United States

The Luminescence dating method is based on the capability of quartz and k-feldspar to absorb and store energy from environmental ionising radiation and release it after sunlight exposition. The method date the last daylight exposure of these siliciclastic grains. Sun exposition also for very little time bleached (zeroed) the system that, eventually, could be recharged again. Recently, Sohbati et al. (2011) demonstrated that the zeroing effect of light on luminescence signal works also on rock surfaces, leaving an increasing residual signal with depth. On this principle is based a brand-new luminescence technique termed Rock Surface Dating (RSD), that analyses the luminescence signal-VS-depth profiles and can yield both burial and exposure ages of rock surfaces. The RSD is used to calculate the burial age of gravelly sediment (pebbles to boulders) and, it has been successfully applied on Holocene gravelly beaches deposits (Souza et al., 2021). The Late Pleistocene marine terrace of Cala Mosca (Sardinia, Italy) is composed of gravel beach deposits and considered one of the Mediterranean Sea reference-sites for the Last Interglacial (Eemian/Tyrrhenian; Marine Isotopic Stage 5e). The sedimentary sequence is characterised by a thick cobbly transgressive gravel lag resting unconformable on the wave cut platform carved on Miocene bedrock overlain by a well-developed, highly fossiliferous, prograding mixed sandy-gravelly pocket beach system. The attribution to Tyrrhenian of the marine terrace, has been based on presence of fossils of the so-called “Senegalese fauna” (Strombus bubonius and Patella ferruginea) considered typical of the Eemian/Tyrrhenian stage and U/Th ages performed on fragments of Cladocora caespitosa (138 ± 8 ka and 122 ± 5 ka) which confirmed the MIS 5e stage. Here we present the preliminary independent results performed with RSD technique on cobbles collected at the base of the Cala Mosca gravelly beach deposits. The RSD estimated burial age is of 117 ± 8 ka. This is in good agreement with previous data, confirming the enormous potential of RSD method to date gravel beach deposits and extending its application to Late Quaternary period. Furthermore, the cobbles exposure-time before burial has been estimated of about two months, giving some clues on the beach dynamics.

SGI 2021

The Rock Surface luminescence Dating: a new technique to date Late Quaternary gravelly marine terraces

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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.


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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.

poster

Here we present an integrated calcareous plankton and geochemical record from the Tethyan Terche and Madeago sections (NE Italy), deposited in a middle-lower bathyal setting. These sections record a negative Carbon Isotope Excursion corresponding to Eocene Thermal Maximum 2 (ETM2, ~54 Ma). Our planktic foraminiferal and calcareous nannofossil records show significant, though temporary, changes in both sections across this event. No significant dissolution occurred that could have affected the assemblages. Warm index surface-dweller Acarinina increased while of the deeper-dweller chiloguembelinids and subbotinids declined in abundance. A test reduction of up to 50% compared to pre-event sizes for both surface- and deeper dwellers planktic foraminiferal is particularly marked at Madeago. While symbiont bleaching can reduce growth, both symbiont and asymbiotic planktic foraminifers were affected at the same scale in our sections at the ETM2, and hence not a likely cause of the size reduction. The enhanced surface remineralization of organic matter due to warming may have reduced the food input at the thermocline, thus contracting the deeper ecological niches. The calcareous nannofossil assemblages provide evidence of increased surface water eutrophy during the ETM2. The increase in small placoliths Toweius and Ericsonia may indicate that dwarfism also affected nannofossil assemblages, though to a lesser degree. We thus hypothesize that the ETM2 perturbation impacted the entire upper water column possibly changing stratification and niche spaces. To establish whether the observed dwarfism was related to environmental stressors which are not commonly linked to the ETM2 climatic perturbation, we quantified the Hg (ppb), TOC (wt%) and Hg/TOC (ppb/wt%) geochemical proxies through our sections. Results show an increase in Hg in both sections at the base of the ETM2. We attribute this increase to coeval submarine igneous events that might have introduced biolimiting metals, which changed plankton productivity and possibly affected test size. However, we cannot exclude reworking of the metal because we record an increase in sedimentation rate and nannofossil rework at the ETM2. We suggest that the plankton dwarfism, here documented for the first time across the ETM2, could be the result of the coupled effect of increase in biolimiting metals and changes in the physicochemical structure of the upper water column.

Evidence of Tethyan calcareous plankton dwarfism across the ETM2

We present here data on changes in Mg/Ca derived paleotemperatures from the southern Atlantic Site 1263 across the Early Eocene Climatic Optimum (EECO; ~53-49 Ma). The EECO, that records the peak of Cenozoic warmth, and possibly of the CO2 pressure (e.g., Zachos et al., 2001, Sciences; Anagnostou et al. 2016, Nature Inglis et al., 2020 Clim. Past), induced climatic and paleoceaographic changes that significantly impacted planktic foraminferal assemblages. The main change, recorded form several sites (Atlantic and Pacific Oceans, Tethys) is the permanent and markedly declined in abundance and diversity of the mixed-layer dwelling symbiotic bearing genus Morozovella coupled with the increase of genus Acarinina (Luciani et al., 2016; Luciani et al. 2017a; Luciani et al. 2017b; D’Onofrio et al., 2020). This decline occurred at the EECO beginning, close to the carbonate isotope excursion known as ‘J event’ (~53 Ma). In addition, a reduction in morozovellid test-size occurred across EECO as recorded from Atlantic ODP sites 1051, 1258 and 1263. Several potential stressors may explain both the reduced size and the permanent morozovellid decline. These include algal photosymbiont inhibition (bleaching), increase in temperature, decrease in pH and/or calcite saturation state. Even though a bleaching test at Site 1051 revealed only a transient reduction of algal-symbiont relationships just after the morozovellid abundance decline (Luciani et al., 2017a), a general reduction in δ13C gradient (~ 0.5 ‰) between morozovellids and the thermocline dweller Subbotina spp. through the EECO is recorded from the Atlantic sites. This suggests that the former group became less reliant on photosymbionts and/or may have moved to slightly deeper depth in the mixed-layer. Even though a link with the EECO perturbation is evident, the driving causes of the recorded modifications are still unknown. Detailed paleotemperatures across the observed changes were lacking. We therefore obtained Mg/Ca derived paleotemperatures from Site 1263 through Laser Ablation, a method widely applied. Preliminary Mg/Ca data reveal that Morozovella crater and M. subbotinae record a major warming across EECO greater than that of Acarinina coalingensis and A. soldadoensis.Although the exact causes of photosymbiont bleaching can be manifold, increased temperature is considered a primary cause of bleaching in present tropical larger benthic foraminifera (e.g., Hallock, 2000). The higher rise in temperature recorded by morozovellid may explain the reduced symbiotic relationship and suggests one possible reason for their reduction in abundance and size, even though other potential stressor such as pH decrease should be explored. We record from Site 1263 also a temperature increase at the thermocline that may be one of the causes explaining the drop in abundance of subbotinids and chiloguembelinids at the EECO. 

Mg/Ca Paleotempertures changes at the demise of plankic foraminiferal genus Morozovella across the Early Eocene Climatic Optimum  (Site 1263, Southern Atlantic Ocean)

The genus Xenophora comprises species of marine gastropods, known from the Cretaceous and still living today, which have the ability to form their shells agglutinating objects with different origins, from other shells to bio- or lithoclasts. Different agglutination potentials are shown by species of Xenophora, from species lacking attachments to others completely covered, as the case of the Mediterranean Xenophora crispa (König, 1825). Shell sections of fossil (Early Pleistocene, Arda and Stirone Rivers, Italy) and recent specimens (Mediterranean Sea, Spain) of X. crispa were here analyzed at the Scanning Electron Microscope (SEM) and powders, collected from different parts of the shell, at X-Ray Diffraction (XRD), in order to characterize in detail the microstructure and the mechanisms, function and behaviour of the agglutination in the same species through time, in this case over about 2 millions of years. Also, as the Arda and Stirone River sections were deposited during the Early Pleistocene, this research allows to examine if and how these parameters varied during a climate change. Indeed, the Early Pleistocene was a time interval characterized by several climatic oscillations linked to glacial/interglacial cycles and the Mediterranean area was strongly affected by these climatic changes showing in marine environment a progressive climatic cooling. This study shows that the functional purpose of the agglutination in X. crispa may be related to a snowshoe strategy to successfully colonize muddy substrates, coupled with tactile and olfactory camouflage. Indeed, this species secretes in the columella and peripheral edge of both fossil and recent specimens a less dense and a more organic rich calcitic fabric, possibly to lighten the shell thickest parts in order not to sink in soft sediments and to facilitate the shell raising from the substrate to create a protected feeding area. This behaviour and the shell microstructure seem to have been maintained by X. crispa over 2 My time span, thus allowing to suppose that this species did not suffer the climatic cooling of the Early Pleistocene.

From the Early Pleistocene to the Recent: how is Xenophora crispa biomineralization varied?

The Mediterranean is a semi-enclosed sea formed by two sub-basins, the eastern Mediterranean (E-Med) and the western Mediterranean (W-Med), connected through the Strait of Sicily. Four main deep-water convection cells fuel the Thermohaline circulation of the Mediterranean (Med-THC). In the E-Med, deep water is formed in the Adriatic Sea and the Aegean Sea, while an intermediate-water is formed in the Levantine Sea (Levantine Intermediate Water, LIW). The Western Mediterranean Deep Water is formed in the Gulf of Lions. Since all cells are interconnected, variations in one cell could be transferred to the others by modifying the Med-THC. The present study focuses on the analysis of the sediment core NDT-6-2016 at the west flank of Sicily channel, recovered at 1066 m of water depth, which is nowadays located bellow the interphase layer between the eastern and western originated water-masses. Therefore, this location is suitable for exploring changes in the inter-basin water exchange along the last 15 kyr cal. BP. Nd isotopes measured in planktic foraminifera coatings allow estimating changes in the export rates of the eastern Mediterranean source-water (ESW) masses underlying the occurrence of two anomalous events: The Younger Dryas characterized by an outflowing excess of ESW and the last sapropel (S1) with opposite circumstances. The export rates of EMS waters are estimated to have been up to three times higher during the YD than during the S1. These results are discussed in the context of other geochemical, sedimentological and micropaleontological proxies that allow us to have a more complete picture of the oceanographic changes associated to these events of Med-THC major reorganization.

Water-Masses exchange through the Straitof Sicily during the Last Deglacial and Early Holocene

Transgressive deposits accumulate during relative sea-level rises and accompanying the landward migration of the coastline can be recognised through gradual or abrupt landward shifts of facies, or  deepening-upward  facies trends that culminate in a surface of maximum flooding. The offshore area of Marzamemi (SR, Sicily), in the south-eastern portion of the Hyblaean foreland, represents an excellent site for the study of transgressive deposits and their connection with the sea-level changes. From a geomorphological point of view, the study area is part of the Pantani area, a coastal stretch characterized by a series of lagoons, elongated parallel to the actual coastline and separated by the open sea by elevated ridges of Tyrrhenian calcarenites and by coastal sand barriers.In this area, through the integrated interpretation of  new multibeam data (MBES) and high-resolution seismic profiles (SPARKER), we have reconstructed the development of deposits connected to the Transgressive System Tract and Highstand System Tract of the last eustatic cycle. Along the northern sector, three submerged lagoonal systems (L1, L2 and L3) mark important steps, of the Late Quaternary sea-level rise, possibly representing periods of lowered sea-level rise. The deepest lagoon L1 is bounded to the west by the 45 m isobath, which identifies a cuspate relief representing a paleo-coastline constituted by the outcropping Tyrrhenian substratum (Calcarenites of Marzamemi), only locally covered with highstand deposits. Southwards, the L1 is characterized by a smooth morphology interpreted to correspond with beach deposits, while in the central portion a system of tidal bars and channels is widespread as imaged in the seismic profiles. Westwards, the lagoon L2 marks a second step of the last sea-level rise, with the development of a paleo-coastline in correspondence of the 35 m isobath. The L2 shows morphological features similar to the L1, with the presence of extensive beach deposits to the south and two cliffs that bounded L2 to the west and to the east. Finally, 20 m isobath corresponds to the third significant step of the sea-level rise, and is associated with the paleo-coastline bounding to the west the lagoon L3. The latter hosted two islets and was confined to the east and west by high cliffs made up by the calcarenite substratum. Only to the south L3 displays a smooth morphology corresponding to beach deposits. Furthermore, a wide delta oriented west-east and characterized by an irregular trend due to the presence of numerous distributary channels is present within L3. In the southern sector, likely due a different inheritance of regressive morphologies the transgressive setting features was significantly different and submerged lagoons did not form. Here the outcropping calcarenite substratum is affected by the development of meandering paleo-rivers and karst structures, such as numerous depressions (poljes), commonly developed along the Mediterranean karst regions.

Morphological quaternary evolution of coastal plain in response to sea-level changes: example from South-East Sicily

The reconstruction of timing and modes of the last marine transgression is often hampered by the scarceness of available indicators due to bad preservation, lack of formation or difficult accessibility. This is particularly true for the first period of the Holocene, between 11.7 and 7.5 ka cal BP, when the rate of transgression was high and the relative sea level rose from -80 to -10 m MSL (Vacchi et al., 2016). Shoreline deposits and erosional landforms have long been recognized as the main geomorphological indicators of past sea levels. However, such features (e.g. beach ridges, tidal notches) can only form and be preserved over peculiar geometries of the shelf (Cattaneo & Steel, 2003). A major group of potential indicators which, up to date, is largely underrepresented, is constituted by paleo tidal inlets. Being excavated up to several meters below the surrounding lagoon and filled during the migration or deactivation of the inlet, such landforms may represent outstanding archives with a potentially high chance of preservation from erosion. Paleo tidal inlets can be recognized and cataloged through shallow sub-bottom profiling methods. Through the analysis of almost 7000 km of high resolution seismic profiles collected in the northern Adriatic Sea, more than 100 paleo tidal inlets were recognized. Such features date to the early Holocene and constitute one of the few widespread witnesses of the post-LGM marine transgression in the area. The paleo tidal inlets of the northern Adriatic represent essential features for the paleo-geographic and paleo-environmental reconstruction and provide new data to constrain the position of transgressive coastlines. Reference examples of paleo tidal inlets have been recognized near the Po Delta (Ronchi et al., 2019), offshore of Chioggia (Ronchi et al., 2018), but also in the Gulf of Trieste. The unexpected presence of widespread lagoons environments during a phase of strong RSL rise is the result of the interplay between sediment dispersal operated by the main fluvial actors of the area and phases of slowdown of the RSL rise.

Transgressive lagoons and paleo tidal inlets in the northern Adriatic Shelf: geomorphological indicators of the last RSL rise

The study of the climate changes of the last centuries allows comparison of data from historical documents, instrumental and paleodata records with multi-decadal variability arising from external forcing and internal climate variability. In this framework, the marine fossil records represent a fantastic archive to document the climatic variability over the last 500 yrs. In this framework, Globorotalia truncatulinoides oscillations have been recorded from several marine sediment cores collected in the central and western Mediterranean Sea. G. truncatulinoides represents a deep dwelling winter species in the Mediterranean Sea and its life-cycle is characterized by a vertical migration in the water column. The abundances of this species over the last 500 yrs demonstrates its potential value as bio-indicator of particular oceanographic condition during the Maunder Minimum (MM) event of the Little Ice Age (LIA). The comparison between the G. truncatulinoides abundance patterns of the Balearic Basin, central and south Tyrrhenian Sea and central and eastern Sicily Channel allows to highlight a similar response of this species during the MM event in the central-western Mediterranean Sea. The ecological meanings of this species and its peculiar high abundance percentage values in the total assemblages suggest the development of enhanced vertical mixing conditions during MM winter season with a strong advection of nutrients from the nutrient-rich deeper layers and enhances the productivity levels in the mixed layer. The intensified vertical mixing could be linked to persistence of an atmospheric blocking event recorded by several authors during the MM. In fact, this time-interval is characterized by an atmospheric blocking event. These particular climatic conditions could be responsible of intense deep vertical mixing phenomenon during the winter season producing the ideal ecological conditions for G. truncatulinoides proliferation. In addition, we suggest that maximum abundance of G. truncatulinoides left coiled is a response to more active dense water formation within the Mediterranean Sea during a cold time-period such as the MM. This research has been financially supported by the ERC-Consolidator TIMED project (REP-683237).

The planktonic foraminifera Globorotalia truncatulinoides in Central - Western Mediterranean Sea during the Little Ice Age

During the late Quaternary, the Kurdistan Region of Iraq (north-eastern part of ancient Mesopotamia) was the scenario of several fundamental cultural events including the dispersal of Homo to Eurasia, the origin of agriculture and adoption of domesticates, the beginning of urbanization, and the formation of the first state entities. The role played by climate and environmental changes on these cultural processes was highly debated, but local, continuous, and well-dated paleoclimatic records are still missing. In this contribution, we present the preliminary results of a palaeoclimatological and paleoenvironmental investigation in this area, which aims to reconstruct a detailed framework of the relationship between global climatic changes, regional environmental and hydrological responses, and human adaptation during the Late Quaternary, with a special look to the Holocene. Speleothems were collected along the eastern slopes of northern Zagros from the Hassārok Cave, near Shaqlawa township, in the northern Kurdistan Region of Iraq. Preliminary geochemical and geochronological results provide information on Holocene climatic variability in the region. Environmental and paleoclimatic data have been compared with archaeological information to infer and quantify the effects of climatic changes (if any) on human exploitation of natural resources, settlement dynamic and major shift in subsistence strategies and land use.

A speleothem-based reconstruction of the Late Quaternary climate-environmental-human nexus in the Kurdistan Region of Iraq

An improved understanding of the chronology of Antarctic ice sheet deglaciation since the Last Glacial Maximum-LGM represents a fundamental tool to better define the origin of past and future meltwater influx in the global oceans (Whitehouse et al., 2012). Relict shorelines and other evidence of past Relative Sea Level (RSL) evolution were widely used to understand past ice sheet history and to improve predictions of climate-sea level relationship evolution (Khan et al., 2015). In the last decades, RSL data in the Antarctic region have been mostly produced using raised marine features such as beach and marine deposits, marine terraces and isolation basins. The chronology of these paleo sea-level stands has been established through geomorphological and stratigraphic techniques (John & Sugden, 1971; Fretwell at al., 2010) and supported by radiometric dating from samples found in beach deposits and marine/freshwater sediments (Simms et al., 2011; Watcham et al., 2011). Here we present a new cartographic approach, currently carried out along the Antarctic Peninsula and South Shetland Islands, which has a twofold aim: (i) the creation of an open access dataset including information about paleo-shorelines by using a uniform collecting pattern, and (ii) the production of a coherent database which can be used for improved spatial analyses useful to define the Antarctic shoreline evolution as well as better constrain the chronology of the deglacial history. As demonstrated by other free data-repositories (https://www.bgs.ac.uk/geological-data/national-geological-repository/) and similar examples (https://warmcoasts.eu/world-atlas.html), the new cartographic instrument, built in web-GIS format, will represent a very important tool for Antarctic coast investigations and a tool for better focusing future researches.

Implementing a cartographic repository of the postglacial Antarctic paleo-shorelines

The marine sedimentary sequence of Cala Mosca bay (Sw Sardinia) is well-known and studied since the beginning of the past century and is considered a key stratigraphic section for the Marine Isotope Stage (MIS) 5e (~125 ka) or “Tyrrhenian/Eemian” highstand around the Mediterranean basin. In particular, this sedimentary wedge is interpreted as a beach system placed on a wave-cut platform forming a single marine terrace craved on the Miocene bedrock. A newly performed multidisciplinary (sedimentological, stratigraphical, chronological and tectonical) approach clearly reveals that the Cala Mosca single geomorphological marine terrace is in fact the result of two superimposed marine units (unconformity bounded unit U3a and U3b) separated by a composite unconformity surface associated with two different transgressive-regressive (T-R) cycles (T1 and T2). The lower T1 cycle is characterized by a cobbly transgressive gravel lag resting unconformable (wave-cut platform) on Miocene bedrock overlain by a well-developed prograding mixed sandy-gravelly pocket beach system (regressive phase). Obtained luminescence ages (pIRIR225 protocol), date T1 at 137±7, 134±7 ka confirming the MIS 5e stage attribution. The second marine cycle T2 lays unconformable on T1 and consists of a m-thick maximum gravelly body interpreted as a poorly-developed beach system formed on a rocky shore at the toe of retreating cliffs (transgressive phase). Obtained luminescence age dates T2 at 92 ± 6 ka supporting the MIS 5c stage attribution. T1 and T2 two cycles are separated by a composite unconformity surface developed during the post-MIS 5e sea-level fall and subsequent rise (early MIS5c). The T1 deposits were almost completely eroded during the second transgressive event and T2 sedimentary bodies reoccupied in part the same position of T1 forming an apparent single morphological unit. In this new light, the paradigm of Late Pleistocene tectonic stability of the Island seems to be abandoned and a more complex evolutionary history of Sardinia has to be build up. In particular, the interplays between global sea-level changes, region low-rate uplift, and localized rapid normal fault activity would explain the presence of a MIS5e and MIS5c composite marine terrace at the "locus typicus" of the Eemian in Sardinia.

The Rock Surface luminescence Dating: a new technique to date Late Quaternary gravelly marine terraces

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