Magnetic Properties of the Jurassic Sedimentary Rocks of the Central High Atlas Affected by a Regional Chemical Remagnetization
- Pablo Calvín
- María Bógalo
- Juan Villalaín
- Teresa Román-Berdiel
- Irene Falcón
- Sara Torres-López
- Tania Mochales
- Angela Herrejón-Lagunilla
- Casas Sainz, Antonio M. (coord.)
- Calvín Ballester, Pablo (coord.)
- Román Berdiel, María Teresa (coord.)
- Villalaín, J. J (coord.)
Verlag: Cham, Switzerland : Springer, cop. 2023
ISBN: 9783031166921
Datum der Publikation: 2023
Seiten: 249-284
Art: Buch-Kapitel
Ziele für nachhaltige Entwicklung
Zusammenfassung
This chapter presents the results of numerous rock experiments carried out on Jurassic marine carbonates and red beds from the Central High Atlas, which have been affected by a regional remagnetization related to burial. As in other sedimentary rocks affected by chemical remagnetizations, the analyzed samples show a characteristic magnetic fingerprint. The dominant magnetic mineralogy of carbonates is composed of non-interacting uniaxial magnetite, in the superparamagnetic (SP) and stable single domain (SSD) states. Besides, a variable contribution of pyrrhotite is present in most of the samples. The combined presence of neoformed magnetite and pyrrhotite seems to be indicative that these rocks have reached temperatures around 200–250 °C, compatible with previous studies of illite crystallinity. ARM and IRM unmixing curves define a very characteristic pattern for remagnetized carbonates differentiated from other rocks types bearing magnetite. On the other hand, the high temperature susceptibility curves used to characterize the magnetic anisotropy studies show different contribution of paramagnetic and ferromagnetic (s.l.) minerals. Among paramagnetic phases, it is expected the presence of phyllosilicates and pyrite that can be the precursors of the neoformation of magnetite and pyrrhotite both during burial in natural conditions and in the different performed experiments. With regard to the ferromagnetic (s.l.) fractions, magnetite is the dominant phase with a minor contribution of pyrrhotite. In red beds, rock magnetic experiments show a dominance of hematite with different contribution of magnetite. In general, the susceptibility curves show a dominance of paramagnetic signal to the bulk susceptibility.