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Emplacement ages of Paleoproterozoic mafic dyke swarms in eastern Dharwar craton, India: Implications for paleoreconstructions and support for a ∼30° change in dyke trends from south to north

Söderlund, Ulf ; Bleeker, Wouter ; Demirer, Kursad ; Srivastava, Rajesh K. ; Hamilton, Michael ; Nilsson, Mimmi ; Pesonen, Lauri J. ; Samal, Amiya K. ; Jayananda, Mudlappa ; Ernst, Richard E. ; Srinivas, Madabhooshi

Precambrian research, 2019-08, Vol.329, p.26-43 [Periódico revisado por pares]

Elsevier B.V

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  • Título:
    Emplacement ages of Paleoproterozoic mafic dyke swarms in eastern Dharwar craton, India: Implications for paleoreconstructions and support for a ∼30° change in dyke trends from south to north
  • Autor: Söderlund, Ulf ; Bleeker, Wouter ; Demirer, Kursad ; Srivastava, Rajesh K. ; Hamilton, Michael ; Nilsson, Mimmi ; Pesonen, Lauri J. ; Samal, Amiya K. ; Jayananda, Mudlappa ; Ernst, Richard E. ; Srinivas, Madabhooshi
  • Assuntos: Earth and Related Environmental Sciences ; Eastern Dharwar craton ; Geologi ; Geology ; Geovetenskap och miljövetenskap ; India ; Mafic dyke swarms ; Natural Sciences ; Naturvetenskap ; Oroclinal bending ; Paleoproterozoic ; U-Pb baddeleyite
  • É parte de: Precambrian research, 2019-08, Vol.329, p.26-43
  • Descrição: •The MS presents 18 U-Pb baddeleyite Paleoproterozoic ages on seven different dyke swarms across the Dharwar craton, India.•This is a major step forward in our understanding of the LIP record of this important craton (which is thought to be a principal constituent of Superia, Sclavia, Nuna/Columbia and Rodinia supercontinents), with implications for Paleoproterozoic reconstructions.•We also infer a 30° counter clock-wise rotation of the northern Dharwar block relative to the southern block from changes in trends of various swarms and basement geology. Large igneous provinces (LIPs) and especially their dyke swarms are pivotal to reconstruction of ancient supercontinents. The Dharwar craton of southern Peninsular India represents a substantial portion of Archean crust and has been considered to be a principal constituent of Superia, Sclavia, Nuna/Columbia and Rodinia supercontinents. The craton is intruded by numerous regional-scale mafic dyke swarms of which only a few have robustly constrained emplacement ages. Through this study, the LIP record of the Dharwar craton has been improved by U-Pb geochronology of 18 dykes, which together comprise seven generations of Paleoproterozoic dyke swarms with emplacement ages within the 2.37–1.79 Ga age interval. From oldest to youngest, the new ages (integrated with U-Pb ages previously reported for the Hampi swarm) define the following eight swarms with their currently recommended names:NE–SW to ESE–WNW trending ca. 2.37 Ga Bangalore-Karimnagar swarm.N–S to NNE–SSW trending ca. 2.25 Ga Ippaguda-Dhiburahalli swarm.N–S to NNW–SSE trending ca. 2.22 Ga Kandlamadugu swarm.NW–SE to WNW–ESE trending ca. 2.21 Ga Anantapur-Kunigal swarm.NW–SE to WNW–ESE trending ca. 2.18 Ga Mahbubnagar-Dandeli swarm.N–S, NW–SE, and ENE–WSW trending ca. 2.08 Ga Devarabanda swarm.E–W trending 1.88–1.89 Ga Hampi swarm.NW–SE ca. 1.79 Ga Pebbair swarm. Comparison of the arcuate trends of some swarms along with an apparent oroclinal bend of ancient geological features, such as regional Dharwar greenstone belts and the late Archean (ca. 2.5 Ga) Closepet Granite batholith, have led to the hypothesis that the northern Dharwar block has rotated relative to the southern block. By restoring a 30° counter clockwise rotation of the northern Dharwar block relative to the southern block, we show that pre-2.08 Ga arcuate and fanning dyke swarms consistently become approximately linear. Two possible tectonic models for this apparent bending, and concomitant dyke rotations, are discussed. Regardless of which deformation mechanisms applies, these findings reinforce previous suggestions that the radial patterns of the giant ca. 2.37 Ga Bangalore-Karimnagar dyke swarm, and probably also the ca. 2.21 Ga Anantapur-Kunigal swarm, may not be primary features.
  • Editor: Elsevier B.V
  • Idioma: Inglês
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