Paleointensity determination of late cretaceous basalts in northwest South Korea: Implications for low and stable paleofield strength in the Late Cretaceous

Bongsu Chang, Wonnyon Kim, Seong-Jae Doh, Yongjae Yu

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

To clarify geomagnetic field behavior in the Late Cretaceous, paleointensity and rock-magnetic studies were carried out on basalts with K-Ar ages of 78.6 ± 2.5 and 73.1 ± 1.6 Ma in northwest South Korea. A total of 314 samples (262 from six lava flows and 52 from massive basalts) were subjected to Thellier-type IZZI paleointensity experiments. Through the application of seven paleointensity selection criteria that mainly verify the thermal alteration of magnetic minerals and the stability of remanence direction, fifteen paleointensity data were obtained from five of the lava flows. Based on rock-magnetic experiments and microscopic observations, it is revealed that the measured paleointensity is carried by single-domain (titano)magnetite. The site-mean paleointensities ranged 13.1-21.3 μT, which corresponds to a virtual axial dipole moment of 2.3-3.8 × 1022 Am2. The combination of this result with selected data from the IAGA paleointensity database establishes the existence of different dipole moments according to rock type. In particular, the geomagnetic field strength recorded in Late Cretaceous crystalline volcanic rock was relatively low and stable, with a mean dipole moment of 4.0 ± 1.9 × 1022 Am2 regardless of geomagnetic field reversals.

Original languageEnglish
Pages (from-to)1501-1513
Number of pages13
JournalEarth, Planets and Space
Volume65
Issue number12
DOIs
Publication statusPublished - 2013 Jan 1

Fingerprint

South Korea
geomagnetic field
basalt
geomagnetism
rocks
Cretaceous
lava flow
dipole moments
lava
rock
thermal alteration
magnetic mineral
crystalline rock
magnetite
volcanic rock
remanence
experiment
volcanology
field strength
minerals

Keywords

  • Basalts
  • IZZI protocol
  • Korea
  • Late Cretaceous
  • Paleointensity

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

Cite this

Paleointensity determination of late cretaceous basalts in northwest South Korea : Implications for low and stable paleofield strength in the Late Cretaceous. / Chang, Bongsu; Kim, Wonnyon; Doh, Seong-Jae; Yu, Yongjae.

In: Earth, Planets and Space, Vol. 65, No. 12, 01.01.2013, p. 1501-1513.

Research output: Contribution to journalArticle

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