Processing Notes

IODP-MSP drilling and logging contractor: ESO

Hole: M0080A

Expedition: 381

Location: Gulf of Corinth (Ionian Sea)

Latitude: 38° 7' 12.1467" N

Longitude: 23° 5' 10.6138" E

Logging date: December 15 – 17, 2017

Sea floor depth (driller's): 350.22 mbsl

Sea floor depth (logger's): 349.2 mbsl

Total penetration: 534.10 mbsf (drillers)

Core recovery:  78%

Oldest sediment recovered: n/a at time of writing

Lithologies: mud, clay, sand, gravel, breccia

TOOL USED: 2PSA (Full Waveform Sonic Probe)

Recording mode: upper and lower sections - 10 kHz, middle section – 15 kHz (compressional waveforms).

Remarks about the recording:

The 2PSA sonic probe of Mount Sopris measures compressional wave velocities of the formation. The 2PSA is composed of an acoustic transmitter and 4 receivers. The transmitter transmits an acoustic signal that propagates through the borehole fluid to the rock interface where some of the energy is critically refracted along the borehole wall. As a result of wavefront spreading (Huygens principle), some of the refracted energy is transmitted back into the borehole. Where energy is transmitted back into the borehole adjacent to a receiver the receiver picks up the signal, amplifies it, digitizes it and then sends the digitized signal to the surface. The recorded waveforms are examined, and wave arrival times selected (picking). The arrival times are the transit times of the acoustic energy. By measuring the acoustic transit time and knowing the distance between receivers (1 foot), the sonic velocity of the rock is calculated. Acoustic waves are highly dependent on borehole conditions. Larger cavities causes the induced wave to scatter and acoustic energy is lost more rapidly.

The data was filtered (frequency filter) in such a way that only the energy around the induced frequency (source) was analyzed. Waveform picking was done manually in the WellCAD software package. Time picks were saved and the acoustic velocities were calculated (using the receiver spacing of 1 ft).

The acoustic data acquired with the tool acquisition software were converted into ASCII format. Each of the four waveforms generally consists of 525 samples, each recorded every 4 microseconds. Each row of the binary file consists of the entire waveform, preceded by depth.

The following files were converted:

381-M0080A_2psal-10RX1-proc.txt

381-M0080A_2psal-10RX2-proc.txt

381-M0080A_2psal-10RX3-proc.txt

381-M0080A_2psal-10RX4-proc.txt

381-M0080A_2psamid-15RX1-proc.txt

381-M0080A_2psamid-15RX2-proc.txt

381-M0080A_2psamid-15RX3-proc.txt

381-M0080A_2psamid-15Rx4-proc.txt

381-M0080A_2psau-10RX1-proc.txt

381-M0080A_2psau-10RX2-proc.txt

381-M0080A_2psau-10RX3-proc.txt

381-M0080A_2psau-10RX4-proc.txt

Additional information about the drilling and logging operations can be found in the Operations section of the Site Chapter in IODP Proceedings of Expedition 381.
For further questions about the data, please contact:

Erwan Le Ber

University of Leicester

Phone: 011-44-116-252-3327

Fax: 011-44--116-252-3918

E-mail: elb51@le.ac.uk