Nano-magnetite aggregates in red soil on low magnetic bedrock

Published: 20 February 2020| Version 1 | DOI: 10.17632/m4gvh8p4cf.1
Contributors:
Qi Zhang,
Erwin Appel,
Shouyun Hu,
Robert Pennington,
Jannik Meyer,
Udo Neumann,
Michael Burchard,
Frederik Allstaedt

Description

This Dataset includes supporting materials for a paper that is submitted to JGR-Solid Earth. Soil and lake sediments are important paleoclimate archives and the sediments are often related to soil input. To better understand such settings, we studied the magnetic properties of red soil, its low-magnetic bedrock, and sub-recent sediments of Caohai Lake (CL) in Heqing Basin (HB), China. Red soil is highly magnetic with susceptibilities (ꭕ) of ~10-5 m3/kg, dominated by pedogenic nano-magnetite (~10-15 nm) arranged in aggregates of ~100 nm, causing superparamagnetic (SP) behavior that tails into the stable single-domain (SSD) range. For some samples, the SIRM was thermally demagnetized in a TD48 (ASC Scientific) furnace. we obtained detailed IRM acquisition curves with 46 steps up to 2.0 T and applied unmixing with log-normal distributions using the MAX UnMix routine of Maxbauer et al. (2016). Datasets are ready for acquisition curves modeling. TEM results and frequency dependence ꭕ(f) suggest partial disintegration of the aggregates and increased alteration of the nanoparticles during the transfer of red soil material to CL. we subjected ten samples to citrate-bicarbonate-dithionite (CBD) treatment, which removes fine iron oxide particles in the samples (Hunt et al., 1995). X-ray diffraction (XRD) analysis of the magnetic extracts was performed, data for figure plotting and model setups are available in these datasets.

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