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Spatial and temporal variations of Rb/Sr ratios of the bulk surface sediments in Lake Qinghai.

Xu H, Liu B, Wu F - Geochem. Trans. (2010)

Bottom Line: Two out of eight cores show similar trends between Rb/Sr ratios and precipitation indices on decadal scales; however, the other cores do not show such relationship.The result of this study suggests that physical weathering and chemical weathering in Lake Qinghai catchment have opposite influence on Rb/Sr ratios of the bulk sediments, and they compete in dominating the Rb/Sr ratios of lake sediments on different spatial and temporal scales.Therefore, it is necessary to study the geochemistry of Rb/Sr ratio of lake sediments (especially that on short term timescales) particularly before it is used as an indicator of weathering intensity of the catchment.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710075, China. xuhai@ieecas.cn.

ABSTRACT
The Rb/Sr ratios of lake sediments have been suggested as indicators of weathering intensity by increasing work. However, the geochemistry of Rb/Sr ratios of lake sediments is variable between different lakes. In this study, we investigated the spatial and temporal patterns of Rb/Sr ratios, as well as those of other major elements in surface sediments of Lake Qinghai. We find that the spatial pattern of Rb/Sr ratios of the bulk sediments correlates well with that of the mass accumulation rate, and those of the terrigenous fractions, e.g., SiO2, Ti, and Fe. The temporal variations of Rb/Sr ratios also synchronize with those of SiO2, Ti, and Fe of each individual core. These suggest that Rb/Sr ratios of the surface sediments are closely related to terrigenous input from the catchment. Two out of eight cores show similar trends between Rb/Sr ratios and precipitation indices on decadal scales; however, the other cores do not show such relationship. The result of this study suggests that physical weathering and chemical weathering in Lake Qinghai catchment have opposite influence on Rb/Sr ratios of the bulk sediments, and they compete in dominating the Rb/Sr ratios of lake sediments on different spatial and temporal scales. Therefore, it is necessary to study the geochemistry of Rb/Sr ratio of lake sediments (especially that on short term timescales) particularly before it is used as an indicator of weathering intensity of the catchment.

No MeSH data available.


Temporal relationship between Rb/Sr ratios and terrigenous fraction (exemplified by SiO2 contents here) for core #1, #2, QH0701, QH0707, QH0708, and QH0711.
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Figure 4: Temporal relationship between Rb/Sr ratios and terrigenous fraction (exemplified by SiO2 contents here) for core #1, #2, QH0701, QH0707, QH0708, and QH0711.

Mentions: Fig. 4 shows the temporal relationship between Rb/Sr and SiO2 contents. For each individual core, the Rb/Sr ratios are positively linearly correlated with SiO2 contents. This positively linear relationship also exist between Rb/Sr ratios and other elements in Group/(i.e. Al2O3, Fe2O3, K2O, Ti, etc. Figures not shown), suggesting that high fraction of terrigenous detritus correlates with high Rb/Sr ratios of the bulk sediments. This is consistent with the spatial relationship between Rb/Sr ratios and SiO2 and Ti contents (Fig. 3).


Spatial and temporal variations of Rb/Sr ratios of the bulk surface sediments in Lake Qinghai.

Xu H, Liu B, Wu F - Geochem. Trans. (2010)

Temporal relationship between Rb/Sr ratios and terrigenous fraction (exemplified by SiO2 contents here) for core #1, #2, QH0701, QH0707, QH0708, and QH0711.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2909147&req=5

Figure 4: Temporal relationship between Rb/Sr ratios and terrigenous fraction (exemplified by SiO2 contents here) for core #1, #2, QH0701, QH0707, QH0708, and QH0711.
Mentions: Fig. 4 shows the temporal relationship between Rb/Sr and SiO2 contents. For each individual core, the Rb/Sr ratios are positively linearly correlated with SiO2 contents. This positively linear relationship also exist between Rb/Sr ratios and other elements in Group/(i.e. Al2O3, Fe2O3, K2O, Ti, etc. Figures not shown), suggesting that high fraction of terrigenous detritus correlates with high Rb/Sr ratios of the bulk sediments. This is consistent with the spatial relationship between Rb/Sr ratios and SiO2 and Ti contents (Fig. 3).

Bottom Line: Two out of eight cores show similar trends between Rb/Sr ratios and precipitation indices on decadal scales; however, the other cores do not show such relationship.The result of this study suggests that physical weathering and chemical weathering in Lake Qinghai catchment have opposite influence on Rb/Sr ratios of the bulk sediments, and they compete in dominating the Rb/Sr ratios of lake sediments on different spatial and temporal scales.Therefore, it is necessary to study the geochemistry of Rb/Sr ratio of lake sediments (especially that on short term timescales) particularly before it is used as an indicator of weathering intensity of the catchment.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710075, China. xuhai@ieecas.cn.

ABSTRACT
The Rb/Sr ratios of lake sediments have been suggested as indicators of weathering intensity by increasing work. However, the geochemistry of Rb/Sr ratios of lake sediments is variable between different lakes. In this study, we investigated the spatial and temporal patterns of Rb/Sr ratios, as well as those of other major elements in surface sediments of Lake Qinghai. We find that the spatial pattern of Rb/Sr ratios of the bulk sediments correlates well with that of the mass accumulation rate, and those of the terrigenous fractions, e.g., SiO2, Ti, and Fe. The temporal variations of Rb/Sr ratios also synchronize with those of SiO2, Ti, and Fe of each individual core. These suggest that Rb/Sr ratios of the surface sediments are closely related to terrigenous input from the catchment. Two out of eight cores show similar trends between Rb/Sr ratios and precipitation indices on decadal scales; however, the other cores do not show such relationship. The result of this study suggests that physical weathering and chemical weathering in Lake Qinghai catchment have opposite influence on Rb/Sr ratios of the bulk sediments, and they compete in dominating the Rb/Sr ratios of lake sediments on different spatial and temporal scales. Therefore, it is necessary to study the geochemistry of Rb/Sr ratio of lake sediments (especially that on short term timescales) particularly before it is used as an indicator of weathering intensity of the catchment.

No MeSH data available.