Data Publication

Magnetochronostratigraphic data from marine sediments off Patagonia, SE Pacific – cores from expedition MR16-09 Leg 2, Japanese RV Mirai, 2017

Nowaczyk, Norbert R. | Liu, Jiabo | Hagemann, Julia | Arz, Helge W. | Iwasaki, Shinya | Murayama, Masafumi

GFZ Data Services

(2024)

Sediment cores PC02, PC03, and PC04 were recovered during the ship expedition MR16-09 Leg 2 of Japanese RV Mirai in 2017 (Murata et al., 2017) using piston corers. For paleo- and rock magnetic analyses clear plastic boxes with a volume of 7 cm3 were pressed into the split halves of the generally 1 m long sections of the sediment cores. X-ray fluoresence (XRF) scans were performed with an Itrax XRF Corescanner (Cox Analytical systems) at Kochi Core Center, Japan (Hagemann et al. 2024). The downcore resolution was set to 5 mm, and the scans were performed with a Mo X-ray tube at 30 kV and 55 mA for a measurement time of 15 s. The Itrax X-ray beam was set to 0.2 mm × 20 mm. Measurements of low-field magnetic susceptibility (klf same as: k-bulk) and its anisotropy (AMS) were performed with an AGICO MFK1-A susceptibility meter. The principal AMS axes Kmax, Kint, and Kmin, the three axes of the anisotropy ellipsoid, were used to calculate the degree of anisotropy, as well as the shape factor of anisotropy. The frequency dependency of magnetic susceptibility was determined with an automated MAGNON Variable Field Susceptibility Meter (VFSM) by measuring magnetic susceptibility at different frequencies with logarithmically equidistant steps at a field amplitude of 250 µT. Susceptibilities of core PC02 samples were measured at 7 frequencies F from 375 Hz to 4775 Hz. Samples from cores PC03 and PC04 were measured at 5 frequencies from 475 to 4775 Hz. The frequency dependency Dk/Dlog(F) then was determined by linear regression of susceptibility k versus the decadal logarithm of frequency F. Values are given as decay rate in percent over one frequency decade (% / decade (F)) relative to the measurement at the lowest frequency. Thus, values obtained are negative. Measurements of the natural remanent magnetization (NRM) and of the anhysteretic remanent magnetization (ARM) were performed with a 2G 755 SRM long-core cryogenic magnetometer. ARMs were produced with a 2G660 single-axis alternating field (AF) demagnetizer using 100 mT alternating field and 50 µT static field. NRMs and ARMs both were stepwise demagnetized with the in-line 3-axes AF demagnetizer of the cryogenic magnetometer. AF steps for NRM: 0, 5, 10, 15, 20, 30, 40, 50, 65, 80, 100 mT. AF steps for ARM: 0, 10, 20, 30, 40, 50, 65, 80 mT. Iso-thermal remanent magnetizations (IRM) were imparted with a 2G 660 pulse magnetizer using 1500 mT for producing a saturation magnetization (SIRM) and -200 mT for remagnetization of the low-coercive fraction. Measurements were performed with a Molyneux spinner magnetometer. Data records were turned into time series by applying the age model for PC03 (Hagemann et al., 2024), correlating PC02 to PC03, and correlating PC04 to PC03 (back to 140 ka) and further using the PISO1500 paleointensity stack (Channell et al., 2009), paleomagnetic data from the Black Sea (Liu et al., 2020, Nowaczyk et al., 2021), and paleoclimatic data from Antarctica (Jouzel et al., 2007; Bazin et al., 2013) for reference for older core sections.

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