Characteristics of VRM in oceanic basalts
Item
Title (Dublin Core)
en-US
Characteristics of VRM in oceanic basalts
Description (Dublin Core)
en-US
Laboratory experiments, each lasting several weeks, have been conducted to establish the characteristics of viscous remanent magnetization (VRM) in oceanic basalts from many sites of the Deep Sea Drilling Program (DSDP). VRM is most pronounced in low-coercivity basalts whose natural remanences (NRM) have low median destructive fields, less than 100 Oe. A simple logarithmic acquisition law is rarely obeyed, but two or three distinct stages are instead observed, in each of which a logarithmic dependence of VRM intensity on acquisition time may be assumed. This observation leads to a simple interpretational model for the nature of VRM in DSDP basalts, but also implies that extrapolation of laboratory observations to geological times is not meaningful. Instead, the ratio of laboratory VRM (acquired in a 1 Oe field during 1000 h) to NRM is used as a minimum indicator of the potential seriousness of VRM. Experiments show that VRM acquired in the presence of NRM is more serious than VRM acquired in alternating field (AF) demagnetized samples. As most published VRM data in DSDP basalts were obtained after AF demagnetization, these are regarded also as minimum estimates of the significance of VRM acquired by oceanic basalts in situ. The consequences of the common occurrence of such an unstable component of magnetization in the oceanic basalt layer are considered in relation to the nature and distribution of oceanic magnetic quiet zones. The Cretaceous, and possibly the Jurassic, magnetic quiet zones are considered adequately explained by constant paleomagnetic field polarity. However, if VRM is a substantial and widespread magnetization component in the oceanic crust, it may not always be appropriate to interpret oceanic magnetic anomalies (or their absence) as an exact record of paleomagnetic field behavior. Remagnetization of the oceanic crust by VRM acquisition may be a viable alternative explanation of the origin of the marginal magnetic quiet zones.
ARK: https://n2t.net/ark:/88439/y064370
Permalink: https://geophysicsjournal.com/article/206
ARK: https://n2t.net/ark:/88439/y064370
Permalink: https://geophysicsjournal.com/article/206
Creator (Dublin Core)
Lowrie, W.
Kent, D.V.
Subject (Dublin Core)
en-US
VRM
en-US
DSDP
en-US
Oceanic basalts
en-US
Magnetic quiet zones
en-US
Oceanic magnetic anomalies
en-US
Experiment
Publisher (Dublin Core)
en-US
Journal of Geophysics
Date (Dublin Core)
1977-12-12
Type (Dublin Core)
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
en-US
Peer-reviewed Article
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
https://journal.geophysicsjournal.com/JofG/article/view/206
Source (Dublin Core)
en-US
Journal of Geophysics; Vol 44 No 1 (1977): Journal of Geophysics; 297-315
2643-2986
2643-9271
Language (Dublin Core)
eng
Relation (Dublin Core)
https://journal.geophysicsjournal.com/JofG/article/view/206/166