Appendix A Data Inventory

A1 Geophysical data Inventory

A wide range of seismo-acoustic data have been employed to effect this study, the table below summarizes data type and specifications.

DATA TYPE ACQUISITION PARAMETERS INSTRUMENTS RELEVANT PROCESSING FINAL DATA SPECS

AUV-Borne Multibeam Bathymetry

5 Km long east west lines, 200m spacedThe AUV was flying 60m off the seafloor

Simrad EM 2000Multibeam echosounder

Attitude Parameters Correction,Inertial Navigation Drift CorrectionSound Velocity CorrectionSounding Editing

Seafloor bathymetry 5m bin size

NR1 Side Scan Sonar Acoustic

Back Scatter Imagery

89 lines 3 km long, 15m apartSubmarine flying 10m off the seafloor

US Navy manufactured177.5 kHz Side Scan Sonar

Navigation Editing and CorrectionAttitude Parameter CorrectionSlant Range CorrectionBeam Pattern CorrectionTopography CorrectionAngle Varying Gain CorrectionDespeklingMosaiking

Acoustic Backscatter Imagery 20cm pixel resolution

3D Multichannel Oil Industry

seismic Volume

Acquisition Date: 10/23/99 – 07/06/2000Data Acquired by: CGGShooting Orientation: North-SouthRecording Instrument: Syntron 480Streamer Type: SyntronSource/Streamer Positioning: GPS/DGPSAirgun Source: 4180 cubic inchesGun Depth: 7.5 meters +/- 1 meterShotpoint Interval: 62.5 meters per CMP lineCMP Crossline Separation: 40 metersGroup Interval: 25 metersRecording Channel: 288 per streamerStreamer Depth: 9 meters +/- 1.5 metersStreamer Length: 7200 metersRecord Length: 12.288 secondsSample Interval: 2 millisecondsNominal Fold: 57.6

Resample to 4 msStatic correction (-128 ms)Merge navigation and seismic dataRadon filter (multiplesuppression)Trace-to-trace equalizationSignature deconvolutionSpherical divergence and gaincorrection3D azimuthal DMOPre-stack (F-K) migrationVelocity analysisSpiking/predictive deconvolutionLow-cut filter (4 Hz)Remove gain correctionNMOStackDe-migrate – output raw stackTrace interpolationFinite difference migration –output raw migration

Dominant Frequency 50 Hz:Vertical Resolution about 50mPenetration about 2.5km

Surface Source Deep Receiver

(SSDR) v

Vertical incidence single channelseismic profiler96 line 3 km long 50m spaced in the North South direction, 100m spaced in the East West direction

Source 80 Cubic Inch Sodera Watergan GPS positionedReceiverCastum Build single channel ministreamer USBL positioned

EMD Time domain filteringSpherical DivergencePhase Conjugation DeconvolutionKirkoff migration

Dominant frequency 1.5kHz, , vertical resolution 1m; penetration up to 400m

2D AUV Borne High Resolution

Chirp Subbottom Profiles

5 Km long east west line, 200m spacedThe AUV was flying 60m off the seafloor

Edgetech Chirp Sub-bottom profiler carried on AUV. Frequency modulatedbetween 2 and 8 kHz, Record length of 300 ms and 63-ms sampling interval.

Datum Static CorrectionChirp pulse Matching Filter

Dominant frequency 2.5 kHz, vertical resolution about 10cm; penetration up to 50m

A2 Biological data inventory

Biological data were obtained entirely through examinations of visual images (pictures and videos). The table below summarizes visual data, provenience, and quality. Figures A1 displays the location of the video surveys.

Video Survey Image Sample

Cruise/ Platform C/O JSL 2002 – Johnson Sea Link submersible

Screenshot from video acquired during the C/O JSL 2002.

Dive hours 10

Format file .IFO (4 dvd)

Image quality Very Good

Parameters display Salinity, Temperature and depth

Navigation file No navigation file

Dive-log Dive-log with landmark points

Video Survey Image Sample

Cruise/ Platform Deep See-Camera Cruise (2006) – SSD Service Station

Device

Screenshot from video acquired during the C/O Deep See-Camera Cruise 2006.

Dive hours 10

Format file .IFO (10 dvd)

Image quality Good

Parameters display Coordinate, heading, time, data

Navigation file .txt files (long. Lat, time, code dive)

Dive-log Good dive-log

Video Survey Image Sample

Cruise/ Platform C/O JSL 2006 – Johnson Sea Link submersible

Screenshot from video acquired during the C/O JSL 2006.

Dive hours 15

Format file .avi (high resolution) and format with low resolution

Image quality Very good

Parameters display Time, data, salinity, temperature, depth (missing in one

file)

Navigation file 10 .txt files (longitude, latitude and time). 215 seafloor

pictures and associated to navigation files are available

(2272x1704 pix).

Dive-log N/A

Video Survey Image Sample

Cruise/ Platform SSD 2009-2010 - Service Station Device

Dive hours 4

Format file .AVI

Image quality Poor (sediments and particles in the water column)

Parameters display Coordinates, heading, time, data

Screenshoot from video acquired during the C/O

SSD 2009-2010.

Navigation file N\A

Dive-log N\A

Video Survey Image Sample

Cruise/ Platform Lophelia II 2010 – Jason/Medea

Dive hours 17

Format file 20 dvd (four for each operative camera)

Image quality Excellent (1103 seafloor pictures)

Parameters display No available

Navigation file .csv files (YYYY/MM/DD HH:MM:SS unixSeconds

filename lat long)

Dive-log N\A

Video Survey Image Sample

Cruise/ Platform Alvin Cruise (2010) - DSV Alvin submersible

Screenshoot from video acquired during the C/O Alvin 2010.

Dive hours 7

Format file .AVI (10 dvd)

Image quality Very good

Parameters display Data, heading and depth

Navigation file .txt (offset error)

Dive-log N\A

Video Survey Image Sample

Cruise/ Platform HOS Sweetwater 2011(British Petroleum) – Canyon

Triton XL Remotely Operated Vehicle

Picture acquired by ROV during the HOS Sweetwater cruise.

Dive hours No video, 330 pictures

Format file .tiff

Image quality Excellent

Parameters display N\A

Navigation file N\A

Dive-log N\A

Figure A1. Locations and origin of the video surveys.

Screenshoot from video acquired during the C/O Lophelia II 2010.

A3 Geological data inventory

Over 100 geological samples have been collected in several stages from 2005-2015 and include

gravity cores (maximum penetration 7.5m), jumbo piston cores (maximum penetration 18m) and

push-cores (maximum penetration 0.5m) collected via ROV. Figure A2 shows the location of the

geological samples. Note that many samples have been collected only a few meters apart and

therefore cannot be distinguished at the figure scale.

The character of the host sediment surrounding the Woolsey Mound to a distance of at least 3 km

consists of poorly sorted, fine-silt-rich sediment with minor amounts of clay and sand-size

foraminifera (Brunner, 2007; Brunner and Ingram, 2008; Ingram et al., 2010). A homogeneous,

heavily bioturbated, light olive mud, which contains as much as 10% planktonic foraminiferal sand

and 40% carbonate, caps the section to a depth of about 1 m and is largely Holocene in age, based

on the planktonic foraminifera (Z Zone of Kennett and Huddlestun, 1972). A dark olive mud with

large burrows filled by light olive mud underlies the Holocene interval. The foraminiferal sand

content in this unit and all those beneath is reduced to a fraction of a percent, and total carbonate is

reduced to 10-20% by weight [Brunner, personal communication]. The mottles grade into thinly

stratified, brown and olive mud layers below, each layer being 1-2 cm thick. The mottled unit

corresponds to most of the deglacial period (Zone Y1 of Kennett and Huddlestun, 1972).

A clay-rich horizon with a distinct reddish hue and filled with reworked, pre-Quaternary

nannofossils (Marchitto and Wei, 1995) lies at or just below the base of the mottled unit. The

reddish layer corresponds to deglacial meltwater event 1A (Aharon, 2006; Montero-Serrano et al.,

2009). Radiocarbon dating of the horizon (Brunner and Ingram, 2008; Ingram et al., 2010)

produced an age of ~14.2-14.7 ka. The reddish layer covers much of the central and western slope

of the Gulf of Mexico and is a useful datum level (Montero-Serrano et al., 2009).

The stratal, layered units below the mottled mud (to a maximum cored depth of 15 m) vary in color

and sharpness of stratal contacts, and some intervals contain frequent, well-sorted, silt layers,

typically no thicker than 1 mm (Brizzolara and Brunner, 2012; Brunner and Brizzolara, 2011).

Many intervals contain Tasmanites, an algal cyst. The lithofacies is similar to that reported in the

Wisconsinan sections of DSDP Leg 96 (Bouma et al., 1986). The planktonic foraminifera are

consistent with a Wisconsinan age (Y Zone of Kennett and Huddlestun, 1975).

The sediment within the Woolsey mound, in general, has the same lithostratigraphy as described

above, but some cores appear overprinted by diagenetic alteration. The sediment in these cores is a

clear, light gray in contrast to the brown and olive hues described above. The gray intervals contain

few or are barren of foraminifera, sometimes contain large, Vesicomyid clam valves, sometimes

contain the pin–prick marks of exsolving gas, and often contain carbonate nodules surrounded by

light gray areole. Lapham et al. (2008) report that the geochemistry in such cores supports

authigenic carbonate formation related to methanogenesis.

Figure A2 General overview of geological cores location and lithofacies analysis result (modified from Macelloni et al., 2013)

References

Aharon, P., 2006. Entrainment of meltwaters in hyperpycnal flows during deglaciation superfloods in the Gulf of Mexico. Earth and Planetary Science Letters, 241, 260-270.

Bouma, A.H., Coleman, J.M., Meyer, A.W., (Eds.), 1986. Initial Reports of the Deep-Sea Drilling Project, Leg 96. Washington D.C., U.S. Government Printing Office, pp. 563–576.

Brizzolara, J.L., and Brunner, C.A., 2012. Lithostratigraphy of jumbo piston cores from the Woolsey Mound, the northern Gulf of Mexico. Journal of the Mississippi Academy of Sciences, v. 57, no. 1, p. 121.

Brunner, C.A., 2007. Stratigraphy and Paleoenvironment of Shallow Sediments from MC118. Proceedings of Gulf of Mexico Hydrates Research Consortium Annual Meeting, October 10, 2007, Oxford, Ms.

Brunner, C.A., and Brizzolara, J.L., 2011. Lithostratigraphy and physical properties of jumbo piston cores from the Woolsey Mound. Oral presentation at the MMRI Methane Consortium Annual Meeting, Jackson, Ms., 8 November 2011.

Brunner, C.A., and Ingram, W., 2008. Stratigraphy and paleoenvironment of shallow sediments from MC118. Oral presentation at the MMRI Methane Consortium Annual Meeting, Oxford, Ms., October 2008.

Ingram, W.C., Meyers, S.R., Brunner, C.A., and Martens, C.S., 2010. Evaluation of Late Pleistocene-Holocene sedimentation surrounding an active seafloor gas hydrate and cold seep field on the Northern Gulf of Mexico Slope. Mar. Geol., 278, 43-53.

Kennett, J.P., Huddlestun, P., 1972. Late Pleistocene paleoclimatology, foraminiferal biostratigraphy and tephrochronology, Western Gulf of Mexico. Quaternary Research 2, 38–69.

Lapham, L.L., Chanton, J.P., Martens, C.S., Woolsey, R.J., 2008. Microbial activity in surficial sediments overlying acoustic wipe-out zones at a Gulf of Mexico cold seep. Geochemistry. Geophysics. Geosystem. 9, Q06001.

Marchitto, T.M., K.-Y. Wei, 1995. History of the Laurentide meltwater flow to the Gulf of Mexico during the last deglaciation, as revealed by reworked calcareous nannofossils. Geology, 23, 779-782.

Montero-Serrano J., C., Bout-Roumazeilles, V., Tribovillard, N., Sionneau, T., Riboulleau, A., Bory, A., Flower B., 2009. Sedimentary evidence of deglacial megafloods in the northern Gulf of Mexico (Pigmy Basin). Quaternary Science Review, 28, pp. 3333–3347.