TY - JOUR
T1 - 40Ar/39Ar dating of 1.0-1.1 Ga magnetizations from the São Francisco and Kalahari cratons
T2 - tectonic implications for Pan-African and Brasiliano mobile belts
AU - Renne, Paul R.
AU - Onstott, Tullis C.
AU - D'Agrella-Filho, Manoel S.
AU - Pacca, Igor G.
AU - Teixeira, Wilson
N1 - Funding Information:
We thank A. Pedreira and A.K. Kneedler for assistancew ith fieldwork and mineral separations, J.K.W. Lee, C.-H. Lo and M. Debiche for assistance with computer programs for thermal modelling/Ar diffusion, 4°Ar/39Ar data analysis and tectonic reconstruction(sr espectively)R, .B. Har-graves for critical comments and discussionsa, nd S.M. Swapp for assistancew ith electron microprobe analysis. We appreciatea n anonymous reviewer'sc onstructivceo mmentsa, nd Kevin Burke's effusive punditry regarding the manuscript. This research was funded by the U.S. NSF (grants EAR-8451696 and EAR-8805529) and by the Brazilian CNPq, FAPESP and FINEP. This work is contribution No. 21 of the IGCP 257 "Precambrian Dyke Swarms".
PY - 1990/12
Y1 - 1990/12
N2 - Paleomagnetic poles from 1.1-1.0 Ga dyke swarms in eastern Brazil (São Francisco Craton) are compared with 1.0 Ga poles from granulites of the Namaqua Province in southern Africa (Kalahari Graton). The intrusive ages of dykes are estimated from 40Ar/39Ar dating of outgassed biotites from baked country rocks. The age of magnetization for the granulites is derived by combining 40Ar/39Ar hornblende and biotite dates. When restored to a Mesozoic pre-drift configuration the paleomagnetic poles are in crude spatial agreement but are temporally discordant. To satisfy both paleomagnetic and geochronologic constraints, a reconstruction involving separation of the São Francisco and Kalahari cratons is required, indicating that the intervening Pan-African (Brasiliano) mobile belt may record a craton-craton collision.
AB - Paleomagnetic poles from 1.1-1.0 Ga dyke swarms in eastern Brazil (São Francisco Craton) are compared with 1.0 Ga poles from granulites of the Namaqua Province in southern Africa (Kalahari Graton). The intrusive ages of dykes are estimated from 40Ar/39Ar dating of outgassed biotites from baked country rocks. The age of magnetization for the granulites is derived by combining 40Ar/39Ar hornblende and biotite dates. When restored to a Mesozoic pre-drift configuration the paleomagnetic poles are in crude spatial agreement but are temporally discordant. To satisfy both paleomagnetic and geochronologic constraints, a reconstruction involving separation of the São Francisco and Kalahari cratons is required, indicating that the intervening Pan-African (Brasiliano) mobile belt may record a craton-craton collision.
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U2 - 10.1016/0012-821X(90)90165-T
DO - 10.1016/0012-821X(90)90165-T
M3 - Article
AN - SCOPUS:0025631460
SN - 0012-821X
VL - 101
SP - 349
EP - 366
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 2-4
ER -