Sonic Waveform Data
IODP-USIO logging contractor: LDEO-BRG
Hole: 1256D
Expedition: 309
Location: Guatemala Basin (NE equatorial Pacific)
Latitude: 6° 44.163' N
Longitude: 91° 56.061' W
Logging date: July 17-18, 2005
Sea floor depth (driller's): 3645.4 mbrf
Sea floor depth (logger's): 3643.5 mbrf
Total penetration: 752 mbsf (Leg 206)
Total core recovered: 227m (47.8%) (Leg 206)
Oldest sediment recovered: Calcareous nannofossil ooze (Middle Miocene) at Hole 1256B during the ODP
Lithologies: Clay-rich sediments and calcareous nannofossil ooze (sediments); basalt (basement)
TOOL USED: DSI (Dipole Sonic Imager)
Recording modes: Monopole P&S, Upper and Lower Dipole, and Stoneley.
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.
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
Number of rows: 3248
The following files have been loaded (Phase 1):
DSI from FMS/DSI/GPIT/SGT (casing at ~ 3914.5 mbrf)
309-1256D_ph1_mono_up.bin: 3878.42 - 4373.27 mbrf
309-1256D_ph1_ldip_up.bin: 3878.42 - 4373.27 mbrf
309-1256D_ph1_st_up.bin: 3878.42 - 4373.27 mbrf
309-1256D_ph1_udip_up.bin: 3878.42 - 4373.27 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.