Grain Size of Quartz as an Indicator of Winter Monsoon Strength on the Loess Plateau of Central China during the Last 130,000 Yr

1995 ◽  
Vol 43 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Jule Xiao ◽  
Stephen C. Porter ◽  
Zhisheng An ◽  
Hisao Kumai ◽  
Shusaku Yoshikawa
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Loess Plateau ◽  
Winter Monsoon ◽  
Central China ◽  
Atmospheric Conditions ◽  
Dust Transport ◽  
Chinese Loess ◽  
Weathering Processes ◽  
Monsoon Strength

AbstractThe Chinese loess-paleosol sequence constitutes an important record of variations in Asian monsoon climate over the past 2.4 myr. Magnetic susceptibility of loess and paleosols has been used as a proxy for summer monsoon intensity, while median grain size has been regarded as a measure of the strength of winter monsoon winds that were responsible for most of the dust transport. However, median grain size is only an approximate index of winter monsoon strength because both paleosols and loess have been modified, to various degrees, by weathering processes that have produced pedogenic clay. The quartz component of loess and paleosols is largely unaffected by weathering processes and therefore constitutes a more reliable proxy index of monsoon wind strength. Median grain size (Qmd) and maximum grain size (Qmax) values of monomineralic quartz isolated from the loess-paleosol section at Luochuan in the central Loess Plateau are characterized by two main intervals during the last ca. 130,000 yr when these parameters were significantly greater than 9 and 85 μm, respectively, and three main intervals when they were lower. The data imply that the winter monsoon weakened during the intervals with low Qmd and Qmax values, which coincide with marine oxygen isotope stages 5, 3, and 1, and was strongest ca. 67,000 and 20,000 yr ago during isotope stages 4 and 2. However, both quartz grainsize records display second-order high-frequency, high-amplitude variations, which are lacking in the magnetic susceptibility record, that imply rapid and significant changes in atmospheric conditions that affect dust transport and deposition.

Out-of-phase evolution between summer and winter East Asian monsoons during the Holocene as recorded by Chinese loess deposits

2014 ◽  
Vol 81 (3) ◽  
pp. 500-507 ◽  
Author(s):  
Dunsheng Xia ◽  
Jia Jia ◽  
Guanhua Li ◽  
Shuang Zhao ◽  
Haitao Wei ◽  
...  
Keyword(s):  
Loess Plateau ◽  
East Asian Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
Chinese Loess Plateau ◽  
Magnetic Minerals ◽  
The Holocene ◽  
Chinese Loess ◽  
Southern Chinese ◽  
Monsoon Strength

AbstractWe analyzed climate proxies from loessic-soil sections of the southern Chinese Loess Plateau. The early Holocene paleosol, S0, is 3.2 m thick and contains six sub-soil units. Co-eval soils from the central Loess Plateau are thinner (~ 1 m). Consequently higher-resolution stratigraphic analyses can be made on our new sections and provide more insight into Holocene temporal variation of the East Asian monsoon. Both summer and winter monsoon evolution signals are recorded in the same sections, enabling the study of phase relationships between the signals. Our analyses consist of (i) measurements of magnetic properties sensitive to the production of fine-grained magnetic minerals which reflect precipitation intensity and summer monsoon strength; and (ii) grain-size analyses which reflect winter monsoon strength. Our results indicate that the Holocene precipitation maximum occurred in the mid-Holocene, ~ 7.8–3.5 cal ka BP, with an arid interval at 6.3–5.3 cal ka BP. The winter monsoon intensity declined to a minimum during 5.0–3.4 cal ka BP. These results suggest that the East Asian summer and winter monsoons were out of phase during the Holocene, possibly due to their different sensitivities to ice and snow coverage at high latitudes and to sea-surface temperature at low latitudes.

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.

Magnetic susceptibility evidence of monsoon variation on the Loess Plateau of central China during the last 130,000 years

1991 ◽  
Vol 36 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Zhisheng An ◽  
George J. Kukla ◽  
Stephen C. Porter ◽  
Jule Xiao
Keyword(s):  
Magnetic Susceptibility ◽  
Loess Plateau ◽  
Summer Monsoon ◽  
Central China ◽  
Chinese Loess Plateau ◽  
Climate Index ◽  
Chinese Loess ◽  
Monsoon Variability ◽  
Monsoon Intensity ◽  
Isotope Record

AbstractThe magnetic susceptibility of loess and paleosols in central China represents a proxy climate index closely related to past changes of precipitation and vegetation, and thus to summer monsoon intensity. Time series of magnetic susceptibility constructed for three loess-paleosol sequences in the southern part of the Chinese Loess Plateau document the history of summer monsoon variation during the last 130,000 yr. They correlate closely with the oxygen isotope record of stages 1 to 5 in deep-sea sediments. Soils were forming during intervals of strong summer monsoon, whereas loess units were deposited at times of reduced monsoon intensity. The Chinese loess-paleosol sequence can thus be viewed as a proxy record of Asian monsoon variability extending over the last 2.5 myr.

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.

Dependence of Near-Surface Magnetic Susceptibility on Dust Accumulation Rate and Precipitation on the Chinese Loess Plateau

2001 ◽  
Vol 55 (3) ◽  
pp. 271-283 ◽  
Author(s):  
Stephen C. Porter ◽  
Bernard Hallet ◽  
Xihao Wu ◽  
Zhisheng An
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Loess Plateau ◽  
Surface Sediment ◽  
Accumulation Rate ◽  
Central China ◽  
Mean Annual Precipitation ◽  
Magnetic Minerals ◽  
Near Surface ◽  
Dust Accumulation

AbstractMagnetic susceptibility (MS) of surface sediment varies systematically across the Loess Plateau in central China, decreasing exponentially from >200×10−8 m3/kg at the northern margin of the Qinling Shan to ≤30×10−8 m3/kg near the southern margin of the Mu Us Desert. MS correlates highly with loess median grain size (r2=0.79), which decreases south-southeastward across the plateau. It also correlates with mean annual temperature (MAT) and mean annual precipitation (MAP) (r2=0.58 and 0.60, respectively), and with their product MAT×MAP (r2=0.83), which is considered a measure of potential pedogenic activity. Because regional isopleths depicting grain size and the primary meteorological parameters are nearly parallel, it is difficult to determine their relative influence on MS. A simple MS model, based on the observed spatial variation in loess thickness, permits quantitative assessment of the effect of the dust accumulation rate on the MS signal of surface sediment and isolates the likely role of climate in the production of magnetic minerals. The model suggests that 84% of the loess MS variance is dictated by the diluting effect of dust and 10–11% is associated with meteorological factors, primarily precipitation. The observed and modeled relationships support hypotheses that attribute variations in MS in the loess-paleosol succession to varying rates of dust deposition and in situ production of magnetic minerals in the accretionary soils, both of which are controlled by monsoon climate.

Paleowind directions from the magnetic fabric of loess deposits in the western Chinese Loess Plateau and implications for dust provenance

2021 ◽  
pp. 1-14
Author(s):  
Xinbo Gao ◽  
Qingzhen Hao ◽  
Junyi Ge ◽  
Long Han ◽  
Yu Fu ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Winter Monsoon ◽  
Magnetic Fabric ◽  
Chinese Loess Plateau ◽  
Dust Transport ◽  
Chinese Loess ◽  
Asian Winter Monsoon ◽  
Aeolian Deposits ◽  
Westerly Winds ◽  
Magnetic Lineations

Abstract The aeolian loess-paleosol sequences in the Chinese Loess Plateau (CLP) are an excellent archive of variations in atmospheric circulation in the geological past. However, there is no consensus regarding the roles of the East Asian winter monsoon and westerly winds in transporting the dust responsible for loess deposition during glacial and interstadial periods. We conducted detailed measurements of the anisotropy of magnetic susceptibility (AMS) on two parallel loess profiles covering the most recent 130 ka in the western CLP to determine paleowind directions. Results show that the magnetic lineations of the loess and paleosol units in both sections are significantly clustered along the northwest to southeast direction. These observations demonstrate that the prevailing wind system responsible for dust transport in the western CLP was the northwesterly winter monsoon, rather than the westerly winds. The AMS-derived dust-bearing wind direction was relatively stable during the last glacial and interglacial cycle in the western CLP, consistent with sedimentary and AMS evidence from the eastern CLP. Accordingly, it is reasonable to conclude that large areas of deserts and Gobi deserts areas located in the upwind direction were the dominant sources for the aeolian deposits of the Loess Plateau.

Variability of East Asian Winter Monsoon in Quaternary Climatic Extremes in North China

2000 ◽  
Vol 54 (3) ◽  
pp. 321-327 ◽  
Author(s):  
Huayu Lu ◽  
Ko van Huissteden ◽  
Jie Zhou ◽  
Jef Vandenberghe ◽  
Xiaodong Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Summer Monsoon ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
Climatic Extremes ◽  
Asian Winter Monsoon ◽  
Monsoon Intensity ◽  
Monsoon Strength

In order to examine high-frequency variations of East Asian winter monsoon in Quaternary climatic extremes, two typical loess–paleosol sequences in the Chinese Loess Plateau were investigated. Sandy layers in the loess deposits, the “Upper sand” and “Lower sand” (layers L9 and L15, respectively), which represent a high-resolution record of paleomonsoon changes, have been sampled at intervals of 5–6 cm from sections at Luochuan and Xifeng. The grain size and magnetic susceptibility was measured for all samples. The grain-size results (a proxy of winter monsoon strength) indicate that the winter monsoon strength fluctuated on a millennial timescale during cold climatic extremes, with climatic events of a few hundred to a few thousand years. However, the winter monsoon was relatively stable during warm periods. The magnetic susceptibility signal (a proxy of summer monsoon intensity) is practically constant over the same period. This is tentatively explained by the assumption that the summer monsoon intensity was too low to be recorded in the magnetic susceptibility signal. The intensified winter monsoon events show periodicities in a range of 1000 to 2770 yr, with a dominant cycle of approximately 1450 yr. The detection of this oscillation in older glacial stages strongly suggests that it may be a pervasive cycle of the cold climatic phases of the Quaternary. Millennial-scale variations of the winter monsoon may be caused by instability of the westerly jet, which is determined by temperature differences between the polar and the equatorial regions.

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