Interdisciplinary Groups: Causes and consequences of perturbations to magmatic, hydrothermal, and biological systems

Moderator: Tim Shank

Participants (list your name here):
    •    Ken Rubin
    •    David Graham
    •    Breea Govenar
    •    Deb Kelley
    •    Anna-Louise Reysenbach
    •    Joe Resing
    •    Peter Rona
    •    Vicki Ferrinni
    •    Maya Tolstoy
    •    Robert Weekly
    •    Adam Soule
    •    Allison Fundis

Goals:
1) identify and examine the diverse range of causes of geological, geochemical, and biological perturbations
2) identify the diverse range of consequences for these perturbations – are they different at the 3 ISSes
3) examine the spatial and temporal length scales of these perturbations and their affects on the various linkages (see linkage diagram)
strawman: how system perturbations may affect system linkages (click thumbnail or here to see full image)
4) determine if we have enough information to make a diagram that shows the causes, consequences, & observed scales identification of datasets ready for integration (e.g., Geological, geochemical, and biological results from both ISS and non-ISS sites, including Axial Seamount, Gorda Ridge, Loihi Seamount, Galapagos Rift, NW Rota, W. Mata, NELSC, Gakkel Ridge, and the Northern and Southern Mid-Atlantic Ridge)
    •    magnitudes and timescales of system response to volcanic perturbations (both near-field and far field)
    •    what is the duration of "volcanic crises" and characterizing system responses during prolonged (multi-month) events
    •    non volcanic perturbations - tectonic, magma intrusion: is system perturbation proportional to event size, length scale, frequency?
    •    What are the major (and minor) perturbations to faunal communities at the Lau, EPR, and Endeavor ISS?
    •    What are the relationships between temporal perturbations (e.g., frequency of eruptions, cracking, chimney collapse, shifts in fluid chemistry) on faunal composition in Lau Basin, EPR, and Endeavor?
    •    What's more important to the immediate post-eruptive colonization of these ISS' by animals? Larval availability or microbial community structure on the basalt (or perhaps free-living symbionts in the water column)? What else?
    •    Does volcanic substrate type and texture (e.g., flow types, lava textures and vesicularity, flows versus pyroclastrs) play a role in post-eruptive colonization?

Notes from the first phase of the discussion:

Cascading effects of perturbations:
e.g., something causes phase separation, which changes local habitat, which to an animal feels like a perturbation.

Perturbation 1: Idealized Eruption:
Causes = stress release failure of the crust due to magma or volatile over pressure, rifting event
Response (A):
    ◦    carapace cracks
    ◦    earthquakes
    ◦    volatiles precede the melt into the crust
    ◦    litho to hydrostatic pressure regime
    ◦    volatiles exsolve from magma
    ◦    volatiles may phase separate in hydrothermal fluids resident in the crust
    ◦    diking-injection of magma into the crust, stress changes in crust
    ◦    event plume forms
Next set of responses (B):
    ◦    eruption on the seafloor (days)
    ◦    vaporization
    ◦    catastrophic habitat change (animals dies, microbes die, pulse of burnt organic matter, expulsion of subsurface microbes from the system)
    ◦    some consumption in the water column
    ◦    volatile release
    ◦    pyroclastics formation in some instances.
    ◦    Plume(s) forms
    ◦    particles and heat transferred to water column.
    ◦    Reorganization of fluid flow pathways in the subsurface and associated fractures
Next set of responses after effusion stop (c) minutes to hours:
    ◦    microbes colonize (minutes)
    ◦    microbial mats (biofilm formation - within hours)
    ◦    fluid flow reorientation continues
    ◦    something happens to high-T fluid chemistry, massive increase in diffuse flow,
Next set of responses after effusion stop (d) days:
    ◦    grazers arrive (crabs fish, amphipods, limpets) associated with mats (days)
    ◦    microbial succession changes
    ◦    non-ponded lava flows fully solidify
    ◦    no new surface sulfide edifices
Next set of responses after effusion stop (d) weeks:
    ◦    hydrologic changes continue
    ◦    larvae settle
    ◦    hydrothermal fluid temperatures recover
Next set of responses after effusion stop (e) months:
    ◦    decrease in aerial extent of diffuse flow,
    ◦    dike starts cooling, macrofaunal colonization
    ◦    basalt alteration initiates
    ◦    chimneys start,
    ◦    eruption floc stops,
    ◦    event plumes dissipate

Next set of responses after effusion stop (e) years:
    ◦    fluid compositions relax to steady state
    ◦    additional vents form
    ◦    to be continued…

How would these differ at each ISS or elsewhere?
What about repeating this thought experiment for other types of perturbations?
Other General comments:
What aspects of the system or at what sites do we know enough about the baseline to identify perturbations?
20 yr records of carbon isotopes tell us volatile inputs into the system

Reference material:
R2K time critial studies page: http://www.ridge2000.org/science/tcs/index.php
TCS final report (attached)