United States

Cold seep environments are often associated with chemosynthetic communities at the seafloor, reflecting the spatial distribution and magnitude of methane fluxes in the sediment underneath. Quantifying areal fluxes and rates of consumption via anaerobic oxidation of methane (AOM) is extremely important for better understanding the future response of the benthic filter to climate-induced ocean warming. Short-time-scale transient processes such as tides, seasonal bottom water temperature fluctuations are efficiently recorded in unsteady-state pore water profiles. However, to interpret the long-term trends in methane fluxes and controlling factors one needs to integrate this data with sedimentary proxies and conduct paleo-reconstructions. We present a case study from the SW Barents Sea at Leirdjupet Fault Complex, where active methane seepage has been observed in summer 2018 from 295 m to 350 m water depth and is associated with microbial mats and tubeworms. We discuss the modern seepage conditions based on pore water data and habitat maps generated through Object-Based Image Analysis (OBIA) classification, and discuss the history of seepage recorded in sediment cores. A new ROV survey conducted in June 2021 in the same area revealed a very different situation compared to 2018, consistent with the long-term reconstructions since Late Weichselian deglaciation.

SGI 2021

Every cold seep tells a story: the case study of Leirdjupet Fault Complex, SW Barents Sea

**Attenzione, gli orari riportati nel PROGRAMMA (icona calendario) si riferiscono al fuso orario locale dell’utente. Il fuso orario ufficiale del Congresso è Central European Time (CET).**

L'Istituto Nazionale di Oceanografia e Geofisica Sperimentale - OGS e il Dipartimento di Matematica e Geoscienze dell'Università di Trieste sono orgogliosi di ospitare il 90° Congresso della Società Geologica Italiana a Trieste dal 14 al 16 settembre 2021. La modalità del congresso è interamente online.

Con il motto "Geologia senza frontiere" questo evento mira a promuovere le Scienze della Terra come disciplina scientifica proiettata nel futuro, oltre i confini geografici, politici e disciplinari, per comprendere meglio l'interno del Pianeta Terra e la struttura del sottosuolo, difendere la società da pericolosi eventi geologici, comprendere meglio la variabilità climatica, pianificare l'utilizzo delle georisorse in modo etico e nel rispetto dell'ambiente.


**Please note, times listed in the SCHEDULE tab (calendar icon) reflect YOUR LOCAL TIME ZONE. The main timezone for this conference will be Central European Summer Time.**

The National Institute of Oceanography and Experimental Geophysics - OGS and the Department of Mathematics and Geosciences of the University of Trieste are proud to host the 90th Congress of the Italian Geological Society in Trieste on 14-16 September 2021.  The Congress will be held entirely online.

With the motto "Geology Without Borders" this event aims to promote Earth Sciences as a scientific discipline projected into the future, beyond geographical, political and disciplinary boundaries, to better understand the interior of Planet Earth and the structure of the subsurface, defend society from dangerous geological events, better understand climatic variability, plan the use of geo-resources in an ethical way and respecting the environment.


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Earth Sciences should be understood not only as necessary for a better understanding of the interior of the planet Earth, but also as a defense of society from dangerous geological events, for the understanding of climatic variations, for the planning and use of georesources in a ethical and respecting and protecting the environment.

technical paper

A morphodynamic study of a scraped artificial dune built on the sandy beach of Porto Garibaldi (Comacchio, Italy) as a barrier to protect beach facilities from sea storms during the winter season was implemented by analysing Unmanned Aerial Vehicle (UAV)-derived products, such as digital elevation models (DEMs) and orthophotos. The role of elevation data uncertainty and uniform thresholds for change detection (TCDs) on the interpretation of morphodynamic estimations related to non-extreme sea and wind conditions was analysed. The analysed DEMs showed a reasonable agreement with ground truth surveys (Global Navigation Satellite System, GNSS), with RMSE < 0.05 m. The significance of the identified changes was determined by applying a set of TCDs. In this case, a threshold of 0.15 m was able to detect the majority of the morphological variations. However, the set of TCD ≤ 0.15 m was considered to properly discuss the significance of minor changes and the uncertainty of volume change calculations. During the analysed period (21 December 2016–20 January 2017), while water levels and waves affected the front of the artificial dune by eroding the berm area, the aeolian forcing (i.e. winds) remodelled the entire dune, moving the loose sand around the dune and further inland. Notably, sediment volumes mobilised by sea and wind forcing were comparable. In the case of extreme storms, it is expected an important degradation of the dune while preserving the touristic concessions from flooding and beach erosion. It is suggested that UAV-derived coastal morphological variations should be interpreted by integrating a set of uniform thresholds to detect significant changes with the uncertainty generated by the propagation of the original uncertainty of the elevation products. Additionally, the characteristics of the morphodynamic drivers should be evaluated by adopting uncertainty-aware approaches. In this way, the contribution of subtle morphological changes, which magnitudes are comparable with the instrumental accuracy and/or the assessed propagated uncertainty, can be properly accounted for.

Uncertainty of UAV-derived DEMs and significance of detected morphodynamics: the case study of a scraped dune in the Northern Adriatic

Coastal erosion coupled with human-induced pressure has severely affected the coastal areas of the Mediterranean region in the past and continues to do so with increasing intensity today  (Luijendijk et al., 2018). In this context, the Pisa coastal plain shows a long history of erosion, which started at the beginning of the nineteenth century. In this work, shoreline positions derived from historical maps as well as airborne and DGPS (Differential Global Positioning System) surveys were analyzed in a GIS (Geographic Information System) environment to identify the main changes that have occurred in the last 142 years. These analyses were compared with 100 years of discharge data measured at the S. Giovanni alla Vena gauge to identify a possible correlation between the two sets of information. Finally, Sentinel-2 and Landsat images were studied to identify the dispersion of sediments transported by the Arno River. In particular, we found a minimum of fluvial discharge in the years 1954, 1978, and 2012 corresponding to a peak of erosion, while the reduced erosion rate and the fluvial discharge increased in the years 1928–1944, 1954–1975, and after 2012 (Bini et al., 2021). A key topic in the study of the coastal evolution, is the availability of a reliable and quick method of shoreline survey. In this context we would like to identify a new and valid beach topography-based algorithm, able to identify the shoreline. We apply the Structure from Motion (SfM) techniques to reconstruct a high-resolution Digital Elevation Model using a drone for image acquisition. The algorithm is based on the variation of the topographic beach profile caused by the transition from water to sand. The SfM technique is not efficient when applied to reflecting surfaces like sea water resulting in a very irregular and unnatural profile over the sea (Kohv et al., 2017). Taking advantage of this fact, the algorithm searches for the point in the space where a beach profile changes from irregular to regular, causing a transition from water to land. The algorithm is promoted by the release of a QGIS v3.x plugin, which allows the easy application and extraction of other shorelines (Luppichini et al., 2020).

Investigate the coastal environment evolution: climatic and morphological cause and a new method for shoreline identification

The present geomorphology of the Volturno river delta and related strandplains is largely a product of an intricate long-term relationships between geological evolution and human impacts. In order to assess the main drivers of the changed landscape in the last 150 years, a multidisciplinary study was carried out by combining historical and geological data. A 150 year cartographic sources were acquired, georeferenced and managed into a GIS environment. Some 1800 well log stratigraphic data were acquired and interpreted to reconstruct the stratigraphic architecture of the plain. Historical analysis has produced documentary evidence of the geomorphological evolution of the area since the end of the XVII century, when, during the Spanish vice-kingdom, it was subjected to major land reclamation. More than 500 km of canals were built in the coastal area. The development of agriculture and farming on reclaimed land promoted urbanization and increasing landscape fragmentation. The peak was attained between the 1960s and the 1990s, when landscape pattern structure increased in complexity with major alterations of alluvial channels and of the deltaic environment, and retreat of the coastline. Land use maps were reconstructed for the 1957 and 2012. The overgrowth of the urban areas to the sea, coupled with intensification of agricultural and tourism activities, resulted in the loss of high quality ecosystems such as the humid coastal setting, the lacustrine/marshy back-dune area and, in most cases, also the beach-dune system. The negative sedimentary balance resulting from the reclamation works on the river courses, together with the interventions along the Volturno river basin, resulted in an accelerated and severe coastal erosion. Coastline displacement was calculated at 7 time points, showing timing and causes of trends and rates of variation. The anthropic impacts were compared with the subsidence trends previously assessed. The lack of an unequivocal correlation of the latter with agricultural land use and zootechnical farm location indicates that these human activities do not exert a significant impact on regional subsidence rates. On the contrary, a net overlay of the subsiding areas with the geological architecture was recognized and in particular with the areal distribution and thickness of deposits such as clayey silts, clays and peats. From geotechnical point of view, these soils can be classified as fine-grained soil (mostly clayey) with poor mechanical properties (high compressibility and low strength). Moreover, the inclusion of significant amount of peat and organic matter clearly reflects high values for the coefficient of secondary compression. The subsidence rates, coupled with the sea level rise due to climatic changes, increase the vulnerability of the coast to erosion, flooding and storm surge and aquifer salinization.

The changing geomorphology of the Volturno delta and coast (northern Campania, Italy): human influence and geological architecture

Shoreline variability is a key factor in coastal studies. In the last decades, remote sensing techniques have been widely applied and several algorithms for shoreline detection have been developed to extract the so called Satellite Derived Shorelines (SDS). Multispectral and hyperspectral satellites provide images covering large areas with high spatial and temporal resolution, allowing to perform a near real-time analysis of shorelines worldwide. There are several open source algorithms (e.g. SHOREX (Pardo-Pacual et al., 2012) and CoastSat (Vos et al., 2019)) for shoreline detection at sub-pixel level, using freely available multispectral images (Landsat and Sentinel constellations). However, open source applications for SDSs analysis using hyperspectral data are not yet available. Recently the Agenzia Spaziale Italiana (ASI), has launched the PRISMA mission (PRecursore IperSpettrale della Missione Applicativa), offering medium-spatial (30 m) and high spectral (smaller than 12 nm) resolution. In this study we present the performance of the CoastSat algorithm applied to multispectral images. Additionally, we show the capability of hyperspectral techniques applied to PRISMA images to detect the shoreline given their higher spectral resolution. The performance of the CoastSat algorithm was evaluated in two different microtidal beaches of the Italian Adriatic coast (Emilia-Romagna and Marche Regions): Punta Marina (PM) and Sirolo (SIR). The beach at PM is a typical intermediate fine-sandy beach, while SIR is a mixed coarse sand-gravel reflective beach. SDSs were compared to RTK-DGPS surveyed shorelines, measured following the upper limit of the swash zone, and with shorelines derived from a video monitoring station, after manual mapping on variance images. The shoreline derived from in-situ surveys were coincident with Landsat-5, Landsat-7 and Sentinel-2 satellite overpasses The influence on the identification of SDSs of the run-up extent and beach morphodynamic state was evaluated. The obtained RMSE ranges between ~ 6.5 and 14 m at both sites, indicating that the shoreline is effectively obtained from multispectral images at sub-pixel level. In addition, we analysed the shoreline derived from a PRISMA hyperspectral image of PM. We found that similar results can be obtained using hyperspectral images.

Performance of remote sensing algorithms for shoreline mapping under different beach morphodynamic conditions

The Mediterranean coastal areas have been recognized as the most sensitive regions to actual climate and environmental changes. The increased frequency, intensity, spatial extent, duration, and timing of storm events due to climate change can increase the susceptibility of low-lying coastal areas to seawater flooding. The impact of climate change is expected to be strong in areas characterized by severe anthropogenic disturbances. In this context, the understanding of the interaction between beach dynamics, human impact, benthic marine habitat and climate forcing appears crucial for scientists and coastal planners to evaluate coastal risks and to develop the best measures to mitigate them. This work aims to improve the knowledge of the short‐term effects of storm events on the coastline morphology of natural, microtidal, wave dominated beaches located in the western Mediterranean trough the images processing from the data of video monitoring system at Piscinnì beach (SW Sardinia). The morphodynamic states and the spatial shoreline variability of this natural beach has been assessed in our study, during two years of data acquisition, from August 2013 to August 2015 along a 0.3 km stretch of sandy beach. During this period severe storm events mainly related to south-westerly winds (about 50 km/h on average) were happened. For the evaluation of morphodynamic states we carried out forty-two time-exposure (timex) images from three hundred snapshot, with a frequency of 1Hz, of a single recording interval during the storm events, that allow us to understand the morphology of the shoreface (configuration of bars and troughs). For the spatial shoreline variability, we rectified and georeferenced a single snapshot from the day before, during, and two days after the storm event. These images has been loaded in a GIS software where the shoreline was mapped, and the results showed an erosion and a consequent accretion of the studied beach of about 20 m in two days after the event (SW wind and waves) as a result of the deposition of the Posidonia oceanica beach-cast litter. Another significant result is the clear reconfiguration of nearshore bars linked to the wave energy flux, calculated by the Copernicus Marine Environment Monitoring Service. A better knowledge of this morphological response induced by storm events is crucial for coastal managers to define beach management plans (for example beach cleaning practice), to prevent coastal risk and to understand the importance of seagrass berm deposition in the formation of natural Mediterranean beaches.

Short-term effects of storm events on the coastline morphology of a Mediterranean microtidal wave-dominated beach (Piscinnì, SW Sardinia)

A complex set of feedback mechanisms has allowed our planet to stay habitable for most of its 4.5 billion years of evolutionary history. During this time, life has significantly influenced the surface redox state of our planet, impacting the diversity of minerals available, the planet's atmospheric composition and long term climate stability. While the coevolution of the geosphere and biosphere has been recognized for some time for some events and processes (for example the Great Oxidation Event), the extent and diversity of coupled life-planet processes remains unclear. In this talk I'll review the current knowledge regarding geosphere-biosphere coevolution, highlighting biological processes that have a significant planetary scale impact and might have played a key role in influencing Earth evolutionary trajectory and habitability.

Geosphere and Biosphere co-evolution through space and time

Microbes colonize some of Earth’s most extreme environments, sometimes providing refugees for symbionts and decomposers. The vesicles in porous basalt and basanite of deep-sea volcanoes support flourishing subsurface micro-ecosystems, which are part of the deep biosphere of the igneous oceanic crust. Despite the abundance and antiquity of cryptoendoliths in structural cavities of the oceanic crust, the evolution and ecology of these cryptic ecosystems remain mostly elusive. Here we report morphological and geochemical properties of microbial body fossils in rock samples collected from Vesteris Seamount during cruise MSM86 of MS Maria S. Merian in 2019. The highly porous basanites exhibit densely intergrown filamentous networks and laminated deposits on vesicle walls of probable biotic origin preserved as secondary minerals like manganese- or iron-oxides and others. Morphological evidence suggests the dominance of fungi among filamentous fossils, whereas basal coatings on internal vesicle walls resembling minute stromatolites are interpreted as remains of iron- or manganese-oxidizing chemolithoautotrophic bacteria. Hand samples, thin sections, and polished slabs of vesicular basanite also yielded in vivo fungal mycelia associated with globular, botryoidal, and dendritic stromatolites. The spatial relation and growth of fungal filaments upon a basal microbialite suggests a symbiotic-like relation of the supposably autotrophic bacteria and the heterotrophic fungi. Such association would explain the recent findings of a vital fungi community in the oceanic lithosphere.

Crypts in porous basanite: Extreme environments hosting fungal-bacterial micro-ecosystems in a deep-sea volcano, Vesteris Seamount, Greenland Sea

Microbial communities carry out the core redox reactions that control biogeochemical cycles of elements and nutrients mainly thanks to enzymes that use transition metals as catalytic cofactors, suggesting a direct link with the environmental availability of those metals. As Earth’s biosphere and geosphere have coevolved over time, the availability of these metals has changed, influencing surface redox conditions as well as cycling of elements and volatiles, leading to new and more abundant reductant-oxidant pairs, probably impacting the evolution and distribution of metabolic processes and expanding the network of microbial metabolism. Electron transfer reactions are the common thread of the history of life from the very beginning, and the emergence of proteins capable of incorporating metals that facilitate redox reactions is the foundation of the strong link between biosphere and geosphere. The delivery of life’s relevant transition metals is controlled to a first order by tectonic processes. We present here geochemical and microbiological coupled analysis of data from over 250 geothermal locations globally. Our work aims to look for links between the delivery of biologically important transition metals to the surface through plate tectonics and microbial functional diversity. Our dataset reveals correlations between key microbial functions and differences in the delivery of the key metal cofactors to the surface of our planet. Understanding which processes determine the delivery of biologically important transition metals, and how these affect the distribution of microbial enzymes critical for biogeochemistry, will allow to shed light on the interaction between Earth’s geosphere and biosphere, opening new doors not only on better understanding our planet, but also on what are the characteristics to look for in a planet potentially suitable for life.

Linking plate tectonic settings and microbial functions on a global scale

Subduction zones are critically involved in recycling of volatiles and elements between the surface and planetary interior and play a key role in climate stability and planetary habitability. Both in the forearc and backarc regions the lithosphere is affected by the deformation induced by the plate movements, generally favouring lithosphere fractures formations and the widespread origination of deeply-sourced springs, hot or cold, that carry deep fluids and gases up to the surface. These fluids and gases originate from the subducting slab as well as from the interaction of the rising fluids and melting with the overlying crust, and generate "hot spots" of microbial diversity and activity driven by the sharp redox, geochemical and often thermal gradients. Given their direct connection with the subsurface, deeply-sourced springs can be used as a window into the deep to understand processes happening at depth. To be able to use deeply-sourced springs as conduits to the subsurface we need to be able to deconvolve the surface signals from the deep subsurface ones. Despite the abundance of studies looking at the microbiology of hot springs globally, there are relatively few studies linking microbial diversity to the underlying geological processes, and especially in the backarc regions information are scarce. Here we present data on the microbial diversity of the deeply sourced springs along the backarc of the volcanic complex of Puna, Argentina, and assess the extent of influence from surface processes of the spring communities. We conclude that surrounding soil and shallow subsurface microbial communities minimally contribute to the diversity of the deeply sourced fluids that thus represent key samples to investigate the deep continental subsurface.

Deeply-sourced springs microbial diversity: a window into the deep of the Earth 

Being at the boundary between marine and continental realms, marine caves are affected by wide environmental variability for the interaction of marine and continental waters; for this, they are natural laboratories for studying the effects of seasonal and long-term environmental variability also in the perspective of global changes. The first studies of benthic foraminifera from marine caves of the Mediterranean Sea have been carried out in the Gulf of Orosei in the context of a scientific project which started in 2014 and has continued to this day. They demonstrated that benthic foraminifera are very sensitive environmental proxies in these habitats, due to their high diversity and adaptability. The Bue Marino system is constituted by North, Middle and South Branch which join together close to the coast. The study of benthic foraminifera and sediment texture from surface samples, associated with parameters of bottom water, indicated that the Middle Branch was characterized by warmer, saltier and less oxygenated water than the rest of the cave, and by finer sediment with abundant vegetal debris, probably supplied from the mainland during strongly rainy periods (Romano et al., 2021). Then, it was reasonable hypothesizing that cave sediments, although deposited in enclosed environment, are reliable archives of past climatic changes. A 18 cm long sediment core, collected in 2018 in the Middle Branch, was studied for grainsize and benthic foraminifera in order to highlight evidence of temporal changes of environmental conditions and their causes. In the whole core, sediment texture was homogeneous, with prevailing sand and silt in similar proportions, while clay was less abundant and gravel nearly absent. Two hyaline (Ammonia inflata and A. tepida) and one agglutinated species (Eggerelloides advenus), dominated the assemblage, accounting for a total of 70-92%. A main change occurred along the core, at 11 cm depth, for the shift from an assemblage in the lower section with prevailing A. inflata, to another one where the highly opportunistic E. advenus and A. tepida dominated. Of these two assemblages, the latter was more similar to that recorded in the surface sample (0-2 cm), collected at the same sampling station, for the dominance of E. advenus, despite A. inflata slightly prevailed on A. tepida. It was interpreted as the result of a highly organically-enriched environment where opportunistic taxa benefited of abundant degraded organic material under low-oxygen conditions. The prevalence of the “indifferent” A. inflata in the lower core suggests less stressed conditions with minor supply of continental vegetal debris, probably due to less frequent and/or intense rainy episodes in past times.

Paleoecological reconstruction and modern analogues from foraminiferal proxies in the Middle Branch of Bue Marino Cave (Sardinia, Italy). Work in progress

Every cold seep tells a story: the case study of Leirdjupet Fault Complex, SW Barents Sea

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Uncertainty of UAV-derived DEMs and significance of detected morphodynamics: the case study of a scraped dune in the Northern Adriatic

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Diachronic and environmental analysis in the Ragusa province, southern Sicily (Italy)

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Every cold seep tells a story: the case study of Leirdjupet Fault Complex, SW Barents Sea

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Next from SGI 2021

Uncertainty of UAV-derived DEMs and significance of detected morphodynamics: the case study of a scraped dune in the Northern Adriatic

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Diachronic and environmental analysis in the Ragusa province, southern Sicily (Italy)

Stay up to date with the latest Underline news!

PRESENTATIONS

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RESOURCES

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