Reliable paleointensity determinations from Late Cretaceous volcanic rocks in Korea with constraint of thermochemical alteration SCIE SCOPUS

Cited 2 time in WEB OF SCIENCE Cited 1 time in Scopus
Title
Reliable paleointensity determinations from Late Cretaceous volcanic rocks in Korea with constraint of thermochemical alteration
Author(s)
Kim, Wonnyon; Doh, Seong-Jae; Yu, Yongjae
KIOST Author(s)
Kim, Won Nyon(김원년)
Publication Year
2018-06
Abstract
Paleointensity determinations were carried out from Late Cretaceous (similar to 77 Ma) volcanic rocks in Korea using a Thellier-type IZZI experimental protocol with systematic partial thermal remanent magnetization (pTRM) checks. Various data selection criteria were used to estimate reliable paleointensities. We set stringent threshold values for each parameter to ensure that there was: (1) a linear relationship between natural remanent magnetization (NRM) lost and TRM gained; (2) negligible thermal alteration of magnetic minerals; and (3) univectorial decay of NRM towards the origin. From the 336 samples, similar to 88% were rejected because of an insufficient extrapolated NRM fraction in the best-fit line (f(vds) < 0.6), highlighting that f(vds) is the most stringent selection criterion in this study. For the 31 accepted samples, paleointensities range from 6.4 to 30.4 mu T. Among the 31 samples, eight samples yielded extremely low paleointensities. Although single-domain (titano)magnetite was identified as the stable paleointensity recorder, oxidation of superparamagnetic fractions upon repeated heating probably caused enhancement of pTRM acquisition and yielded a low paleointensity estimate. Apart from these low paleointensities (n = 8) as screened by a newly proposed data selection criterion of Delta k < 0.2, the remaining 23 samples have a mean paleointensity of 23.1 +/- 4.8 mu T, corresponding to a virtual axial dipole moment (VADM) of 40.8 +/- 8.5 ZAm(2), which is similar to 50% of the present-day VADM.
ISSN
0031-9201
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/892
DOI
10.1016/j.pepi.2018.04.004
Bibliographic Citation
PHYSICS OF THE EARTH AND PLANETARY INTERIORS, v.279, pp.47 - 56, 2018
Publisher
ELSEVIER SCIENCE BV
Subject
SUBMARINE BASALTIC GLASS; GEOMAGNETIC-FIELD; INTENSITY VARIATIONS; MAGNETIC-FIELD; LAVA FLOWS; GEODYNAMO; SELECTION; THELLIER; CRITERIA
Keywords
Paleointensity; virtual axial dipole moment (VADM); Late Cretaceous; single-domain (SD); superparamagnetic (SP)
Type
Article
Language
English
Document Type
Article
Publisher
ELSEVIER SCIENCE BV
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