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New palaeointensity results from Cretaceous basalt of Inner Mongolia, China |
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| Authors: | Xixi Zhao Peter Riisager Ulrike Draeger Zhong Zheng |
| Institution: | a Department of Earth Sciences, University of California, Santa Cruz, 1156 High Str., Santa Cruz, CA 95064, USA b Geological Museum, University of Copenhagen, 5-7 Øster Voldgade, 1350 Copenhagen K, Denmark c Geosciences Division, Sogokaihatsu Co. Ltd., No. 2 Sanko Building, Nishi-Koiwa 1-30-16, Edogawa-ku, Tokyo 133-0057, Japan |
| Abstract: | We present new Thellier-Thellier palaeointensity results from three cooling units (32 samples) of Inner Mongolia lava flows (91.7 Ma) emplaced during the Cretaceous Normal Superchron (CNS). Based on rock-magnetic and microscopy observations the magneto-mineralogy of all samples is determined to be primary and unaltered high-Ti titanomagnetite. Accepted palaeointensity determinations, obtained in the 80-200 °C temperature interval, are of good technical quality with positive standard partial thermoremanent magnetisation (pTRM) checks and pTRM-tail checks. Obtained palaeointensity estimates range from 14.7 to 28.0 μT, with virtual axial dipole moments (VADM) of 2.4 to 4.6 (× 1022 Am2). The data agree well with recently published results from the same region and, combining the two datasets, we obtain independent estimates from six different cooling units yielding a time-averaged VADM of 3.2 ± 1.6 (× 1022 Am2). These data suggest a relatively low dipole moment towards the end of the Cretaceous Normal Superchron. |
| Keywords: | Thellier palaeointensity method Cretaceous Normal Superchron China |
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