Paleomagnetic Key Pole for Congo/São Francisco Craton During Nuna Interval (ca. 1600–1300 Ma) - Research

Sep 2, 2026

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The Congo/São Francisco (C/SF) craton, a major Proterozoic cratonic block, lacked reliable paleomagnetic constraints for the Nuna supercontinent interval (ca. 1600–1300 Ma). New paleomagnetic results from recently dated mafic dykes in Curaçá, Brazil (1506.7 ± 6.9 Ma) provide a new paleomagnetic key pole. The ChRM yields a pole at 10.1°N, 9.6°E, supported by a baked-contact test, and indicates moderate paleolatitudes. Similar directions were observed in other Mesoproterozoic intrusions, enabling Nuna’s 1.5 Ga core reconstructions and suggesting separation around 1.38 Ga.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages18

Reading Time45 min

AccessFree to download

Article history

Abstract

Paleomagnetic key pole results

Reconstruction of Nuna core options

Timing of craton separation

| a r t i c l e i n f o | | a b s t r a c t | | --- | --- | --- | | Article history:
Received 22 January 2016
Revised 8 August 2016
Accepted 11 September 2016
Available online 19 September 2016 | | The Congo/São Francisco (C/SF) craton, one of the largest cratons in Proterozoic paleogeography, has been lacking reliable paleomagnetic data for the supercontinent Nuna interval (ca. 1600–1300 Ma). Here we provide a new paleomagnetic key pole for this craton from recently dated maﬁc dykes in the Curaçá(1506.7 ± 6.9 Ma) region of Brazil. The characteristic remanent magnetization (ChRM) direction D = 070.6􀀁 , I = 54.0􀀁 (k = 22. 1 and a95 = 13.1􀀁 ) corresponds with a paleomagnetic pole at 10.1􀀁 N, 009.6􀀁 E (K = 15.6, A95 = 15.8􀀁 ), which places C/SF craton in moderate paleolatitudes at the time of remanence acquisition. Primary nature of the paleomagnetic remanence is supported by a baked-contact test. A similar ChRM direction was obtained for four Mesoproterozoic maﬁc intrusions in Chapada Diamantina region. The new pole, only from Curaçá, for C/SF allows us to reconstruct the extended core of the supercontinent Nuna at 1.5 Ga. Based on coeval 1.5 Ga and 1.38 Ga magmatism in Baltica, Siberia and C/SF, we favor the position where Southwest Congo is reconstructed against present South-Southeast (S-SE) Baltica. We explore two alternative 1.5 Ga reconstructions of Nuna’s core. In both of them Baltica and Laurentia are shown in the well-deﬁned NENA (Northern Europe North America) ﬁt, together with Siberia in a tight ﬁt to northern Laurentia. In reconstruction option A, more traditional ﬁt of Amazonia with Baltica is shown, modiﬁed from the geologically based SAMBA (South AMerica BAltica) model to accommodate paleomagnetic data. In this option, however, West Africa must be extricated from SAMBA because C/SF has taken its place. For reconstruction option B, Amazonia is shifted to lie adjacent to NE Laurentia and West Baltica. In both options SW Congo is reconstructed against S-SE Baltica, but in option B there is a tighter ﬁt between them, and there is a better match with our new paleomagnetic data for C/SF. In either option, separation of C/SF from Baltica and Siberia probably occurred at 1.38 Ga, the age of pronounced maﬁc magmatism throughout this sector of Nuna.
􀀃 2016 Elsevier B.V. All rights reserved. | | Keywords: Paleomagnetism Supercontinent Nuna
Columbia Mesoproterozoic Congo/São Francisco | | | | Site | Str/dip | Width (m) Age (Ma) | Lat (􀀁 N)/Long (􀀁 E) (N/)b/n | D (􀀁 ) | I (􀀁 ) | a95 (􀀁 ) | k | Plat (􀀁 N) | Plong (􀀁 E) A95 (􀀁 ) | K | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Site Str/dip Width (m) Age (Ma) Lat (􀀁 N )/Long (􀀁 E ) (N/ )b/n D (􀀁 ) I (􀀁 ) a95 (􀀁 ) k Plat (􀀁 N ) Plong (􀀁 E ) A95 (􀀁 ) K | S 13C07 : dyke, 3 blocks, not in-situ 57/ ? 35 􀀁 9.61/319.89 9/0
S 13C09 : dyke, 3 blocks, not in-situ 67/ ? 15 􀀁 9.60/320.20 9/0
S13C11: dyke 47/ ? 15 􀀁 9.48/320.21 9/7 080.7 54.4 22.2 8.4 􀀁 0.9 012.7 | | --- | --- |

FAQs

What paleomagnetic data were used to build the new key pole for the Congo/São Francisco craton?

The study used paleomagnetic measurements from recently dated mafic dykes in the Curaçá region of Brazil, including characterization of the ChRM direction and pole computation.

How was the primary nature of the paleomagnetic remanence assessed?

A baked-contact test was used to support that the paleomagnetic remanence is primary rather than overprinted.

How do the new pole results affect reconstruction of Nuna’s core and the timing of separation?

With the new Curaçá-based pole, the study reconstructs Nuna’s core at 1.5 Ga using two NENA-constrained options and favors a scenario where separation of C/SF from Baltica and Siberia occurred around 1.38 Ga.

Sep 2, 2026

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