Papers by Adriano Mazzini
Mud volcanism is a natural phenomenon manifesting at the surface of the body with spectacular eru... more Mud volcanism is a natural phenomenon manifesting at the surface of the body with spectacular eruptions and a large variety of morphologies resulting both from explosive and effusive activity. In this study, we targeted two large (MVs) in Azerbaijan (Lokbatan and Goturdagh) characterized by different behaviors in eruptive activity. We investigated them using a multidisciplinary approach including field observation combined with drone photogrammetry, InSAR imaging, subsurface multisource survey, geotechnical analyses of mud breccia flows and numerical stability modeling in order to reveal the way the mud flows.Lokbatan most recently erupted in August 2022. Field observations in September 2022, before significant modification by rain, reveal that this most recent eruption, albeit small in terms of extruded mud breccia, triggered the disruption of huge segmented portions of the older mud flows that extend for more than 1 km. This was identified by the formation of series of fractures r...
Quaternary Science Reviews
<p>Lake Baikal (Russia) represents a unique natural laboratory for multidis... more <p>Lake Baikal (Russia) represents a unique natural laboratory for multidisciplinary studies of various geological phenomena. In particular, the diffused migration of fluids at numerous locations throughout this deep basin, manifests at the lake floor displaying a variety of degassing sites.<br>Here we report the geophysical results collected during a dedicated marine expedition conducted in the framework of the international Training Through Research education project “Class@Baikal”. The seismo-acoustic surveys were acquired using a chirp profiler, "sparker" source, and a towed streamer. The data collected from various localities of the lake revealed the presence of acoustic anomalies. We extracted these portions of data to characterize the different types of anomalies that are inferred to be associated with fluid migration and ultimately gas saturation in the sediments.<br>Indicators of fluid saturation are typically represented by dramatic increase or decrease in the amplitude of the signal, change in the wave pattern, inversion of the reflections, line of correlation deviation due to the velocity effect. The dimensions and dynamic characteristics of the signal were determined for each zone displaying one of these peculiarities. Three types were identified - 1) bright spots 2) sub-vertical zones of loss of correlation and 3) local morphologically positive structures. The "bright spot" (type 1) anomalies are mainly confined to faults, zones of vertical fluid migration, and mud volcanic structures. Such anomalies have high amplitude and sometimes display phase inversion. Subvertical correlation loss zones (type 2) are characterized by low amplitudes relative to the host sediments and are sometimes accompanied by "bright spot" type anomalies. Positive morphology (type 3) structures are also often found together with types 1 and 2.<br>Using these data, we created a map of the distribution of the types of amplitude anomalies, presumably associated with the gas saturation in the sediment. Next, we compared this map with the localities of known geochemical anomalies that had been determined from the analyses of the sampled sediments. In addition, the areas of seismo-acoustic anomalies were compared with the areas of the BSR (Bottom Simulating Reflector boundary) that are generally interpreted as an indicator for the presence of gas hydrates. Gas saturation in the sediments was verified by bottom sampling several localities that displayed anomalies type 1-3. Although not all the identified anomalies were ground-truthed, the approach proposed herein represents a promising tool for future sampling campaigns aiming to map the gas composition of various sites of the lake. Conducting accurately positioned coring and measuring the gas content in the sampled sediments, we envisage calibrating these results with the acoustic signature registered in the amplitude anomalies distribution map.</p>
<p>The Barents Sea region is an area of extensive erosion that occurred dur... more <p>The Barents Sea region is an area of extensive erosion that occurred during the Cenozoic due to a tectonic uplift followed by several Quaternary glaciations. Several hydrocarbon fields have been discovered in the region where gas leakage through the seafloor is widespread. One of the promising regions of hydrocarbon occurrence is the north-western sector of the Russian Barents Sea. This poorly studied region has been recently targeted for scientific studies by several expeditions conducted in the framework of the Training Through Research program (TTR). The obtained geophysical and geological data revealed the presence of numerous acoustic and bathymetry anomalies (e.g., gas chimneys, bright spots, pockmarks) that are associated with higher gas content in the sampled sediments.</p><p>Here we combine (i) a set of shallow seismic data acquired during recent TTR expeditions (sparker seismic and sub-bottom profiling sections) with (ii) conventional deep seismic sections and (iii) a database of geochemical surveys of cored sediments. These merged data are used to compile a comprehensive database for the north-western sector of the Russian Barents Sea providing information on:</p><ul><li>the area of the potential Mesozoic reservoirs reaching the seafloor</li> <li>distribution of the seismically interpreted fluid pathways reaching the surface</li> <li>the position of the known or inferred seafloor seepage sites</li> </ul><p>One of the major goals is to correlate the geology of the outcropping strata with the variations of gas and water geochemistry, and ultimately to link the mapped/inferred fluid migration pathways to the Triassic-Jurassic reservoirs which are known to have high hydrocarbon potential in this region. Finally, the compiled database may represent a useful tool to geochemically characterize so far undiscovered hydrocarbon fields.</p>
European geosciences union general assembly, 2016
Moscow University Geology Bulletin, 2021
The Gydratny Fault extends in the SW–NE direction for over 60 km in the central basin of Lake Bai... more The Gydratny Fault extends in the SW–NE direction for over 60 km in the central basin of Lake Baikal. During the Class@Baikal-2019 expedition we conducted a multidisciplinary study coupling seismic and gas sampling obtained from bottom sediment profiles intersecting the fault zone. Seismic profiles revealed that the central and northeastern sector of the fault have a pronounced footwall on the lake floor with stronger acoustic anomalies related to gas saturation in the sediments. The southwestern sector of the fault system is instead less pronounced on the lake floor with increasingly thicker hemipelagic deposits further to the west. All sampling station profiles indicate that the pore gas in the sediments is methane-dominated with greater gas concentrations at the localities above the fault. Accordingly, gas molecular and isotope composition revealed that the highest concentrations are present in the central and northeastern segments of the fault zone and in particular associated with the MSU hydrate-bearing structure and the Novosibirsk and Ukhan mud volcanoes. These structures reveal the highest concentrations of methane and C2+ homologues, as well as the highest methane carbon isotope compositions (δ13CCH4 = –57‰ VPDB) and near-surface gas hydrate accumulations. The southwestern segment of the fault is characterized by the lowest gas concentrations in the sediments and the lowest δ13CCH4 (–76‰ VPDB). By combining the geophysical and geochemical data obtained from the profiles, we propose the dominant gas migration mechanisms at various segments of the Gydratny Fault. Where the fault is well-expressed on the bottom relief (the central and northeastern sectors) focused migration is more pronounced and the thermogenic component of the methane is transported by advection from deeper units. Where the fault underlays relatively thick modern sediments (i.e., in the southwestern segment), deeper rising thermogenic gases and a significant portion of microbial methane are transported by combined diffusion and advection mechanisms, respectively. Our results reveal that this laterally extensive tectonic structure is an efficient pathway for fluid migration hosting numerous mud volcanoes and gas hydrate bearing structures. This study provides useful insights for the interpretation of offshore oil and gas geochemical prospects.
30th International Meeting on Organic Geochemistry (IMOG 2021), 2021
Summary This paper presents the results of surface geochemical exploration of Lake Baikal bottom ... more Summary This paper presents the results of surface geochemical exploration of Lake Baikal bottom sediments. Such studies provide information on the quality, thermal maturity, age, and distribution of the underlying source rock in under-explored and poorly understood basin. The studies presented in the work were obtained during the Class@Baikal expeditions (2014–2020). Gas-geochemical and biomarker study permit determine that the initial organic matter of both gas and oil source rocks has a mixed origin with a predominance of the terrestrial component. Most of the samples of organic matter from the bottom sediments showed a severe biodegradation process. The samples from the oil seep present a unimodal distribution with n-C23 to n-C25 as the major peaks. The CPI values ∼ 0.97, and the Pr/Ph ratio is close to 1 indicating an input of algal/microbial organic matter with a significant input of terrestrial matter. Biomarkers evidence the high maturity of initial organic matter (end of the oil generation zone - the beginning of the gas generation zone). Thus, the ratio Ts / (Ts + Tm) up to 0.78 (Parameter MPI-1 up to 1.59). The δ13C isotopic composition ranges between −26 and −28‰ indicates a terrestrial organic matter origin.
Marine and Petroleum Geology, 2017
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Contemporary studies conducted in northern polar regions reveal that permafrost stability plays a... more Contemporary studies conducted in northern polar regions reveal that permafrost stability plays an important role in the modern carbon cycle as it potentially stores considerable quantities of greenhouse gases. Rapid and recent warming of the Arctic permafrost is resulting in significant greenhouse gas emission, both from physical and microbiological processes. The potential impact of greenhouse gas release from Antarctica is now also being investigated. In Antarctica, the McMurdo Dry Valleys comprise 10% of the ice-free soil surface areas in Antarctica and like the northern polar regions are also warming albeit from lower mean temperatures. The work presented herein examines a comprehensive sample suite of soil gases (e.g., CO2, CH4 and He) concentrations and CO2 flux measurements conducted in the Taylor Valley during the Austral summer 2019/2020. Analytical results reveal the presence of significant concentrations of CH4, CO2 and He (up to 18,447 ppmv, 34,400 ppmv and 6.49 ppmv, respectively) at the base of the active layer. When compared with the few previously obtained measurements, we observe increasing CO2 flux rates (estimated CO2 emission in the study area of 21.6 km2 ≈ 15 tons day-1). The distribution of the gas anomaly, when compared with geophysical investigations, implies an origin from deep brines migrating from inland (potentially from beneath the Antarctic Ice Sheet) towards the coast beneath the permafrost layer. These newly obtained data provide a baseline for future investigations aimed at monitoring the changing rate of greenhouse gas emission from Antarctic permafrost, and the potential origin of gases, as the southern polar region warms.
EGU General Assembly Conference Abstracts, Apr 1, 2019
Warming global climate threatens the stability of the polar regions and may result in cascading b... more Warming global climate threatens the stability of the polar regions and may result in cascading broad impacts. Studies conducted on permafrost in the Arctic regions indicate that these areas may store almost twice the carbon currently present in the atmosphere. Therefore, permafrost thawing has the potential to magnify the warming effect by doubling the more direct anthropogenic impact from burning of fossil fuels, agriculture and changes in land use. Permafrost thawing may also intensify the Rn transport due to the increase of fluid saturation and permeability of the soil. A detailed study of 222Rn and 220Rn activity levels in polar soils constitutes a starting point to investigate gas migration processes as a function of the thawing permafrost. Although several studies have been carried out in the Arctic regions, there is little data available from the Southern Hemisphere. The Italian – New Zealand “SENECA” project aims to fill this gap and to provide the first evaluations of gas concentrations and emissions from permafrost and/or thawed shallow strata of the Taylor Valley, Antarctica. Taylor Valley is one of the few Antarctic regions that are not covered by ice and therefore is an ideal target for permafrost investigations. Results from our field measurements highlight very low values for 222Rn and higher values for 220Rn, suggesting a shallow source. Usually the measured 222Rn activity values are controlled by the radionuclide content in the soil, the temperature of the soil, the porosity of the soil, and the water content. We applied the Akerblom formula to calculate the radon at equilibrium with the activity concentration of the 226Ra on the collected soil samples, and the presence of 222Rn amounts higher than those naturally produced by the outcropping sediments is detected. These results demonstrate the presence of preferential gas pathways through the permafrost from a deep source. It is the first time that this type of study has been performed in Antarctica and can make a significant contribution to understanding the melting permafrost processes and its implications for the environment. This dataset also represents an important benchmark for future measurements to track the melt progress of Antarctic permafrost.
Goldschmidt2022 abstracts, 2022
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Papers by Adriano Mazzini