干旱区生态环境知识资源中心(Arid): Formation of geochemical anomalies in loess-paleosol sequence at the Dahu Gold Mine, central China: A clastic-hydromorphic-gaseous dispersion model

Arid

DOI	10.1016/j.gexplo.2019.02.009
	Formation of geochemical anomalies in loess-paleosol sequence at the Dahu Gold Mine, central China: A clastic-hydromorphic-gaseous dispersion model
	Lin, Xin 1,2; Meng, Ganggang 1; Chang, Haiqin 1; Zhang, Miaomiao 1; Fu, Yalong 1
通讯作者	Lin, Xin
来源期刊	JOURNAL OF GEOCHEMICAL EXPLORATION
ISSN	0375-6742
EISSN	1879-1689
出版年	2019
卷号	200 页码:201-212
英文摘要	Modern mineral exploration requires a comprehensive understanding of how geochemical anomalies form, particularly where the mineral deposits are covered by unconsolidated sediments. However, the mechanisms that form anomalies vary as a function of cover type and are not well understood. The Dahu Gold Mine in central China is characterized by a lode gold deposit, overlain by a younger loess-paleosol sequence (including saprolite). Thus, the site provides an opportunity to examine how elements associated with primary mineralization have been dispersed through the loess to form anomalies in this poorly-investigated cover type. Fine-grained ( < 74 mu m) samples were collected to determine the concentrations of Au, Cu, Pb, Zn, As, Mo, Co, Ni and Mn in the loess-paleosol sequence. The results from two vertical profiles over the deposit show that anomalies of Au, As, Mo, Pb, Zn and Cu were developed in three layers. From the bottom up, it includes (1) the saprolite, (2) the lower Wucheng Loess and (3) the upper Lishi Loess. In contrast, nonmineralized Co, Ni and Mn show a uniform distribution along the profiles. The vertical profile outside the context of primary mineralization, however, shows no anomalous zones of metal enrichment. Generally, the anomalies in the lower Wucheng Loess and upper Lishi Loess are 2 to 5 times higher than the background, for instance, > 70 mu g/g of Pb vs. the average 30 mu g/g of Pb in the Chinese loess. Anomalies in the saprolite are interpreted to have formed by in-situ weathering of the primary mineralized rocks. In contrast, anomalies in the lower Wucheng Loess which correspond to the calcrete horizon were probably formed by the precipitation of metals from ascending Ca (HCO3)(2) -rich mineralized groundwater. The S-N directed horizontal profile shows that anomalies of Au, Cu, Mo and Pb in the upper Lishi Loess which are not in direct contact with the mineralization, spatially coincide with major faults (i.e. the Huashan Frontal Fault) and fractures in the loess-paleosol sequence. Moreover, Pb isotopic ratios documented for the sulphide ores and anomalous and background loess suggest that they are partially derived from the sulphide ores. The anomalies in the upper Lishi Loess are interpreted to be formed by a possible gaseous dispersion process. Elements, probably in metallic form (e.g. nanoparticulate Au), were carried by gases that flowed up faults and fractures to the surface and were precipitated in carbonate-rich clayey loess. Therefore, the formation of anomalies in the loess-paleosol sequence is a synthesis of clastic, hydromorphic and gaseous dispersion processes.
英文关键词	Geochemical anomaly Loess-paleosol sequence Dispersion mechanism Dahu gold deposit central China
类型	Article
语种	英语
国家	Peoples R China
收录类别	SCI-E
WOS记录号	WOS:000460904500016
WOS关键词	SOUTHEASTERN WEIHE GRABEN ; DEPOSITS ; EXPLORATION ; REGOLITH ; FIELD ; MINERALIZATION ; OVERBURDEN ; TRANSPORT ; DESERT ; FAULTS
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/217032
作者单位	1.Changan Univ, Sch Earth Sci & Resources, Xian 710054, Shaanxi, Peoples R China; 2.UNESCO, Int Ctr Global Scale Geochem, Langfang 065000, Peoples R China
推荐引用方式 GB/T 7714	Lin, Xin,Meng, Ganggang,Chang, Haiqin,et al. Formation of geochemical anomalies in loess-paleosol sequence at the Dahu Gold Mine, central China: A clastic-hydromorphic-gaseous dispersion model[J],2019,200:201-212.
APA	Lin, Xin,Meng, Ganggang,Chang, Haiqin,Zhang, Miaomiao,&Fu, Yalong.(2019).Formation of geochemical anomalies in loess-paleosol sequence at the Dahu Gold Mine, central China: A clastic-hydromorphic-gaseous dispersion model.JOURNAL OF GEOCHEMICAL EXPLORATION,200,201-212.
MLA	Lin, Xin,et al."Formation of geochemical anomalies in loess-paleosol sequence at the Dahu Gold Mine, central China: A clastic-hydromorphic-gaseous dispersion model".JOURNAL OF GEOCHEMICAL EXPLORATION 200(2019):201-212.