ODP Technical Note 10


A. Introduction

Core orientation involves two primary components, rotation about an axis parallel to the core barrel, and translation along this axis. Tools are routinely available aboard JOIDES Resolution to assist with orientation of APC cores for paleomagnetic studies of sediments; additional developmental tools assist with translation and rotation of RCB cores for hard-rock core orientation and general data integration. Orienting APC cores is easier than orienting RCB cores for several reasons. First, APC cores are collected rapidly in soft sediments. Recovery is often close to 100%, and it is likely that the APC core barrel maintains its rotational orientation during the few seconds that a core is collected. In addition, each APC core retains its orientation relative to the core barrel after the core is collected. Thus only one downhole tool is needed for APC orientation: a "multishot" compass which records the rotational orientation of the core barrel before, during, and after the barrel is fired into the sediments. Orientation of RCB cores requires that several additional data types be collected and combined, and that individual pieces of core be oriented separately.

Core Orientation, Section B.
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