Lakes in the Sibillini Mountains National Park (Central Italy)

Padula

Carosi

Rossetti³

et al. 2021

Environments

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Temporary high-elevation lakes represent vulnerable and unstable environments strongly threatened by tourism, hydrogeological transformations and climate changes. In-depth scientific knowledge on these peculiar habitats is needed, on which to base integrated and sustainable management plans. Freshwater diatoms, thanks to their high diversity and their particular sensitivity to the water chemistry, can be considered powerful ecological indicators, as they are able to reflect environmental changes over time. The aim of the present study was to analyze the diatomic diversity of the Pilato and Palazzo Borghese lakes, two small temporary high-mountain basins, falling in a protected area within the Apennine mountains chain (central Italy). Diatoms data were collected, at the same time as 12 physicochemical parameters, through six microhabitat samplings, from 17 June to 30 August 2019. In both lakes, a total of 111 diatomic species and varieties were identified. The most species-rich genera were Gomphonema, Navicula, and Nitzschia. The Pilato Lake showed a diatomic community dominated by few species, favored by more stable and predictable environmental conditions than the Palazzo Borghese Lake, which hosted a more diversified community, guaranteed by greater spatial and temporal heterogeneity. Both lakes were characterized by the presence of diatomic species typical of good quality waters. The occurrence of numerous aerial species reflected adaptation strategies adopted to colonize environments subjected to extended drought periods. Endangered diatomic species of particular conservational interest were recorded, confirming the need to preserve their habitats.

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Palaeoenvironmental significance of sponge spicules in pre-Messinian crisis sediments, Northern Italy

Costa

Bavestrello

Cattaneo‐Vietti

et al. 2021

Facies

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The Messinian Salinity Crisis (MSC) created a substantial negative impact on the Mediterranean marine fauna and flora because hypersaline conditions were established in many marginal basins. At the northern margin of the Tertiary Piedmont Basin, Northern Italy, the Messinian successions exposed at Banengo and Moncalvo recorded the transition into and through the MSC with well-preserved nanno-, micro-and macrofossils. Siliceous sponge spicules present in these pre-MSC sediments reflect the sponge population in this area with twenty different morphological types of spicule identified, twelve of them attributable to sponge genera of the modern Mediterranean sponge fauna. The most common genera were Stelletta, Geodia and Dercitus, with fewer records of Tethya, Chondrilla, Alectona and Samus. Only two types of spicule belong to species not currently present in the Mediterranean sponge fauna and are putatively attributed to the tropical species Stelletta purpurea and Diplastrella megastellata. The sponge assemblage thriving before the onset of the MSC provided new information on the sponge diversity and palaeoenvironment of this northern sector of the palaeo-Mediterranean basin over this crucial period. These data, integrated with information derived from the associated fossils (nannofossils, benthic and planktic foraminifers, and bryozoans), indicate that the considered sites were coastal localities, with sediments rich in an organic matter likely derived from phytoplankton blooms. At both sites, the presence of patchy rocky substrates on the seafloor is testified by a diversified group of sponges typical of hard substrata. These rocks were, very likely, carbonate as suggested by the presence of spicules of typical boring sponges. In the studied sites, common epiphytic foraminifers and bryozoan segments indicate the presence of Posidonia seagrass or algal meadows.

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Integrated micropaleontological study of the Messinian diatomaceous deposits of the Monferrato Arc (Piedmont basin, NW Italy): New insights into the paleoceanographic evolution of the northernmost Mediterranean region

Cited by 7 publications

References 92 publications

From biogenic silica and organic matter to authigenic clays and dolomite: Insights from Messinian (upper Miocene) sediments of the Northern Mediterranean

From biogenic silica and organic matter to authigenic clays and dolomite: Insights from Messinian (upper Miocene) sediments of the Northern Mediterranean

The Diatomic Diversity of Two Mediterranean High-Elevation Lakes in the Sibillini Mountains National Park (Central Italy)

Palaeoenvironmental significance of sponge spicules in pre-Messinian crisis sediments, Northern Italy

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