| Texto completo | |
| Autor(es): |
Fu, Roger R.
[1]
;
Hess, Kimberly
[1]
;
Jaqueto, Plinio
[2, 3]
;
Novello, Valdir F.
[2]
;
Kukla, Tyler
[4]
;
Trindade, Ricardo I. F.
[2]
;
Strikis, Nicolas M.
[5]
;
Cruz, Francisco W.
[2]
;
Ben Dor, Oren
[6, 1]
Número total de Autores: 9
|
| Afiliação do(s) autor(es): | [1] Harvard Univ, Dept Earth & Planetary Sci, 20 Oxford St, Cambridge, MA 02138 - USA
[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo - Brazil
[3] Univ Minnesota, Dept Earth & Environm Sci, Minneapolis, MN - USA
[4] Stanford Univ, Dept Geol Sci, Stanford, CA 94305 - USA
[5] Univ Fed Fluminense, Niteroi, RJ - Brazil
[6] Harvard Univ, Dept Phys, Cambridge, MA 02138 - USA
Número total de Afiliações: 6
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Frontiers in Earth Science; v. 8, JAN 14 2021. |
| Citações Web of Science: | 0 |
| Resumo | |
Quantum diamond microscope (QDM) magnetic field imaging is a recently developed technique capable of mapping magnetic field sources in geologic samples at 1 micrometer resolution. Applying QDM imaging to speleothems can provide high-resolution time series of detrital input into the cave environment, which, in turn, can yield useful paleoenvironmental information. Here we map the magnetic field over a speleothem from midwest Brazil over a 174 year timespan with annual to sub-annual resolution and perform backfield remanence acquisition experiments to quantify changes in the magnetic grain population through time. We find that magnetic particles occur in highly enriched layers of 10-100 mu m thickness that sample the same detrital source population. Combined with petrographic observations and electron microprobe mapping of Mg and Ca, we conclude that detrital enrichment in our sample is caused by drier conditions leading to slow or halted speleothem growth. This interpretation is compatible with oxygen isotopic data and implies that speleothem magnetism can be used to infer the past occurrence of drought and potentially quantify their duration. Future high-resolution magnetic imaging of speleothems may provide additional insight into the mechanism of detrital enrichment and establish their role as a proxy for local moisture and infiltration. (AU) | |
| Processo FAPESP: | 16/24870-2 - Significado ambiental do magnetismo em espeleotemas |
| Beneficiário: | Plinio Francisco Jaqueto |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |