GMPV8.1 | Fluid Flow in the upper crust: geysers, hydrothermal vents, mud volcanoes and cold seeps and their role for life
Fluid Flow in the upper crust: geysers, hydrothermal vents, mud volcanoes and cold seeps and their role for life
Convener: Adriano Mazzini | Co-conveners: Matteo Lupi, Giuliana Panieri
| Thu, 18 Apr, 10:45–12:30 (CEST)
Room -2.21
Posters on site
| Attendance Thu, 18 Apr, 16:15–18:00 (CEST) | Display Thu, 18 Apr, 14:00–18:00
Hall X1
Orals |
Thu, 10:45
Thu, 16:15
Fluid flow in the Earth’s crust is driven by pressure gradients and temperature changes induced by internal heat. The expression of crustal fluid flow is associated with a range of structural and geochemical processes in the basement and sedimentary basins. Groundwater, hydrothermal brines and gases circulating in the subsurface interact with local structures across different tectonic and geological settings. Under near-lithostatic conditions, fluids and rocks are expelled vertically to the near-surface, featuring a variety of surficial geological phenomena ranging from hydrothermal systems to sedimentary and hybrid volcanism and cold seeps onshore and offshore. These vertical fluid flow expressions and piercement structures are characterised by complex sedimentary deformation and geochemical reactions where life can adapt to thrive in extremely harsh environments, making them ideal windows to the deep biosphere. Several studies have shown that CO2- and CH4-dominated (or hybrid) vents played a key role in the evolution of our planet and the cycles of life during several geological eras. Similar structures on other planets are promising sites for exploration where habitable niches could have been present. Furthermore, the elevated pore pressures often encountered in reservoirs at depth make piercements ideal natural laboratories to capture precursors of seismic events and dynamically triggered geological processes. Yet, the geochemical and geophysical processes associated with the evolution of these vertical fluid flow features and piercements remain poorly understood.
This session welcomes contributions from the community working on magmatic and sedimentary environments and the domains where they interact on Earth and in the Universe using geophysical, geochemical, biological, microbial, geological, remote sensing, numerical and laboratory studies to promote a better understanding of modern and paleo fluid-driven systems in the upper crust. In particular, we call for contributions from 1) investigations of tectonic discontinuities pre-existing geological structures; 2) the geochemical reactions occurring at depth and the surface, including micro- and biological studies; 3) geophysical imaging and monitoring of fluid flow systems associated with vertical fluid expulsion at the upper crust; 4) experimental and numerical studies about fluid flow evolution; 5) studies of piercement dynamics related to climatic and environmental implications.

Orals: Thu, 18 Apr | Room -2.21

Chairpersons: Adriano Mazzini, Matteo Lupi, Giuliana Panieri
On-site presentation
Gerhard Bohrmann, Miriam Roemer, Yann Marcon, Thomas Pape, Chieh-Wei Hsu, Daniel Smrzka, and Ian MacDonald

Asphalt deposits have been described from several places of the ocean floor, like the Gulf of Mexico, the Santa Barabra Basin, the Angolan margin and the southwest Atlantic Ocean offshore Brazil. The term asphalt volcanism has been introduced as a novel type of hydrocarbon seepage after an area of approximately 1 km2 solidified asphalt was found on top of one of the Campeche Knolls in the southern Gulf of Mexico named Chapopote. Visual seafloor surveys revealed extensive surface deposits of solidified asphalt and light crude oil, emanating from sites along the rim of a crater-like structure in 2.900 m water depth. Large areas of the asphalt deposits were colonized by vestimentiferan tubeworms, bacterial mats, and other biological communities. Also discovered alongside the asphalt were locations of sediment/gas hydrate interlayering associated with emanating gas and oil bubbles from the seafloor. Seafloor mapping in the Southern Gulf of Mexico revealed various morphological elevations like knolls and ridges which all are related to salt diapirism of the underlying sediment sequences. Most of those features show crater like areas associated with seepage. During recent expeditions, the crater structures of Mictlan Knoll and Tsanyao Yang Knoll were measured in high resolution with an AUV and sampled in detail and visually examined with MARUM ROV QUEST4000. Although large areas are also covered with lava-like asphalt sheets, the asphalt seems not to be flown at higher temperatures. Extrusion of heavy liquid oil in form of whips or sheets were observed at several locations which indicate a slow consolidation of the liquid oil to form firm asphalt. After extrusion, chemical and physical changes in the asphalt generate increasing viscosity gradients both along the flow path and between the flow’s surface and core. This allows the asphalt to form pāhoehoe lava-like shapes and to support dense chemosynthetic communities over timescales of hundreds of years.

How to cite: Bohrmann, G., Roemer, M., Marcon, Y., Pape, T., Hsu, C.-W., Smrzka, D., and MacDonald, I.: Asphalt Volcanism versus Asphalt Seepage - Examples from the Campeche-Sigsbee Salt Province, Southern Gulf of Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5775,, 2024.

On-site presentation
Luca Fallati, Giuliana Panieri, Claudio Argentino, Andrea Giulia Varzi, Stefan Bünz, and Alessandra Savini

Cold-seeps have a unique geo-ecological significance in the deep-sea environment. They impact the variability of present-day submarine sedimentary environments, affecting the evolution of the landscape over time and creating a variety of submarine landforms, one of which is Mud Volcanoes (MVs). MVs form due to mud, fluids, and gas extrusion, mainly methane, from deeper sedimentary layers. These natural gas seepage systems could significantly affect climate change and the global carbon cycle. We present a comprehensive method that combines ROV-based multibeam mapping and underwater photogrammetry to enhance the understanding of the physical relationships between geomorphic units characterizing the Hakon Mosby Mud Volcano (HMMV) and the distribution of associated habitats.

HMMV is indeed characterized by high thermal and geochemical gradients from its centre to the margins, resulting in a clear zonation of chemosynthetic communities. Our approach integrates multi-resolutions and multi-sources data acquired using a work-class ROV. The ROV-based microbathymetry data helped to identify the different types of fine-scale submarine landforms in the central part of HMMV. This revealed three distinct geomorphic units, with the central hummocky region being the most complex. ROV images were analyzed using a defined structure from motion workflow to study this area further, producing millimetric resolution 2D and 3D models. Object-Based Image Analysis (OBIA), applied on orthomosaics, allowed us to obtain a fine classification of main benthic communities covering a total area of 940m2, including the active seepage area of the hummocky rim. Four major substrate types were identified in these regions: uncovered mud, bacterial mats high-density, bacterial mats low- density, sediments and tubeworms. Their relationship with terrain morphology and seepage activity were investigated at different spatial scales, contributing to a deeper understanding the ecological functioning of cold seep ecosystems in MVs.

The proposed workflow and innovative processing techniques could serve as a model for future studies on cold-seep systems. These investigations aim to clarify the extent to which geomorphic, biogeochemical, and ecological processes occurring in extreme environments are inherently linked and marked by the spatial patterns found in associated habitats and sedimentary environments. 

How to cite: Fallati, L., Panieri, G., Argentino, C., Varzi, A. G., Bünz, S., and Savini, A.: Combining ROV-based acoustic data and underwater photogrammetry to characterize Hakon Mosby Mud Volcano (Barents Sea) cold seep systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10620,, 2024.

On-site presentation
Irene Viola, Stefan Bünz, Panieri Giuliana, and Zattin Massimiliano

Seabed fluid flow is a globally significant natural process with implications for various aspects of the marine and global environment.

The study focuses on methane seeping from a newly investigated pockmark in one of the most significant seepage province in the world: the West Svalbard continental drift. The study was conducted on historical databases compared with new geophysical data acquired during Akma2 Ocean Senses expedition in may 2022. The expedition employed ROV technology, SBP data, heat flow and bathymetric data to uncover unprecedented insights into the geological and environmental factors at play. In particular, the study conducted on this active gas-seeping pockmark provided insight about its formation, migration, geothermal and gas exchanges and impact on the marine environment. The importance of understanding the mechanisms and identifying seabed fluid flow is emphasised for comprehending its distribution over time and space. The features associated with fluid flow are determined by fluid and migration mechanisms, influenced by the stress environment within sediments.

This study adds new information that can be used for understanding the impact of seabed fluid flow for addressing environmental hazards, evaluating energy resources, and climate changes.

How to cite: Viola, I., Bünz, S., Giuliana, P., and Massimiliano, Z.: Geophysical characterisation of an actively gas-seeping pockmark on the West-Svalbard continental slope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11343,, 2024.

On-site presentation
Clarisse Goar, Pierre-Antoine Dessandier, Giuliana Panieri, Erwan Roussel, Erwan Pelleter, Claudio Argentino, and Daniela Zeppilli

Here, we present data focusing on the diversity and ecology of benthic foraminifera from different hydrothermal vent fields on the Mid-Atlantic Ridge at low and high latitudes and mud volcanoes leaking methane. This study aims to understand the controlling factors ruling the communities’ structure, including environmental parameters (sediment nature, geochemical dynamic associated with seafloor massive sulfide areas) and food source (primary production and chemosynthetic microbial communities). This study aims to i) fulfil a lack of knowledge of hydrothermal vent biodiversity, ii) determine interactions between foraminifera and their ecosystem, and iii) establish a bio-indicator of extreme environments, environmentally dynamic.

We collected samples from two active vent sites, TAG and Snake Pit, in their periphery at low latitude and on the under-ice Aurora vent in the Arctic, showing contrasted mineralogy, pore water chemistry and organic matter compounds. The response of benthic foraminifera shows quite a stable community in the large periphery, while particular communities are observed in sediment with clear evidence of hydrothermal influence. For the mud volcano and active vents, a specific community of soft-body foraminifera and/or agglutinated species seems to be adapted to extreme environments, including species poorly known. Environmental data highlight a stronger impact of the habitat connected to microbial mats than organic matter availability. These preliminary results support the powerful use of benthic foraminifera in extreme environments to evaluate biodiversity and environmental changes but also highlight the need to improve the taxonomy of deep-sea soft-shelled foraminifera.  

How to cite: Goar, C., Dessandier, P.-A., Panieri, G., Roussel, E., Pelleter, E., Argentino, C., and Zeppilli, D.: Development of a bio-indicator for extreme benthic ecosystem: the use of benthic foraminifera, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22432,, 2024.

On-site presentation
Andrea Giulia Varzi, Giulia Galimberti, Aaron Micallef, Alessandra Savini, and Paula Andrea Ramirez Zapata

When referring to gas in marine sediment, we mean natural gas trapped in the sub-bottom sediments and escaping from the sub-seafloor into the marine environments. Among gases, methane is the most common one, and may have diverse origins, including both thermogenic or microbial sources. Natural seepages are globally distributed, with notable occurrences along  continental margins. They significantly affect the local marine ecosystems and the surrounding substrate, other than being a wake-up call in terms of geohazards.

Since the discovery of the Chuchupa and Ballenas fields in the 1970s, the offshore Colombian Caribbean has been considered a gas province mainly dominated by methane, most likely generated by microbial/thermogenic activities. Nevertheless, there is still little knowledge of this area. Since methane is a potent greenhouse gas, it is important to evaluate the contribution of seabed emissions to the global budget. This is particularly true when they are located in relative shallow waters since they represent an important source of the methane flux from lithosphere to hydrosphere and finally atmosphere. Moreover, methane-enriched environments are peculiar habitats and hot-spot of biodiversity.

The Colombian project “Methane Seep Hunting: a multi-scale and multi-method approach” aims at developing a multi-scale and multi method approach to detect methane seeps, determine their current/past seepage activity, and identify their source using the state of art technology in the Colombian Caribbean. Specifically, it aims at the characterization of the methane seeps discovered in the Moñito continental shelf.

Ship-based MEBS data collection over about 220 km2 of seafloor performed in May 2022 revealed the presence of more than 20.000 pockmarks, at places associated to the presence of flares in the water column. In addition, other positive morphologies have been recognized, depicting the presence of a past and/or present fluid flow system.

Keywords: geomorphology; methane seeps; pockmarks; fluid flow system; Colombian Caribbean; tropics; climate change 

How to cite: Varzi, A. G., Galimberti, G., Micallef, A., Savini, A., and Ramirez Zapata, P. A.: Methane seeps features characterization on the Moñito continental shelf, Colombian Caribbean, through a multi-scale and multi-method approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14206,, 2024.

On-site presentation
Paolo Madonia and the The INGV-PROMUD team

Mud volcanoes (MVs) are geological structures built by the ejection of a multiphase mixture, composed of cold gases (principally methane), high salinity waters and clayey sediments, dragging rock fragments at the surface. This mixture ascends along lithological or structural discontinuities, creating features as cones or pools. Beyond MVs role in global warming (they are the second natural methane source), they can be a source for geohazards: their ordinary activity can be interrupted by paroxysmal events, characterized by gas blasts and sudden expulsions of huge amounts of mud, whose fallout and subsequent flow can damage facilities and endangering animal and human lives. In spite of the geo-risk associated to their activity, a surveillance protocol of MVs have never been implemented. Large earthquakes or hydrocarbon exploration drillings have been claimed as possible triggers of MVs paroxysms, but the related scientific debate have not led to unanimous conclusions.

The INGV-PROMUD project ( is aimed to investigate the indicators of the activity of MVs, with the ultimate goal of individuating possible precursors of paroxysmal events. It is a 3-years (2023-2025) multidisciplinary project, based on data acquired by both permanent networks and spot surveys in two main study sites in Italy: the Salse di Nirano (Northern Apennines, ) and the Maccalube di Aragona (Sicily), both managed as nature reserves by the regional governments of Emilia-Romagna and Sicily, respectively.

Research activities are subdivided in 5 Working Packages (WPs):

 WP1 - Seismology, Tectonics, Tilt, hydrology and vegetation analysis, deals with i) analysis of the background seismic noise wavefield and its role in the identification and monitoring of degassing sources and conduits; ii) response of MVs systems to earthquakes and links with regional tectonic structures; iii) tilt observations and their role in monitoring MVs activity; iv) hydrological regime and its influence on MVs activity; v) evolution of the river network as a consequence of MVs activity; vi) vegetation distribution as a marker of MVs evolution in space and time; vii) radio nuclides emissions by soil driven by MVs activity.

WP2 - Remote Sensing and Topography, performs remote sensing for terrain and surface modelling, aimed to identify deformation patterns related to changes in styles, amplitude and rates of MVs activity. It integrates ground data by GNSS with aerial surveys acquired by UAV, with the aim of identifying possible inflation/deflation cycles as proxies of MVs activity. In addition, historical documents and testimonies from the past will be collected and analysed for reconstructing events occurred also in the pre-instrumental era.

WP3 - Geochemistry, Stratigraphy and Rock Magnetism, aimed to measure flux/composition changes of emitted fluids as a proxy of MVs activity, and includes the study of active microbiological communities. Micropaleontological and stratigraphic study will be applied for depth determination of the mud source. The magnetic properties of mud and of the country rocks will be also studied.  

WP4 – Geophysics, is carrying out resistivity and magnetic surveys, for unravelling the geometry of buried structures.

WP5 - Scientific Outreach, manages the project website, produces multimedia material and performs risk education activities in schools.

How to cite: Madonia, P. and the The INGV-PROMUD team: The INGV-PROMUD Project: multidisciplinary monitoring of Mud Volcanoes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15574,, 2024.

On-site presentation
Marlysa Vivier, Hongliang Wang, Viktoriya Yarushina, and Adriano Mazzini

Mud volcanism is a geological phenomenon broadly diffused in active and passive tectonic settings and it is typically associated with petroleum systems. The mechanisms driving this process are the overpressure resulting from the generation of hydrocarbons at depth combined with the gravitative instability (e.g., shale buoyancy and density inversion) of the more buoyant rapidly buried sediments.

Mud volcanoes experience episodic short-lived eruptive events during which the overpressured fluids and sediments are burst at the surface featuring spectacular explosive events. The erupted material is termed “mud breccia” and represents a mixture of all the lithologies that are intersected by the mud volcano conduit. The overpressured fluids driving the growing diapir promote the grinding and fracturing of the buried sedimentary formations throughout the conduit. As a result, the erupted mud breccia is a mixture of fine-grained sediments (i.e. matrix=clay, silt and sand) and larger clasts. Clasts can vary in size from few centimetres up to several cubic meters. So far it remained unclear how large clasts can travel from sedimentary sequences buried at several kilometers depth.

Here we present some numerical modelling experiments to simulate the rise of large blocks moving from the roots of the mud volcano feeder channel and ultimately reaching the surface during the powerful eruptions.

First, we study the slow rise of large clasts within the growing diapir of buoyancy sediment in the deep part of the mud volcano conduit. The geodynamical two-phase (solid + fluid) flow equations of mass balance, force balance and Darcy’s law are solved with Pseudo-transient method. The preliminary results shows that long distance (e.g. several km) transport of clasts within the diapir is possible, under the driven force provided by the buoyancy of the sediment and the upward fluid flow. The actual rise speed is dependent on the viscosity and the permeability of the solid matrix.

Second, we apply a Verlet method model to simulate the eruption phase. We assume that the eruptive events occur when at shallow depth within the conduit is reached an overpressure sufficient to overcome the overburden lithospheric pressure. When these conditions occur, and when the overpressured fluids are expelled at the surface, the fluidization of the sediments is triggered, and large clasts may be transposrted to their final destination at the surface. Preliminary results reveal that during this process large clasts can be transported. This method focuses on the movement of the clasts themselves. The viscosity of the surrounding fluids is taken into account with a linear drag force. Nevertheless, a method considering the movement of the surrounding fluids could be a possible improvement.

How to cite: Vivier, M., Wang, H., Yarushina, V., and Mazzini, A.: Mud volcanism and mud breccia clasts: how did they reach the surface?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10456,, 2024.

On-site presentation
Claudio Argentino, Giuliana Panieri, Eivind Bjørnå, Pierre-Antoine Dessandier, Eva Ramirez-Llondra, and Stefan Buenz

The increasing number of active vents discovered worldwide, and new observations of basin-scale plumes suggest an underestimated role of hydrothermal systems in the ocean element cycling. This is especially true for slow-ultraslow spreading ridges which represent ca. 50% of the global mid-ocean ridge system and have only recently been recognized to host hydrothermal activity. Here, we present new data from sediment cores collected during HACON19 and HACON21 cruises at Aurora Vent Field, Arctic Ocean. We describe and interpret the hydrothermal signals recorded in the sediments at various distances from the active vents, based on core scanning (X-Rays, XRF, Multisensor scanner), and mineralogical and geochemical (XRF%) analyses on discrete samples. Metalliferous sediments surround the vents, with predominance of sulfide and (hydr)oxide minerals. Plume deposits are found several kilometers from the active vent, and their stratigraphic distribution in the longer gravity cores provided insights into the history and dynamics of vent activity since the last Ice age.

Acknowledgments: this research was supported by HACON project (Research Council of Norway grant No. 274330) and AKMA project (Research Council of Norway grant No. 287869).

How to cite: Argentino, C., Panieri, G., Bjørnå, E., Dessandier, P.-A., Ramirez-Llondra, E., and Buenz, S.: Origin and composition of hydrothermal sediments at Aurora Vent Field, southern Gakkel Ridge (82.9°N), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21263,, 2024.

On-site presentation
Patricia Fehrentz, Magnús Tumi Guðmundsson, Hannah Iona Reynolds, Sidney R. Gunnarson, Joaquin Munoz Cobo Belart, and Michaela Chodora

The heat transfer dynamics in volcanic geothermal areas determine the options for geothermal energy exploration. Intrusive and eruptive events provide additional heat input into the geothermal system, as cooling and solidification of the magma heats the surrounding host rock and water in the porous matrix. The evaporation of the water leads to convection and an advective rise of steam in the fissures. Steam rises further and diffuses into the atmosphere depending on wind conditions. The heat lost by steam released to the atmosphere is in many cases one of the significant parameters that determine the heat budget of a geothermal system.

The Krafla fires describe a period of volcanic activity at the Krafla volcano in North-East Iceland from 1975 to 1984 with nine volcanic eruptions and several more intrusive events. This activity was part of a major rifting episode where several meters of widening occurred along the Krafla fissure swarm. The rifting and associated intrusive activity had a significant effect on the geothermal system. Aerial photographs taken during or a few months after each eruption are used to determine the position and size of the fumaroles and associated steam generation. The heat output of the steam clouds is empirically related to its area, expressed as a power-law function (Hochstein & Bromley, 2001). The escape of water vapor, and thus the prevalence of fumaroles associated with these events, is mainly evident on the eruptive fissures. Surface alteration is prevalent and a sign of current or recent steaming. The results for heat lost to the atmosphere can be compared with the heat released by the cooling of the magmatic intrusions formed in the upper crust, providing heat to the existing geothermal area.

How to cite: Fehrentz, P., Guðmundsson, M. T., Reynolds, H. I., Gunnarson, S. R., Belart, J. M. C., and Chodora, M.: Estimates of heat release to the atmosphere related to effusive volcanic eruptions and intrusive activity during the 1975-84 rifting episode of Krafla, NE-Iceland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8033,, 2024.


Posters on site: Thu, 18 Apr, 16:15–18:00 | Hall X1

Display time: Thu, 18 Apr 14:00–Thu, 18 Apr 18:00
Chairpersons: Giuliana Panieri, Adriano Mazzini, Matteo Lupi
Sedimentary systems
Shalala Huseynova, Namaz Yusubov, and Ibrahim Guliyev

Mud volcanism represents one of the unique natural phenomenon that reflects subsurface processes characterized by movement of large volumes of sediments and fluids in the Earth’s crust. The significant part of world mud volcanoes is concentrated within the on- and offshore Azerbaijan, South Caspian basin (SCB).

The study integrates comprehensive geological, geophysical and geochemical database and presents the results of the analysis of the sedimentary environments in SCB to understand origin and development of mud volcanism in the context of the evolution of the basin. The interpretation of new 2D and 3D seismic data shows that the roots mud volcanoes do not extend below the base of Oligocene-Lower Miocene Maikop Group. The features of sedimentation were studied in details and the sedimentation model of Maikop Group was suggested.

According to the geochemical data and thermobaric conditions Maikop Group considered as the main hydrocarbon source rock within the South Caspian basin. Sedimentary environment during Oligocene-Early Miocene within the territory of Azerbaijan and adjacent Caspian Sea characterized by the complex interaction of various sedimentary processes resulted in the formation of a unique sedimentary complex. The accumulation of Maikop deposits is associated with the beginning of the formation of the folded mountain structures of the Greater Caucasus, the Kopetdag, and the Elbors mountain systems surrounding the SCB, which were the main provenance of clastic material. According to seismic data, the thickness of Maikop sediments currently reaches 3000 m indicating high sedimentation rates over such a relatively short period of geological time. The recent paleontological and geochemical data suggests that Maikop deposits accumulated mainly in the deep marine environment. The rapid burial and subsidence of Maikop sediments occurred because of subsequent intense (avalanche) sedimentation, especially in the Pliocene-Quaternary period. Due to rapid burial, Maikop sediments remain underconsolidated, water-saturated and represent a plastic clay mass, overlapped by thick sequence of denser sediments of the Low Pliocene Productive Series. Thus, as a result of deep subsidence and subsequent catagenic transformations Maikop medium turned into closed physico-chemical system characterized by specific elision processes. The sedimentary environment providing the 20.5 km thick sedimentary filling of the SCB controls mass, fluid and energy transfer within the basin, resulted in formation of mud volcanoes and hydrocarbon accumulations.

Structural interpretation of seismic and geological data, carried out over the past 25 years, indicates that the hydrocarbon deposits discovered in SCB are confined to rootless structures, i.e. injection folds. The formation of injection folds in the sedimentary cover occurs at different stages of basin development due to the alternation of transgressive and regressive series of sediments represented by the layers of clay and sand. All the folds are complicated with mud volcanoes indicating genetic relationship between them, thus the results of paleoreconstructions suggest that mud volcanism in the study area appears to be synchronized in time and space with the growth of anticlinal folds. The mechanism of mud volcano formation based on the gravitational instability has been suggested.

How to cite: Huseynova, S., Yusubov, N., and Guliyev, I.: Impact of sedimentary environment on mechanism of mass, fluid and energy transport in the South Caspian basin , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5963,, 2024.

Giuliana Panieri, Claudio Argentino, Alessandra Savini, Luca Fallati, and Eva Ramirez Llodra

The Arctic seafloor has emerged as a pivotal asset, playing a crucial role in fostering intensified exploitation activities and the incoming deep-sea mining industry, particularly in the so-called "extreme environments" where deep-sourced fluids reach the seafloor at hydrothermal vents and hydrocarbon seeps. Positioned as a promising frontier for resource extraction, exploring the Arctic seafloor is significant with the expanding reach of human exploitation. The ongoing reduction in sea ice coverage in the Arctic region facilitates resource exploration and opens up previously inaccessible areas for scientific investigation.

The paramount importance of comprehending the unique geological and ecological characteristics of the Arctic seafloor becomes evident in the quest for sustainable and responsible exploitation. As a response to this imperative, the integration of seafloor optical and acoustic seafloor and sub-seafloor imaging, and bio-geochemical analyses represents a pivotal approach. This integration allows the reconstruction of comprehensive models delineating geological processes, including the dynamics of hydrothermal and hydrocarbon systems.

This presentation aims to show the effectiveness of a multidisciplinary and multiscale approach in exploring extreme environments through a selection of case studies. Encompassing remote sensing, geochemistry, biology, and a range of seafloor imaging techniques, these studies highlight the complexity and unicity of these environments. Furthermore, we will show how those integrated studies equip both the public and policymakers with essential information, fostering a balanced approach that reconciles economic interests with environmental conservation in the realm of Arctic seafloor exploration.

How to cite: Panieri, G., Argentino, C., Savini, A., Fallati, L., and Ramirez Llodra, E.: Exploring extreme environments at the Arctic seafloor: comprehensive studies integrating science, sustainability, and responsible resource exploitation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16796,, 2024.

Hybrid systems
Walter D'Alessandro, Kyriaki Daskalopoulou, Fausto Grassa, Andrea Vieth-Hillebrand, Martin Zimmer, Samuel Niedermann, and Heiko Woith

Tectonic structures such as faults and fractures act as preferential pathways for gas ascent and their consequent release into the atmosphere. Magma-derived gases are widespread throughout the western Eger Rift (Czech Republic), an intraplate region without active volcanism but with the occurrence of mid-crustal earthquake swarms. Geogenic COdischarges from the Počatky–Plesná fault zone (PPZ), Mariánské Lázně Fault (MLF), Bad Brambach (BB), and a deep local fault (DLF) have been sampled since 2021. Gases were analysed for their chemical (CO2, N2, O2, Ar, He, CH4, and H2) and isotopic contents (noble gases, CO2, and CH4). Results showed that CO2 is the dominant gas species (concentrations > 99.4%), with the remaining gases being present in minor amounts. The He isotopic composition for gas samples from the PPZ and MLF is typical for the subcontinental lithospheric mantle (SCLM - with 3He/4He ratios between 5 and 6 RA), while gases from BB and the DLF show a lower mantle input (3He/4He is 3.2 and 2.4 RA, respectively). δ13CCO2 data reflect a SCLM CO2 signature (-4 to -1 ‰ vs. V-PDB). First CH4 isotopic data present values between -52.0 and -47.1 ‰ vs. V-PDB for δ13CCH4 and between -307 and -284 ‰ vs. V-SMOW for δ2HCH4. With the exception of samples collected from the MLF that show a clear thermogenic CH4 origin, all the other samples present isotopic values and CH4/(C2H6+C3H8) ratios that suggest a likely biogenic origin, with secondary processes playing a crucial role on the gases’ isotopic signature. It should be noted that low CH4concentrations (<100 μmol/mol) correspond to low CH4/3He ratios (around 104) in CO2-rich magmatic gases, suggesting a possible common origin for these gases. Therefore, multiple origins of CH4 (biogenic and volcanic-geothermal) cannot be excluded.

This research is a part of the MoCa - “Monitoring Carbon” project and this work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 461419881.

How to cite: D'Alessandro, W., Daskalopoulou, K., Grassa, F., Vieth-Hillebrand, A., Zimmer, M., Niedermann, S., and Woith, H.: First indications on CH4 origin in the CO2-dominated gas discharges of the western Eger Rift (Czech Republic), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12897,, 2024.

Adriano Mazzini, Zhang Naizhong, Giuseppe Etiope, Mellinda Aimee Jajalla, Mayuko Nakagawa, and Alexis Gilbert

The Goshogake hydrothermal field in Tohoku, northern Japan, is located on the western flank of the Akita Yakeyama volcano. This N-S elongated field extends over ~20-25 acers and is placed over a tectonic discontinuity that controls the migration of hydrothermal fluids. A variety of surface degassing manifestations can be distinguished including small hydrothermal lakes, clustered bubbling pool fields, active mud erupting gryphons, sulfur-rich fumaroles and localized apparently oil-rich pools. So far it remains unclear if this system and the released gases are purely magmatic or if is also involved the migration of mantle-derived fluids interacting with buried sedimentary deposits. Here we report the result of field observations and fluid samples analyses. The measured temperatures of the active seepage sites range from 33 to 97 °C (in large part higher than 90 °C), while pH is overall low at all sites (i.e. ~2.5).

Gas analyses reveal that all the active sites are CO2-dominated with slightly higher CH4 content in the colder and mud seeping sites. While CO2 has a distinct mantle-derived isotopic signature, the origin of methane is still debated. The apparent d13C thermogenic signature of methane, could also be related to an abiotic origin which would be consistent with a CO2-dominated geothermal system. The presence of oil, if confirmed, could be related to shallow-sourced hydrothermal oil (e.g. similar to that described by Didyk and Simoneit (1989), or, more interestingly, could indicate that this active site is part of a petroleum system potentially linked with deeply buried lacustrine sediments that fill a 1-Ma-caldera formed after a ignimbrite eruption. The possible presence of these deposits in the erupted mud has been suggested by Komatsu et al., (2019) based on mineralogical analyses.

To further test this hypothesis, we are now conducting multiple analyses on the samples recovered from 6 locations at the Goshogake field, including the isotope analysis of water, gas, oil and mud compositions to unravel the source of these fluids as well as the reactions that took place at this site. If confirmed, Goshogake could potentially be the first example of known sedimentary hosted geothermal system in Japan. We speculate that targeted fieldworks would likely identify other hybrid systems in the country.

How to cite: Mazzini, A., Naizhong, Z., Etiope, G., Jajalla, M. A., Nakagawa, M., and Gilbert, A.: The Goshogake hydrothermal field (northern Japan): purely geothermal or hybrid sediment-hosted?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9133,, 2024.

Volcanic systems
Matteo Lupi, Salvatore Alparone, Mimmo Palano, Tullio Ricci, Anthony Finizola, and Andrea Ursino

Although not all volcanic unrests lead to eruptions, it is generally accepted that magmatic activity is what causes volcanoes to awake. Alternatively, hydrothermal processes are often invoked to explain inflation and deflation dynamics. Magmatic brines have physical properties in between deep magmas and shallow hydrothermal fluids. Yet, to date we have no physical models accounting for geophysical signals that may be generated by the fluid flow of magmatic brines.

Vulcano, the southernmost island of the Aeolian Volcanic Archipelago, Italy, entered into unrest in September 2021. The island experienced intense ground deformation,  fumarole temperature and gas emissions increases, and a marked augmentation of seismicity.

For the first time since the deployment of broadband stations in 2005, very long period (VLP) seismic events were detected in the seismic records. Certain aspects of the geophysical signals recorded during the unrest are probably not fully compatible with traditional causal models involving fresh magma rising at depth or with a hydrothermal scenario.  In this contribution we discuss alternative scenarios and investigate whether fluid flow of magmatic brines may play a key role in understanding volcanic unrests.

How to cite: Lupi, M., Alparone, S., Palano, M., Ricci, T., Finizola, A., and Ursino, A.: Non-eruptive unrest and the role of magmatic brines, Vulcano, Italy., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21336,, 2024.

Gianluca Lazzaro, Agostino Semprebello, Salvatore Magazù, Maria Teresa Caccamo, Alessandro Gattuso, Domenico Traina, Sabina Morici, Cinzia Giuseppina Caruso, and Manfredi Longo

Submarine hydrothermal systems attract increasing interest from the scientific community, as they emit huge amounts of both elements and energy. However, in relation to their extreme environmental conditions (e.g. high temperature and pressure, low Ph) direct measurements can be challenging to perform.

In this context, passive hydroacoustics may represent a powerful technique for both short- and long-term monitoring as the typical source mechanisms of the hydrothermal fields, directly related to ascending fluids, radiate sound pressure following different acoustic modes.
Here we present preliminary results obtained by using a spectral approach for estimating the gas flow emission rate starting from the acoustic dataset collected between 22nd and 26th August 2022 on a stationary flux vent located at ~1.8 metres depth, inside the shallow hydrothermal field at Baia di Levante in Vulcano island (Aeolian Islands, Italy).

To carry out the estimation of the gas flow emission rate emitted by the hydrothermal vent, we implemented a customised inverse modelling algorithm based on a spectral method founded upon the assumption that the acoustic signature of a single bubble event evolves over time as a sinusoid that exponentially decays. According to this approach, we refined  the formulation of a forward model for the sound radiated by a stationary, high-flux  bubbles’ plume, then the path was backward analysed through the proposed inversion algorithm, which allowed us to obtain the estimated value of the flow emission rate.
High-resolution audio frames were recorded by using hydrophones [1 - 12800] Hz, that were deployed in the proximity of the investigated vent, collecting a total amount of  7  bursts of  ~10 hour-long each. 

Preliminary analyses of the Power Spectral Density (PSD) and Pressure Power Spectrum highlighted the presence of different persistent energetic frequency peaks over the environmental background noise coherently with the dynamics of the hydrothermal field. The most energetic ones, likely due to the acoustic signal radiated by a large, resonant bubble plume, consistently confirmed the coupling of the estimated radius with direct observations. 

The performed analysis allowed us to identify the main features of the vent, characterised by bubbles radii up to 0.03 m that produce the main energetic peak centred at ~100 Hz, along with smaller bubbles generating less energetic peaks up to 2 kHz. Therefore, the algorithm was set to work in a wide frequency range, spanning from 60 Hz to 2060 Hz, in order to estimate all the gas released by the vent.

The estimated flow emission rate  for the investigated period retrieved values spanning from 3.31 to 6.98 litres per minute, with a mean value of 4.97 litres per minute, in good agreement with the direct observations. These results confirm that passive acoustic methods represent a valid and robust tool for both monitoring and research activity in submarine hydrothermal fields, providing a long-lasting instrument able to detect the fluctuations connected to the variations of such natural systems.

How to cite: Lazzaro, G., Semprebello, A., Magazù, S., Caccamo, M. T., Gattuso, A., Traina, D., Morici, S., Caruso, C. G., and Longo, M.: Inverse modelling as a powerful tool for gas flow emission rate estimation from stationary hydrothermal vents  (Vulcano Island, Aeolian archipelago, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18259,, 2024.

Chiara Del Ventisette, Domenico Montanari, Alessandra Sciarra, Adriano Mazzini, Marco Bonini, Franco Tassi, Federico Fischanger, Stefano Del Ghianda, Riccardo Lanari, Florence Begue, and Matteo Lupi

The Formiche di Grosseto are three islets, of about 1,500 m2, included in the Tuscan Archipelago, Italy. The islets rise abruptly from a seabed approximately 100 meters deep in correspondence of a structural high separating Neogene basins of the Tuscan Shelf. Onshore it is possible to observe hydrothermal breccias and speleothems. Offshore, CO2-rich submarine thermal fluids discharge from several springs with temperatures as high as 41°C. These submarine springs are mainly located along the Northern scarp at depths ranging from 6 to 32 m below the sea level.

To better understand the past and present nature of these fluid-driven systems extending offshore, a multidisciplinary exploration campaign was undertaken in the framework the TEMPEST and MIGRATE projects.

The main islet, offers a superb continuous outcrop of the Liassic carbonate rocks forming the backbone of the island.  Fault and fracture systems have been characterized across different scales to create a representative model. Multiple drone-flights have been performed to obtain an optical image for faults and fractures mapped over the islands. Drone-derived observations have been verified in the field and integrated in the structural model. Fractures and structural key geometries have been captured by means of a 2-D fracture network analysis with a circular sampling window. Connectivity within the fracture network have been parameterized by characterizing the different types of fracture terminations and intersections, which have been used to understand the structural architecture controlling the fluid flow. Rocks, hydrothermal breccias and calcitic precipitates have been analysed with cathodoluminescence and stable isotopes. Furthermore, a surface electrical resistivity (ERT) survey was carried out on the islet of Formica Grande di Grosseto - the main inslet - for the characterization of the subsoil up to 20-25 meters deep. The inversion shows a possible upflow of fluids, centred where the hydrothermal breccia has been found. Finally, CO2 diffuse-degassing soil flux measurements were also performed along these alignments.

The integrated study of the collected data pointed out that the northern part of the major islet is marked by upwelling of hot hydrothermal fluids. This was confirmed by a manual excavation that revealed rising thermal fluids - temperature of about 38°C- which was previously unknown on the island. Geochemical investigations have been conducted on the island's fluids, on the already known submarine thermal discharges as well as on the known thermal springs located inland, in the proximity of the Formiche di Grosseto area. 

The chemical compositions of the Formiche water samples are similar to those of seawater, although marked by significant enrichments of SO4, Ca and B and Mg depletion. These compositional characteristics are likely to be ascribed to the mixing of seawater with hydrothermal fluids. Our preliminary results aim to assess the origin of the discharged fluids and their relation with local and regional tectonics, providing an example of how multidisciplinary integrated exploration can be effectively conducted even in challenging contexts.

How to cite: Del Ventisette, C., Montanari, D., Sciarra, A., Mazzini, A., Bonini, M., Tassi, F., Fischanger, F., Del Ghianda, S., Lanari, R., Begue, F., and Lupi, M.: Multidisciplinary exploration for geofluids in small islands, the case study of the Formiche di Grosseto islets, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21768,, 2024.