Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

Masahiko Sato, Shinji Yamamoto, Yuhji Yamamoto, Yoshihiro Okada, Masao Ohno, Hideo Tsunakawa, Shigenori Maruyama

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensities (M IRM) are larger than 4∈×∈10-12 Am2, while natural remanent magnetization (NRM) intensities (M NRM) are below 4∈×∈10-12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of M NRM∈ ∈4∈×∈10-12 Am2 and M IRM∈ ∈4∈×∈10-12 Am2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c) values (>10 mT) or high M NRM/M IRM values (>∼0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM/M IRM values (<∼0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM/TRM ratios shows field intensities consistent with the average geomagnetic field intensity at the Tanzawa tonalitic pluton for last 5 Myr.

Original languageEnglish
Article number150
JournalEarth, Planets and Space
Volume67
Issue number1
DOIs
Publication statusPublished - Dec 22 2015

Fingerprint

magnetic property
natural remanent magnetization
pluton
Japan
zircon
remanent magnetization
rocks
crystal
magnetic properties
magnetization
single crystals
rock
thermoremanent magnetization
magnetometer
crystals
remanence
magnetic mineral
magnetometers
pyrrhotite
geomagnetic field

All Science Journal Classification (ASJC) codes

  • Geology
  • Space and Planetary Science

Cite this

Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan. / Sato, Masahiko; Yamamoto, Shinji; Yamamoto, Yuhji; Okada, Yoshihiro; Ohno, Masao; Tsunakawa, Hideo; Maruyama, Shigenori.

In: Earth, Planets and Space, Vol. 67, No. 1, 150, 22.12.2015.

Research output: Contribution to journalArticle

Sato, Masahiko ; Yamamoto, Shinji ; Yamamoto, Yuhji ; Okada, Yoshihiro ; Ohno, Masao ; Tsunakawa, Hideo ; Maruyama, Shigenori. / Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan. In: Earth, Planets and Space. 2015 ; Vol. 67, No. 1.
@article{4852bfb880c943f593ae346b86a7eb6b,
title = "Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan",
abstract = "This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensities (M IRM) are larger than 4∈×∈10-12 Am2, while natural remanent magnetization (NRM) intensities (M NRM) are below 4∈×∈10-12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of M NRM∈ ∈4∈×∈10-12 Am2 and M IRM∈ ∈4∈×∈10-12 Am2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c) values (>10 mT) or high M NRM/M IRM values (>∼0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM/M IRM values (<∼0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM/TRM ratios shows field intensities consistent with the average geomagnetic field intensity at the Tanzawa tonalitic pluton for last 5 Myr.",
author = "Masahiko Sato and Shinji Yamamoto and Yuhji Yamamoto and Yoshihiro Okada and Masao Ohno and Hideo Tsunakawa and Shigenori Maruyama",
year = "2015",
month = "12",
day = "22",
doi = "10.1186/s40623-015-0317-9",
language = "English",
volume = "67",
journal = "Earth, Planets and Space",
issn = "1343-8832",
publisher = "Terra Scientific Publishing Company",
number = "1",

}

TY - JOUR

T1 - Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

AU - Sato, Masahiko

AU - Yamamoto, Shinji

AU - Yamamoto, Yuhji

AU - Okada, Yoshihiro

AU - Ohno, Masao

AU - Tsunakawa, Hideo

AU - Maruyama, Shigenori

PY - 2015/12/22

Y1 - 2015/12/22

N2 - This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensities (M IRM) are larger than 4∈×∈10-12 Am2, while natural remanent magnetization (NRM) intensities (M NRM) are below 4∈×∈10-12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of M NRM∈ ∈4∈×∈10-12 Am2 and M IRM∈ ∈4∈×∈10-12 Am2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c) values (>10 mT) or high M NRM/M IRM values (>∼0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM/M IRM values (<∼0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM/TRM ratios shows field intensities consistent with the average geomagnetic field intensity at the Tanzawa tonalitic pluton for last 5 Myr.

AB - This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensities (M IRM) are larger than 4∈×∈10-12 Am2, while natural remanent magnetization (NRM) intensities (M NRM) are below 4∈×∈10-12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of M NRM∈ ∈4∈×∈10-12 Am2 and M IRM∈ ∈4∈×∈10-12 Am2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c) values (>10 mT) or high M NRM/M IRM values (>∼0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM/M IRM values (<∼0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM/TRM ratios shows field intensities consistent with the average geomagnetic field intensity at the Tanzawa tonalitic pluton for last 5 Myr.

UR - http://www.scopus.com/inward/record.url?scp=84942115920&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84942115920&partnerID=8YFLogxK

U2 - 10.1186/s40623-015-0317-9

DO - 10.1186/s40623-015-0317-9

M3 - Article

VL - 67

JO - Earth, Planets and Space

JF - Earth, Planets and Space

SN - 1343-8832

IS - 1

M1 - 150

ER -