Central Asia is one of the most significant loess regions on Earth, with an important role in understanding Quaternary climate and environmental change. However, in contrast to the widely investigated loess deposits in the Chinese Loess Plateau, the Central Asian loess—paleosol sequences are still insufficiently known and poorly understood. Through field investigation and review of the previous literature, the authors have investigated the distribution, thickness and age of the Xinjiang loess, and analyzed factors that control these parameters in the Xinjiang in northwest China, Central Asia. The loess sediments cover river terraces, low uplands, the margins of deserts and the slopes of the Tianshan Mountains and Kunlun Mountains and are also present in the Ili Basin. The thickness of the Xinjiang loess deposits varies from several meters to m. We consider persistent drying, adequate regional wind energy and well-developed river terraces to be the main factors controlling the distribution, thickness and formation age of the Xinjiang loess. The well-outcropped loess sections have mainly developed since the middle Pleistocene in Xinjiang, reflecting the appearance of the persistent drying and the present air circulation system. However, the oldest loess deposits are as old as the beginning of the Pliocene in the Tarim Basin, which suggests that earlier aridification occurred in the Tarim Basin rather than in the Ili Basin and the Junggar Basin.
Ages for hominin occupation in Lushi Basin, middle of South Luo River, central China.
LOPES 1. In southern South America it occurs in Argentina, Bolivia, Paraguay and Uruguay, and its presence in southern Brazil was never studied in detail. It consists of fine-very fine silt with subordinate sand and clay, found mostly in lowland areas between Pleistocene coastal barriers. Caliche and iron-manganese nodules are also present. The only fossils found so far are rodent teeth and a tooth of a camelid Hemiauchenia paradoxa.
China. Its western part, referred to as the West Qinling, constitutes a unit of northeastern Magnetostratigraphic results from the m-thick Xihe loess-soil sequence (NL-VI), located been sufficiently weak to prevent the erosion of the aeolian deposits. Dating the sedimentary sequences within the intermontane basins.
This lists the logos of programs or partners of NG Education which have provided or contributed the content on this page. Powered by. In some parts of the world, windblown dust and silt blanket the land. This layer of fine, mineral -rich material is called loess. Loess is mostly created by wind , but can also be formed by glacier s. When glaciers grind rocks to a fine powder, loess can form. Stream s carry the powder to the end of the glacier. This sediment becomes loess. Loess ranges in thickness from a few centimeters to more than 91 meters feet.
Unlike other soil s, loess is pale and loosely packed. In parts of China, residents build cave-like dwellings in thick loess cliff s.
Loess geochemistry and Cenozoic paleoenvironments
Create citation alert. Buy this article in print. Journal RSS feed. Sign up for new issue notifications. The loess deposits widely distributed in the Central Shandong Mountains are significant terrestrial palaeoclimatic archives in the alluvial plain of eastern China.
A high-resolution magnetostratigraphy combined with optically stimulated luminescence dating indicated that the age of the section base is approximately
Lu Yanchou, J. Prescott, G. Robertson, J. Hutton; Thermoluminescence dating of the Malan loess at Zhaitang, China. Geology ; 15 7 : — Although the widespread loess deposits of north China have been well described, there has been limited information on the absolute age of the various layers. Loess, a wind-carried deposit exposed to sunlight and subsequently buried, should be amenable to dating by thermoluminescence.
Through use of the fine grain technique, ages from 18 to 84 ka have been obtained for a sequence in the Malan loess exposed in the Zhaitang section near Beijing.
Magnetostratigraphic dating of the hominin occupation of Bailong Cave, central China
In this paper, we reviewed and discussed the recent progress and perspectives mentioned in the research of paleo Asian monsoon activities from the records of loess-paleosol sequences and lacustrine sediments in East Asia. Loess-paleosol sequences and lacustrine sediments in East Asia have been recorded terrestrial environmental changes associated with East Asian monsoon activities since the beginning of Quaternary. The researches to reconstruct the activities of paleo East Asian monsoon started in by Heller and Liu , and has been stored much information on the formation and variability of the monsoon in the last two decades.
Onset of loess deposition might begin in 2. Also, the millennial time-scale variation of the monsoon activities can be recognized in the last glacial time. The recent research on Red Clay underlying the loess-paleosol sequence may point out that the formation of the monsoon activities dates back to 7 or 8 Ma.
Magnetostratigraphic dating of early humans in China. Rixiang the southern Loess Plateau in north-central China, to the Three Pleistocene lacustrine and fluvial deposits, which have magnetostratigraphically dated by Zhu et al. ().
The loess of the Chinese Loess Plateau CLP potentially provide an important source of information about history of continental aridity, uplift of the Tibetan Plateau, global atmospheric circulation and are closely related to the evolution of the polar ice sheets e. Pye, ; Ding et al. In China, loess sediments not only deposit on the Loess Plateau but also accumulate in other arid, semi-arid and semi-humid areas.
In recent years, increasing interest has been focused on the loess outside the CLP in order to derive more local to global palaeoenvironmental information from a wider area e. Fang et al. To the east of the CLP, loess sediments widely distributed in Central Shandong Mountains CSM are significant terrestrial palaeoclimatic archives in the semi-humid region of eastern China. It is also sensitive records of East Asian monsoon changes for situating in a key region connected to the Eurasian Plate and the Pacific Ocean.
However, compared with the detailed work on the loess sediments from the CLP, loess sediments in CSM region have not been well investigated. In recent years, the relatively unified understanding of the loess sedimentation on CSM mainly focused on its genesis and provenance: 1 the loess of CSM was characterized by typical aeolian based on the field stratigraphic characteristics and grain size analysis Liu et al.
However, research into the stratigraphy and palaeoclimatology in the CSM region are limited due to the controversy of chronology. Zheng et al. Peng et al. While the latter chronology seems to be more reasonable on the basis of the correlation with established loess-palaeosol sequences in the CLP and marine isotope records, there is a lack of robust justification at other loess sections in the CSM region.
Official websites use. Share sensitive information only on official, secure websites. Radiocarbon dating late Quaternary loess deposits using small terrestrial gastropod shells Quaternary Science Reviews.
monsoon variation on the Loess Plateau of central China during the last and Liu, T. S. () Magnetostratigraphic dating of loess deposits in China.
As one of the longest and most continuously deposited terrestrial sedimentary archives in the world, Chinese loess—paleosol sequences record paleoclimatic and paleomagnetic variations at a range of time scales. Magnetostratigraphic studies provide a first-order chronological framework for Chinese loess sequences. In this review, we highlight recent developments in loess magnetostratigraphy, including pedostratigraphy based on magnetic susceptibility variations.
We highlight progress in understanding the mechanisms by which the natural remanent magnetization NRM is acquired and discuss in detail the fidelity of paleomagnetic recording in loess records, including the recording of magnetic polarity reversals, excursions, and relative paleointensity variations. Finally, we discuss future prospects for studies of loess NRM. Roberts As one of the longest and most continuously deposited terrestrial sedimentary archives in the world, Chinese loess—paleosol sequences record paleoclimatic and paleomagnetic variations at a range of time scales.
Loess-soil sequences are among the best terrestrial records of paleoenvironments. Those in northern China provide a 22 million-year Ma geological history of the Asian deserts dust sources , winter monsoon dust carrier and summer monsoon moisture carrier winds, and the regional vegetation. Loess geochemistry represents one of the most dynamic research fields in loess-based Paleoclimatology.
Some of the most frequent approaches are reviewed here with emphasis to the loess deposits in China. The formation of loess fundamentally requires: 1 a sustained source of dust with poor vegetation, 2 adequate winds to transport the dust, and 3 a suitable accumulation site positive, relatively flat and tectonically stable topography.
Therefore, it is clear that aeolian dust accumulation on the Chinese bess Our magnetostratigraphic dating of the Red Clay when combined with that of the by dry desert, and bess was subsequently deposited on the Chinese Loess Plateau.
Here, we present the results of a detailed magnetostratigraphic investigation of the sedimentary sequence of hominin-bearing Bailong Cave in Yunxi Basin, central China. The Bailong Cave hominin-bearing layer is dated to the early Brunhes Chron, close to the Matuyama-Brunhes geomagnetic reversal at 0. Our findings, coupled with other records, indicate the flourishing of early humans in mainland East Asia during the Mid-Pleistocene climate transition MPT.
This suggests that early humans were adapted to diverse and variable environments over a broad latitudinal range during the MPT, from temperate northern China to subtropical southern China. The chronology of human evolution in different paleoclimatic and paleoenvironmental settings is an intriguing topic in the study of human origins 1 , 2 , 3 , 4. During the past three decades considerable progress has been made toward dating the stratigraphic record that contains Paleolithic artifacts or hominin fossils in China 1 , 7 , 8 , 9 , 10 , 11 , thus significantly contributing to our understanding of early human occupation in mainland East Asia.
The Qinling Mountains are the traditional dividing line between temperate northern China and subtropical southern China. Significantly, intermontane basins in the southern piedmont of the Qinling Mountains have yielded numerous fossil-containing and archeological localities 12 , 13 , 14 , 15 , 16 , Thus, the Qinling Mountains and adjacent areas in central China are a key area for studying human occupation in East Asia and for exploring the hominin migration route between southern and northern China 16 , 17 , 18 , 19 ,
The hysteresis loop parameters show large variation of magnetic mineral size in different sedimentary contexts: it is larger in subtidal sediment than in terrigenous sediment and even larger than in shallow sea sediment. This trend is correlative with distance to sediment source and dynamic strength. Magnetic susceptibility MS and sediment grain size behave so differently in some sedimentary facies that certain big environmental changes can be clearly revealed.
However, the frequently used excellent climatic proxies such as MS and grain size in loess and deep sea sediments fail to record such climatic cycles revealed by oxygen isotope in continental sea.
with the two late Matuyama excursions dated at about Ma and Ma (Yang et al., Key words: Geomagnetic excursion, paleomagnetism, magnetostratigraphy, loess, Matuyama Chron, Olduvai, Loess-paleosol sequences in the Chinese Loess Plateau facts indicate that loess-paleosol deposits have the poten-.
Although the Matuyama—Brunhes boundary MBB in the Chinese Loess Plateau CLP is very important in reliably correlating Quaternary loess with other sediments in the world, particularly with marine and polar ice cores, its exact stratigraphic position remains controversial. Previous investigations usually placed the MBB between paleosol unit S8 and loess unit L8 in various locations.
To better understand the spatial differences in the MBB position, a high-resolution paleomagnetic study was conducted in a loess section of the Lantian Basin at the southern margin of the CLP. However, the regional anomalously low magnetic susceptibility in paleosols S7 and S8 indicates that it is more reliable to determine the paleoclimate boundaries between loess and paleosol horizons of this segment with median grain size. Then, the MBB in the Yushan section can be correlated with the bottom of paleosol S7, corresponding to the older part of interglacial marine isotope stage This result temporally reconciles the striking discrepancy of the position of the MBB recorded in between loess and other typical sedimentary sequences, and further confirms that the stratigraphic position of the MBB could spatially vary to a certain extent due to regional sedimentary or paleoclimatic conditions in the marginal areas of the CLP.
Moreover, the climate offset defined by the magnetic susceptibility and median grain size of the section can be preliminarily attributed to the regional geology and paleoenvironment background. A multiproxy-based stratigraphic division is considered very necessary when paleomagnetic and climatic boundaries are defined exactly in a specific area of the southern CLP.
In North China, there is an area of over km 2 blanketed by the late Cenozoic aeolian sediments Liu Previous paleomagnetic studies on the CLP have made significant achievements on the definition of the initial age of aeolian dust accumulation in North China e. However, the stratigraphic position of the latest geomagnetic reversal, the Matuyama—Brunhes M—B geomagnetic reversal, in loess remains controversial.
It varies in different loess sections in the CLP.
Metrics details. The termination of the Jaramillo normal to reverse subchron is a key chronostratigraphic marker for dating global Pleistocene sedimentary sequences. However, the stratigraphic position of the geomagnetic polarity reversal varies greatly across the Chinese Loess Plateau CLP , from near the bottom of paleosol unit S9 to the middle-upper part of S Here, we present paleomagnetic and rock magnetic results from high-resolution sampling of the Yushan loess section of the Lantian Basin located within the southern CLP.
Our combined analyses determine that the polarity reversal is located in the middle-lower part of the paleosol unit S This stratigraphic position is lower than most of other studies conducted throughout the CLP.
A Geologic Time Scale, Cambridge University Press (). Heller and Liu, . F. Heller, T.S. LiuMagnetostratigraphic dating of loess deposits in China.
J Hum Evol , 59 5 , 17 Aug Cited by: 1 article PMID: J Hum Evol , 56 2 , 31 Dec Cited by: 5 articles PMID: