Borehole Seismic Data

 

Science operator: Texas A&M University

Hole: U1471E

Expedition: 359

Location: Maldive Archipelago (central equatorial N Indian Ocean)

Latitude: 4° 45.9829' N

Longitude: 73° 8.0929' E

Logging date: November 25, 2015

Sea floor depth (driller's): 430.3 m DRF

Sea floor depth (logger's): 430.5 m WRF (HRLA/MSS/APS/HLDS/EDTC/HNGS Main Run)

Total penetration:  1434 m DRF (1003.7 m DSF)

Total core recovered: 171.54 m (42.1 % of cored section)

Oldest sediment recovered: Middle Miocene

Lithology: Lithified foraminifer-rich packstone and wackestone.

SEISMIC TOOL USED: VSI (Versatile Seismic Imager)

The logging data was recorded by Schlumberger in LDF/DLIS format. All processing, including first arrival picking and stacking, was performed by Schlumberger during Expedition 359. The data was then converted into SEGY format at USIO/LDEO, using tcode developed in house.

The VSI string hung up at about 1042 m WRF,which corresponded to one of the narrow readings on the caliper log from the previous run. Since all attempts to pass the bridge failed, 30 shots in 5 stations were acquired above that depth. Proper anchoring of the tool was made difficult by the large hole diameter and by the rapidly degrading hole conditions.

Stacks are generally calculated with at least nine good traces.

All the data in the SEGY files are sorted shot by shot (i.e. chronologically).

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 International Ocean Discovery Program, Expedition 359.

For any question about the data or about the LogDB database, please contact LogDB support: logdb@ldeo.columbia.edu.