Paleoproterozoic mafic dyke swarms from the Dharwar craton; paleomagnetic poles for India from 2.37 to 1.88 Ga and rethinking the Columbia supercontinent

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• 作者：Mercedes E. Belica^a ; ^{sadiebelica@gmail.com" class="auth_mail} ; ^{21383835@student.uwa.edu.au" class="auth_mail} ; Elisa J. Piispa^b ; Joseph G. Meert^a ; Lauri J. Pesonen^c ; Jü ; ri Plado^d ; Manoj K. Pandit^e ; George D. Kamenov^a ; Matthew Celestino^a
• 刊名：Precambrian Research
• 出版年：May, 2014
• 年：2014
• 卷：244
• 期：Complete
• 页码：100-122
• 全文大小：3877 K

文摘

Here we report new paleomagnetic and geochronologic results from the Dharwar craton (south India) from 2.37 to 1.88 Ga. The presence of a 鈭?5,000 km² radiating dyke swarm with a fanning angle of 65掳 is confirmed within Peninsular India at 1.88 Ga. North of the Cuddapah basin the dykes are oriented NW-SE and progress to an E-W orientation further south, converging at a focal point southeast of the basin. The Grand Mean dual polarity paleomagnetic pole falls at 36.5掳N and 333.5掳E (D = 129.1掳, I = 4.2掳, 伪95 = 4.5掳, 位 = 2.1掳) for 29 sites from the present study combined with previously published sites. Our continental reconstruction for India at 鈭?.9 Ga conflicts with the archetypal Columbia model, suggesting that the exact configuration needs modification. We also report two separate paleomagnetic directions from NW-SE (D = 3.2掳, I = 56.4掳, 伪95 = 17.9掳, 位 = 37掳) and N-S (D = 240.1掳, I = 鈭?5.5掳, 伪95 = 10.9掳, 位 = 47.7掳) trending 鈭?.2 Ga dykes. We attribute this difference in directions to the separate magmatic pulses at 2.18 and 2.21 Ga identified by . Our results place India at intermediate latitudes from 2.21 to 2.18 Ga and are supported by a positive baked contact test. New paleomagnetic results from E-W and NW-SE trending 2.37 Ga dykes, combined with previous work in the Dharwar craton, yields a Grand Mean dual polarity paleomagnetic pole at 15.1掳N and 62.2掳E (A95 = 4.0掳), placing India at polar latitudes (D = 88.7掳, I = 鈭?1.7掳, 伪95 = 4.8掳, 位 = 73.7掳). Here we also report a shallow NE direction (D = 52.2掳, I = 鈭?.5掳, 伪95 = 6.3掳) previously classified as a secondary magnetization from three dykes near the Cuddapah basin. A baked contact test and petrophysical analysis of two cross-cutting dykes supports a primary remanence. Finally we present a Paleoproterozoic Apparent Polar Wander Path (APWP) for the Dharwar craton, and examine paleogeographic relationships between India and other cratonic blocks for the 2.37-1.88 Ga time interval