TANG Yong-yong¹, ZHANG Ke-xue^2*, TIAN Ya-jiang³, ZHANG Jia-wei⁴, HUANG Zhi-long¹, WU Tao^1,5

(1. State Key Lab of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. 1st General Team, Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou, Guiyang 551400, China;
3. Guizhou Institute of Geophysical and Geochemical Prospecting, Guiyang 550018, China;
4. Guizhou Geological Survey, Guiyang 550081, China; 5. University of Chinese Academy of Sciences, Beijing 100049, China)

Abstract: The western Hunan and eastern Guizhou are significant Pb-Zn metallogenic areas in China with similar geological settings of metallogeny. However, the Pb-Zn deposits in the eastern Guizhou are much smaller in size than those in the western Hunan. It remains unclear about the reasons for this differential mineralization. In this paper, we have carried out a comparative study between REE compositions of ore-stage hydrothermal calcites of the Bokouchang, Xiunao, and Kema deposits in the eastern Guizhou and representative deposits in the same metallogenic belt (Huayuan, Niujiaotang deposits) and some typical super-large Pb-Zn deposits in other areas (Jinding and Huize deposits), to provide a constraint for understating the source of ore-forming materials. Calcites from Bokouchang, Xiunao, and Kema deposits in the eastern Guizhou have similar REE distribution patterns with characteristics of low ΣREE contents (1.6×10-6－22.5×10-6), little differentiation between LREE and HREE, negative Ce anomalies (δCeSN=0.62－0.81), and positive Gd and Y anomalies (δGdSN=0.78－1.23, δYSN=0.99－1.78), indicating that the REE of ore-forming fluids could be mainly sourced from the ore-hosted carbonate of the Lower Cambrian Qingxudong Formation. In contrast, calcites of the Huayuan and Niujiaotang deposits have relatively high ΣREE contents (average 28×10-6 and 24×10-6), implying an addition of REE-rich fluids or water-rock interactions between the ore-forming fluid and underlying REE-rich basement. Calcites of the Jinding and Huize deposits have the highest ΣREE contents (average 78×10-6 and 73×10-6) and positive Eu anomalies (average δEuSN=1.11 and 1.55), suggesting that the ore-forming fluids had experienced high-temperature water-rock interaction in the deep part of crust or basement. It is concluded that the ore-forming fluids of Pb-Zn deposits in the eastern Guizhou could have dominantly originated from the host rocks of marine carbonates, whereas those of the Huayuan, Niujiaotang, Huize, and Jinding deposits, could be derived from a mixture of variously sourced fluids or strongly interacted with underlying basement rocks. The multi-sourced fluids or strong water-rock reaction between ore-forming fluid and REE-rich basement rocks could be significant causes for the formation of the large and super-large Pb-Zn deposits.

Keywords: The ore genesis; rare earth elements; calcite; Pb-Zn deposit; the western Hunan－eastern Guizhou metallogenic domain

ACTA MINERALOGICA SINICA Vol. 40, No.4, 2020, page 356-366