Earth Science Frontiers ›› 2012, Vol. 19 ›› Issue (3): 7-18.
• Article • Previous Articles Next Articles
WANG Xue-Qiu
Received:
Revised:
Online:
Published:
Abstract:
In order to recognize the evolution of the Earth and global changes, it is necessary to set up consistent Globalscale Geochemical Baselines as a reference. “Geochemical Baseline” is known as the database and the accompanying element distribution maps by systematically documenting the concentration and spatial distribution of chemical elements and compounds on the Earths surface, which can be applied to quantified the future humaninduced or natural changes in the chemistry of the present Earth and the past chemical evolution induced by geological processes. China Geochemical Baselines (CGB), as a part of the Global Geochemical Baselines, is to document both concentrations and spatial distribution of nearlyall chemical elements across whole China. China Geochemical Baseline Networks are designed based on 1∶200000 map sheets of 1°(lng.)×40′ (lat.), approximately 1500 grids covering all over China. Approximately 10000 rock samples for primary lithosphere baselines and 6000 soil samples for secondary pedosphere had been collected across the China land surface. Eightyone geochemical indicators including 78 chemical elements are determined by ICPMS/AES following 4acid digestion and by XRF following fusion as backbone methods combined with other 10 analytical methods. Analytical quality is under strict control by using standard reference samples to obtain harmonious highquality data. In the present paper the author shows some of the examples for the use of preliminary results of the spatial distribution of elements to understand the past and to predict the future. Ir geochemical anomalies have been discovered in the suspected Cretaceous and Tertiary (KT) boundary ranging from 0.2×10-9 to 0.8×10-9 whereas Ir concentration baselines in Cretaceous and Tertiary rocks are less than 0.02×10-9. It is likely that the Iridium in the suspected boundary is of extraterrestrial origin, providing us with understanding the extinction of dinosaurs due to the impact of an earthcrossing asteroid. It has been found that the dramatic changes of CaO distribution occurred in the past 15 years from 1994 to 2009. The average concentration decreases from 0.53% to 0.41%, the area of CaO<1% extends from 872000 km2 to 1073000 km2, increased 23% as compared to that in 1994, due to the leaching of CaCO3 by acid rains caused by human activities.
Key words:  , Geochemical Baselines; lithosphere; pedosphere; past evolutions; future changes
CLC Number:
P632
P628
WANG Xue-Qiu. Global Geochemical Baselines: Understanding the past and predicting the future.[J]. Earth Science Frontiers, 2012, 19(3): 7-18.
0 / / Recommend
Add to citation manager EndNote|Ris|BibTeX
URL: https://www.earthsciencefrontiers.net.cn/EN/
https://www.earthsciencefrontiers.net.cn/EN/Y2012/V19/I3/7