AUTHOR=Yu Liang , Yan Maodu , Guan Chong , Li Bingshuai , Fu Qiang , Xu Wanlong , Feng Zhantao , Zhang Dawen , Shen Miaomiao , Xu Zunbo , Niu Zhichao 

TITLE=Remagnetization of Carboniferous Limestone in the Zaduo Area, Eastern Qiangtang Terrane, and Its Tectonic Implications

JOURNAL=Frontiers in Earth Science

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.825943

DOI=10.3389/feart.2022.825943

ISSN=2296-6463

ABSTRACT=<p>Robust paleomagnetic results through geological time are one of the keys to understand the drift history of the eastern Qiangtang terrane (EQT). Here, we presented comprehensive petrographic observations and rock magnetic and paleomagnetic analyses of the early Carboniferous Upper Zaduo (ZD) limestone Formation (C<sub>1</sub>z<sub>2</sub>) from the Sulucun (SLC) section in the Zaduo area, EQT, to investigate its magnetic originality and geological significance. A total of 12 sites (131 samples) were collected. Photomicrograph observations indicate that the limestone samples were characterized by widespread carbonate veinlets. Electron microprobe and energy dispersive spectrometry analyses confirm that authigenic magnetite formed after pyrite. Rock magnetic analyses reveal the dominant magnetic minerals of pyrite and magnetite, with ‘wasp-waisted’ hysteresis loops and close to the “remagnetization trend” hysteresis parameters. Based on both thermal and alternating field demagnetizations, the characteristic remanent magnetization directions for most samples were isolated: D<sub>g</sub> = 6.3°, I<sub>g</sub> = 50.1°, k<sub>g</sub> = 54.9, α<sub>95</sub> = 6.2° <italic>in-situ</italic>, and D<sub>s</sub> = 330.2°, I<sub>s</sub> = 58.9°, k<sub>s</sub> = 5.9, and α<sub>95</sub> = 20.5° after 2-step tilt correction. The κ (α<sub>95</sub>) value decreases (increases) after tilt-correction, and the ChRM directions failed both the <xref ref-type="bibr" rid="B46">McFadden (1990)</xref>, <xref ref-type="bibr" rid="B76">Watson and Enkin (1993)</xref> fold tests, indicating post-folding magnetizations. The 11 site-mean directions yield a mean <italic>in-situ</italic> paleopole of 84.4°N, 200.3°E, and A<sub>95</sub> = 6.8°, which is coincident with the post ∼53 Myr (especially around 40 Ma) paleopoles of the region. We therefore interpreted that these early Carboniferous limestone samples contain remagnetized magnetizations and that they were obtained after 53 Ma, most likely around 40 Ma, due to the far-field effect of the India–Eurasia collision.</p>