Limestones of western Newfoundland that magnetized before Devonian folding but after Middle Ordovician lithification

A positive fold test and a negative conglomerate test help determine when and how stable remanence was acquired in the Middle Ordovician Table Head Group limestones of the Port au Port Peninsula of Newfoundland. The limestones magnetized after lithification and incorporation as clasts into a Middle...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Author: Hodych, Joseph P.
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union 1989
Subjects:
Table Head
Newfoundland
Online Access:https://research.library.mun.ca/6206/
https://research.library.mun.ca/6206/1/LIMESTONES.OF.WESTERN.NEWFOUNDLAND.pdf
https://research.library.mun.ca/6206/3/LIMESTONES.OF.WESTERN.NEWFOUNDLAND.pdf
https://doi.org/10.1029/GL016i001p00093
Description
Summary:A positive fold test and a negative conglomerate test help determine when and how stable remanence was acquired in the Middle Ordovician Table Head Group limestones of the Port au Port Peninsula of Newfoundland. The limestones magnetized after lithification and incorporation as clasts into a Middle Ordovician breccia. Hence, the limestones do not carry a detrital or other primary remanence despite their very low conodont colour alteration index of 1. The remanence may be thermoviscous or diagenetic and was acquired before Devonian folding. This suggests the need for caution in interpreting paleomagnetic results from other early Paleozoic limestones whose remanence resides in magnetite of blocking temperature lower than 400°C.

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