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Ordovician palaeogeography with new palaeomagnetic data from the Montagne Noire (Southern France)

Nysaether, E; Torsvik, Trond H LU ; Feist, R; Walderhaug, HJ and Eide, EA (2002) In Earth and Planetary Science Letters 203(1). p.329-341
Abstract
A joint palaeomagnetic and Ar-40/Ar-39 study has been performed on two olistolithic blocks from the Cabrieres Wildflysch in the Montagne Noire region of the Massif Central in France. There, andesitic volcanic and volcaniclastic rocks of Llanvirn-Early Caradoc age (ca 470-458 Ma) occur. Despite extensive secondary alteration, destruction of the dominant magnetic mineral phase and Ar-40/Ar-39 whole rock experiments that demonstrate that the volcanic rocks suffered significant argon loss, a positive fold test and the presence of dual polarities suggest that a primary, Ordovician magnetisation has mostly survived. This is one of the few documented cases where the argon system was substantially reset whilst a subordinate set of small,... (More)
A joint palaeomagnetic and Ar-40/Ar-39 study has been performed on two olistolithic blocks from the Cabrieres Wildflysch in the Montagne Noire region of the Massif Central in France. There, andesitic volcanic and volcaniclastic rocks of Llanvirn-Early Caradoc age (ca 470-458 Ma) occur. Despite extensive secondary alteration, destruction of the dominant magnetic mineral phase and Ar-40/Ar-39 whole rock experiments that demonstrate that the volcanic rocks suffered significant argon loss, a positive fold test and the presence of dual polarities suggest that a primary, Ordovician magnetisation has mostly survived. This is one of the few documented cases where the argon system was substantially reset whilst a subordinate set of small, relatively unaltered magnetite grains, probably hosted in silicates, still carry the original, in this case Ordovician, remanence. The new data show that the Montagne Noire region was located at high southerly latitudes (68degrees (+19)/(-15)) during the Mid-Ordovician. This latitude represents the location for NW Gondwana of which the Massif Central was a part. Palaeomagnetic data from all the Central European massifs and terranes demonstrate a close link to the Gondwana Margin during the Lower and Middle Ordovician. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ordovician, Armorican Massif, paleomagnetism, Central Massif, paleogeography
in
Earth and Planetary Science Letters
volume
203
issue
1
pages
329 - 341
publisher
Elsevier
external identifiers
  • wos:000179078800025
  • scopus:0037107926
ISSN
1385-013X
DOI
10.1016/S0012-821X(02)00847-6
language
English
LU publication?
yes
id
f07bc756-ff13-411a-84ee-271c001c662a (old id 324285)
date added to LUP
2007-11-16 16:49:00
date last changed
2017-10-22 03:44:06
@article{f07bc756-ff13-411a-84ee-271c001c662a,
  abstract     = {A joint palaeomagnetic and Ar-40/Ar-39 study has been performed on two olistolithic blocks from the Cabrieres Wildflysch in the Montagne Noire region of the Massif Central in France. There, andesitic volcanic and volcaniclastic rocks of Llanvirn-Early Caradoc age (ca 470-458 Ma) occur. Despite extensive secondary alteration, destruction of the dominant magnetic mineral phase and Ar-40/Ar-39 whole rock experiments that demonstrate that the volcanic rocks suffered significant argon loss, a positive fold test and the presence of dual polarities suggest that a primary, Ordovician magnetisation has mostly survived. This is one of the few documented cases where the argon system was substantially reset whilst a subordinate set of small, relatively unaltered magnetite grains, probably hosted in silicates, still carry the original, in this case Ordovician, remanence. The new data show that the Montagne Noire region was located at high southerly latitudes (68degrees (+19)/(-15)) during the Mid-Ordovician. This latitude represents the location for NW Gondwana of which the Massif Central was a part. Palaeomagnetic data from all the Central European massifs and terranes demonstrate a close link to the Gondwana Margin during the Lower and Middle Ordovician.},
  author       = {Nysaether, E and Torsvik, Trond H and Feist, R and Walderhaug, HJ and Eide, EA},
  issn         = {1385-013X},
  keyword      = {Ordovician,Armorican Massif,paleomagnetism,Central Massif,paleogeography},
  language     = {eng},
  number       = {1},
  pages        = {329--341},
  publisher    = {Elsevier},
  series       = {Earth and Planetary Science Letters},
  title        = {Ordovician palaeogeography with new palaeomagnetic data from the Montagne Noire (Southern France)},
  url          = {http://dx.doi.org/10.1016/S0012-821X(02)00847-6},
  volume       = {203},
  year         = {2002},
}