| Title | Emplacement ages of Paleoproterozoic mafic dyke swarms in eastern Dharwar craton, India: Implications for paleoreconstructions and support for a similar to 30 degrees change in dyke trends from south to
north |
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| Author | Soderlund, U; Bleeker, W ; Demirer, K; Srivastava, R K; Hamilton, M; Nilsson, M; Pesonen, L J; Samal, A K; Jayananda, M; Ernst, R E; Srinivas, M |
| Source | Precambrian Research vol. 329, SI, 2019 p. 26-43, https://doi.org/10.1016/j.precamres.2018.12.017 |
| Image |  |
| Year | 2019 |
| Alt Series | Natural Resources Canada, Contribution Series 20200272 |
| Publisher | Elsevier |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Dharwar craton; India |
| Lat/Long WENS | 74.0000 80.0000 19.0000 12.0000 |
| Subjects | paleontology; igneous and metamorphic petrology; mafic rocks; dykes, mafic; uranium; lead; baddeleyite; oroclines; Proterozoic |
| Illustrations | location maps; tables; Concordia diagrams; plots; photographs; diagrams |
| Released | 2018 12 20 |
| Abstract | Large igneous provinces (LIPS) and especially their dyke swarms are pivotal to reconstruction of ancient super continents. 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 degrees 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. |
| GEOSCAN ID | 326684 |
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