Mineral magnetic record of the Chinese loess and paleosols

Maher, Barbara A.; Thompson, Roy

doi:10.1130/0091-7613(1991)019<0003:mmrotc>2.3.co;2

Cited by 383 publications

(222 citation statements)

References 6 publications

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“…Chen et al (1999) demonstrated that high-resolution magnetic susceptibility records can be correlated with temperature deduced from the Vostok ice core in Antarctica (Jouzel et al, 1987), with episodic occurrences of cold air over Greenland (the millennial-scale Dansgaard-Oeschger cycles recorded in the GRIP ice core) (Dansgaard et al, 1993), and with the so-called Heinrich events (massive iceberg release events) and Bond cycles (episodes of unusually cold surface waters) (Bond et al, 1993). By combining 10 Be and susceptibility measurements, Heller et al (1993) deduced that high rainfall occurred at around 25 and 55 ka and that reduced rainfall of ~530 mm/yr occurred in the The higher magnetic susceptibility of paleosols compared to loess results from the neoformation of fine-grained magnetite/maghemite during pedogenesis (Zhou et al, 1990;Maher and Thompson, 1991). The fine-grained magnetic particles produced by pedogenesis typically occur in the superparamagnetic (SP) or single domain (SD) grain size range.…”

Section: A Brief History Of Loess Studiesmentioning

confidence: 99%

“…It is now recognized that dust from the Gobi and other deserts in north and northeast China began to accumulate in response to increased uplift of the Tibetan Plateau, and the associated changes in Asian atmospheric circulation patterns that resulted from this uplift (Fang et al, 1999;Sun and An, 2002). Magnetostratigraphy (Heller and Liu, 1982, 1984, 1986Sun et al, 1997;Ding et al, 2001;Evans and Heller, 2001;Qiang et al, 2001;Wang et al, 2006;Liu et al, 2010) and detailed rock magnetic studies (Maher and Thompson, 1991;Banerjee et al, 1993;Introduction Chapter 1 4 1984, 1986;Kukla et al, 1988;Hovan et al, 1989;Ding et al, 2002) and short-term climate instability Zhu et al, 2004;Liu et al, 2005a), have been obtained for the last 2.6 Ma from Chinese loess/paleosol sequences. Liu (1984, 1986) first recognized that low-field magnetic susceptibility variations in Chinese loess/paleosol sequences correlate with marine oxygen isotope records.…”

Section: A Brief History Of Loess Studiesmentioning

confidence: 99%

“…Identification of the position of geomagnetic reversals for the past 2.6 Ma has enabled correlation of magnetic susceptibility profiles to the marine δ 18 O record (Kukla et al, 1990;Ding et al, 2000). Magnetic susceptibility peaks occur within paleosols as a result of magnetite/maghemite formation during pedogenesis; the intervening loess units have much lower magnetic susceptibilities (Kukla et al, 1990;Maher and Thompson, 1991;Heller and Evans, 1995). Despite this first-order success in establishing the loess chronology through orbital tuning of paleoclimatically sensitive parameters such as magnetic susceptibility (Lu et al, 1999;Heslop et al, 2000;Ding et al, 2002), a consistent chronology for the Chinese loess still does not exist.…”

Section: Introductionmentioning

confidence: 99%

“…Paleomagnetic studies have been crucial in establishing the chronology of paleoclimate variations recorded by Chinese loess sequences Liu, 1982, 1984;Rolph et al, 1989;Maher and Thompson, 1991). Identification of the position of geomagnetic reversals for the past 2.6 Ma has enabled correlation of magnetic susceptibility profiles to the marine δ 18 O record (Kukla et al, 1990;Ding et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Most studies have emphasized the role of detrital magnetite and the pedogenic formation of superparamagnetic (SP)/ single domain (SD) magnetite and maghemite (Zhou et al, 1990;Maher and Thompson, 1991;Hus and Han, 1992;Verosub et al, 1993;Liu et al, 2005a, b). The spontaneous magnetization of magnetite and maghemite is two orders of magnitude higher than that of hematite or goethite (Dunlop and Özdemir, 1997), which means that they dominate the magnetic signal.…”

Section: Introductionmentioning

confidence: 99%

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How does Chinese loess become magnetized?

Zhao

Roberts

2010

Earth and Planetary Science Letters

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Thick loess deposits on the Chinese Loess Plateau provide an outstanding archive of paleoclimate, geomagnetic field and paleoenvironmental changes over at least the last 2.6 Ma. Much work on magnetic polarity reversals, pedogenic magnetic enhancement and climatic change has been carried out over the past 30 years. However, questions about how Chinese loess becomes magnetized remain unanswered. In this thesis, I have sought to address key questions concerning magnetization processes in the Chinese loess. To understand magnetization processes, it is important to understand which magnetic minerals are present and the processes that caused them to be present. Magnetic and other analyses of both loess and paleosol samples indicate that pedogenic superparamagnetic and single domain magnetite and hematite can be present. The mass concentration of hematite can exceed 90% of the magnetic particle assemblage. An eolian dust deposition simulator designed for laboratory redeposition experiments was then used to demonstrate that both a depositional remanent magnetization (DRM) and a post-depositional remanent magnetization (PDRM) can be acquired by Chinese loess. Water content significantly affects the efficiency of PDRM acquisition. No significant PDRM was observed when the water content was below a critical threshold of 40%. Published paleomagnetic data from the Chinese loess indicate the widespread occurrence of inclination error. Detailed paleomagnetic studies of U-channel samples from the last loess/paleosol sequence at Yuanbao were made to assess whether the Chinese loess can accurately record geomagnetic relative paleointensity variations. Three normalized remanence records were determined using conventional normalization as well as the pseudo-Thellier method. Strong coherence among the normalized remanence records indicate that the whole range of magnetic minerals has been affected by pedogenesis. Poor similarity among published normalized remanence records from the Chinese loess, as well as with marine relative paleointensity records indicate that the Chinese loess is not suitable for relative paleointensity determinations. The range of magnetic minerals present and their varying distribution within loess and paleosol sediments indicate that the magnetization is due to a mixture of remanence acquisition mechanisms including DRM, PDRM, chemical remanent magnetization (CRM) and viscous remanent magnetizations, which also indicates complexities in remanence acquisition that will complicate attempts to extract relative paleointensity information. This thesis has provided an improved understanding of the mechanisms of Chinese loess magnetization, and re-emphasizes the importance of pedogenic CRM acquisition.

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Section: A Brief History Of Loess Studiesmentioning

confidence: 99%

Section: A Brief History Of Loess Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

How does Chinese loess become magnetized?

Zhao

Roberts

2010

Earth and Planetary Science Letters

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Environmental magnetic indicators of the sedimentary context of archaeological sites in the Shangqiu area of China

Jing

Rapp

1998

Geoarchaeology

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Environmental magnetic techniques provide significant potential for characterizing sediments and soils and inferring their sources. This article discusses the application of environmental magnetic techniques in the study of an evolving landscape in the Shangqiu area, China, an archaeologically important region for investigating the origin of Shang civilization. Two magnetic parameters—anhysteretic remanent magnetization (ARM) and low‐field magnetic susceptibility (χ)—are employed to discriminate the pre‐Neolithic paleosol from the historic alluvium. In order to quantitatively interpret magnetic measurements, ARM versus χ plots are utilized with rigorous statistical analyses including group comparison and discriminant classification. With the ARM/χ classification model defined by the pre‐Neolithic paleosol and historic alluvium, the sediment sources of three anthropogenic deposits (A‐1, A‐2, and A‐3 from oldest to youngest) are addressed. Magnetic data clearly show that A‐1 and A‐3 are closely associated with the pre‐Neolithic paleosol and historic alluvium, respectively. Cultural mixing processes might be partially responsible for the formation of A‐2. © 1998 John Wiley & Sons, Inc.

show abstract

Environmental magnetic indicators of the sedimentary context of archaeological sites in the Shangqiu area of China

Jing

Rapp

1998

Geoarchaeology

View full text Add to dashboard Cite

Environmental magnetic techniques provide significant potential for characterizing sediments and soils and inferring their sources. This article discusses the application of environmental magnetic techniques in the study of an evolving landscape in the Shangqiu area, China, an archaeologically important region for investigating the origin of Shang civilization. Two magnetic parameters-anhysteretic remanent magnetization (ARM) and low-field magnetic susceptibility ()-are employed to discriminate the preNeolithic paleosol from the historic alluvium. In order to quantitatively interpret magnetic measurements, ARM versus plots are utilized with rigorous statistical analyses including group comparison and discriminant classification. With the ARM/ classification model defined by the pre-Neolithic paleosol and historic alluvium, the sediment sources of three anthropogenic deposits (A-1, A-2, and A-3 from oldest to youngest) are addressed. Magnetic data clearly show that A-1 and A-3 are closely associated with the pre-Neolithic paleosol and historic alluvium, respectively. Cultural mixing processes might be partially responsible for the formation of A-2.

show abstract

Mineral magnetic record of the Chinese loess and paleosols

Cited by 383 publications

References 6 publications

How does Chinese loess become magnetized?

How does Chinese loess become magnetized?

Environmental magnetic indicators of the sedimentary context of archaeological sites in the Shangqiu area of China

Environmental magnetic indicators of the sedimentary context of archaeological sites in the Shangqiu area of China

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