Document Type

Article

Publication Date

12-28-2015

Keywords

Viscous remanent magnetization, VRM

Abstract

Viscous remanent magnetization (VRM) may partially overprint original magnetization in rocks displaced by geomorphic events. An established theoretical relationship between the time and temperature of acquisition of VRM and the time and temperature of demagnetization suggests that laboratory demagnetization (unblocking) of VRM can be used to estimate the displacement age of rocks. We test this hypothesis at four nested glacial moraines in the Icicle Creek drainage of central Washington, the ages of which were previously determined by cosmogenic surface exposure dating. The moraines are composed primarily of granodiorite boulders, and magnetic remanence is carried dominantly by magnetite. Both the maximum and average pVRM demagnetization temperatures (TD) increase with relative age of the moraines. For the three younger moraines, the average TD yields an age comparable to the cosmogenic age, within uncertainty of pVRM acquisition temperature. Uncertainty in the acquisition and demagnetization temperatures can limit the utility of pVRM for absolute dating.

Publication Title

Geophysical Research Letters

Volume

42

Issue

24

First Page

10,647

Last Page

10,654

Required Publisher's Statement

©2015. American Geophysical Union. All Rights Reserved DOI: 10.1002/2015GL066381

Comments

AGU allows authors to deposit their journal articles in an institutional repository if the version is the final published citable version of record, the AGU copyright statement is clearly visible on the posting, and the posting is made 6 months after official publication by the AGU.

Subjects - Topical (LCSH)

Geomagnetism--Washington (State)--Icicle Creek; Fluvial geomorphology--Washington (State)--Icicle Creek; Moraines--Washington (State)--Icicle Creek

Geographic Coverage

Washington (State)

Genre/Form

reports

Type

Text

Language

English

Format

application/pdf

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