Wireline Sonic Waveform Data
IODP logging contractor: USIO/LDEO
Expedition: 341
Hole: U1421A
Location: Gulf of Alaska
Latitude: 59° 30.4399' N
Longitude: 143° 2.7395' W
Logging date: July 27, 2013
Sea floor depth (driller's): 729.7 m DRF
Sea floor depth (logger's): 729 m WRF
Total penetration: 702.7 m DSF (1432.4 m DRF)
Core recovery: 20% of cored interval
Oldest sediment recovered: < 0.5 Ma (biostratigraphy)
Lithologies: mud with and without lonestones, diamict, drilled rock, diatom ooze
TOOL USED: DSI (Dipole Sonic Imager)
Recording mode: Monopole P&S and Upper and Lower Dipole (all passes).
Remarks about the recording: none.
MONOPOLE P&S MODE: measures compressional and hard-rock shear slowness. The monopole transmitter is excited by a high-frequency pulse, which reproduces conditions similar to previous sonic tools.
UPPER DIPOLE MODE: measures shear wave slowness using firings of the upper dipole transmitter.
LOWER DIPOLE MODE: measures shear wave slowness using firings of the lower dipole transmitter.
Acoustic data are recorded in DLIS format. Each of the eight waveforms generally consists of 512 samples, each recorded every 10 (monopole P&S) and 40 microsec (dipolemodes), at depth intervals of 15.24 cm (6 inches).The original data in DLIS format is first loaded on a Sun system using GeoFrame software. The packed waveform data files are run through a GeoFrame module that applies a gain correction and then converted into ASCII and finally binary format.
Number of columns: 4097
Number of rows: 5287 (downlog)
Number of rows: 5371 (main)
Number of rows: 2769 (repeat)
The following files have been loaded:
DIT/DSI/HLDS/EDTC-B (Downlog, drill pipe at ~92 m WSF)
341-U1417E_ldip_d.bin: -67.5-738 m WSF
341-U1417E_mono_d.bin: -67.5-738 m WSF
341-U1417E_udip_d.bin: -67.5-738 m WSF
DIT/DSI/HLDS/EDTC-B (Main, drill pipe at ~92 m WSF)
341-U1417E_ldip_main.bin: -122.45-695.94 m WSF
341-U1417E_mono_main.bin: -122.45-695.94 m WSF
341-U1417E_udip_main.bin:-122.45-695.94m WSF
DIT/DSI/HLDS/EDTC-B (Recorded open hole)
341-U1417E_ldip_rep.bin: 274.09-695.94 m WSF
341-U1417E_mono_rep.bin: 274.09-695.94 m WSF
341-U1417E_udip_rep.bin: 274.09-695.94m WSF
The sonic waveform files are depth-shifted to the seafloor (-729 m) but they are not depth-matched to the reference run. Please refer to the 'depth_matches' folder in the hole index page for the depth-matching values and to the "DEPTH SHIFT" section in the standard processing notes for further information.
Additional information about the drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition report, Proceedings of the Integrated Drilling Program, Expedition 341.