Sonic Waveform Data
IODP-USIO logging contractor: LDEO-BRG
Hole: U1320A
Expedition: 308
Location: Brazos-Trinity Basin IV (Gulf of Mexico)
Latitude: 27° 18.0809'N
Longitude: 94° 23.2537'W
Logging date: June 9-10, 2005
Sea floor depth (driller's): 1480.4 mbrf
Sea floor depth (logger's): 1478 mbrf
Total penetration: 299.6 mbsf
Total core recovered: 83.7 %
Oldest sediment recovered: Pleistocene to Holocene
Lithologies: turbiditic muds and debris flows
TOOL USED: DSI (Dipole Sonic Imager)
Recording mode: Monopole P&S, Cross-Dipole, and Stoneley mode.
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.
CROSS-DIPOLE MODE: uses alternate firings of upper and lower dipole transmitter, thus allowing acquisition of orthogonally polarized data for anisotropy studies.
STONELEY MODE: measures low-frequency Stoneley wave slowness. The monopole transmitter, driven by a low-frequency pulse, generates the Stoneley wave.
Acoustic data are recorded in DLIS format. Each of the eight waveforms generally consists of 512 samples (256 in cross-dipole mode), each recorded every 10 (monopole P&S) and 40 microsec (all dipole modes), 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 then converted into ASCII and finally binary format.
Each line is composed of the entire waveform set recorded at each depth, preceded by the depth value. In the general case of 8 receivers with 512 samples per waveform, this corresponds to 1 + 4x512 = 4097 columns. In this hole, the specifications of the files are:
Number of columns: 4097 (4098 in cross dipole files)
Number of rows: 1539 (pass 1)
Number of rows: 1602 (pass2)
The following files have been loaded:
DSI from FMS/DSI/GPIT/NGT (Pass 1, open hole)
U1320A-mono_p1.bin: 1545.03-1779.42 mbrf
DSI from FMS/DSI/GPIT/NGT (Pass 2, open hole)
U1320A-cd_ldip_cl_p2.bin: 1530.55-1774.54 mbrf
U1320A-cd_ldip_il_p2.bin: 1530.55-1774.54 mbrf
U1320A-cd_udip_cl_p2.bin: 1530.55-1774.54 mbrf
U1320A-cd_udip_il_p2.bin: 1530.55-1774.54 mbrf
U1320A-mono_p2.bin: 1530.55-1774.54 mbrf
U1320A-st_p2.bin: 1530.55-1774.54 mbrf
The sonic waveform files are not depth shifted to a reference run or to the seafloor. For depth shift to the sea floor, please refer to the DEPTH SHIFT section in the standard log documentation file.