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doi:10.2204/iodp.proc.304305.204.2009

Introduction

One of the main objectives of Integrated Ocean Drilling Program (IODP) Expedition 304/305 was to drill a deep hole inside the Atlantis Massif, an oceanic core complex located at 30°N in the inside corner of the intersection of the Mid-Atlantic Ridge with the Atlantis Fracture Zone (see the “Expedition 304/305 summary” chapter). IODP Hole U1309D was drilled to 1415.5 meters below seafloor (mbsf); it is the second deepest hole in slow-spread crust after Ocean Drilling Program (ODP) Hole 735B on the Southwest Indian Ridge (Dick et al., 2000). In this report we present a series of laboratory measurements carried out at Géosciences Montpellier (France) to quantify the electrical properties of the oceanic crustal rocks recovered from Hole U1309D. Our knowledge of the in situ structure of oceanic crust is partly based on geophysical investigations, including downhole measurements (e.g., Goldberg, 1997). The analysis of marine geophysical data requires a complete understanding of the intrinsic physical properties of investigated crustal sections. Electrical measurements are used to evaluate the porosity structure of low-porosity igneous rocks (e.g., Pezard, 1990) and are presented in this report together with density and porosity measurements. This work follows the study of electrical properties of gabbroic rocks sampled in Hole 735B at the Southwest Indian Ridge (Pezard et al., 1991; Ildefonse and Pezard, 2001)

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