Integrated regional scale view of Milos submarine hydrothermalism

2020 ◽  
Author(s):  
Valentine Puzenat ◽  
Jean-Emmanuel Martelat ◽  
Javier Escartin ◽  
Thibaut Barreyre ◽  
Nuno Gracias ◽  
...  
Keyword(s):  
High Temperature ◽  
Satellite Imagery ◽  
Autonomous Underwater Vehicle ◽  
Regional Scale ◽  
Hydrothermal Activity ◽  
Seafloor Mapping ◽  
Biological Communities ◽  
Bacterial Mats ◽  
Volcanic Islands ◽  
Submarine Hydrothermal Activity

<p>Submarine hydrothermal activity is common at the flanks of volcanic islands, and in some cases, occurring at very shallow water (0-100 meter depth). These sites are a key target for systematic seafloor mapping to understand the location, geometry and nature of hydrothermal discharge. These data are also critical for monitoring the temporal variability of these dynamic systems, while providing a context for instrumental measurements, sampling and other observations (e.g., temperature of outflow, chemistry, etc.). Here we present a systematic mapping of the Milos hydrothermal system in the Hellenic volcanic Arc, characterized by submarine gas emissions, high-temperature outflow, bacterial mats, precipitation of hydrothermal minerals, and small hydrothermal constructs and edifices. We have mapped this site at regional scales using satellite imagery (World-View2 images from the DigitalGlobe foundation), complemented with aerial photography acquired with drones, and high-resolution seafloor photomosaics (<1 cm resolution) from underwater imagery acquired by the autonomous underwater vehicle Sparus II (University of Girona). </p><p>Our drone and AUV mapping ground truths the correlation between patterns in satellite imagery and hydrothermal outflow, associated to mineral precipitates and/or bacterial mats at the seafloor. This mapping also reveals a clear organization of the hydrothermal outflow in sandy areas. In particular, polygonal patterns are common and often associated with inactive or actively bubbling pockmarks. These areas, showing white bacterial mats and hydrothermal precipitates, are rippled, suggesting that the hydrothermal precipitates do not consolidate the sediment. White precipitates display subseafloor temperatures >50°C at depths of 10 to 50 cm. The white areas are bound by bands of seafloor with a hummocky structure due to intense bioturbation, that obliterates the ripples, with widths of up to a few meters. This area shows subseafloor temperatures of 20-40°C, and corresponds to a transition from the high-temperature white zones and the seafloor with ripples and no hydrothermal precipitates. This area exhibits subseafloor temperatures similar to those of seawater, and can be associated with seagrass. These patterns reveal a clear organization of a narrowly focused hydrothermal outflow that controls the biological communities at the seafloor and subseafloor. We will discuss the implications of these observations to quantify hydrothermal fluxes in the study area.</p><p><br><br></p>

Volcanic submarine hydrothermal activity from satellites : regional mapping and temporal evolution in shallow water systems

2020 ◽  
Author(s):  
Jean-Emmanuel Martelat ◽  
Javier Escartin ◽  
Thibaut Barreyre
Keyword(s):  
Shallow Water ◽  
Satellite Imagery ◽  
Regional Scale ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Spectral Bands ◽  
Hydrothermal Convection ◽  
Bacterial Mats ◽  
Near Shore ◽  
Volcanic Islands

<p>Risk assessment at active volcanic islands link to populated areas is of first importance. We evaluate the potential of satellite imagery to map and monitor the activity of shallow-water hydrothermal systems, which are often found at volcanic islands. For this study, we used publicly available data and proprietary WorldView-2 satellites images, with spectral bands that can penetrate up to water depths of 30 m. Shallow water hydrothermal sites are visible on satellite imagery, primarily with publicly available data, demonstrating the potential of satellite imagery to study and monitor shallow water hydrothermal activity. We focus our work on volcanic islands, showing intense near-shore, shallow-water hydrothermal activity, and distinct styles of hydrothermal venting. Satellite imagery constrains regional outflow geometry and the temporal variability or stability of these systems. Milos Island shows hydrothermal outflow associated with reflective mineral precipitates and/or bacterial mats, which are stable over time (2010-2014). These outflows locally define polygonal patterns likely associated with hydrothermal convection in porous media. In Kueishantao Island individual hydrothermal plumes charged with particles are visible at the sea surface, and display great variability in intensity and distribution of plume sources (2002-2019). Worldwide we have identified ~15 shallow water hydrothermal sites with satellite imagery, that are similar to either the Milos system (e.g., Vulcano and Panarea, Italy), or the Kueishantao system (numerous sites in Pacific volcanic islands). This study demonstrates that satellite imagery can be used to map and monitor different types of shallow-water hydrothermal systems, at regional scale, and monitor their evolution. Satellite data provides not only regional and temporal information on these systems, unavailable to date, but also the regional context for follow-up in situ field data and observations (e.g., instrumental monitoring, sampling, observations and mapping with divers or AUVs) to understand both the nature and dynamics of these systems, and ultimately the associated fluxes.</p>

Detachment-parallel recharge explains high discharge fluxes at the TAG hydrothermal field

2021 ◽  
Author(s):  
Lars Rüpke ◽  
Zhikui Guo ◽  
Sven Petersen ◽  
Christopher German ◽  
Benoit Ildefonse ◽  
...  
Keyword(s):  
High Temperature ◽  
Hanging Wall ◽  
Massive Sulfide ◽  
Hydrothermal Activity ◽  
High Heat ◽  
Heat Fluxes ◽  
Long Distance ◽  
High Discharge ◽  
Circulation Mode ◽  
Spreading Ridges

Abstract Submarine massive sulfide deposits on slow-spreading ridges are larger and longer-lived than deposits at fast-spreading ridges1,2, likely due to more pronounced tectonic faulting creating stable preferential fluid pathways3,4. The TAG hydrothermal mound at 26°N on the Mid-Atlantic Ridge (MAR) is a typical example located on the hanging wall of a detachment fault5-7. It has formed through distinct phases of high-temperature fluid discharge lasting 10s to 100s of years throughout at least the last 50,000 years8 and is one of the largest sulfide accumulations on the MAR. Yet, the mechanisms that control the episodic behavior, keep the fluid pathways intact, and sustain the observed high heat fluxes of up to 1800 MW9 remain poorly understood. Previous concepts involved long-distance channelized high-temperature fluid upflow along the detachment5,10 but that circulation mode is thermodynamically unfavorable11 and incompatible with TAG's high discharge fluxes. Here, based on the joint interpretation of hydrothermal flow observations and 3-D flow modeling, we show that the TAG system can be explained by episodic magmatic intrusions into the footwall of a highly permeable detachment surface. These intrusions drive episodes of hydrothermal activity with sub-vertical discharge and recharge along the detachment. This revised flow regime reconciles problematic aspects of previously inferred circulation patterns and can be used as guidance to one critical combination of parameters that can generate substantive mineral systems.

scholarly journals Geomagnetic Survey to Explore High-Temperature Geothermal System in Blawan-Ijen, East Java, Indonesia

2018 ◽  
Vol 31 ◽  
pp. 02003 ◽  
Author(s):  
Yunus Daud ◽  
Syamsu Rosid ◽  
Fikri Fahmi ◽  
Faris Maulana Yunus ◽  
Reza Muflihendri
Keyword(s):  
High Temperature ◽  
Magnetic Anomaly ◽  
Volcanic Rocks ◽  
Hydrothermal Activity ◽  
Geothermal System ◽  
Geothermal Area ◽  
Variation Reduction ◽  
Geomagnetic Survey ◽  
Surface Alteration ◽  
Steep Topography

Ijen geothermal area is high-temperature geothermal system located in Bondowoso regency, East Java. It is categorized as caldera-hosted geothermal system which is covered by quaternary andesitic volcanic rocks with steep topography at the surrounding. Several surface thermal manifestations are found, such as altered rocks near Mt. Kukusan and a group of Blawan hotsprings in the northern part of the caldera. Geomagnetic survey was conducted at 72 stations which is distributed inside the caldera to delineate the existence of hydrothermal activity. Magnetic anomaly was obtained by reducing total magnetic measured on the field by IGRF and diurnal variation. Reduction to pole (RTP) method was applied with geomagnetic inclination of about -32°. In general, the result shows that high magnetic anomaly is distributed at the boundary of study area, while low magnetic anomaly is observed in the centre. The low anomaly indicates demagnetized rock that probably caused by hydrothermal activity. It has a good correlation with surface alteration observed close to Mt. Kukusan as well as high temperature reservoir drilled in the centre of caldera. Accordingly, the low magnetic anomaly also presents the possibility of geothermal reservoir in Ijen geothermal area.

scholarly journals EXPEDITIONAL EXPLORATION OF THE KURIL ISLANDS IN 2020

2020 ◽  
Vol 4(48) ◽  
pp. 101-107
Author(s):  
E.G. Kalacheva ◽  
Keyword(s):  
Diffusion Flux ◽  
Field Work ◽  
Hydrothermal Activity ◽  
Kuril Islands ◽  
Thermal Fields ◽  
Analytical Work ◽  
Magmatic Volatiles ◽  
The Kuril Islands ◽  
Volcanic Islands ◽  
Relationship Of

This report provides a brief description of the field work on the Kuril Islands. It was performed within the framework of the R&D theme, projects of the RSF and the RFFR, which are realized in the laboratory of postmagmatic processes of the Institute of Volcanology and Seismology FEB RAS. Hydrological and hydrochemical works were performed on the rivers draining the slopes and thermal fields of the Sinarka, Kuntomintar volcanic massifs (Shiashkotan Island), and the Vernadsky and Karpinsky Ridges (Paramushir Island). The study of the chemical erosion of volcanic islands and the assessment of the hydrothermal export of magmatic volatiles are the goals of this work. Infrared photography was taken and the total flux of volcanic SO2 and diffusion flux of CO2 were measured on thermal fields in the caldera of Golovnin volcano. A detailed hydrogeochemical survey was made on the thermal fields of the Ebeko volcano to study the relationship of volcanic and hydrothermal activity of the volcano. For further analytical work, a large number of water and gas samples were taken and a representative collection of rocks and sediments was collected during the expedition.

scholarly journals An estimate of ice wedge volume for a High Arctic polar desert environment, Fosheim Peninsula, Ellesmere Island

2018 ◽  
Vol 12 (11) ◽  
pp. 3589-3604 ◽  
Author(s):  
Claire Bernard-Grand'Maison ◽  
Wayne Pollard
Keyword(s):  
Satellite Imagery ◽  
Regional Scale ◽  
High Arctic ◽  
Ellesmere Island ◽  
The Arctic ◽  
Ground Ice ◽  
Polar Desert ◽  
Ice Volume ◽  
Carbon Release ◽  
Wedge Volume

Abstract. Quantifying ground-ice volume on a regional scale is necessary to assess the vulnerability of permafrost landscapes to thaw-induced disturbance like terrain subsidence and to quantify potential carbon release. Ice wedges (IWs) are a ubiquitous ground-ice landform in the Arctic. Their high spatial variability makes generalizing their potential role in landscape change problematic. IWs form polygonal networks that are visible on satellite imagery from surface troughs. This study provides a first approximation of IW ice volume for the Fosheim Peninsula, Ellesmere Island, a continuous permafrost area characterized by polar desert conditions and extensive ground ice. We perform basic GIS analyses on high-resolution satellite imagery to delineate IW troughs and estimate the associated IW ice volume using a 3-D subsurface model. We demonstrate the potential of two semi-automated IW trough delineation methods, one newly developed and one marginally used in previous studies, to increase the time efficiency of this process compared to manual delineation. Our methods yield acceptable IW ice volume estimates, validating the value of GIS to estimate IW volume on much larger scales. We estimate that IWs are potentially present on 50 % of the Fosheim Peninsula (∼3000 km2), where 3.81 % of the top 5.9 m of permafrost could be IW ice.

Hydrothermal exploration and astrobiology: oases for life in distant oceans?

2004 ◽  
Vol 3 (2) ◽  
pp. 81-95 ◽  
Author(s):  
Christopher R. German
Keyword(s):  
High Temperature ◽  
Organic Synthesis ◽  
Autonomous Underwater Vehicle ◽  
De Novo ◽  
The Arctic ◽  
Ocean Ridges ◽  
Abiotic Organic Synthesis ◽  
Preliminary Identification ◽  
Slow Spreading ◽  
Hydrothermal Fields

High-temperature submarine hydrothermal fields on Earth's mid-ocean ridges play host to exotic ecosystems with fauna previously unknown to science. Because these systems draw significant energy from chemosynthesis rather than photosynthesis, it has been postulated that the study of such systems could have relevance to the origins of life and, hence, astrobiology. A major flaw to that argument, however, is that modern basalt-hosted submarine vents are too oxidizing and lack the abundant free hydrogen required to drive abiotic organic synthesis and/or the energy yielding reactions that the most primitive anaerobic thermophiles isolated from submarine vent-sites apparently require. Here, however, the progress over the past decade in which systematic search strategies have been used to identify previously overlooked venting on the slow-spreading Mid-Atlantic Ridge and the ultra-slow spreading Arctic and SW Indian Ridges is described. Preliminary identification of fault-controlled venting in a number of these sites has led to the discovery of at least two high-temperature hydrothermal fields hosted in ultramafic rocks which emit complex organic molecules in their greater than 360 °C vent-fluids. Whether these concentrations represent de novo organic synthesis within the hydrothermal cell remains open to debate but it is probable that many more such sites exist throughout the Atlantic, Arctic and SW Indian Oceans. One particularly intriguing example is the Gakkel Ridge, which crosses the floor of the Arctic Ocean. On-going collaborations between oceanographers and astrobiologists are actively seeking to develop a new class of free-swimming autonomous underwater vehicle, equipped with appropriate chemical sensors, to conduct long-range missions that will seek out, locate and investigate new sites of hydrothermal venting at the bottom of this, and other, ice-covered oceans.

Interaction of submarine volcanic and high-temperature hydrothermal activity proposed for the formation of the Agrokipia, volcanic massive sulfide deposits of Cyprus

1992 ◽  
Vol 29 (9) ◽  
pp. 1928-1936 ◽  
Author(s):  
James M. Hall
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Hydrothermal Vents ◽  
Massive Sulfide ◽  
Hydrothermal Activity ◽  
Hydrothermal Fluids ◽  
Spreading Ridge ◽  
Sulfide Deposits ◽  
Original Surface ◽  
Massive Sulfide Deposits

The results of drilling near the spreading-ridge-type, volcanic-hosted, massive sulfide deposits of Agrokipia, Cyprus, are described. Mineralization and associated argillic hydrothermal alteration occur over intervals of 5–130 m and at depths of 80–230 m beneath the original surface of the oceanic crust. Mineralization occurs in massive flows that probably represent a locally ponded sequence up to 300 m thick. Abundant glass–aphanitic basalt transitions are present from about 100 m below the surface of the ponded sequence, with glass abundances locally reaching 60% of the section. A novel hypothesis, involving the presence of active, high-temperature hydrothermal vents beneath the cooling ponded sequence, with the passage of hydrothermal fluids through the still molten lava, is proposed to account for the observations. While this hypothesis is reasonable, the inferred processes have not, as yet, been demonstrated under either laboratory or field conditions. The seafloor expression of this system was probably one of widely distributed, low-temperature, fluid emission over the surface of a lava pond in the axial graben of a spreading ridge.

Submarine hydrothermal activity and gold-rich mineralization at Brothers Volcano, Kermadec Arc, New Zealand

2011 ◽  
Vol 46 (5-6) ◽  
pp. 541-584 ◽  
Author(s):  
Cornel E. J. de Ronde ◽  
Gary J. Massoth ◽  
David A. Butterfield ◽  
Bruce W. Christenson ◽  
Junichiro Ishibashi ◽  
...  
Keyword(s):  
New Zealand ◽  
Hydrothermal Activity ◽  
Submarine Hydrothermal Activity
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