Borehole Seismic Data Processing (Re-Entry Phase 3)

IODP-USIO logging contractor: LDEO-BRG

Hole: 1256D, re-entry (Logging Phase 3)

Expedition: 312

Location: Guatemala Basin (NE equatorial Pacific)

Latitude: 6° 44.163' N

Longitude: 91° 56.061' W

Logging date: December 20-23, 2005

Sea floor depth (driller's): 3645.4 mbrf

Sea floor depth (logger's): 3643.5 mbrf

Total penetration: 1507.1 mbsf

Total core recovered: 252 m (18.5 % of cored section)

Oldest sediment recovered: Calcareous nannofossil ooze (Middle Miocene) at Hole 1256B during ODP Leg 206

Lithologies: Clay-rich sediments and calcareous nannofossil ooze (sediments); basalt and gabbro (basement)

TOOL USED: VSI (Vertical Seismic Imager)

The logging data was recorded by Schlumberger in DLIS format. All processing, including first arrival picking and stacking, was performed by Schlumberger during Expedition 312. The data was then converted into SEGY format at the Borehole Research Group of the Lamont-Doherty Earth Observatory, using the SEGY Save module in GeoFrame.

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).

Gilles Guerin

Phone: 845-365-8671

Fax: 845-365-3182

E-mail: Gilles Guerin

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia