Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America
Fe-bearing minerals are a tiny fraction of the composition of speleothems. They have their origin in the karst system or are transported from the drainage basin into the cave. Recent studies on the magnetism of speleothems focused on the variations of their magnetic mineralogy in specific time inter...
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Frontiers Media S.A.
2021-04-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2021.634482/full |
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| author | Plinio Jaqueto Ricardo I. F. Trindade Joshua M. Feinberg Janine Carmo Valdir F. Novello Nicolás M. Stríkis Francisco W. Cruz Marília H. Shimizu Ivo Karmann |
| author_facet | Plinio Jaqueto Ricardo I. F. Trindade Joshua M. Feinberg Janine Carmo Valdir F. Novello Nicolás M. Stríkis Francisco W. Cruz Marília H. Shimizu Ivo Karmann |
| author_sort | Plinio Jaqueto |
| collection | DOAJ |
| description | Fe-bearing minerals are a tiny fraction of the composition of speleothems. They have their origin in the karst system or are transported from the drainage basin into the cave. Recent studies on the magnetism of speleothems focused on the variations of their magnetic mineralogy in specific time intervals and are usually limited to a single sample. In this study, we describe a database of environmental magnetism parameters built from 22 stalagmites from different caves located in Brazil (South America) at different latitudes, comprising different climates and biomes. The magnetic signal observed in these stalagmites is dominated by low-coercivity minerals (∼20 mT) whose magnetic properties resemble those of the magnetite formed in pedogenic environments. Also, a comparison with few samples from soils and the carbonate from cave’s walls shows a good agreement of the magnetic properties of speleothems with those of soil samples, reinforcing previous suggestions that in (sub-)tropical regimes, the dominant magnetic phase in speleothems is associated with the soil above the cave. Spearman’s rank correlation points to a positive strong correlation between magnetic concentration parameters (mass-normalized magnetic susceptibility, natural remanent magnetization, anhysteretic remanent magnetization, and isothermal remanent magnetization). This implies that ultrafine ferrimagnetic minerals are the dominant phase in these (sub-)tropical karst systems, which extend across a diverse range of biomes. Although the samples are concentrated in the savannah biome (Cerrado) (∼70%), comparison with other biomes shows a higher concentration of magnetic minerals in speleothem underlying savannahs and lower concentration in those underlying moist broadleaf forests (Atlantic and Amazon biome) and dry forests (Caatinga). Thus, rainfall, biome, and epikarst dynamics play an important role in the concentration of magnetic minerals in speleothems in (sub-)tropical sites and indicate they can be an important target for paleoenvironmental research in cave systems. |
| first_indexed | 2024-12-16T11:30:47Z |
| format | Article |
| id | doaj.art-ff1adc3d2dd647798343040aecd24967 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-16T11:30:47Z |
| publishDate | 2021-04-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Earth Science |
| spelling | doaj.art-ff1adc3d2dd647798343040aecd249672022-12-21T22:33:15ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632021-04-01910.3389/feart.2021.634482634482Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South AmericaPlinio Jaqueto0Ricardo I. F. Trindade1Joshua M. Feinberg2Janine Carmo3Valdir F. Novello4Nicolás M. Stríkis5Francisco W. Cruz6Marília H. Shimizu7Ivo Karmann8Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo (USPmag), São Paulo, BrazilDepartamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo (USPmag), São Paulo, BrazilDepartment of Earth and Environmental Sciences, Institute for Rock Magnetism, University of Minnesota, Minneapolis, MN, United StatesDepartamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo (USPmag), São Paulo, BrazilInstituto de Geociências, Universidade de São Paulo, São Paulo, BrazilDepartamento de Geoquímica, Universidade Federal Fluminense, Niterói, BrazilInstituto de Geociências, Universidade de São Paulo, São Paulo, BrazilCenter for Weather Forecasting and Climate Studies (CPTEC), National Institute for Space Research (INPE), Cachoeira Paulista, BrazilInstituto de Geociências, Universidade de São Paulo, São Paulo, BrazilFe-bearing minerals are a tiny fraction of the composition of speleothems. They have their origin in the karst system or are transported from the drainage basin into the cave. Recent studies on the magnetism of speleothems focused on the variations of their magnetic mineralogy in specific time intervals and are usually limited to a single sample. In this study, we describe a database of environmental magnetism parameters built from 22 stalagmites from different caves located in Brazil (South America) at different latitudes, comprising different climates and biomes. The magnetic signal observed in these stalagmites is dominated by low-coercivity minerals (∼20 mT) whose magnetic properties resemble those of the magnetite formed in pedogenic environments. Also, a comparison with few samples from soils and the carbonate from cave’s walls shows a good agreement of the magnetic properties of speleothems with those of soil samples, reinforcing previous suggestions that in (sub-)tropical regimes, the dominant magnetic phase in speleothems is associated with the soil above the cave. Spearman’s rank correlation points to a positive strong correlation between magnetic concentration parameters (mass-normalized magnetic susceptibility, natural remanent magnetization, anhysteretic remanent magnetization, and isothermal remanent magnetization). This implies that ultrafine ferrimagnetic minerals are the dominant phase in these (sub-)tropical karst systems, which extend across a diverse range of biomes. Although the samples are concentrated in the savannah biome (Cerrado) (∼70%), comparison with other biomes shows a higher concentration of magnetic minerals in speleothem underlying savannahs and lower concentration in those underlying moist broadleaf forests (Atlantic and Amazon biome) and dry forests (Caatinga). Thus, rainfall, biome, and epikarst dynamics play an important role in the concentration of magnetic minerals in speleothems in (sub-)tropical sites and indicate they can be an important target for paleoenvironmental research in cave systems.https://www.frontiersin.org/articles/10.3389/feart.2021.634482/fullenvironmental magnetismspeleothem magnetismSouth Americarock magnetismkarst systemstalagmites |
| spellingShingle | Plinio Jaqueto Ricardo I. F. Trindade Joshua M. Feinberg Janine Carmo Valdir F. Novello Nicolás M. Stríkis Francisco W. Cruz Marília H. Shimizu Ivo Karmann Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America Frontiers in Earth Science environmental magnetism speleothem magnetism South America rock magnetism karst system stalagmites |
| title | Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America |
| title_full | Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America |
| title_fullStr | Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America |
| title_full_unstemmed | Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America |
| title_short | Magnetic Mineralogy of Speleothems From Tropical-Subtropical Sites of South America |
| title_sort | magnetic mineralogy of speleothems from tropical subtropical sites of south america |
| topic | environmental magnetism speleothem magnetism South America rock magnetism karst system stalagmites |
| url | https://www.frontiersin.org/articles/10.3389/feart.2021.634482/full |
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