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.

Nie, J., Peng, W., Pfaff, K., Möller, A., Garzanti, E., Ando', S., et al. (2013). Controlling factors on heavy mineral assemblages in Chinese loess and red clay. PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY, 381-382, 110-118 [10.1016/j.palaeo.2013.04.020].

Controlling factors on heavy mineral assemblages in Chinese loess and red clay

GARZANTI, EDUARDO;ANDO', SERGIO;
2013

Abstract

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.
Articolo in rivista - Articolo scientifico
Heavy mineral; Loess; Paleoclimate; Provenance; Red Clay; Ecology, Evolution, Behavior and Systematics; Paleontology; Earth-Surface Processes; Oceanography
English
2013
381-382
110
118
none
Nie, J., Peng, W., Pfaff, K., Möller, A., Garzanti, E., Ando', S., et al. (2013). Controlling factors on heavy mineral assemblages in Chinese loess and red clay. PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY, 381-382, 110-118 [10.1016/j.palaeo.2013.04.020].
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/65165
Citazioni
  • Scopus 47
  • ???jsp.display-item.citation.isi??? 42
Social impact