Paleoproterozoic Geomagnetic Field Strength From the Avanavero Mafic Sills, Amazonian Craton, Brazil
Autor: | Franklin Bispo-Santos, Ricardo I.F. Trindade, A. Di Chiara, Adrian R. Muxworthy |
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Rok vydání: | 2017 |
Předmět: |
Geochemistry & Geophysics
CRÁTON 010504 meteorology & atmospheric sciences INNER-CORE NUCLEATION SAMPLES Amazonian Earth science 04 Earth Sciences SUBMARINE BASALTIC GLASS 010502 geochemistry & geophysics GEODYNAMO 01 natural sciences paleointensity Precambrian Paleontology Sill Geochemistry and Petrology 0105 earth and related environmental sciences geography Science & Technology 02 Physical Sciences geography.geographical_feature_category PALEOMAGNETIC EVIDENCE PSEUDO-SINGLE-DOMAIN INTENSITY Inner core Amazonian Craton South America THERMOREMANENT MAGNETIZATION PALEOINTENSITY METHOD Craton Geophysics Earth's magnetic field Physical Sciences MULTIDOMAIN Period (geology) Mafic Brazil Geology |
Zdroj: | Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
ISSN: | 1525-2027 |
Popis: | A recent hypothesis has suggested that Earth's inner core nucleated during the Mesoproterozoic, as evidenced by a rapid increase in the paleointensity (ancient geomagnetic field intensity) record; however, paleointensity data during the Paleoproterozoic and Mesoproterozoic period are limited. To address this problem, we have determined paleointensity from samples from three Paleoproterozoic Avanavero mafic sills (Amazonian Craton, Brazil): Cotingo, 1782 Ma, Puiuà 1788, and Pedra Preta, 1795 Ma. We adopted a multi-protocol approach for paleointensity estimates combining Thellier-type IZZI and LTD-IZZI methods, and the non-heating Preisach protocol. We obtained an average VDM value of 1.3 ± 0.7 × 1022Am2 (Cotingo) of 2.0 ± 0.4 × 1022Am2 (Puiuà) and 6 ± 4 × 1022Am2 (Pedra Preta); it is argued that the Cotingo estimate is the most robust. Our results are the first data from the upper Paleoproterozoic for South America and are comparable to data available from other regions and similar periods. The new data do not invalidate the hypothesis of that Earth's inner core nucleated during the Mesoproterozoic. |
Databáze: | OpenAIRE |
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