Paleomagnetic constraints on the age of the Botucatu Formation in Rio Grande do Sul, southern Brazil

Anais da Academia Brasileira de Ciências

Endale Tamrat¹  Marcia Ernesto¹ 

[1] ,Universidade de São Paulo Instituto de Astronomia, Geofísica e Ciências Atmosféricas Departamento de GeofísicaSão Paulo SP ,Brasil

关键词: paleomagnetism;    Botucatu Formation;    magnetostratigraphy;    magnetic anisotropy;    Late Jurassic;    Paleomagnetismo;    Formação Botucatu;    magnetoestratigrafia;    anisotropia magnética;    Jurássico Superior;   

DOI  :  10.1590/S0001-37652006000300016

来源: SciELO

【 摘 要 】

Paleomagnetic and rockmagnetic data are reported for the aeolian Botucatu Formation, in the southern Brazilian State of Rio Grande do Sul. Oriented samples were taken from a section located between the cities of Jaguari and Santiago. After thermal and alternating field demagnetization, both normal and reversed characteristic remanent magnetizations were found. These results yielded 13 reversed and 5 normal polarity sites, composing a magnetostratigraphic column displaying a sequence of reversed-normal-reversed polarity events. The paleomagnetic pole calculated for 18 sites is located at 114.7ºE, 78.5ºS (dp=8.1º; dm=1.2º), after restoring the strata to the paleohorizontal. This paleomagnetic pole indicates a Late Jurassic-Early Cretaceous age to the Botucatu Formation in the investigated area, and places the sampling sites at paleolatitudes as low as 21ºS.

【 授权许可】

CC BY   
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