78 Recent Advances in Precambrian Geology

Monday, 1 November 2010
8:00 AM - 12:00 PM
Mile High Ballroom 1CD

OH MY! MALANI PALEOMAGNETISM AGAIN?

Paper number: 78-9
Program: Technical Sessions
Time: 10:00 AM – 10:15 AM

Authors

Abstract

The 750-800 Ma Malani felsic province in Rajasthan, India has been the focus of numerous paleomagnetic studies over the past 30 years (Athavale et al., 1963; Klootwijk, 1975, Torsvik et al., 2001; Gregory et al, 2008). Paleomagnetic data in all those studies are remarkably consistent. Nearly all paleomagnetic data are of a single polarity (mean D=358, I=+65) with the exception of a single dyke (D=195, I=-60). The Malani pole meets 6 of 7 quality criteria in the Van der Voo (1990) scheme and is considered by some to be the most robust Neoproterozoic pole for India. These data, when compared to results from Australia indicate that a Neoproterozoic coherence of East Gondwana is not tenable. In spite of the quality of these data, some authors question the pole on several grounds. As an example, Yoshida and Upreti (2006) cite a possible Cambrian remagnetization based on reported 40Ar/39Ar results on Malani related rocks. Others have suggested that the Malani rocks (placed on the “Marwar” microcontinent) were not part of greater India and therefore, the Malani pole, while reliable, does not reflect the position of India at ~750-775 Ma.

We have sampled some additional dykes in the Malani province that provide further reliability constraints on the pole and discuss the evidence for cratonic coherence of the Malani province to greater India.