A Thick Negative Polarity Anomaly in a Sediment Core From the Central Arctic Ocean: Geomagnetic Excursion Versus Reversal

Liu, Jianxing1,2; Shi, Xuefa1,2; Liu, Yanguang1,2; Liu, Qingsong2,3; Liu, Yan4,5; Zhang, Qiang5,6; Ge, Shulan1,2; Li, Jinhua2,4

2019-11-11

10.1029/2019JB018073

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   影响因子和分区

2169-9313

2169-9356

There are two distinctly different views on Quaternary sedimentation rates in the central Arctic Ocean, namely, that they were on cm/kyr or on mm/kyr scales, largely as a result of divergent interpretations of magnetic reversal stratigraphy. This study provides new evidence to help resolve this controversy in the form of an almost 1-m-thick negative polarity interval located at similar to 1.15 m below the seafloor in a 4.15-m-long sediment core from the Lomonosov Ridge, central Arctic Ocean. This thick polarity anomaly was first revealed through alternating field demagnetization of natural remanent magnetization on u-channel samples. It was subsequently confirmed to be an authentic signal of a syndepositional geomagnetic field by integrating detailed rock magnetic studies, transmission electron microscopy with energy-dispersive X-ray spectroscopy analyses of magnetic extracts, and both alternating field and thermal demagnetization of discrete paleomagnetic samples. Here we conclude that it is more reasonable to interpret the reversed interval as a record of the Matuyama Chron rather than a Brunhes-aged excursion, which yields mean sedimentation rates of similar to 1.5 mm/kyr and similar to 0.5 mm/kyr in the Brunhes and Matuyama Chrons, respectively. These estimates are remarkably lower than assumed in most recent studies, but in good agreement with both previous magnetostratigraphic and recent geochemical studies relative to the decay of Be and U-series isotopes, which might indicate "sediment-starved" environments at least in some parts of this region. Overall, our results not only imply that chronostratigraphy in the central Arctic Ocean remains open to debate but also warrant further investigations in this microfossil-barren region.

SCI

英语

NI论文

其他

Opening Foundation of the Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology[MGQNLM201704]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000495559300001

AMER GEOPHYSICAL UNION

GEOSCIENCES

Web of Science

1.MNR, Inst Oceanog 1, Key Lab Marine Sedimentol & Environm Geol, Qingdao, Shandong, Peoples R China
2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qiangdao, Peoples R China
3.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen, Peoples R China
4.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing, Peoples R China
5.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing, Peoples R China
6.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing, Peoples R China

Liu, Jianxing,Shi, Xuefa,Liu, Yanguang,et al. A Thick Negative Polarity Anomaly in a Sediment Core From the Central Arctic Ocean: Geomagnetic Excursion Versus Reversal[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2019,124(11):10687-10703.

Liu, Jianxing.,Shi, Xuefa.,Liu, Yanguang.,Liu, Qingsong.,Liu, Yan.,...&Li, Jinhua.(2019).A Thick Negative Polarity Anomaly in a Sediment Core From the Central Arctic Ocean: Geomagnetic Excursion Versus Reversal.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,124(11),10687-10703.

Liu, Jianxing,et al."A Thick Negative Polarity Anomaly in a Sediment Core From the Central Arctic Ocean: Geomagnetic Excursion Versus Reversal".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 124.11(2019):10687-10703.