Paleosecular variations during the last glacial period from Tengchong Qinghai Lake, Yunnan Province, China

Yang, X., Zhang, T., Zhang, E., Toney, J. , Zhou, Q. and Xie, Y. (2022) Paleosecular variations during the last glacial period from Tengchong Qinghai Lake, Yunnan Province, China. Journal of Geophysical Research: Solid Earth, 127(3), e2021JB023. (doi: 10.1029/2021jb023459)

Abstract

In recent years, the evolution of the magnetic flux lobes in terms of location and intensity has been attributed to paleosecular variation of the geomagnetic field, reflecting outer-core fluid convection close to the core-mantle boundary. However, most results were based on observational data for the past 400 years supplemented by sparse archeomagnetic studies with data for approximately 3 kyr. In this paper, we construct a relative paleointensity (RPI) record and an inclination record spanning the past ∼90 kyr based on two cores from Tengchong Qinghai Lake (Yunnan Province, China), a closed crater lake that formed in the late Pleistocene. The evolution of flux lobes and the non-dipole field can be assessed on a much longer time scale. Although the concentration and domain state of magnetic grains in the cores vary significantly, the RPI record is still representative of geomagnetic field features in the region of Yunnan Province, China. The contrasting trends in RPI with the records for eastern China since the late Holocene indicate the southeastward migration of the Siberian flux lobe. During the last glacial period, the RPI records of Tengchong Qinghai Lake and the North Atlantic Ocean show opposite trends, denoting the diverse and strong influence of the two flux lobe systems. The strong reverse flux lobe in the North Atlantic Ocean strengthened the non-dipole field, while the weak normal flux lobe in Tengchong weakened the non-dipole field.

• Item Type: Articles
• Additional Information: This study was co-supported the National Second Expedition to the Tibetan Plateau (2019QZKK0707), the National Natural Science Foundation of China (Grant No. 41872217; 41672162), and Guangdong Province Introduced Innovative R and D Team of Geological Processes and Natural Disasters around the South China Sea (Grant No. 2016ZTO6N331).
• Keywords: Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Geochemistry and Petrology, Geophysics
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Toney, Professor Jaime
• Authors: Yang, X., Zhang, T., Zhang, E., Toney, J., Zhou, Q., and Xie, Y.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Journal of Geophysical Research: Solid Earth
• Publisher: American Geophysical Union
• ISSN: 2169-9356
• ISSN (Online): 2169-9313
• Published Online: 26 February 2022
• Copyright Holders: Copyright © 2022 American Geophysical Union
• First Published: First published in Journal of Geophysical Research: Solid Earth 127(3): e2021JB023
• Publisher Policy: Reproduced in accordance with the publisher copyright policy