Paleomagnetic studies conducted on board the JOIDES Resolution during Leg 195 consist of remanent magnetization measurements of archive-half sections before and after alternating-field (AF) demagnetization, magnetic remanence measurements on discrete samples collected from the working half of core sections, magnetic susceptibility measurements on whole-core sections, and a limited set of rock-magnetic measurements on discrete samples. Discrete samples were collected from working halves in standard 8-cm3 plastic cubes with the arrow on the bottom of the sampling box pointing upcore. Hard rock samples were either cut using a parallel saw or drilled using a nonmagnetic drill. The sampling frequency for rock-magnetic characterization was one sample per core at Site 1200 and one to two samples per core section at Site 1201. Sampling at Site 1202 was restricted to six oriented discrete samples because of time constraints at the end of Leg 195. Intervals of drilling-related core deformation were avoided.
Measurements of remanent magnetization were carried out using an automated pass-through cryogenic direct current superconducting quantum interference device (DC-SQUID) magnetometer (2-G Enterprises model 760-R) with an in-line AF demagnetizer (2-G Enterprises model 2G600) capable of producing peak fields of 80 mT with a 200-Hz frequency. The background noise level of the magnetometer onboard environment is ~3 x 10-10 Am2. The large volume of core material within the sensing region of the magnetometer, which is on the order of 100 cm3, permits accurate measurements of cores with remanent intensities as weak as ~10-5 A/m.
The standard ODP magnetic coordinate system was used (+x: vertical upward from the split surface of archive halves; +y: left along split surface when looking upcore; and +z: downcore).
Natural remanent magnetization was routinely measured for all sedimentary archive-half sections at 5-cm intervals. Measurements at core and section ends and within intervals of drilling-related core deformation were edited during data processing. AF demagnetization was applied at 5, 10, 15, and 20 mT. All discrete sample measurements were also made on the pass-through magnetometer using a sample boat that held six discrete cube samples at 20-cm intervals.
Discrete samples were AF demagnetized using the in-line demagnetizer installed on the pass-through cryogenic magnetometer at 5-mT steps to 40 mT and at 10-mT steps to 80 mT. An Analytical Services Company model IM-10 impulse magnetizer, which can apply pulsed fields from 20 to 1200 mT, was used for studies of the acquisition of stepwise isothermal remanent magnetization (IRM), saturation IRM (SIRM), and backfield SIRM of selected discrete samples. The SIRM of selected discrete samples was thermally demagnetized using a Schonstedt model TSD-1 thermal specimen demagnetizer at 100° steps to 300°C, 50° steps to 550°C, and 20° steps to 640°C. Spurious fields inside the oven do not exceed 100 nT and are generally <5 nT inside the cooling chamber. Temperature gradients over the central 30.5-cm length of the oven are on the order of 10°C, with an absolute temperature accuracy within 20°C of the set value. An anhysteretic remanent magnetization was imparted to each discrete sample by exposing it to both a constant 0.05-mT field and a slowly decaying 100-mT alternating field. The low-field volume susceptibility for discrete samples was measured using a Bartington MS2 meter attached to a MS2C sensor with a coil diameter of 33 mm.
Magnetic susceptibility was measured for each whole-core section as part of the MST analysis (see "Physical Properties"). The MST susceptibility meter (a Bartington MS2 meter containing an MS2C sensor with a coil diameter of 88 mm and an inducing field frequency of 0.565 kHz) was set on SI units, and the values were stored in the Janus database in raw meter units. To convert to true SI volume susceptibilities, these values were multiplied by 10-5 and then multiplied by a correction factor to take into account the volume of material that passed through the susceptibility coils. The correction factor for a standard ODP core is ~0.66 (= 1/1.5). This correction was applied for all figures illustrating magnetic susceptibilities in the "Paleomagnetism" sections in each site chapter of this volume. The data were not corrected for undersized core, core gaps, or the end effects of each section.
Core orientation of the APC was achieved with a Tensor tool mounted on the core barrel. The Tensor tool consists of a three-component fluxgate magnetometer and a three-component accelerometer rigidly attached to the core barrel. The information from both sets of sensors allows the azimuth and dip of the hole to be measured, as well as the azimuth of the double-line orientation mark on the core liner. Orientation is not usually attempted for the top three cores (~30 mbsf) until the bottom-hole assembly is sufficiently stabilized in the sediment. Core orientation by the Tensor tool is relative to magnetic north.
Where AF demagnetization successfully isolated the primary component of remanent magnetization, paleomagnetic inclinations and declinations were used to assign a magnetic polarity to the stratigraphic column. An interpretation of the magnetic polarity stratigraphy, with constraints from the biostratigraphic data, is presented in the "Site 1201" chapter. The magnetic polarity timescale of Cande and Kent (1995) and timescale of Berggren et al. (1995b) were used.