Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction
We have carried out a palaeomagnetic investigation of the upper middle Devonian marly limestone of the Hazzel Matti Formation outcropping at Meredoua in the northern Ahaggar in the Sahara Desert. The Givetian age of the formation is well constrained by palaeontological arguments. The formation has b...
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fthighwire:oai:open-archive.highwire.org:gji:119/1/166 2023-05-15T18:23:14+02:00 Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction Smith, Brigitte Moussine-Pouchkine, Alexis Ahmed, Ali Aït Kaci 1994-10-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/119/1/166 https://doi.org/10.1111/j.1365-246X.1994.tb00920.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/119/1/166 http://dx.doi.org/10.1111/j.1365-246X.1994.tb00920.x Copyright (C) 1994, Oxford University Press Articles TEXT 1994 fthighwire https://doi.org/10.1111/j.1365-246X.1994.tb00920.x 2016-11-16T17:21:51Z We have carried out a palaeomagnetic investigation of the upper middle Devonian marly limestone of the Hazzel Matti Formation outcropping at Meredoua in the northern Ahaggar in the Sahara Desert. The Givetian age of the formation is well constrained by palaeontological arguments. The formation has been deformed later than the Moscovian (upper middle Carboniferous). In the altered yellowish samples and in the heterogeneous samples made of mixed fresh and altered zones, several obviously secondary magnetization components are present. In the freshest bluegrey samples a SE down-dipping component can be isolated, particularly when a combined thermal and AF treatment is applied. This component, observed in 53 samples from three sites, passes the fold test of McFadden & Lowes (1981) and McFadden & Jones (1981) at the 95 per cent probability level. the mean direction for the three sites after tilt correction is: D s = 118.9°, I s ,=34.2°, k = 378, α 95 = 6.3°, which corresponds to a south pole (MER) situated at φ p = 61.7°, λ p = -16.2°, A 95 = 4.2° and places the site area under a palaeolatitude of -18.8°. However, the best grouping of the directions is achieved after 85 per cent of unfolding using a statistical method based on a bivariate extension of the Fisher's statistics (Legoff 1990; Legoff, Henry & Daly 1992). Such a tilt correction changes the pole position by 1.5°. As the α 95 and K curves obtained from stepwise unfolding display a broad minimum and maximum value respectively, and because there was probably slight original syn-sedimentary dips, it is likely that 85 per cent of tilt correction is not significantly different from complete unfolding. The magnetic behaviour of the samples upon thermal and AF demagnetization, the evolution of the initial susceptibility upon thermal treatment, hysteresis cycles and investigation of the magnetic mineralogy through microscope examination and electron microprobe analyses lead to the following conclusion: greigite was probably a primary magnetic mineral ... Text South pole HighWire Press (Stanford University) South Pole Daly ENVELOPE(63.761,63.761,-67.513,-67.513) Geophysical Journal International 119 1 166 186 |
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Articles Smith, Brigitte Moussine-Pouchkine, Alexis Ahmed, Ali Aït Kaci Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction |
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description |
We have carried out a palaeomagnetic investigation of the upper middle Devonian marly limestone of the Hazzel Matti Formation outcropping at Meredoua in the northern Ahaggar in the Sahara Desert. The Givetian age of the formation is well constrained by palaeontological arguments. The formation has been deformed later than the Moscovian (upper middle Carboniferous). In the altered yellowish samples and in the heterogeneous samples made of mixed fresh and altered zones, several obviously secondary magnetization components are present. In the freshest bluegrey samples a SE down-dipping component can be isolated, particularly when a combined thermal and AF treatment is applied. This component, observed in 53 samples from three sites, passes the fold test of McFadden & Lowes (1981) and McFadden & Jones (1981) at the 95 per cent probability level. the mean direction for the three sites after tilt correction is: D s = 118.9°, I s ,=34.2°, k = 378, α 95 = 6.3°, which corresponds to a south pole (MER) situated at φ p = 61.7°, λ p = -16.2°, A 95 = 4.2° and places the site area under a palaeolatitude of -18.8°. However, the best grouping of the directions is achieved after 85 per cent of unfolding using a statistical method based on a bivariate extension of the Fisher's statistics (Legoff 1990; Legoff, Henry & Daly 1992). Such a tilt correction changes the pole position by 1.5°. As the α 95 and K curves obtained from stepwise unfolding display a broad minimum and maximum value respectively, and because there was probably slight original syn-sedimentary dips, it is likely that 85 per cent of tilt correction is not significantly different from complete unfolding. The magnetic behaviour of the samples upon thermal and AF demagnetization, the evolution of the initial susceptibility upon thermal treatment, hysteresis cycles and investigation of the magnetic mineralogy through microscope examination and electron microprobe analyses lead to the following conclusion: greigite was probably a primary magnetic mineral ... |
format |
Text |
author |
Smith, Brigitte Moussine-Pouchkine, Alexis Ahmed, Ali Aït Kaci |
author_facet |
Smith, Brigitte Moussine-Pouchkine, Alexis Ahmed, Ali Aït Kaci |
author_sort |
Smith, Brigitte |
title |
Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction |
title_short |
Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction |
title_full |
Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction |
title_fullStr |
Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction |
title_full_unstemmed |
Palaeomagnetic investigation of Middle Devonian limestones of Algeria and the Gondwana reconstruction |
title_sort |
palaeomagnetic investigation of middle devonian limestones of algeria and the gondwana reconstruction |
publisher |
Oxford University Press |
publishDate |
1994 |
url |
http://gji.oxfordjournals.org/cgi/content/short/119/1/166 https://doi.org/10.1111/j.1365-246X.1994.tb00920.x |
long_lat |
ENVELOPE(63.761,63.761,-67.513,-67.513) |
geographic |
South Pole Daly |
geographic_facet |
South Pole Daly |
genre |
South pole |
genre_facet |
South pole |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/119/1/166 http://dx.doi.org/10.1111/j.1365-246X.1994.tb00920.x |
op_rights |
Copyright (C) 1994, Oxford University Press |
op_doi |
https://doi.org/10.1111/j.1365-246X.1994.tb00920.x |
container_title |
Geophysical Journal International |
container_volume |
119 |
container_issue |
1 |
container_start_page |
166 |
op_container_end_page |
186 |
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