Data Report: Reoriented structures in the East Pacific Rise basaltic crust from ODP Hole 1256D, Leg 206: integration of core measurements and electrical-acoustic images

Abstract

Brittle structures (open fractures and veins) from basaltic oceanic crust drilled at Ocean Drilling Program (ODP) Site 1256 (Guatemala Basin, Pacific Ocean) during Leg 206 were reoriented to the geographic coordinates by (1) correlating structures observed on the core with unoriented images of the exterior of the core and (2) correlating core structures and unoriented images with oriented borehole images. The images of the exterior of the core were obtained by scanning wholecore pieces with the Deutsche Montan Technologie Digital Color CoreScan system. In the unrolled core images, nonhorizontal planar structures (e.g., veins, faults, or fractures) produce sinusoidal-shaped curves. These can be matched to similar-shaped features imaged along the borehole wall. The borehole images were obtained by the Formation MicroScanner (FMS)-sonic (Dipole Sonic Imager) tool string and the Ultrasonic Borehole Imager (UBI). The FMS provides high-resolution electrical resistivity–based images of borehole walls. FMS images are oriented to magnetic north using the General Purpose Inclinometer Tool. This allows the dip and azimuth of geological features intersecting the hole to be measured from the processed FMS image. The UBI features a high-resolution transducer that provides acoustic images of the 1Tartarotti, P., Crispini, L., Einaudi, F., and Campari, E., 2006. Data report: reoriented structures in the East Pacific Rise basaltic crust from ODP Hole 1256D, Leg 206: integration of core measurements and electrical-acoustic images. In Teagle, D.A.H., Wilson, D.S., Acton, G.D., and Vanko, D.A. (Eds.), Proc. ODP, Sci. Results, 206: College Station, TX (Ocean Drilling Program), 1–26. doi:10.2973/ odp.proc.sr.206.004.2006 2Dipartimento di Scienze della Terra, Universita di Milano, via Mangiagalli 34, 20133 Milano, Italy. Correspondence author: paola.tartarotti@unimi.it 3DIPTERIS, Dipartimento per lo Studio del Territorio e delle sue Risorse Universita’ di Genova, Corso Europa 26, 16132 Genova, Italy. 4Laboratoire de Geophysique et Hydrodynamique en Forage, Universite de Montpellier II, ODP/ Naturalia et Biologia (NEB) ISTEEM, cc56, 34095 Montpellier, France. Initial receipt: 30 April 2005 Acceptance: 22 December 2005 Web publication: 20 November 2006 Ms 206SR-004 P. TARTAROTTI ET AL. DATA REPORT: REORIENTED STRUCTURES IN THE EAST PACIFIC RISE 2 borehole wall. The UBI was used in hard rocks for the first time in the history of the ODP during Leg 206.