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DOI: 10.1016/j.palaeo.2013.04.020
论文题名:
Controlling factors on heavy mineral assemblages in Chinese loess and red clay
作者: Nie J.; Peng W.; Pfaff K.; Möller A.; Garzanti E.; Andò S.; Stevens T.; Bird A.; Chang H.; Song Y.; Liu S.; Ji S.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 381-382
起始页码: 110
结束页码: 118
语种: 英语
英文关键词: Heavy mineral ; Loess ; Paleoclimate ; Provenance ; Red Clay
英文摘要: Heavy-mineral analysis is a sensitive technique in constraining provenance of sandstone, but has rarely been applied to loess. Here we report a heavy-mineral study of selected samples from the Luochuan, Xifeng and Caoxian loess-Red Clay sections on the Chinese Loess Plateau, based on the novel QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) technique. We found that heavy mineral assemblages of loess deposited through the past 500. kyr are similar and unchanged by post-depositional chemical dissolution. In contrast, in samples deposited from 900. ka to 3. Ma, the relative proportion of stable minerals tends to increase down section. In addition, the Xifeng samples consistently display higher contents of unstable ferromagnesian minerals than the Luochuan samples. Detailed analysis of surface textures displayed by different minerals by optical methods indicates that such a compositional difference can be ascribed to more effective diagenetic dissolution for the Luochuan section, explained by more extensive percolation of interstitial waters in wetter climatic conditions. Interestingly, heavy-mineral assemblages in the underlying upper Miocene Red Clay from Xifeng (deposition age. ~. 7. Ma) are similar to those of recent loess deposited since 500. ka. This similarity indicates that climate and/or local preservation conditions hampered dissolution reactions, thus helping to preserve an original provenance signal that remained largely unchanged throughout the considered time period. Our study demonstrates that climatically- and time-controlled diagenesis plays a key role in determining the composition of heavy-mineral assemblages contained in loess deposited several hundreds of thousands years ago. We also show that by using both QEMSCAN and traditional optical techniques on the same samples we can obtain fundamental complementary information for a correct interpretation of the heavy-mineral assemblage. © 2013 Elsevier B.V.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69721
Appears in Collections:过去全球变化的重建

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作者单位: Key Laboratory of Western China's Environment System, Ministry of Education, Lanzhou University, Lanzhou, Gansu 730000, China; Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, CO 80401, United States; Department of Geology, University of Kansas, 1475 Jayhawk Boulevard, Lawrence, KS 66045, United States; Department of Earth and Environmental Scienceso, Universita' di Milano-Bicocca, Piazza della Scienza 4, 20126 Milano, Italy; Centre for Quaternary Research, Department of Geography, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, P.O. Box 17, Xi'an, 710075, China

Recommended Citation:
Nie J.,Peng W.,Pfaff K.,et al. Controlling factors on heavy mineral assemblages in Chinese loess and red clay[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,381-382
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