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

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.

Magnetochronostratigraphic data from sediments in the Drake Passage – cores from expedition PS97, German RV Polarstern, 2016

Sediment cores were recovered during the ship expedition of German RV Polarstern in 2016 (PS97) using piston corers. For paleo- and rock magnetic analyses clear plastic boxes of 20×20×15 mm were pressed into the split halves of the generally 1 m long sections of the sediment cores. In order to determine the direction of the characteristic remanent magnetization (ChRM), demagnetization results of the NRM were subjected to principal component analysis (PCA) according to Kirschvink (1980). The PCA also provided the maximum angular deviation (MAD) as a measure of the precision of the determined ChRM direction. ChRM declinations obtained by PCA were rotated around a vertical axis until the declinations of all samples falling into a circular window of 35° around the direction expected from a geocentric axial dipole (-72.9°) yielded a mean of 0°. ChRM data from core PS97-085-1 (-85-3) were tentatively tilted by +17° (-7°) around the EW axis in order to parallel the maximum in the inclination distribution with the inclination of a geocentric axial dipole field. The anhysteretic susceptibility K(ARM) is defined as the ARM intensity normalised by the static field used for producing the ARM. The anhysteretic susceptibility normalised by the low field bulk susceptibility K(ARM)/klf then is a magnetic grain size proxy with low (high) ratios indicating relatively large (small) magnetite particles. In order to discriminate samples being dominated by low-coercive minerals (magnetite, Fe3O4 and greigite, Fe3S4) from samples being dominated by high-coercive minerals (mostly hematite, Fe2O3), the S-ratio was calculated using S=0.5×(1-[IRM(-200 mT)/SIRM(1500 mT)]). S-ratios range from 0 to 1, with: dominance of magnetite/greigite: 0<<S≤1, and dominance of hematite: 0≤S<<1. As another grain size proxy the ARM intensity was normalised by the SIRM: (1000×ARM/SIRM) with low (high) ratios indicating relatively large (small) magnetite particles. The factor of 1000 is introduced in order to avoid small numbers. Relative paleointensity variations were estimated by three different proxies: slope of NRM vs. ARM of common demagnetization steps (slope(NRM/ARM)), NRM intensity demagnetized with 30 mT normalized with bulk susceptibility klf (pjk(30mT)), and NRM intensity demagnetized with 30 mT normalized with saturation magnetization SIRM (pjs(30mT)). Data records were turned into time series by correlation to dated reference records from Antarctica (Wu et al., 2021) and the Black Sea (Liu et al., 2021).

Rock magnetic data from sediments from the Arkhangelsky Ridge, SE Black Sea, II - cores from expedition MSM33, German RV Maria S. Merian, 2013

This data publication includes standard rock magnetic data related to concentration, coercivity and magneto-mineralogy versus depth from twelve sediment cores recovered from the Arkhangelsky Ridge in the Southeastern Black Sea, German RV Maria S. Merian expedition MSM33 in 2013: MSM33-51-3, MSM33-52-1, MSM33-53-1, MSM33-54-3, MSM33-55-1, MSM33-56-1, MSM33-57-1, MSM33-60-1, MSM33-61-1, MSM33-62-2, MSM33-63-1, MSM33-64-1. The data are related to publications by Liu et al. (2018, 2019, 2020), Liu (2019) and Nowaczyk et al. (2012, 2013, 2018, 2021a, b). Sediment cores were recovered using gravitiy and piston corers. For paleo- and rock magnetic analyses clear plastic boxes of 20×20×15 mm were pressed into the split halves of the generally 1 m long sections of the sediment cores. Data are provided as 12 ASCII files (.dat, one for each core) with metadata header and are decribed in the associated data description file (pdf).

Rock magnetic data from sediments from the Arkhangelsky Ridge, SE Black Sea: I - cores from expedition M72/5, German RV Meteor, 2007

This data publication includes standard rock magnetic data related to concentration, coercivity and magneto-mineralogy versus depth from six sediment cores (M72/5-22GC3, M72-5-22GC4, M72-5-22GC6, M72-5-22GC8, M72-5-24GC3, M72-5-25GC1), collected at the Arkhangelsky Ridge in the Southeastern Black Sea during the marine expedition M72/5 of the German research vessel RV METEOR (in May 2007). The data are related to publications by Liu et al. (2018, 2019, 2020), Liu (2019) and Nowaczyk et al. (2012, 2013, 2018, 2021a, b). Sediment cores were recovered using gravity corers. For paleo- and rock magnetic analyses clear plastic boxes of 20×20×15 mm were pressed into the split halves of the generally 1 m long sections of the sediment cores. Data are provided as six ASCII files (.dat, one for each core) with metadata header, followed by 12 data columns and are decribed in the associated data description file (pdf).

Paleosecular variation data for marine isotope stage 6 from SE Black Sea sediments

This data publication includes stacked paleomagnetic data, inclinations, declinations, and relative paleointensities, for the time interval 120 to 180 ka, comprising data from twelve sediment cores recovered from the Arkhangelsky Ridge in the Southeastern Black Sea; German RV Meteor expedition M72/5 in 2007: M72/5-22GC6, M72/5-22GC8; German RV Maria S. Merian expedition MSM33 in 2013: MSM33-51-3, MSM33-52-1, MSM33-54-3, MSM33-56-1, MSM33-57-1, MSM33-60-1, MSM33-61-1, MSM33-62-2, MSM33-63-1, MSM33-64-1. The data are also described in Nowaczyk et al. (2021). Sediment cores were recovered using gravitiy and piston corers. For paleo- and mineral-magnetic analyses clear plastic boxes of 20×20×15 mm were pressed into the split halves of the generally 1 m long sections of the sediment cores. Data are provided as six ASCII files (.dat, one for each core) with metadata header, followed by 12 data columns and are decribed in the associated data description file (pdf).

Paleo- and rock magnetic data from cores MSM33-53-1, M72-5-22GC4, M72-5-25GC1 from the southeastern Black Sea

This data publication includes paleo and rock magnetic data from three sediment cores, MSM33-53-1, M72-5-22GC4, M72-5-25GC1, collected in the southeastern Black Sea during the marine expeditions M72/5 of the German research vessel RV METEOR (in 2007) and MSM33 of the German research vessel RV Maria S. Merian (in 2013). The data are supplement to Nowaczyk et al. (2020) and have already been described in Liu et al. (2018, 2019, 2020), Liu (2019) and Nowaczyk et al. (2012, 2013). The cores were sampled at intervals between 1.7 and 3.0 cm. Core M72/5-22GC4 was also continuously subsampled using u-channels. All material was subjected to detailed paleo- and rock magnetic analyses. As a main result the Laschamps geomagnetic excursion at around 41 ka could be revealed (Nowaczyk et al., 2012, 2013, Liu et al., 2020). This feature of the geomagnetic field was characterized by a short but full reversal and very low intensities of the Earth’s magnetic field. However, data is more or less compromised due to the post-depositional precipitation of the magnetic iron suphide greigite (Fe3S4), mainly depending on water depth of the coring sites. Provided data demonstrate the impact of greigite as well as the differences between discrete sample and u-channels (Nowaczyk et al., 2020). Data are provided as several ASCII files providing most relevant rock magnetic and paleomagnetic parameters, the age model as well as detailed information on the location, water depth, cruises and dates.

LSMOD.2 - Global paleomagnetic field model for 50 -- 30 ka BP

Global spherical harmonic paleomagnetic field model LSMOD.2 describes the magnetic field evolution from 50 to 30 ka BP based on published paleomagnetic sediment records and volcanic data. It is an update of LSMOD.1, with the only difference being a correction to the geographic locations of one of the underlying datasets. The time interval includes the Laschamp (~41 ka BP) and Mono Lake (~34 ka BP) excursions. The model is given with Fortran source code to obtain spherical harmonic magnetic field coefficients for individual epochs and to obtain time series of magnetic declination, inclination and field intensity from 49.95 to 30 ka BP for any location on Earth. For details see M. Korte, M. Brown, S. Panovska and I. Wardinski (2019): Robust characteristics of the Laschamp and Mono lake geomagnetic excursions: results from global field models. Submitted to Frontiers in Earth Sciences

LSMOD.1 - Global paleomagnetic field model for 50 -- 30 ka BP

Global spherical harmonic paleomagnetic field model LSMOD.1 describes the magnetic field evolution from 50 to 30 ka BP based on published paleomagnetic sediment records and volcanic data. The time interval includes the Laschamp (~41 ka BP) and Mono Lake (~34 ka BP) excursions. The model is given with Fortran source code to obtain spherical harmonic magnetic field coefficients for individual epochs and to obtain time series of magnetic declination, inclination and field intensity from 49.95 to 30 ka BP for any location on Earth. For details see M. Brown, M. Korte, R. Holme, I. Wardinski and S. Gunnarson (2018): Earth's magnetic field is probably not reversing. PNAS, 115, 5111-5116.

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