Tracklines

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123°45' 40' 35' 30' 25' 20' 15' 10' 05' 123°00' 55' 50' 45' 40' 35' 30' 25' 20' 15' 122°10'
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PGC 96006 Tracklines

Links: Click on regions of this map to display an enlarged image of the region which includes the sample number of each core and line numbers for each trackline. As the mouse is moved over the map, links are revealed when the icon changes to .

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Themes visible in the above map: TRACKLINES PGC96006, CORE SITES PGC96006, LATITUDE/ LONGITUDE and LAND. The SAMPLE field for CORE SITES PGC96006 contains the core sample numbers. The position of the each core can be found in the LATITUDE and LONGITUDE field. For TRACKLINES PGC96006, the LINE field contains the trackline numbers.

Data Report for CCGS John P. Tully PGC96006 October 15-October 31, 1996
David C. Mosher

This map sheet shows the tracklines and cores collected during expedition PGC96006. Multichannel seismic reflection and Huntec high resolution subbottom profiles were collected simultaneously over the region. The tracklines form a largely east-west grid with over 1300 line-km of data acquired (Tables 1-4) and 17 shallow sediment cores (Table 5). The multichannel system consisted of a Haliburton 0.65 L (40 cu.in.) sleeve gun and an Innovative Transducers Inc. (ITI) 24-channel hydrophone solid array. The array had 3 hydrophones per group and 8 m separation between the centre hydrophone in each group. Separation between the gun and the centre element of the first group was 56 m. The streamer and gun was towed at 1 m below the sea surface. The gun was fired every 16 m using a computer acquiring differential GPS to calculate the offset from the last shot. The sleeve gun was charged to a pressure of about 2000 psi. These seismic data were digitized with a sample interval of 500 µs over a record length of 2048 ms. This sample rate translates to a Nyquist frequency of 1000 Hz, well in excess of the bandwidth of the source. The configuration of the array allowed for a six-fold CDP stack of the data. Initial stacks with semblance velocity analysis were conducted on board the vessel during the survey. For this processing, the data were subsampled to 1 ms sample interval, with no loss of information, and terminated at a record length of 1024 ms.

High resolution reflection data (shallow subbottom) were acquired simultaneously with the multichannel acquisition. The Huntec Deep Tow System employs a boomer source with an internal and external hydrophone receiving array. The boomer source generates a broad band pulse with a centre frequency of about 2.5 kHz, but spans 0.5 to 6 kHz relatively cleanly. The system was run at 1.75 kJoules output. It is deep-towed between 30 and 60 m below the surface in this survey area. Deep towing the system puts the source and receiver closer to the seafloor and away from surface heave. The system is depth and heave compensated. The internal hydrophone is a single cartridge suspended from the boomer plate and is best for high frequency acquisition. The external array is a 4.6 metres long, 10-element oil filled streamer towed from behind the fish. It acquires a broader frequency band than the internal hydrophone, but is subject to heave and more external noise. The internal and external signals were displayed in analogue hardcopy on an EPC9800 chart recorder. The data were recorded on a Sony™ DAT 8-channel recorder and were digitized at 40 µs for a record length of 175 ms (deep-water delays were used to keep the record length short) and written to Exabyte™ tape with a MUSE® digital sonar acquisition system. This sample interval yields a Nyquist frequency of 12.5 kHz. The boomer source was fired every 1.5 m, but was interrupted during acquisition of the multichannel data.

17 piston cores were attempted and 15 recovered sediment, totaling 44.7 m of core sample. Coring targets were selected on the basis of shallow seismic reflection data collected during this cruise. The objectives of coring were to groundtruth the geophysical data, to provide stratigraphic information and to investigate targets identified from seismic reflection, such as shallow faults and unconformities. The cores were described, physical properties measured and subsampled for dateable material (Table 5).

Reference Citation:
Mosher, D.C., 2000. Data Report for CCGS John P. Tully PGC96006
October 15-October 31, 1996, in: Mosher, D.C. and Johnson, S.Y. (Eds.), Rathwell, G.J., Kung, R.B., and Rhea, S.B. (Compilers), Neotectonics of the eastern Juan de Fuca Strait; a digital geological and geophysical atlas. Geological Survey of Canada Open File Report 3931

USGS Tracklines
SHIPS Tracklines
Industry Tracklines

PGC97007 Tracklines

Links: Click on regions of this map to display an enlarged image of the region which includes the sample number of each core and line numbers for each trackline. As the mouse is moved over the map, links are revealed when the icon changes to .

Arc Explorer
Themes visible in the above map: TRACKLINES PGC97007, CORE SITES PGC97007, LATITUDE/ LONGITUDE and LAND. The SAMPLE field for CORE SITES PGC97007 contains the core sample numbers. The position of the each core can be found in the LATITUDE and LONGITUDE field. For TRACKLINES PGC97007, the LINE field contains the trackline numbers.

Data Report for CCGS John P. Tully PGC97007 - Leg I August 5-16, 1997
David C. Mosher

PGC97007 consisted of a grid of lines, largely oriented northeast-southwest, of 850 line-km of single channel seismic reflection data, and 26 piston and vibrocores. It was planned to augment data collected during PGC96006. Single channel seismic reflection and Huntec DTS high resolution subbottom profiles were collected simultaneously over the eastern Juan de Fuca Strait (Tables 1-4). The seismic source consisted of two Bolt 10 cu.in. airguns suspended in a frame, 0.5 m apart and towed at a depth of 0.5 m depth and 15 m behind the stern of the ship. Airguns were pressurized to 1850 psi and fired every 4 m, based on differential GPS positioning. A single EDO model 141B hydrophone cartridge was deep-towed below the airguns to monitor every shot point signature. The relative timing of the firing of the two guns was controlled by a 3-channel Bolt firing unit, permitting 0.1 ms accuracy in firing delay. The shotpoint source signature was monitored on a Zonic model 3525 spectral analyzer. The shot point hydrophone and analyzer provided real-time display of the source signature in time and frequency domains. The source signature was then tuned to maximize the outgoing pulse for shape and frequency content by adjusting the relative firing time of the two guns.

Two hydrophone streamers were used to acquire the single channel seismic reflection data. 1) A Benthos array, which is oil-filled and consists of a single group of 50 elements with 15 cm spacing. It was towed just below the surface, 30 m behind the ship; and 2) A Teledyne array, which has a 25 m active section with 50 hydrophone cartridges. It was towed at 3 m depth, 50 m behind the ship. Signal from these arrays and the single cartridge shot point hydrophone were displayed as analogue hardcopy on an EPC 9800 chart recorder, logged to a SONY™ DAT recorder and digitized at 100 ms for a length of 1000 ms on EXABYTE™ tape with a MUSE® digital sonar acquisition system.

The Huntec Deep Tow System employs a boomer source with an internal and external hydrophone receiving array. The boomer source generates a broad band pulse with a centre frequency of about 2.5 kHz, but spans 0.5 to 6 kHz relatively cleanly. The system was run at 1.75 kJoules output. It is deep-towed between 30 and 60 m below the surface in this survey area. Deep towing the system puts the source and receiver closer to the seafloor and away from surface heave. The system is depth and heave compensated. The internal hydrophone is a single cartridge suspended from the boomer plate and is best for high frequency acquisition. The external array is a 4.6 metres long, 10-element oil filled streamer towed from behind the fish. It acquires a broader frequency band than the internal hydrophone, but is subject to heave and more external noise. The internal and external signals were displayed in analogue hardcopy on an EPC9800 chart recorder, recorded on a SONY™ DAT 8-channel recorder and were digitized at 40 s for a record length of 250 ms (deep-water delays were used to keep the record length short) and written to EXABYTE™ tape with a MUSE® digital sonar acquisition system. This sample interval yields a Nyquist frequency of 12.5 kHz. The boomer source was fired at every 1.0 m, but was interrupted for 1 second during firing and acquisition of the seismic data.

 

Reference citation:
Mosher, D.C., 2000. Data Report for CCGS John P. Tully PGC97007
- Leg I August 5-16, 1997, in: Mosher, D.C. and Johnson, S.Y. (Eds.), Rathwell, G.J., Kung, R.B., and Rhea, S.B. (Compilers), Neotectonics of the eastern Juan de Fuca Strait; a digital geological and geophysical atlas. Geological Survey of Canada Open File Report 3931

USGS Tracklines
SHIPS Tracklines
Industry Tracklines
48°30'
25'
20'
15'
10'
05'
48°00'
123°45' 40' 35' 30' 25' 20' 15' 10' 05' 123°00' 55' 50' 45' 40' 35' 30' 25' 20' 15' 122°10'
Tul99B Next Map >
123°45' 40' 35' 30' 25' 20' 15' 10' 05' 123°00'

Arc Explorer

Themes visible in the above map: CORE SITES 1999, LATITUDE/ LONGITUDE, COASTLINE and LAND. The SAMPLE field for CORE SITES 1999 contains the core sample numbers. The position of the each core can be found in the LATITUDE and LONGITUDE field.

 

 

48°30'
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48°15'