5 results
Search Results
2. Geochemical characteristics of Holocene aeolian deposits and their environmental significance in the Mu Us Desert, northern China.
- Author
-
Liu, Bing, Jin, He‐Ling, Sun, Liang‐Ying, Sun, Zhong, Niu, Qing‐He, and Zhang, Cai‐Xia
- Subjects
ERGS (Landforms) ,HOLOCENE Epoch ,SEDIMENTATION & deposition research ,PALEOPEDOLOGY ,WEATHERING ,DESERTS ,METEOROLOGICAL precipitation - Abstract
This paper addresses the surface and Holocene aeolian deposits in the southeastern Mu Us Desert, N. China, systematically analysing the evolution of the geochemical characteristics of aeolian sand-palaeosol sequences and their environmental significance. Our results indicate that the geochemical components of the Holocene aeolian deposits and surface deposits had the similar material sources, sediment transport and deposition processes in the study region, which were dominated by SiO
2 , Al2 O3 , and Na2 O. In the weathering process of the Jinjie (JJ) profile, the Na, K, and Si presented the slight leaching and migration in general, while the other elements were relatively accumulated. The Holocene aeolian deposits and surface deposits incurred weaker geochemical weathering under cold and dry conditions and were only weakly leached, which implies a relatively arid environment in the Holocene epoch and the modern era. The weathering degree was controlled by the regional temperature and precipitation, and was probably more sensitive to the precipitation changes. In the sedimentary profile, the geochemical parameters and migration of elements demonstrated that there have been several alternating warm-wet and cold-dry intervals in the Mu Us Desert in the Holocene epoch; there were relatively warm and wet conditions prior to 4.6 ka, and it has been cold and dry since then. Six millennial-scale dry events were recorded during the Holocene, which were not only accordant with the history of palaeoclimatic changes in the different latitudes and archives of the Northern Hemisphere, but also correspond to the millennial-scale variation of cosmic radiation and solar activity during that period. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
3. Multiproxy records of Holocene millennial‐scale climatic variations from the aeolian deposit in eastern Horqin dune field, northeastern China.
- Author
-
Liu, Bing, Jin, Heling, Sun, Liangying, Niu, Qinghe, Zhang, Caixia, Xue, Wenping, Liu, Zhengyu, and Tyrrell, S.
- Subjects
CLIMATE change ,HOLOCENE Epoch ,ERGS (Landforms) ,SEDIMENTATION & deposition ,GEOCHEMISTRY - Abstract
The record of the Holocene millennial‐scale climate variations from the aeolian deposit around the monsoonal boundary zone in northern China is poorly understood because the desert sediments are usually scattered and geological archives are discontinuous. Here, we conducted magnetic, sedimentological, and geochemical analyses of the palaeosol‐aeolian sand sequence from the eastern Horqin dune field in northeastern China, which documented the detailed history of climatic variations during the past 7.0 ka. The results indicate that the climate became more humid around 7.0−5.0 ka and approached an optimal humid condition around 5.0–3.6 cal ka BP. Afterward, the moisture condition clearly declined in 3.6–1.3 cal ka BP and was replaced by dry climate at the end. Additionally, we discovered that 10 periodically dry events that punctuated the overall pattern of climatic variations in the region, with times of more than 7.0, 5.7–5.5, 5.5–5.0, 4.6–4.2, 4.2–3.7, 3.6, 3.5–3.3, and 1.3 cal ka BP. These intervals were not only very consistent with the dry/cold events in the monsoonal boundary zone of northern China, owing to weak summer monsoonal strength forced by solar radiation, but were also accordant with the increased Asian winter monsoon strengths induced by environment variations of the high latitude area. This phenomenon probably implies the antiphase relationship between Asian summer and winter monsoons on the Holocene millennial‐scale around the monsoonal boundary zone of northern China. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
4. History of moisture change derived from slope sediments of the eastern Gonghe Basin (northeastern Qinghai-Tibetan Plateau) during the last 17 ka.
- Author
-
Liu, Bing, Jin, Heling, Sun, Liangying, Su, Zhizhu, Zhang, Caixia, and Zhao, Shuang
- Subjects
PALEOPEDOLOGY ,CLIMATE change ,MAGNETIC susceptibility ,LAST Glacial Maximum - Abstract
The palaeosol-loess-aeolian sand sequence in the eastern Gonghe Basin, which is located at the convergence of the Asian summer monsoon, winter monsoon and the westerlies, reveals detailed moisture changes in the northeastern Qinghai-Tibetan Plateau (NETP) during the last 17 ka. Analysis of magnetic susceptibility (MS), total organic carbon, carbonate content, grain size and geochemical parameters indicate that the region was dominated by an extremely dry climate during ~17.0-15.82 ka, accompanying large-scale desert expansion in the last glacial maximum (LGM). Subsequently, the climate became generally dry during 15.82-14.6 ka, an interval in which loess rapidly accumulated. Enhanced humidity occurred at 14.6 ka, probably associated with increased strength of the East Asian summer monsoon. The region experienced slightly decreased moisture at around 6.5 and 5.8 ka. After 2.7 ka, the climate became wetter. This interpretation correlates with climatic records from lacustrine and aeolian deposits in the NETP during the LGM, the last deglaciation and the early-middle Holocene. High climatic moisture in the Late Holocene facilitated the formation of a well-developed palaeosol in the NETP. The effective moisture change in the Gonghe Basin is not simply ascribed to the influences of Asian summer monsoons; instead, it was possibly influenced by the interaction of evaporation and monsoonal precipitation forced by solar insolation variation. The balance between these variables was very influential on the effective moisture change in the closed inland basin of the NETP. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
5. Hierarchy of bounding surfaces in aeolian sandstones of the Jurassic Tordillo Formation (Neuquén Basin, Argentina)
- Author
-
Carlos Zavala, Hernán Maretto, and M. Di Meglio
- Subjects
Aeolian deposits ,Tordillo Formation ,Neuquén Basin ,Argentina ,Jurassic. ,Science ,Geology ,QE1-996.5 - Abstract
The Tordillo Formation is a continental clastic unit deposited in the Neuquén Basin during the Late Jurassic. This paper discusses the stratigraphy of the succession outcropping at the Quebrada del Sapo, with emphasis on the origin, dimensions and hierarchy of bounding surfaces of aeolian deposits. Field survey, supported by the measurement of three detailed stratigraphic sections and line drawings of photographic panels allow the identification of four unconformity bounded units within the succession, informally named as T1, T2, T3 and T4. Units T1 and T3 are composed of conglomerates and pebbly sandstones deposited by density flows in a lacustrine environment. Paleocurrents indicate a source area located in the northeast while the presence of angular sandstone blocks suggests resedimentation processes. T2 and T4 units are composed of fine to medium grained sandstones of aeolian origin, characterized by large scale dunes and minor dry interdunes. Both units have sharp bases, and overlie a deflation surface characterized by the presence of ventifacts. Paleocurrents suggest a paleowind direction from the southwest. Internal bounding surfaces show a hierarchy of at least four discrete surfaces which were numbered according to their crescent extension. Type 1 surfaces are related to the normal advance of the dune front. Type 2 are reactivation surfaces within a single dune set. Type 3 surfaces relate to set superposition. Type 4 surfaces are related to extensive deflation of the dune complex, and define at least nine elementary aeolian sequences in the T4 unit.
- Published
- 2005
- Full Text
- View/download PDF
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.