New archeointensity data from South Brazil and the influence of the South Atlantic Anomaly in South America

Author(s)

Hartmann, Gelvam A. ^[1] ; Poletti, Wilbor ^[2] ; Trindade, Ricardo I. F. ^[2] ; Ferreira, Lucio M. ^[3] ; Sanches, Pedro L. M. ^[4]

Affiliation

^[1] Univ Estadual Campinas, Inst Geociencias, Rua Carlos Gomes 250, BR-13083855 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Geofis, Rua Matao 1226, BR-05508090 Sao Paulo - Brazil

^[3] Univ Fed Pelotas, Inst Ciencias Humanas, Dept Antropol & Arqueol, Inst Ciencias Humanas, Pelotas, RS - Brazil

^[4] Univ Fed Pelotas, Inst Ciencias Humanas, Dept Museol Conservacao & Restauro, Pelotas, RS - Brazil

• Document type: Journal article
• Source: Earth and Planetary Science Letters; v. 512, p. 124-133, APR 15 2019.
• Web of Science Citations: 0

Abstract

We obtained six new high-quality archeointensity results for the Pelotas city region, in South Brazil with ages ranging from 1790 to 1943 CE. Archeointensity measurements were performed with the double heating technique, including partial thermoremanent magnetization (pTRM) checks and pTRM tail-checks. Measurements were corrected from anisotropy of TRM and cooling-rate effects. Archeological sites providing successful results comprised: Charqueada Santa Barbara (1790-1838 CE; 36.4 +/- 0.6 mu T), Chacara da Brigada Militar (1830-1851 CE; 32.6 +/- 2.9 mu T), Casa Numero 08 (1878-1879 CE; 32.1 +/- 3.1 mu T), Colegio da Familia de Eliseu Maciel (1881-1883 CE; 28.7 +/- 2.7 mu T), Fundacao Simon Bolivar (1884-1889 CE; 30.1 +/- 2.0 mu T), Campus Porto UFPel (1942-1943 CE; 27.8 +/- 2.0 mu T). Two other sites did not provide meaningful results. The new data complement previous results obtained in South and Southeast Brazil, Argentina and Chile and provide additional evidence for the rapid decay of the field in the region from about 1500 to 2000 CE. In addition, they show a gradual increase in the contribution of non-dipolar components in the geomagnetic field of South America since 1800 CE, likely indicating a strengthening of the South Atlantic Anomaly over the continent from this time onward. (C) 2019 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/16382-0 - Analysis of the historical geomagnetic field in South America
• Grantee: Wilbor Poletti Silva
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 16/22960-4 - Geomagnetic field strength in the Amazon region from microwave archeointensity measurements
• Grantee: Wilbor Poletti Silva
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)