MidOcean Ridges A Connected System Nedimovic et al

2 -D Seismic Survey over Endeavour Segment • Along-axis and cross-axis seismic lines acquired

Along-Axis Seismic Line Van Ark et al. (2007) • Reflector from layer 2 A:

Cross-Axis Seismic Line Van Ark et al. (2007) • Reflector from layer 2 A:

Seismicity Above Axial Magma Chamber Wilcock et al. (2009) • Seismicity pattern consistent with

Streamer Tomography and Hydrothermal Circulation Newman et al. (in prep) • High resolution seismic

3 -D / 4 -D Seismic Proposal (Carbotte, Nedimovic et al. ) • Endeavour

3 -D / 4 -D Seismic Proposal (Carbotte, Nedimovic et al. ) • 3

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Mid-Ocean Ridges: A Connected System Nedimovic et al. (2008) Carbotte et al. (2006), Van Ark et al. (2007) • Hydrothermal circulation links ocean, seafloor, and crust, including vent communities • How is fluid circulation controlled by faulting, fracture systems, and magma chamber? • How does crust evolve? – Layer 2 A – Magma chamber • 3 -D seismic reflection can tie seafloor geology to subsurface at 50 -100 m resolution

2 -D Seismic Survey over Endeavour Segment • Along-axis and cross-axis seismic lines acquired in 2002 (Carbotte et al, 2006) • 2 -D surveys have much lower resolution than 3 -D • Microseismicity studies around vent fields (Wilcock et al. , 2002)

Along-Axis Seismic Line Van Ark et al. (2007) • Reflector from layer 2 A: alteration boundary or top intrusives • Underlying axial magma lens correlates with seismicity under vent fields • Melt reflector is out-of-plane of 2 -D profile: correct positioning requires 3 -D

Cross-Axis Seismic Line Van Ark et al. (2007) • Reflector from layer 2 A: alteration boundary or top intrusives or both • Underlying restricted axial magma lens dips to east, and sometimes correlates with seismicity under vent fields

Seismicity Above Axial Magma Chamber Wilcock et al. (2009) • Seismicity pattern consistent with fracturing above inflating magma sill • Inflation of AMC facilitates heat transfer, and may control seafloor vent distribution • Can these faults be imaged by 3 -D surveys?

Streamer Tomography and Hydrothermal Circulation Newman et al. (in prep) • High resolution seismic velocity models from towed streamer recording • Fluid migration in oceanic crust inferred from velocities and disruption of reflector at base of layer 2 A

3 -D / 4 -D Seismic Proposal (Carbotte, Nedimovic et al. ) • Endeavour is focus of a broad range of geoscience studies • Understanding seafloor and ocean processes requires detailed knowledge of subsurface • 3 -D seismic reflection surveys can image structures at a “geological scale” • Long-term monitoring also requires knowledge of subsurface changes from repeat surveys • Velocity models can be used for earthquake location

3 -D / 4 -D Seismic Proposal (Carbotte, Nedimovic et al. ) • 3 -D seafloor topography and fine-scale structure require 3 -D seismic imaging – – – • Relation between faulting and magma distribution Controls on hydrothermal venting by faults, crack systems, and melt 3 -D fluid circulation constraints Baseline 3 -D survey for long-term site monitoring of seismicity, fluid chemistry, microbiology etc. by NEPTUNE Canada – • 3 -D Result with 1980 s Technology Subsurface evolution by differencing of monitoring surveys (10 year intervals? ) Possible survey sites: Endeavour vent fields, Axial Volcano, East Pacific Rise – Long-term monitoring of Endeavour by Neptune Canada EPR OSC Kent et al. (2001)