A first paleomagnetic and rock magnetic investigation of calcareous nodules from the Chinese Loess Plateau

Tianshui Yang,Masayuki Hyodo,Zhenyu Yang,Zhiming Sun

doi:10.1186/bf03351803

Tianshui Yang, Masayuki Hyodo + Show 2 more

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https://doi.org/10.1186/bf03351803

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Abstract

Abstract A detailed paleomagnetic and rock magnetic investigation was carried out on calcareous nodule layers embedded in the loess-paleosol sequences near Baoji city, southern Chinese Loess Plateau. The anisotropy of low-field magnetic susceptibility confirms that calcareous nodules retain the primary sedimentary fabric of original deposits. Rock magnetic properties demonstrate that calcareous nodules have the same mineralogy and grain sizes as loess-paleosol deposits. Characteristic remanent magnetizations of calcareous nodules have directions consistent with those of adjacent loess and paleosol deposits. The Punaruu event, previously found from loess deposits in the upper part of loess unit L13 in Weinan, southern Chinese Loess Plateau, is observed at the corresponding stratigraphic level in the calcareous nodule layer. These observations indicate that the calcareous nodule layers preserve primary remanent magnetizations of original deposits before calcification, and that they can contribute to paleomagnetic studies in the Chinese Loess Plateau.

Highlights

Aeolian sediments of the Chinese Loess Plateau (CLP)in north-central China cover an area of about 440,000 km2 (Liu, 1985)
A number of calcareous nodule layers ranging from about 30 cm to >200 cm in thickness are intercalated within the loess-paleosol sequences
Magnetic fabrics of 24 specimens from eight calcareous nodule layers were analyzed by means of anisotropy

Summary

Introduction

Aeolian sediments of the Chinese Loess Plateau (CLP)in north-central China cover an area of about 440,000 km2 (Liu, 1985). 145 oriented block samples were collected from adjacent loess-paleosol units to compare with their paleomagnetic results, especially those around magnetic polarity boundaries. This result suggests that the calcareous nodule layers do preserve the primary sedimentary fabric.

Results

Conclusion