Quantatitive robustness assessment of low-density geochemical mapping: An example of China’s cobalt

doi:10.13745/j.esf.sf.2024.10.34

Abstract

Abstract:

Robustness is a fundamental scientific concern in low-density geochemical mapping, which has long garnered close attention from mapping researchers. However, quantitative understanding of robustness has been lacking due to the lack of effective quantitative assessment methods. In this study, using cobalt element data from two low-density mapping sources—the China Geochemical Baselines project (CGB) and the Regional Geochemical National Reconnaissance project (RGNR)—robustness is quantitatively assessed based on 1546 representative catchments through the utilization of local spatial correlation coefficients; the spatial distribution features and influencing factors are also discussed. On a national scale, robustness was influenced by sediment cobalt (Co) content and geochemical landscape conditions; on a local scale, it was affected by differential erosion in cobalt-rich and Co-poor source areas. In Co-poor environments (sediment Co<13 μg/g) the robustness index (R) value fluctuated around 0.4, while in Co-rich environments (sediment Co>13 μg/g) it increased from 0.4 to above 0.6 with rising Co content. Regions such as karst terrains, tropical rainforests, and semi-arid low hills had R values as high as 0.58 to 0.74, whereas alluvial plains and forested swamp regions had R values below 0.32. This study provides a reference for quantitative evaluaton of low-density mapping, deomonstrating that low-density geochemical mapping has good robustness and promising prospect in the global-scale geochemical mapping.

Key words: robustness, low-density geochemical mapping, cobalt, catchment, GW correlations

CLC Number:

P596

LIU Dongsheng, WANG Xueqiu, NIE Lanshi, ZHANG Bimin, ZHOU Jian, LIU Hanliang, WANG Wei, CHI Qinghua, XU Shanfa. Quantatitive robustness assessment of low-density geochemical mapping: An example of China’s cobalt[J]. Earth Science Frontiers, 2025, 32(1): 23-35.

Figures/Tables 14

References 38

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作者	地区	每个样品控制面积/km²			对比元素
作者	地区	密度1	密度2	密度3	对比元素
Shen和Yan^[17]	中国江西	1	1800		W
成杭新和谢学锦^[18]	中国浙江	1	100~1 000	1 000~10 000	Sb、As、Ag、Sn、Pb、Na₂O
王学求等^[3]	中国新疆	4	25	100	Au、Cu、Mn、As、Hg、U
Smith和Reimann^[4]	美国	航空辐射测量	6 000		K
Demetriades^[19]	希腊	1.77~2.74	500		Pb
Cicchella等^[11]	欧洲		5 000	20 000	CaO、Th、U
聂兰仕^[20]	中国黔西南	1	16~25	100	Au
Birke等^[21]	德国	1.3	380	5 000	Ba、Cu、Cr、Pb、U
Gosar等^[22]	斯洛文尼亚	4	25	625	Hg
程湘等^[23]	印度尼西亚	4	100		Au、Ag、Cu、Zn、Ni
Liu等^[13]	中国新疆	1	180	1 600	Au、As、Sb

作者	地区	每个样品控制面积/km²			对比元素
作者	地区	密度1	密度2	密度3	对比元素
Shen和Yan^[17]	中国江西	1	1800		W
成杭新和谢学锦^[18]	中国浙江	1	100~1 000	1 000~10 000	Sb、As、Ag、Sn、Pb、Na₂O
王学求等^[3]	中国新疆	4	25	100	Au、Cu、Mn、As、Hg、U
Smith和Reimann^[4]	美国	航空辐射测量	6 000		K
Demetriades^[19]	希腊	1.77~2.74	500		Pb
Cicchella等^[11]	欧洲		5 000	20 000	CaO、Th、U
聂兰仕^[20]	中国黔西南	1	16~25	100	Au
Birke等^[21]	德国	1.3	380	5 000	Ba、Cu、Cr、Pb、U
Gosar等^[22]	斯洛文尼亚	4	25	625	Hg
程湘等^[23]	印度尼西亚	4	100		Au、Ag、Cu、Zn、Ni
Liu等^[13]	中国新疆	1	180	1 600	Au、As、Sb

含量区间	RGNR Co含量/(μg·g^-1)	CGB Co含量/(μg·g^-1)
1	2.6~<6.3	1.0~<4.7
2	6.3~<7.7	4.7~<5.8
3	7.7~<8.8	5.8~<7.0
4	8.8~<9.6	7.0~<8.1
5	9.6~<10.3	8.1~<8.8
6	10.3~<11.0	8.8~<9.7
7	11.0~<11.7	9.7~<10.6
8	11.7~<12.1	10.6~<11.4
9	12.1~<13.0	11.4~<12.1
10	13.0~<13.7	12.1~<13.0
11	13.7~<14.7	13.0~<14.1
12	14.7~<15.5	14.1~<15.1
13	15.5~<16.7	15.1~<16.6
14	16.7~<18.6	16.6~<18.6
15	18.6~<60.6	18.6~<80.8

含量区间	RGNR Co含量/(μg·g^-1)	CGB Co含量/(μg·g^-1)
1	2.6~<6.3	1.0~<4.7
2	6.3~<7.7	4.7~<5.8
3	7.7~<8.8	5.8~<7.0
4	8.8~<9.6	7.0~<8.1
5	9.6~<10.3	8.1~<8.8
6	10.3~<11.0	8.8~<9.7
7	11.0~<11.7	9.7~<10.6
8	11.7~<12.1	10.6~<11.4
9	12.1~<13.0	11.4~<12.1
10	13.0~<13.7	12.1~<13.0
11	13.7~<14.7	13.0~<14.1
12	14.7~<15.5	14.1~<15.1
13	15.5~<16.7	15.1~<16.6
14	16.7~<18.6	16.6~<18.6
15	18.6~<60.6	18.6~<80.8