Environmental magnetism: Loess and nalaeosols of the Buenos Aires Formation (Province of Buenos Aires)
Dia-genetic and/or pedogenetic processes produce ferromagnetic phases and/or the dissolution of magnetic minerals. The identification of these magnetic minerals, their grain size and variations through a sedimentary profile enable the determination of the climatic changes that took place during depo...
Guardado en:
| Autor principal: | |
|---|---|
| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00044822_v53_n1_p91_Orgeira |
| Aporte de: |
| Sumario: | Dia-genetic and/or pedogenetic processes produce ferromagnetic phases and/or the dissolution of magnetic minerals. The identification of these magnetic minerals, their grain size and variations through a sedimentary profile enable the determination of the climatic changes that took place during deposition. The results presented here were obtained from a 7.6 m thick profile of typical loess (Buenos Aires Formation, Brunhes magnetic age) located beneath the city of Buenos Aires (Cervino street). On the basis of the variation of the magnetic properties [susceptibilities, isothermal rémanent magnetization (IRM), coercivity of the remanence (Bcr), rémanent acquisition coercive force (H'cr), Sratio, saturation isothermal rémanent magnetization (SIRM), low temperature properties, coercivity force (Be), and magnetization of saturation (Ms), among others] a decrease of ferrimagnetic (magnetite), and an increase of antiferromagnetic (goethite) minerals was observed in the palaeosol levels of the outcrop. Similar magnetic variations were detected in some others levels of the profile, previously not related to palaeosol formation. © 1998 Asociaciön Gcolögica Argentina. |
|---|