Paleoclimatic significance of grain size of loess-palaeosol deposit in Chinese Loess Plateau

1998 ◽  
Vol 41 (6) ◽  
pp. 626-631 ◽  
Author(s):  
Huayu Lu ◽  
Zhisheng An
Keyword(s):  
Grain Size ◽  
Loess Plateau ◽  
Chinese Loess Plateau ◽  
Chinese Loess ◽  
Paleoclimatic Significance

Six million years of magnetic grain-size records reveal that temperature and precipitation were decoupled on the Chinese Loess Plateau during ~ 4.5–2.6 Ma

2013 ◽  
Vol 79 (3) ◽  
pp. 465-470 ◽  
Author(s):  
Junsheng Nie ◽  
Yougui Song ◽  
John W. King ◽  
Rui Zhang ◽  
Xiaomin Fang
Keyword(s):  
Grain Size ◽  
Loess Plateau ◽  
Remanent Magnetization ◽  
Chinese Loess Plateau ◽  
Joint Analysis ◽  
Red Clay ◽  
Chinese Loess ◽  
Proxy Records ◽  
Temperature And Precipitation ◽  
The Chinese Loess Plateau

AbstractMagnetic grain-size variations have been used as sensitive paleoclimate proxies to investigate the evolution of the East Asian summer monsoon, but their relationship with temperature and precipitation is not entirely clear. Here we find that two magnetic grain-size proxy records (χARM/χLF and χARM/SIRM, where χARM, χLF and SIRM are anhysteretic remanent magnetization susceptibility, magnetic susceptibility measured at 470 Hz and saturation isothermal remanent magnetization, respectively) of Chinese loess and red-clay sediments co-vary during the last 6 Ma, except between ~ 4.5 and 2.6 Ma, when these two records had opposite trends. We attribute this disparate behavior to the different responses of χARM/χLF and χARM/SIRM to temperature and precipitation during ~ 4.5–2.6 Ma, when temperature and precipitation on the Chinese Loess Plateau were decoupled. A comparison of the loess and red-clay χARM/χLF and χARM/SIRM records with the global ice-volume proxy records reveals that χARM/χLF is more sensitive to temperature variations than χARM/SIRM. The results suggest that temperature on the Chinese Loess Plateau had a cooling trend from ~ 4.5 to ~ 2.6 Ma, whereas rainfall tended to increase. Our studies demonstrate that joint analysis of loess χARM/χLF and χARM/SIRM records can reveal paleoclimatic information that cannot be revealed by a single parameter.

Late Quaternary aeolian dust input variability on the Chinese Loess Plateau: inferences from unmixing of loess grain-size records

2007 ◽  
Vol 26 (1-2) ◽  
pp. 230-242 ◽  
Author(s):  
Maarten A. Prins ◽  
Mirjam Vriend ◽  
Govert Nugteren ◽  
Jef Vandenberghe ◽  
Huayu Lu ◽  
...  
Keyword(s):  
Grain Size ◽  
Loess Plateau ◽  
Late Quaternary ◽  
Chinese Loess Plateau ◽  
Aeolian Dust ◽  
Chinese Loess ◽  
The Chinese Loess Plateau

Remanence Characteristics of Different Magnetic Grain Size Categories at Xifeng, Central Chinese Loess Plateau

1994 ◽  
Vol 42 (2) ◽  
pp. 162-165 ◽  
Author(s):  
Xiuming Liu ◽  
Tim Rolph ◽  
Jan Bloemendal ◽  
John Shaw ◽  
Tungsheng Liu
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Low Temperature ◽  
Loess Plateau ◽  
Remanent Magnetization ◽  
Chinese Loess Plateau ◽  
Chinese Loess ◽  
The Past ◽  
Low Field ◽  
Grain Size Fractions

AbstractUtilizing the thermal unblocking of low-temperature remanent magnetization in superparamagnetic (SP) ferrimagnets and the low-temperature demagnetization of multidomain (MD) magnetite remanences, the relative proportions of SP, MD, and singledomain (SD and SD-like) ferrimagnets are estimated in the topmost part of a loess section at Xifeng, China, which covers about the past 130,000 yr. SP ferrimagnets are commonly regarded as pedogenic (authigenic) products while the MD component is believed to have a detrital origin. These measurements, therefore, provide new data which improve our understanding of the characteristics and distribution of the different magnetic grain-size fractions present in loess and soils. In particular, our measurements indicate a larger MD fraction in soil than in loess, a result which indicates that although enhancement of the SP ferrimagnet fraction dominates the increased low-field magnetic susceptibility of paleosols, an enhancement of the MD fraction, probably through leaching, also plays an important role during pedogenesis.

scholarly journals Identification and paleoclimatic significance of magnetite nanoparticles in soils

2018 ◽  
Vol 115 (8) ◽  
pp. 1736-1741 ◽  
Author(s):  
Imad A. M. Ahmed ◽  
Barbara A. Maher
Keyword(s):  
Loess Plateau ◽  
Chinese Loess Plateau ◽  
Soil Redox ◽  
Chinese Loess ◽  
Scanning Transmission ◽  
Weakly Magnetic ◽  
Soil Wetting ◽  
Paleoclimatic Significance ◽  
Water Saturated ◽  
The Chinese Loess Plateau

In the world-famous sediments of the Chinese Loess Plateau, fossil soils alternate with windblown dust layers to record monsoonal variations over the last ∼3 My. The less-weathered, weakly magnetic dust layers reflect drier, colder glaciations. The fossil soils (paleosols) contain variable concentrations of nanoscale, strongly magnetic iron oxides, formed in situ during the wetter, warmer interglaciations. Mineralogical identification of the magnetic soil oxides is essential for deciphering these key paleoclimatic records. Formation of magnetite, a mixed Fe2+/Fe3+ ferrimagnet, has been linked to soil redox oscillations, and thence to paleorainfall. An opposite hypothesis states that magnetite can only form if the soil is water saturated for significant periods in order for Fe3+ to be reduced to Fe2+, and suggests instead the temperature-dependent formation of maghemite, an Fe3+-oxide, much of which ages subsequently into hematite, typically aluminum substituted. This latter, oxidizing pathway would have been temperature, but not rainfall dependent. Here, through structural fingerprinting and scanning transmission electron microscopy and electron energy loss spectroscopy analysis, we prove that magnetite is the dominant soil-formed ferrite. Maghemite is present in lower concentrations, and shows no evidence of aluminum substitution, negating its proposed precursor role for the aluminum-substituted hematite prevalent in the paleosols. Magnetite dominance demonstrates that magnetite formation occurs in well-drained, generally oxidizing soils, and that soil wetting/drying oscillations drive the degree of soil magnetic enhancement. The magnetic variations of the Chinese Loess Plateau paleosols thus record changes in monsoonal rainfall, over timescales of millions of years.

scholarly journals Climate Change and Vegetation Evolution during the Transition from Marine Isotope Stage 5 to 4 Based on Two Typical Profiles at the Southern Chinese Loess Plateau

2020 ◽  
Vol 12 (4) ◽  
pp. 1372
Author(s):  
Tieniu Wu ◽  
Huaqing Wu ◽  
Henry Lin ◽  
Tiantian Yang ◽  
Xiaoyang Wu ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Loess Plateau ◽  
Transitional Period ◽  
Marine Isotope Stage ◽  
Chinese Loess Plateau ◽  
Forest Steppe ◽  
Chinese Loess ◽  
Southern Chinese ◽  
Mis 5

The geological transitional period from the Marine Isotope Stage (MIS) 5 to 4 during the Quaternary period is a multidimensional change involving monsoon and precipitation variation, vegetation dynamics, and environmental evolution. The first loess layer (L1) and the first paleosol layer (S1) in the Chines Loess Plateau provide excellent high-resolution terrestrial sediment record for this transition. In this work, grain size (GS), CaCO3 content, magnetic susceptibility (MS), and pollen composition were measured at intervals of 2-cm in two representative L1/S1 profiles in the southern Chinese Loess Plateau to reconstruct records of climatic and vegetative changes during this transition. Our results showed that, in general, the paleo-vegetation type was forest-steppe, with Pinus being the commonest tree, and Chenopodiaceae and Artemisia being common herbs in the study area. The topography had a significant impact on the distribution of paleo-vegetation. The increase of coarse particles, the decrease of magnetic susceptibility, and the rising percentage of Gramineae, Artemisia and Chenopodiaceae pollen, all indicated that the paleoclimate became cooler and drier over the transitional period. Besides, we identified a cool event at about 76.8 ka B.P. as revealed by grain-size curves, and in response to this event, the vegetation changed significantly but lagged several hundred years behind the grain size record. This study confirmed the cooling and drying tendency during the MIS 5 to 4 transition phase in the southern margin of the Chinese Loess Plateau. These findings shed light on the climatic change on vegetation evolution during the MIS 5 to 4 transition period.

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