Carboniferous palaeomagnetic investigations in Morocco: Permian remagnetizations and possible large Carboniferous rotations occurring in Mesetian sedimentary and Jebilets intrusive rocks

Salmon, E.; Edel, Jean–Bernard; Piqué, Alain; Westphal, M.

doi:10.1111/j.1365-246x.1988.tb01391.x

Cited by 9 publications

(2 citation statements)

References 14 publications

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“…These directions correspond to that of the Permian overprint already observed in other studies in Africa (e.g. Daly & Irving 1983; Salmon et al 1988; Aïfa 1993). In the Lower Stephano‐Autunian Formation (sample TG18A on Fig.…”

Section: Palaeomagnetic Analysissupporting

confidence: 89%

Chemical remagnetizations in the Illizi basin (Saharan craton, Algeria) and their acquisition process

Henry

Merabet

Derder

et al. 2004

Geophysical Journal International

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S U M M A R YDuring remagnetization, chemical changes limited to moderate grain growth from pre-existing single domain (SD) grains do not modify the palaeomagnetic direction carried by these grains. Palaeomagnetic direction from new SD grains, on the contrary, is that of the magnetic field during remagnetization. The resulting direction becomes intermediate between the directions carried by previous and new SD grains, as it appears often in case of a partial magnetic overprint. If the growth of pre-existing grains is more important, these grains become large multidomain (MD) and loose the primary magnetization. Stable magnetization is then only related to the new SD grains, which carry the total remagnetization. In the Illizi basin (Saharan platform), these different cases of partial or total magnetic overprint have been observed, resulting from palaeomagnetic studies of different Palaeozoic and Mesozoic formations.

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Section: Palaeomagnetic Analysissupporting

confidence: 89%

Chemical remagnetizations in the Illizi basin (Saharan craton, Algeria) and their acquisition process

Henry

Merabet

Derder

et al. 2004

Geophysical Journal International

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“…This signature strongly contrasts with the late Paleozoic remagnetization seen elsewhere in the Great Basin, as the remagnetization resides in magnetite in all other known cases. Jackson et al [1993] suggested that pyrrhotite, in association with magnetite, may be important in imparting the distinctive rock magnetic properties seen in many ancient remagnetized carbonate rocks, and Salmon et al [1988a, 1988b] have also reported pyrrhotite carrying a Permian signature in remagnetized middle Paleozoic miogeoclinal rocks in Morocco. Indeed, as the magnetite in ancient carbonate rocks is commonly of late diagenetic origin [ McCabe and Elmore , 1989], formation of pyrrhotite at the expense of magnetite may help account for the common lack of primary magnetite capable of recording a stable paleomagnetic signature in such rocks.…”

Section: Discussionmentioning

confidence: 99%

Paleomagnetism of the Notch Peak contact metamorphic aureole, revisited: Pyrrhotite from magnetite+pyrite under submetamorphic conditions

Gillett

2003

J. Geophys. Res.

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[1] On the basis of new demagnetization and rock magnetic experiments, a scattered, twopolarity remagnetization extending throughout the contact metamorphic aureole surrounding the Jurassic Notch Peak granitic stock in western Utah is now thought to reside in metamorphic pyrrhotite rather than in fine-grained hematite. In part, the pyrrhotite formed by in situ reduction of magnetite by pyrite and organic compounds; it could not have been formed by the large-scale introduction of reducing fluids, as isotopic evidence indicates that these metalimestones remained impermeable. At higher grades, some pyrrhotite probably also formed by the reaction of pyrite and Fe-bearing silicates. As magnetite destruction and pyrrhotite formation extends into rocks that are not obviously metamorphosed, the reactions responsible could proceed at very low (less than $200°C) temperatures, and the feasibility of such low-temperature reactions in a closed system is shown by detailed thermodynamic calculations. This study demonstrates that under reducing conditions in the presence of sufficient pyrite, pyrrhotite can form at the expense of magnetite under very mild conditions; indeed, magnetite may be destroyed merely by deep burial. Such a mechanism may help explain the paucity of primary magnetite in ancient sedimentary rocks, particularly since the single-domain and pseudo-single-domain grains capable of retaining a stable paleomagnetic signature over geologic time are extremely fine-grained and hence particularly vulnerable to destruction.

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Integrating facies, mineralogy, and paleomagnetism to constrain the age and provenance of Paleozoic siliciclastic sedimentary rocks along the northern Gondwana margin: insights from the Araba and Naqus formations in western Gulf of Suez, Egypt

Al-Nashar,

Hafez,

El-Moghny

et al. 2024

Int J Earth Sci (Geol Rundsch)

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The depositional ages and provenance of the Paleozoic Araba and Naqus Formations along the northern Gondwanan margin in Egypt have remained uncertain due to a lack of index fossils. Resolving this issue is crucial for understanding regional geology during deposition and subsequent tectonic development. We integrate detailed facies analysis, anisotropy of magnetic susceptibility (AMS), paleomagnetism, and mineralogical data to elucidate the genesis and depositional ages of the Araba and Naqus Formations. Petrographic analyses identified seven distinct facies types, providing insights into sedimentary textures, maturity, and sources, with contributions from igneous and metamorphic sources indicated by heavy minerals. X-ray diffraction (XRD) analysis identified accessory minerals such as quartz, goethite, kaolinite, hematite, and anatase. Paleomagnetism isolated two magnetic components (CA and CN) providing the first robust paleo pole positions at Lat. = 70.8° N, Long. = 308.2° E and Lat. = 37.8° N, Long. = 233.1° E, indicating Cambrian and Carboniferous ages for the Araba and Naqus formations, respectively. Thermal demagnetization constrained these dates using established polarity timescales. Mineralogical data indicated that the Araba Formation originated from an igneous source, while the Naqus Formation had a mixed metamorphic-igneous provenance. The integrated AMS and paleomagnetic data reveal evidence of post-depositional deformation. Specifically, the clustering of maximum AMS axes in the NW–SE direction for both formations, suggests the initial presence of a primary depositional fabric. However, prevalent tectonic activity during the Cenozoic appears to have overprinted and modified this fabric through deformation related to rifting of the Gulf of Suez region. Through this novel multi-proxy approach, we have resolved long-standing uncertainties regarding the formations' depositional ages. Our study thereby provides the first chronostratigraphic framework for these strategically important sedimentary units, significantly advancing understanding of regional Paleozoic geology. Graphical abstract

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Carboniferous palaeomagnetic investigations in Morocco: Permian remagnetizations and possible large Carboniferous rotations occurring in Mesetian sedimentary and Jebilets intrusive rocks

Cited by 9 publications

References 14 publications

Chemical remagnetizations in the Illizi basin (Saharan craton, Algeria) and their acquisition process

Chemical remagnetizations in the Illizi basin (Saharan craton, Algeria) and their acquisition process

Paleomagnetism of the Notch Peak contact metamorphic aureole, revisited: Pyrrhotite from magnetite+pyrite under submetamorphic conditions

Integrating facies, mineralogy, and paleomagnetism to constrain the age and provenance of Paleozoic siliciclastic sedimentary rocks along the northern Gondwana margin: insights from the Araba and Naqus formations in western Gulf of Suez, Egypt

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