A 2207 Ma radiating mafic dyke swarm from eastern Dharwar craton, Southern India: Drift history through Paleoproterozoic

Abstract

We report new TE-TIMS precise Pb-Pb baddeleyite ages together with consistent paleomagnetic results on two Paleoproterozoic mafic dyke swarms, intruding Archean basement rocks in the northern and southern region of Cuddapah basin, Eastern Dharwar Craton. The distinct E-W to NW-SE striking dykes, which gives a weighted mean age of 2206.8 ± 2.1 Ma, confirms the presence of a radiating mafic dyke swarm with a fanning angle of 50°, convergence towards a focal point in the north-western part of Dharwar Craton. The North-South trending parallel dyke swarm yields an emplacement age of 2252.4 ± 1.2 Ma, making this the second oldest well dated dyke swarm of the Dharwar craton after the ∼2367 Ma event.Paleomagnetic results from the ∼2207 Ma radiating dykes have revealed a stable reverse polarity remanence directions with a mean direction of D = 26°, I = 65° (α95 = 6°) and corresponding paleopole situated at 57°N and 113°E (dp = 8°, dm = 10°). Reliable baddeleyite age determinations at paleomagnetic sampling sites, positive baked contact test and a secular variation correlation test proves that the reporting remanence directions are primary. We have also reviewed the published paleomagnetic results from similar N-S dykes, which are yielding a normal polarity with a paleopole position at 16°S and 299°E (dp = 13°, dm = 15°). We consider this result as a key paleopole for the ∼2252 Ma dyke swarm.We have attempted to reconstruct an updated APWP for Dharwar craton utilizing six well constrained key paleopoles from 2.37 Ga to 1.89 Ga periods. The path suggests that the Dharwar craton has relatively rapid drift rate (28.77 cm/yr) from 46° to 53° paleolatitude along with a clockwise rotation (30°) during the short time span of ∼9 Ma (2216 Ma–2207 Ma), when a magnetic polarity reversal occurred. However, we speculate that major tectonic activity or plate tectonic processes were responsible for rapid drift of Dharwar craton at that time. The identification of coeval mafic magmatic episodes (∼2.2 Ga) from several other Archean cratons over the globe firmly supports the popular hypothesis of supercraton breakup at ∼2.2 Ga time.