A palaeomagnetic and Ar-40/Ar-39 study of late precambrian sills in the SW part of the Amazonian craton: Amazonia in the Rodinia reconstruction
(2009) In Geophysical Journal International 178(1). p.106-122- Abstract
- A new key palaeomagnetic pole (Plat. = 64.3 degrees S, Plon. = 271.0 degrees E, N = 14, A(95) = 9.2 degrees; Q = 5) is calculated from a primary magnetization isolated in early Neoproterozoic Aguapei basic sills and dykes hosted by 1.3-1.0 Ga sedimentary rocks from the southwestern part of the Amazon craton. The characteristic remanence carried by stable, pseudo-single domain titanomagnetite shows two antipodal polarities that pass a reversals test. Magnetic anisotropy for most sites shows fabric orientations that are typical of sills, with horizontal magnetic foliations concordant to the flat-lying bedding of the host sedimentary rocks. Ar-40/Ar-39 analyses for one of the sills reveal a well-defined plateau age at 981 +/- 2 Myr. A... (More)
- A new key palaeomagnetic pole (Plat. = 64.3 degrees S, Plon. = 271.0 degrees E, N = 14, A(95) = 9.2 degrees; Q = 5) is calculated from a primary magnetization isolated in early Neoproterozoic Aguapei basic sills and dykes hosted by 1.3-1.0 Ga sedimentary rocks from the southwestern part of the Amazon craton. The characteristic remanence carried by stable, pseudo-single domain titanomagnetite shows two antipodal polarities that pass a reversals test. Magnetic anisotropy for most sites shows fabric orientations that are typical of sills, with horizontal magnetic foliations concordant to the flat-lying bedding of the host sedimentary rocks. Ar-40/Ar-39 analyses for one of the sills reveal a well-defined plateau age at 981 +/- 2 Myr. A tectonic reconstruction for Amazonia relative Laurentia based on this new pole 'is consistent with' a position of the present northwestern part of Amazonia attached with eastern Laurentia close to Greenland at ca. 981 Ma. On basis of palaeomagnetic and geological data, we propose a scenario where Amazonia moved northeastwards along the present southeast coast of Laurentia from ca. 1200 to 980 Ma. By 980 Ma, Amazonia is placed alongside Laurentia and Baltica, in a position similar to other reconstructions of Rodinia but with a significantly different orientation. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1442105
- author
- Elming, S. -A. ; D'Agrella-Filho, M. S. ; Page, Laurence LU ; Tohver, E. ; Trindade, R. I. F. ; Pacca, I. I. G. ; Geraldes, M. C. and Teixeira, W.
- organization
- publishing date
- 2009
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Rock and mineral magnetism, Magnetic fabrics and anisotropy, Palaeomagnetism applied to tectonics
- in
- Geophysical Journal International
- volume
- 178
- issue
- 1
- pages
- 106 - 122
- publisher
- Oxford University Press
- external identifiers
-
- wos:000266979600008
- scopus:67650230184
- ISSN
- 0956-540X
- DOI
- 10.1111/j.1365-246X.2009.04149.x
- language
- English
- LU publication?
- yes
- id
- 1a4adaa2-949e-40e6-9655-51df8ec454a7 (old id 1442105)
- date added to LUP
- 2016-04-01 12:11:03
- date last changed
- 2022-03-28 21:23:59
@article{1a4adaa2-949e-40e6-9655-51df8ec454a7, abstract = {{A new key palaeomagnetic pole (Plat. = 64.3 degrees S, Plon. = 271.0 degrees E, N = 14, A(95) = 9.2 degrees; Q = 5) is calculated from a primary magnetization isolated in early Neoproterozoic Aguapei basic sills and dykes hosted by 1.3-1.0 Ga sedimentary rocks from the southwestern part of the Amazon craton. The characteristic remanence carried by stable, pseudo-single domain titanomagnetite shows two antipodal polarities that pass a reversals test. Magnetic anisotropy for most sites shows fabric orientations that are typical of sills, with horizontal magnetic foliations concordant to the flat-lying bedding of the host sedimentary rocks. Ar-40/Ar-39 analyses for one of the sills reveal a well-defined plateau age at 981 +/- 2 Myr. A tectonic reconstruction for Amazonia relative Laurentia based on this new pole 'is consistent with' a position of the present northwestern part of Amazonia attached with eastern Laurentia close to Greenland at ca. 981 Ma. On basis of palaeomagnetic and geological data, we propose a scenario where Amazonia moved northeastwards along the present southeast coast of Laurentia from ca. 1200 to 980 Ma. By 980 Ma, Amazonia is placed alongside Laurentia and Baltica, in a position similar to other reconstructions of Rodinia but with a significantly different orientation.}}, author = {{Elming, S. -A. and D'Agrella-Filho, M. S. and Page, Laurence and Tohver, E. and Trindade, R. I. F. and Pacca, I. I. G. and Geraldes, M. C. and Teixeira, W.}}, issn = {{0956-540X}}, keywords = {{Rock and mineral magnetism; Magnetic fabrics and anisotropy; Palaeomagnetism applied to tectonics}}, language = {{eng}}, number = {{1}}, pages = {{106--122}}, publisher = {{Oxford University Press}}, series = {{Geophysical Journal International}}, title = {{A palaeomagnetic and Ar-40/Ar-39 study of late precambrian sills in the SW part of the Amazonian craton: Amazonia in the Rodinia reconstruction}}, url = {{http://dx.doi.org/10.1111/j.1365-246X.2009.04149.x}}, doi = {{10.1111/j.1365-246X.2009.04149.x}}, volume = {{178}}, year = {{2009}}, }