Remagnetization of Permian Emeishan basalts: Constraints on the timing of native copper mineralization in northeast Yunnan Province, China



Liu, Chengying, Paterson, Greig A ORCID: 0000-0002-6864-7420, Li, Shihu, Pan, Yongxin and Zhu, Rixiang
(2021) Remagnetization of Permian Emeishan basalts: Constraints on the timing of native copper mineralization in northeast Yunnan Province, China. FRONTIERS IN EARTH SCIENCE, 8. 590939-.

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Abstract

<jats:p>New paleomagnetic results from the Permian Emeishan basalts in the Zhaotong area, NE Yunnan province, China show four natural remanent magnetization components. Detailed stepwise thermal demagnetization of basaltic samples from 16 flows from the Dadi section, which represent basalt units III and IV, isolated two groups of characteristic remanent magnetizations. Samples in unit IV (five flows) record a southwest declination and a moderate downward inclination that is considered to be a partial remagnetized remanence. The bottom flows from unit III (11 flows) record a normal polarity direction, interpreted as a remagnetization, which yields a tilt-corrected mean direction of D<jats:sub>s</jats:sub>/I<jats:sub>s</jats:sub>= 8.8°/31.6° (N = 9, k<jats:sub>s</jats:sub>= 39.7,<jats:italic>α</jats:italic><jats:sub>95</jats:sub>= 8.3°), with a corresponding paleomagnetic pole at 77.1°N, 240.0°E (K = 49.2, A<jats:sub>95</jats:sub>= 7.4°). The secondary directions have steeper inclinations than primary ones that have been successfully recovered from other studies in this area of the Emeishan basalts. By comparison with the Phanerozoic paleomagnetic poles of the South China Block, the preferred timing of remagnetization is the Lower-Middle Jurassic. Field relationships suggest that the remagnetization of the Emeishan basalts is coeval with the spatially related, but localized, copper mineralization. Thus the timing of the main copper mineralization hosted in the Emeishan basalts is hypothesized to occur in the Early-Middle Jurassic.</jats:p>

Item Type: Article
Uncontrolled Keywords: Emeishan basalts, paleomagnetic study, remagnetization, copper mineralization, Early-Middle Jurassic
Depositing User: Symplectic Admin
Date Deposited: 15 Feb 2021 10:37
Last Modified: 15 Mar 2024 14:34
DOI: 10.3389/feart.2020.590939
Open Access URL: https://www.frontiersin.org/articles/10.3389/feart...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3115668