Reactive transport simulations of lateral hydrothermal circulation in oceanic hydrothermal systems

2006 ◽  
Vol 70 (18) ◽  
pp. A11 ◽  
Author(s):  
P. Alt-Epping ◽  
L.W. Diamond
Keyword(s):  
Reactive Transport ◽  
Hydrothermal Systems ◽  
Hydrothermal Circulation

An advanced reactive transport simulation scheme for hydrothermal systems modelling

Geothermics ◽  
2019 ◽  
Vol 78 ◽  
pp. 138-153 ◽  
Author(s):  
Alina Yapparova ◽  
George D. Miron ◽  
Dmitrii A. Kulik ◽  
Georg Kosakowski ◽  
Thomas Driesner
Keyword(s):  
Reactive Transport ◽  
Hydrothermal Systems ◽  
Transport Simulation ◽  
Systems Modelling ◽  
Simulation Scheme

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

<p>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 >50°C, and there is a clear association between hydrothermal circulation and active degassing.</p><p>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 & 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).</p><p>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] [je2]   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] </p><div> <div> <div> </div> </div> <div> <div> </div> </div> <div> <div> </div> </div> </div>

scholarly journals 2D reactive transport simulations of mid-ocean ridge hydrothermal systems

2019 ◽  
Vol 98 ◽  
pp. 05006
Author(s):  
Donald DePaolo ◽  
Eric Sonnenthal ◽  
Nicholas Pester
Keyword(s):  
Reactive Transport ◽  
Hydrothermal Systems ◽  
Maximum Temperature ◽  
Charge Balance ◽  
Seawater Chemistry ◽  
Fluid Chemistry ◽  
Mid Ocean Ridge ◽  
Spreading Rates ◽  
Ocean Ridge ◽  
Model Fluids

Water-rock interactions in mid-ocean ridge hydrothermal systems are a critical part of Earth system evolution. Extensive insights have been developed from vent fluid chemistry and laboratory experiments, but these leave unanswered many questions about the temporal evolution and spatial structure of the hydrothermal systems that can only be addressed with reactive transport simulations. Other issues are the effects of changing spreading rates and seawater chemistry through Earth history. We are addressing this problem using the Toughreact code, starting with 2D static (no seafloor spreading) simulations of the near-axis region where most of the interaction occurs. The simulations use a dual-permeability grid to represent fractured rocks, and also have a formulation for Sr isotope exchange. Vent fluid Ca, Mg, SO4, and Na concentrations and Sr isotopes can be used as a guide to fluid chemical evolution. Initial simulations reproduce modern vent fluid chemistry even with maximum temperature only at 380°C, and suggest that fluids need not be in equilibrium with the rocks at any point in the system. Model fluids continue to evolve chemically even in the upflow zone prior to venting. The effects of different seawater chemical composition, as proposed for the Cretaceous, for example, can be captured with charge-balance models.

Hydrothermal seawater-basalt exchange reactions traced by triple oxygen and strontium isotope values of fluids and epidotes

2020 ◽  
Author(s):  
David Zakharov ◽  
Ryoji Tanaka ◽  
Craig Lundstrom ◽  
David Butterfield ◽  
Mark Reed ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Reactive Transport ◽  
Isotope Exchange ◽  
Hydrothermal Circulation ◽  
Exchange Reactions ◽  
Geologic History ◽  
Oxygen Isotope Exchange ◽  
Ocean Ridges ◽  
Axial Seamount ◽  
Mass Dependent Fractionation

<p>Hydrothermal circulation of seawater at mid-ocean ridges cools the oceanic crust and modulates the oceanic chemistry over multimillion-year time scales. Recent research on mass-dependent fractionation of triple oxygen isotopes allows us to gain a new insight into the seawater-basalt exchange reactions that occur within the oceanic crust. To understand the systematics of triple oxygen isotope exchange, we present a novel combined dataset for Δ<sup>17</sup>O and <sup>87</sup>Sr/<sup>86</sup>Sr isotope values measured in modern seawater-derived vent fluids at the Axial Seamount volcano located on the Juan de Fuca Ridge and oceanic epidotes extracted from altered mid-ocean ridge basalts. Upon reaction with fresh oceanic crust, seawater evolves towards the low Mg compositions characteristic of fluids in equilibrium with basalt. In concert with decreasing Mg content and with decreasing <sup>87</sup>Sr/<sup>86</sup>Sr, the vent fluids at Axial Seamount shift towards values that are 0.04 ‰ lower in Δ<sup>17</sup>O and 2 ‰ higher in δ<sup>18</sup>O compared to initial seawater. The <sup>87</sup>Sr/<sup>86</sup>Sr and Δ<sup>17</sup>O values of epidotes extracted from modern hydrothermally altered basalts reveal a trend of isotope exchange similar to the one defined by the fluids. We suggest that epidotes record isotope shifts that were experienced by fluids in the areas of focused flow within the oceanic crust. Both fluids and epidotes display similar trajectories of Δ<sup>17</sup>O and <sup>87</sup>Sr/<sup>86</sup>Sr shifts which are modeled using a Monte-Carlo simulation of reactive transport in dual-porosity medium. These trajectories provide important constraints on the physical complexity of reactive circulation of seawater within the oceanic crust. We show how the contribution of hydrothermal circulation to the isotope budget of seawater can be changed during geologic history and evaluated based on the studies of fragments of ancient oceanic crust.</p>

scholarly journals Hydrothermal Activity at a Cretaceous Seamount, Canary Archipelago, Caused by Rejuvenated Volcanism

2020 ◽  
Vol 7 ◽  
Author(s):  
Andreas Klügel ◽  
Heinrich Villinger ◽  
Miriam Römer ◽  
Norbert Kaul ◽  
Sebastian Krastel ◽  
...  
Keyword(s):  
Heat Flow ◽  
Basaltic Rock ◽  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Hydrothermal Circulation ◽  
Rock Fragments ◽  
Summit Area ◽  
Fluid Venting ◽  
Dense Coverage ◽  
Shell Fragments

Our knowledge of venting at intraplate seamounts is limited. Almost nothing is known about past hydrothermal activity at seamounts, because indicators are soon blanketed by sediment. This study provides evidence for temporary hydrothermal circulation at Henry Seamount, a re-activated Cretaceous volcano near El Hierro island, close to the current locus of the Canary Island hotspot. In the summit area at around 3000–3200 m water depth, we found areas with dense coverage by shell fragments from vesicomyid clams, a few living chemosymbiotic bivalves, and evidence for sites of weak fluid venting. Our observations suggest pulses of hydrothermal activity since some thousands or tens of thousands years, which is now waning. We also recovered glassy heterolithologic tephra and dispersed basaltic rock fragments from the summit area. Their freshness suggests eruption during the Pleistocene to Holocene, implying minor rejuvenated volcanism at Henry Seamount probably related to the nearby Canary hotspot. Heat flow values determined on the surrounding seafloor (49 ± 7 mW/m2) are close to the expected background for conductively cooled 155 Ma old crust; the proximity to the hotspot did not result in elevated basal heat flow. A weak increase in heat flow toward the southwestern seamount flank likely reflects recent local fluid circulation. We propose that hydrothermal circulation at Henry Seamount was, and still is, driven by heat pulses from weak rejuvenated volcanic activity. Our results suggest that even single eruptions at submarine intraplate volcanoes may give rise to ephemeral hydrothermal systems and generate potentially habitable environments.

scholarly journals Complex subsurface hydrothermal fluid mixing at a submarine arc volcano supports distinct and highly diverse microbial communities

2020 ◽  
Vol 117 (51) ◽  
pp. 32627-32638
Author(s):  
Anna-Louise Reysenbach ◽  
Emily St. John ◽  
Jennifer Meneghin ◽  
Gilberto E. Flores ◽  
Mircea Podar ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Hydrothermal Fluid ◽  
Community Dynamics ◽  
Hydrothermal Systems ◽  
Microbial Colonization ◽  
Hydrothermal Circulation ◽  
Microbial Life ◽  
Mineral Assemblages ◽  
History Of ◽  
Arc Volcano

Hydrothermally active submarine volcanoes are mineral-rich biological oases contributing significantly to chemical fluxes in the deep sea, yet little is known about the microbial communities inhabiting these systems. Here we investigate the diversity of microbial life in hydrothermal deposits and their metagenomics-inferred physiology in light of the geological history and resulting hydrothermal fluid paths in the subsurface of Brothers submarine volcano north of New Zealand on the southern Kermadec arc. From metagenome-assembled genomes we identified over 90 putative bacterial and archaeal genomic families and nearly 300 previously unknown genera, many potentially endemic to this submarine volcanic environment. While magmatically influenced hydrothermal systems on the volcanic resurgent cones of Brothers volcano harbor communities of thermoacidophiles and diverse members of the superphylum “DPANN,” two distinct communities are associated with the caldera wall, likely shaped by two different types of hydrothermal circulation. The communities whose phylogenetic diversity primarily aligns with that of the cone sites and magmatically influenced hydrothermal systems elsewhere are characterized predominately by anaerobic metabolisms. These populations are probably maintained by fluids with greater magmatic inputs that have interacted with different (deeper) previously altered mineral assemblages. However, proximal (a few meters distant) communities with gene-inferred aerobic, microaerophilic, and anaerobic metabolisms are likely supported by shallower seawater-dominated circulation. Furthermore, mixing of fluids from these two distinct hydrothermal circulation systems may have an underlying imprint on the high microbial phylogenomic diversity. Collectively our results highlight the importance of considering geologic evolution and history of subsurface processes in studying microbial colonization and community dynamics in volcanic environments.

Sign in / Sign up

Export Citation Format

Share Document