Page 10 - GeoPRISMS_Newsletter_Spring2018_Neat

Miocene
T8 Shelf break (+/- Pliocene) T7 T6 T5 T4 T3 T2 T1
Pleistocene-recent
0 NW HSM-06A (lowstand wedge) Stacked Late Quaternary SE 0
mass transport deposits
Ariel Bank HSM-01A&B
1 Fault HSM-07A HSM-10A Hikurangi Trough 1
BSR
2 10 ? 9 ? ? 8 ? BSR 6 5 4 HSM-04A Alternative to HSM-04A HSM-05A VB Gisborne Knolls VB 2 3
Deformation
Depth (km) 4 Mesozoic & Paleogene 7 Mesozoic & Paleogene 3 2 VB 1 VB 4 5 Depth (km)
HSM-08A
3
front
backstop or accreted
5
deforming backstop
Neogene rocks?
11
6
7 B? Interplate thrust HKB B 6 7
8 B? in upper HKB B 8
9 9
10 11
Figure 2. Seismic transects in the Top) northern
field area along the IODP Expedition 375
drilling transect (Saffer et al., 2017), and
T13 Uriti Ridge T12 T11 T10 T9 Bottom) southern field area along seismic line
Two-way time (s) 2 4 Pukeroro Ridge Note that flow meters will also be deployed in
PEG09-23. Locations shown as boxes in Figure
1. Arrows T1-T13 in the seismic reflection
profiles are primary fault targets for surveys,
sampling, and fluid flow meter deployments.
2 km
off-fault locations to monitor local volumetric
strain associated with SSEs.
We are specifically targeting fault zones and off-fault locations the deployment of benthic fluid flow meters (Fig. 3) to generate a
between the deformation front and the shelf-break (Fig. 2). Site record of fluid flow rates and composition over a two-year period
locations will be guided by pre-existing multi- and single-beam - the approximate recurrence interval for SSEs in this region. We
sonar data (including seafloor backscatter and water column anticipate deploying about sixteen benthic fluid flow meters, some
indicators of gas seepage), 2D/3D seismic reflection data, and real- co-located with seafloor bottom pressure recorders managed by GNS
time water column multi-beam sonar surveys during the research Science, during the 2019 field program.Although our focus is on the
expedition. Violin-bow heat flow measurements and piston coring northern margin, the location of shallow SSEs and most research
will guide ROV Jason hydroacoustic surveys, Jason heat flow probe activity, we will also conduct ship and ROV operations and deploy
measurements, and the collection of push cores to further identify a subset of fluid flow meters in the southern region of the margin.
sites of active fluid discharge. Finally, the ROV surveys will guide

Figure 3. A) The Mosquito Temperature Logger Release Plate Position B
benthic fluid flow meter A C
(Solomon et al., 2008). The OsmoSampler
Mosquito uses OsmoSamplers
and a tracer injection device Release Plate Position A
to continuously measure fluid
flow rates and sample for fluid Osmotic Pump
composition at multiple depths
beneath the seafloor. Picture Teon Tubing
shows Mosquito prior to
tripping the release plate that Titanium Needles/
pushes the sampling needles Tracer Injection
into the sediment and during
recovery after sampling for
one year at Hydrate Ridge, offshore Oregon. B) OSU violin
heat flow probe that will be used to further constrain B
the thermal state of the forearc and to identify locations
of fluid transport during the SAFFRONZ experiment. C)
Schematic of the CAT meter and a CAT meter deployed in Data
the vicinity of the Mosquito at Hydrate Ridge (Tryon et logger 3.5-m lance
al., 2002; Brown et al., 2005). The CAT meter uses dilution Weight
of a chemical tracer to measure fluid flow through outlet
tubing exiting the top of a collection chamber. An osmotic Stand Sensor tube
pump injects the tracer at a constant rate into the water
stream as it moves through the outlet tubing. Both Acoustic
Mosquitos and CAT meters will be deployed during the telemetry
SAFFRONZ experiment.

10 • GeoPRISMS Newsletter Issue No. 40 Spring 2018