scholarly journals Pleistocene hydrothermal activity on Brokeoff volcano and in the Maidu volcanic center, Lassen Peak area, northeast California: Evolution of magmatic-hydrothermal systems on stratovolcanoes

Geosphere ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 946-982 ◽  
Author(s):  
David A. John ◽  
Robert G. Lee ◽  
George N. Breit ◽  
John H. Dilles ◽  
Andrew T. Calvert ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Volcanic Center ◽  
Lassen Peak

scholarly journals Re-Evaluating the Age of Deep Biosphere Fossils in the Lockne Impact Structure

Geosciences ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 202 ◽  
Author(s):  
Mikael Tillberg ◽  
Magnus Ivarsson ◽  
Henrik Drake ◽  
Martin J. Whitehouse ◽  
Ellen Kooijman ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Crystalline Rock ◽  
Hydrothermal Systems ◽  
Fungal Colonization ◽  
Precambrian Basement ◽  
Impact Event ◽  
Deep Biosphere ◽  
Microbial Ecosystems ◽  
The Impact

Impact-generated hydrothermal systems have been suggested as favourable environments for deep microbial ecosystems on Earth, and possibly beyond. Fossil evidence from a handful of impact craters worldwide have been used to support this notion. However, as always with mineralized remains of microorganisms in crystalline rock, certain time constraints with respect to the ecosystems and their subsequent fossilization are difficult to obtain. Here we re-evaluate previously described fungal fossils from the Lockne crater (458 Ma), Sweden. Based on in-situ Rb/Sr dating of secondary calcite-albite-feldspar (356.6 ± 6.7 Ma) we conclude that the fungal colonization took place at least 100 Myr after the impact event, thus long after the impact-induced hydrothermal activity ceased. We also present microscale stable isotope data of 13C-enriched calcite suggesting the presence of methanogens contemporary with the fungi. Thus, the Lockne fungi fossils are not, as previously thought, related to the impact event, but nevertheless have colonized fractures that may have been formed or were reactivated by the impact. Instead, the Lockne fossils show similar features as recent findings of ancient microbial remains elsewhere in the fractured Swedish Precambrian basement and may thus represent a more general feature in this scarcely explored habitat than previously known.

Hydrothermal activity in a lava dome detected by combined seismic and muon monitoring

2020 ◽  
Author(s):  
Marina Rosas-Carbajal ◽  
Yves Le Gonidec ◽  
Dominique Gibert ◽  
Jean de Bremond d'Ars ◽  
Jean-Christophe Ianigro ◽  
...  
Keyword(s):  
Geophysical Methods ◽  
Hydrothermal Activity ◽  
Observation Point ◽  
Hydrothermal Systems ◽  
Water Infiltration ◽  
Single Observation ◽  
Geological Body ◽  
Continuous Measurements ◽  
Muon Tomography ◽  
Monitoring Tools

<p>Characterizing volcano-hydrothermal activity is crucial for understanding the dynamics of volcanos and the relation between surface observations and deep magmatic activity. It may be also relevant for detecting precursors to magmatic and phreatic eruptions. Traditional monitoring tools such as seismicity and deformation are not always sensitive to hydrothermal activity, therefore it is important to explore new tools that can provide complementary information about the system.</p><p>Muon imaging is increasingly used as a novel tool to complement standard geophysical methods in volcanology, allowing to image large volumes of a geological body from a single observation point. Continuous measurements of the muon flux enable to infer density changes in the system. In volcanic hydrothermal systems, this approach helps to characterize processes of steam formation, condensation, water infiltration and storage. Here we present the results of a combined study in the La Soufrière de Guadeloupe volcano (West Indies, France) where continuous measurements of muon tomography were acquired simultaneously to seismic noise. The combination of these two methods helps to characterize a short-term, shallow hydrothermal event, its localization, and the involved volumes in the volcano. The deployment of networks of various sensors including temperature probes, seismic antennas and cosmic muon telescopes around volcanoes could valuably contribute to detect precursors to more hazardous hydrothermal events.</p>

scholarly journals Critical role of caldera collapse in the formation of seafloor mineralization: The case of Brothers volcano

Geology ◽  
2019 ◽  
Vol 47 (8) ◽  
pp. 762-766 ◽  
Author(s):  
Cornel E.J. de Ronde ◽  
Susan E. Humphris ◽  
Tobias W. Höfig ◽  
Agnes G. Reyes ◽  
Keyword(s):  
Hydrothermal Fluid ◽  
Porphyry Copper ◽  
Critical Role ◽  
Massive Sulfide ◽  
Wall Rock ◽  
Hydrothermal Activity ◽  
Gold Deposits ◽  
Hydrothermal Systems ◽  
Magmatic Fluid ◽  
Caldera Collapse

Abstract Hydrothermal systems hosted by submarine arc volcanoes commonly include a large component of magmatic fluid. The high Cu-Au contents and strongly acidic fluids in these systems are similar to those that formed in the shallow parts of some porphyry copper and epithermal gold deposits mined today on land. Two main types of hydrothermal systems occur along the submarine portion of the Kermadec arc (offshore New Zealand): magmatically influenced and seawater-dominated systems. Brothers volcano hosts both types. Here, we report results from a series of drill holes cored by the International Ocean Discovery Program into these two types of hydrothermal systems. We show that the extent of hydrothermal alteration of the host dacitic volcaniclastics and lavas reflects primary lithological porosity and contrasting spatial and temporal contributions of magmatic fluid, hydrothermal fluid, and seawater. We present a two-step model that links the changes in hydrothermal fluid regime to the evolution of the volcano caldera. Initial hydrothermal activity, prior to caldera formation, was dominated by magmatic gases and hypersaline brines. The former mixed with seawater as they ascended toward the seafloor, and the latter remained sequestered in the subsurface. Following caldera collapse, seawater infiltrated the volcano through fault-controlled permeability, interacted with wall rock and the segregated brines, and transported associated metals toward the seafloor and formed Cu-Zn-Au–rich chimneys on the caldera walls and rim, a process continuing to the present day. This two-step process may be common in submarine arc caldera volcanoes that host volcanogenic massive sulfide deposits, and it is particularly efficient at focusing mineralization at, or near, the seafloor.

Submarine Magmatic-Hydrothermal Systems at the Monowai Volcanic Center, Kermadec Arc

2012 ◽  
Vol 107 (8) ◽  
pp. 1669-1694 ◽  
Author(s):  
M. I. Leybourne ◽  
U. Schwarz-Schampera ◽  
C. E. J. de Ronde ◽  
E. T. Baker ◽  
K. Faure ◽  
...  
Keyword(s):  
Hydrothermal Systems ◽  
Volcanic Center

scholarly journals Volcanic hydrothermal systems as potential analogues of Martian sulphate-rich terrains

2015 ◽  
Vol 95 (2) ◽  
pp. 153-169 ◽  
Author(s):  
A. Rodríguez ◽  
M.J. van Bergen
Keyword(s):  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Geothermal Systems ◽  
Ambient Conditions ◽  
Flow Paths ◽  
Near Surface ◽  
Mineral Associations ◽  
The Status ◽  
History Of ◽  
Active Processes

AbstractRemote sensing observations and rover missions have documented the presence of sulphate-rich mineral associations on Mars. Many of these minerals are paleo-indicators of hydrous, acidic and oxidising environments that must have prevailed in Mars´ distant past, contrary to the present conditions. Furthermore, occurrences of silica together with high Cl and Br concentrations in Martian soils and rocks represent fingerprints of chemically atypical fluids involved in processes operating on the surface or at shallow depth. From field observations at representative active volcanoes in subduction settings, supported by geochemical modelling, we demonstrate that volcanic hydrothermal systems are capable of producing Mars-like secondary mineral assemblages near lakes, springs and fumaroles through the action of acidic fluids. Water–gas-rock interactions, together with localised flow paths of water and fumarolic gas emitted from associated subaerial vents, lead to deposition of a range of sulphates, including gypsum, jarosite, alunite, epsomite and silica. Evaporation, vapour separation and fluid mixing in (near-) surface environments with strong gradients in temperature and fluid chemistry further promote the diversity of secondary minerals. The mineralogical and chemical marks are highly variable in space and time, being subject to fluctuations in ambient conditions as well as to changes in the status of volcanic-hydrothermal activity. It is concluded that active processes in modern volcanic-geothermal systems may be akin to those that created several of the sulphate-rich terrains in the early history of Mars.

scholarly journals Beo v1.0: numerical model of heat flow and low-temperature thermochronology in hydrothermal systems

2019 ◽  
Vol 12 (9) ◽  
pp. 4061-4073 ◽  
Author(s):  
Elco Luijendijk
Keyword(s):  
Heat Flux ◽  
Heat Flow ◽  
Low Temperature ◽  
Thermal History ◽  
Land Surface ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Conductive Heat ◽  
History Of ◽  
Spring Temperatures

Abstract. Low-temperature thermochronology can provide records of the thermal history of the upper crust and can be a valuable tool to quantify the history of hydrothermal systems. However, existing model codes of heat flow around hydrothermal systems do not include low-temperature thermochronometer age predictions. Here I present a new model code that simulates thermal history around hydrothermal systems on geological timescales. The modelled thermal histories are used to calculate apatite (U–Th)∕He (AHe) ages, which is a thermochronometer that is sensitive to temperatures up to 70 ∘C. The modelled AHe ages can be compared to measured values in surface outcrops or borehole samples to quantify the history of hydrothermal activity. Heat flux at the land surface is based on equations of latent and sensible heat flux, which allows more realistic land surface and spring temperatures than models that use simplified boundary conditions. Instead of simulating fully coupled fluid and heat flow, the code only simulates advective and conductive heat flow, with the rate of advective fluid flux specified by the user. This relatively simple setup is computationally efficient and allows running larger numbers of models to quantify model sensitivity and uncertainty. Example case studies demonstrate the sensitivity of hot spring temperatures to the depth, width and angle of permeable fault zones, and the effect of hydrothermal activity on AHe ages in surface outcrops and at depth.

scholarly journals Electrical conductivity of HCl-bearing aqueous fluids to 700 ºC and 1 GPa

2020 ◽  
Vol 175 (12) ◽  
Author(s):  
Steffen Klumbach ◽  
Hans Keppler
Keyword(s):  
Electrical Conductivity ◽  
Elevated Temperatures ◽  
Pure Water ◽  
Negative Temperature ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Ambient Conditions ◽  
Data Points ◽  
Hcl Concentration ◽  
Electrical Conductors

AbstractSubsurface magmatic–hydrothermal systems are often associated with elevated electrical conductivities in the Earthʼs crust. To facilitate the interpretation of these data and to allow distinguishing between the effects of silicate melts and fluids, the electrical conductivity of aqueous fluids in the system H2O–HCl was measured in an externally heated diamond anvil cell. Data were collected to 700 °C and 1 GPa, for HCl concentrations equivalent to 0.01, 0.1, and 1 mol/l at ambient conditions. The data, therefore, more than double the pressure range of previous measurements and extend them to geologically realistic HCl concentrations. The conductivities $$\sigma$$ σ (in S/m) are well reproduced by a numerical model log $$\sigma$$ σ  = −2.032 + 205.8 T−1 + 0.895 log c + 3.888 log $$\rho$$ ρ  + log$$\Lambda_{0}$$ Λ 0 (T,$$\rho$$ ρ ), where T is the temperature in K, c is the HCl concentration in wt. %, and $$\rho$$ ρ is the density of pure water at the corresponding pressure and temperature conditions. $$\Lambda_{0}$$ Λ 0 (T,$$\rho$$ ρ ) is the limiting molar conductivity (in S cm2 mol−1) at infinite dilution, $$\Lambda_{0}$$ Λ 0 (T,$$\rho$$ ρ ) = 2550.14 − 505.10$$\rho$$ ρ  − 429,437 T−1. A regression fit of more than 800 data points to this model yielded R2 = 0.95. Conductivities increase with pressure and fluid densities due to an enhanced dissociation of HCl. However, at constant pressures, conductivities decrease with temperature because of reduced dissociation. This effect is particularly strong at shallow crustal pressures of 100–200 MPa and can reduce conductivities by two orders of magnitude. We, therefore, suggest that the low conductivities sometimes observed at shallow depths below the volcanic centers in magmatic–hydrothermal systems may simply reflect elevated temperatures. The strong negative temperature effect on fluid conductivities may offer a possibility for the remote sensing of temperature variations in such systems and may allow distinguishing the effects of magma intrusions from changes in hydrothermal circulation. The generally very high conductivities of HCl–NaCl–H2O fluids at deep crustal pressures (500 MPa–1 GPa) imply that electrical conductors in the deep crust, as in the Altiplano magmatic province and elsewhere, may at least partially be due to hydrothermal activity.

scholarly journals Arsenic and Antimony in Hydrothermal Plumes from the Eastern Manus Basin, Papua New Guinea

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Zhigang Zeng ◽  
Xiaoyuan Wang ◽  
Haiyan Qi ◽  
Bowen Zhu
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Ambient Seawater ◽  
Hydrothermal Plume ◽  
Rock Interaction ◽  
Eastern Manus Basin ◽  
Manus Basin ◽  
Hydrothermal Plumes

Studies on the concentrations of arsenic (As) and antimony (Sb) in seawater columns are very important for tracing hydrothermal plumes and understanding fluid characteristics of seafloor hydrothermal systems. The total As, Sb, Mn, and Cl− concentrations of three hydrothermal plume seawater column samples have been studied at Stations 18G, 18K, and 18B in the eastern Manus back-arc basin, Bismarck Sea, Papua New Guinea. At Stations 18G and 18K, the plumes above North Su and near the Suzette site in the SuSu Knolls hydrothermal field are both enriched in As, Sb, and Mn and depleted in Cl, as a result of contribution of As-Sb-Mn-enriched and Cl-depleted vent fluid outputs to the hydrothermal plume, which is most likely generated in the subseafloor by fluid-rock interaction, magma degassing, or phase separation (boiling of hydrothermal fluid). The plume at Station 18B is enriched in As, Sb, Mn, and Cl, suggesting that As-Sb-Mn-Cl-enriched fluid discharges from vents, which have been generated by fluid-rock interaction. The concentrations of As and Sb anomalous layers, like manganese (Mn), are higher than those of the other layers in the three hydrothermal plume seawater columns. As and Sb with Mn showed a positive correlation (R2>0.8, p<0.05), and the distributions of As and Sb within the hydrothermal plume are not controlled by particle adsorption or biogeochemical cycles, suggesting that As and Sb, like Mn, can be used to detect and describe the characteristics of hydrothermal plumes in seawater environment. In addition, anomalous layer with As/Sb ratio lower than those of ambient seawater at the same temperature is found in the eastern Manus basin, suggesting that the As/Sb ratio may also act as an effective tracer reflecting the effect of hydrothermal activity on As and Sb in the seawater column.

Tectonic constraints on submarine hydrothermal activity, degassing, and subseafloor gas storage (Milos Shallow Water Hydrothermal System, Greece)

2021 ◽  
Author(s):  
Javier Escartín ◽  
Alex Hughes ◽  
Jean-Emmanuel Martelat ◽  
Valentine Puzenat ◽  
Thibaut Barreyre ◽  
...  
Keyword(s):  
Shallow Water ◽  
Thermal Structure ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Fault System ◽  
Temperature Structure ◽  
Hydrothermal Circulation ◽  
Bacterial Mats ◽  
Geophysical Surveys ◽  
Gas Flares

&lt;p&gt;The Milos hydrothermal field is one of the largest known shallow water hydrothermal systems, and shows both fluid and gas outflow through the seafloor. Recent studies based on imagery acquired by both aerial and submarine drones (Puzenat et al., submitted) reveal several types of fluid outflow associated with bacterial mats along the SE coast of the island (Paleochori, Spathi, and Agia Kyriaki bays). From these observations? include: a) zones of polygonal hydrothermal outflow and associated bacterial mats, b) extended white (bacterial) patches, and c) isolated ones. Subseafloor hydrothermal circulation is hosted in sediments with subseafloor temperatures &gt;50&amp;#176;C, and there is a clear association between hydrothermal circulation and active degassing.&lt;/p&gt;&lt;p&gt;To understand the controls on and relationships between fluid and gas outflow in the area, we need to characterise: a) the nature of the subseafloor (sediment thickness, composition &amp; permeability); b) the distribution of gas and subseafloor fluids, and c) the distribution of gas flares emanating from the seafloor. In November 2020, we conducted a short pilot geophysical study at Paleochori Bay, deploying a towed catamaran with a multibeam echo sounder (iXblue Seapix) to obtain seafloor bathymetry, acoustic backscatter and water column detection of gas flares. We also deployed a sub-bottom profiler (iXblue Echoes 3500 T1) to image sediment architecture and gas/fluid diffusion within the sediment. Our survey focused on Paleochori Bay, surveing areas from ~5 m (nearshore) to ~100 m waterdepth (offshore).&lt;/p&gt;&lt;p&gt;Preliminary results of this geophysical survey suggest that subseafloor gas accumulations play a major role on the nature and structure of hydrothermal activity at Milos. These gas accumulations within the sediments develop along an onshore/offshore fault system, and likely control the shallow subseafloor thermal structure, establishing a thin thermal conductive layer between the roof of gas pockets and the seafloor.[GJ1]&amp;#160;[je2]&amp;#160;&amp;#160; We will report on the link between the distribution and geometry (extent, depth, acoustic nature of the accumulations) of gas pockets, fluid outflows, and gas outflows, all of which will be characterised from both seafloor imagery and subsurface geophysical surveys. We will also discuss how gas pocket geometry may be linked to both fluid flow and subseafloor temperature structure. [HA3]&amp;#160;&lt;/p&gt;&lt;div&gt; &lt;div&gt; &lt;div&gt;&amp;#160;&lt;/div&gt; &lt;/div&gt; &lt;div&gt; &lt;div&gt;&amp;#160;&lt;/div&gt; &lt;/div&gt; &lt;div&gt; &lt;div&gt;&amp;#160;&lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

New insights on the structural setting of the Pisciarelli fumarole field (Campi Flegrei caldera): implications for evolution and eruptive scenarios

2020 ◽  
Author(s):  
Roberto Isaia ◽  
Maria Giulia Di Giuseppe ◽  
Jacopo Natale ◽  
Francesco D'Assisi Tramparulo ◽  
Antonio Troiano ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Seasonal Effects ◽  
Campi Flegrei ◽  
Geochemical Data ◽  
Fluid Circulation ◽  
Campi Flegrei Caldera ◽  
Structural Setting ◽  
Fumarole Field ◽  
Self Potential

&lt;p&gt;The Solfatara-Pisciarelli area, located in the active Campi Flegrei caldera (Italy) hosts an intense hydrothermal activity, whose shallower expression is controlled by a complex pattern of fractures and faults. Volcanological and structural studies may be the key to disclose the relationships between brittle structures and hydrothermal activity, as well as to understand the dynamic processes and possible eruption scenarios. For this purpose, we present the results of a volcanological and structural survey combined with Electrical Resistivity Tomography (ERT) and Self Potential data. Three ERT surveys has been performed in order to reconstruct the Pisciarelli structural setting and the relationships of the main fractures and faults with the underground fluid circulation. Two measured profiles crossing the main mud pool and fumaroles of Pisciarelli and has been repeated every three months to evaluate the possible influence of seasonal effects on the hydrothermal system. These profiles performed during the last year have been compared with a first ERT prospection carried on in correspondence of a 100 m long survey line, which crosses along the W-E direction the Pisciarelli permanent mud pool and its main fumarole. The comparison of the results with temperature, geochemical data and rainfall rates allowed to separate the areas dominated by seasonal effects from areas where deeper injected gasses cumulate in the subsoil. Further indication on the fluid circulation and structures derived by a mapping of the self-potential anomaly realized for the whole Solfatara-Pisciarelli area. The rocks exposed in the Pisciarelli area host a large number of faults and fractures, the latter often related to fault damage zones. Cross-cutting fault and fracture relationships and their relations with the volcanic sequences suggest that NW-SE and NE-SW trending faults are sealed by Solfatara deposits (4.28 ka); whereas E-W and N-S trending faults cross-cut the youngest volcanic succession (Astroni deposits, 4.25 ka). Several landslide deposits were recognized in the higher part of the Pisciarelli fumarole field, mainly due to intense rock fracturing, hydrothermal alteration, mud-pool activity and steep relieves surrounding the mud pool. Ancient landslide deposits overlying mud sediments, similar to those nowadays forming within the active mud pool, cropping out along the slope, at about 5 meters above the present mud pool level. New landslide phenomena could seal off the mud pool and fumaroles of Pisciarelli, with a possible consequence to trigger an hydrothermal explosions as described for other hydrothermal systems in the world.&lt;/p&gt;

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