Palaeomagnetic data from the precambrian Gwalior traps, Central India

Abstract

From alternating-field and thermal demagnetization studies on two dolerite "Traps" in the Gwalior Series (Central India), dated at 1830 f200 m.y., three different palaeomagnetic directions could be distinguished. The characteristic magnetization component, which is considered as the primary magnetization, has a mean direction: D=78', Z=+34.5", a95=5O, k=369, N=4 (Pole: 155.5'E1g0N, dp=3', dm=5.5'). A comparison of the presented data with other Precambrian and Phanerozoic data from the Indian subcontinent might suggest that the Indian subcontinent underwent a continuous anticlockwise rotational movement during the last 1800 m.y.

India's changing place in global Proterozoic reconstructions: A review of geochronologic constraints and paleomagnetic poles from the Dharwar, Bundelkhand and Marwar cratons

“…5. Our results largely confirm the previous studies although our directions are somewhat shallower than the high-coercivity components reported by Klootwijk (1974) and McElhinny et al (1978). The Gwalior traps are all of a single polarity and our combined tiltcorrected mean result has a declination = 73.9 • and an inclination of +4.4 • (k = 22, ␣95 = 11·2 • ).…”

“…Previous studies on the Gwalior traps were based on a limited number of samples from the upper traps in the Gwalior Fort region (Athavale et al, 1963;Klootwijk, 1974;McElhinny et al, 1978). Both Klootwijk (1974) and McElhinny et al (1978) described a shallow low-coercivity component and a slightly steeper high-coercivity component directed toward the east and down. These authors used blanket demagnetization rather than vector analysis.…”

Palaeomagnetics and igneous activity of the area adjoining the south-westem margin of the Cuddapah basin, India

“…These traps may date this group. Klootwijk (1974) has also reported similar RMD for lower Gwalior traps (1830 2 200Myr) as that of the group I1 dykes. None of the group I11 dykes is dated but Anjanappa (1972) has speculated that Tirupathi dykes with similar directions of magnetization to those of the group 111 dykes, could have intruded at the closing stages of the Archaean period.…”

“…Magnetic directions and pole positions of group I (Table 3 ) dykes are similar to those of upper Gwalior traps (Athavale, Radhakrishna Murthy & Sahasrabudhe 1963;Klootwijk 1974) which had been dated by Crawford & Compston (1970) at 1830 f 200Myr. These traps may date this group.…”