Return to Rodinia? Moderate to high palaeolatitude of the São Francisco/Congo craton at 920 Ma
(2015) In Geological Society Special Publication 424(1). p.167-190- Abstract
Moderate to high palaeolatitudes recorded in mafic dykes, exposed along the coast of Bahia, Brazil, are partly responsible for some interpretations that the São Francisco/Congo craton was separate from the low-latitude Rodinia supercontinent at about 1050 Ma. We report new palaeomagnetic data that replicate the previous results. However, we obtain substantially younger U-Pb baddeleyite ages from five dykes previously thought to be 1.02-1.01 Ga according to the 40Ar/39Ar method. Specifically, the so-called «A-normal» remanence direction from Salvador is dated at 924.2±3.8 Ma, within error of the age for the «C» remanence direction at 921.5±4.3 Ma. An «A-normal» dyke at Ilh»us is dated at 926.1±4.6 Ma, and two... (More)
Moderate to high palaeolatitudes recorded in mafic dykes, exposed along the coast of Bahia, Brazil, are partly responsible for some interpretations that the São Francisco/Congo craton was separate from the low-latitude Rodinia supercontinent at about 1050 Ma. We report new palaeomagnetic data that replicate the previous results. However, we obtain substantially younger U-Pb baddeleyite ages from five dykes previously thought to be 1.02-1.01 Ga according to the 40Ar/39Ar method. Specifically, the so-called «A-normal» remanence direction from Salvador is dated at 924.2±3.8 Ma, within error of the age for the «C» remanence direction at 921.5±4.3 Ma. An «A-normal» dyke at Ilh»us is dated at 926.1±4.6 Ma, and two «A-normal» dykes at Olivença have indistinguishable ages with best estimate of emplacement at 918.2±6.7 Ma. We attribute the palaeomagnetic variance of the «A-normal» and «C» directions to lack of averaging of geomagnetic palaeosecular variation in some regions. Our results render previous 40Ar/39Ar ages from the dykes suspect, leaving late Mesoproterozoic palaeolatitudes of the São Francisco/Congo craton unconstrained. The combined «A-normal» palaeomagnetic pole from coastal Bahia places the São Francisco/Congo craton in moderate to high palaeolatitudes at c. 920 Ma, allowing various possible positions of that block within Rodinia.
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- author
- Evans, D. A D ; Trindade, R. I F ; Catelani, E. L. ; D'Agrella-Filho, M. S. ; Heaman, L. M. ; Oliveira, E. P. ; Söderlund, U. LU ; Ernst, R. E. ; Smirnov, A. V. and Salminen, J. M.
- organization
- publishing date
- 2015-05-28
- type
- Chapter in Book/Report/Conference proceeding
- publication status
- published
- subject
- host publication
- Geological Society Special Publication
- series title
- Geological Society Special Publication
- volume
- 424
- issue
- 1
- edition
- 1
- pages
- 24 pages
- publisher
- Geological Society of London
- external identifiers
-
- scopus:84966715272
- ISSN
- 03058719
- DOI
- 10.1144/SP424.1
- language
- English
- LU publication?
- yes
- id
- 208f1d1b-4960-4ff7-8b56-0ea7229ae988
- date added to LUP
- 2016-10-10 14:34:02
- date last changed
- 2022-04-01 02:43:04
@inbook{208f1d1b-4960-4ff7-8b56-0ea7229ae988, abstract = {{<p>Moderate to high palaeolatitudes recorded in mafic dykes, exposed along the coast of Bahia, Brazil, are partly responsible for some interpretations that the São Francisco/Congo craton was separate from the low-latitude Rodinia supercontinent at about 1050 Ma. We report new palaeomagnetic data that replicate the previous results. However, we obtain substantially younger U-Pb baddeleyite ages from five dykes previously thought to be 1.02-1.01 Ga according to the <sup>40</sup>Ar/<sup>39</sup>Ar method. Specifically, the so-called «A-normal» remanence direction from Salvador is dated at 924.2±3.8 Ma, within error of the age for the «C» remanence direction at 921.5±4.3 Ma. An «A-normal» dyke at Ilh»us is dated at 926.1±4.6 Ma, and two «A-normal» dykes at Olivença have indistinguishable ages with best estimate of emplacement at 918.2±6.7 Ma. We attribute the palaeomagnetic variance of the «A-normal» and «C» directions to lack of averaging of geomagnetic palaeosecular variation in some regions. Our results render previous <sup>40</sup>Ar/<sup>39</sup>Ar ages from the dykes suspect, leaving late Mesoproterozoic palaeolatitudes of the São Francisco/Congo craton unconstrained. The combined «A-normal» palaeomagnetic pole from coastal Bahia places the São Francisco/Congo craton in moderate to high palaeolatitudes at c. 920 Ma, allowing various possible positions of that block within Rodinia.</p>}}, author = {{Evans, D. A D and Trindade, R. I F and Catelani, E. L. and D'Agrella-Filho, M. S. and Heaman, L. M. and Oliveira, E. P. and Söderlund, U. and Ernst, R. E. and Smirnov, A. V. and Salminen, J. M.}}, booktitle = {{Geological Society Special Publication}}, issn = {{03058719}}, language = {{eng}}, month = {{05}}, number = {{1}}, pages = {{167--190}}, publisher = {{Geological Society of London}}, series = {{Geological Society Special Publication}}, title = {{Return to Rodinia? Moderate to high palaeolatitude of the São Francisco/Congo craton at 920 Ma}}, url = {{http://dx.doi.org/10.1144/SP424.1}}, doi = {{10.1144/SP424.1}}, volume = {{424}}, year = {{2015}}, }