GUO Hai-yan1,2, XIA Yong1*, HE Shan1,2, XIE Zhuo-jun1, WEI Dong-tian1,2, LEI Bo3
(1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China;
3. Sichuan Institute of Geological Engineering Survey, Chengdu 610017, China)
Abstract: Zhijin phosphorite-type rare-earth deposit in Guizhou Province, China is a giant deposit occurred in the phosphorus-containing strata of the Gezhongwu Formation, with a REE resource of 3.5 Mt. In this study, samples collected from four core drill holes, one outcrop, and one pit were analyzed by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X fluorescence spectrometry (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). Results indicate that the REE dissolved in the structure of phosphorite, rather than occurred in form of independent mineral. The arenaceous phosphorite and the dark part of laminated phosphorite from the bottom of the Gezhongwu Formation are rich in REE. The chemical analysis results of Fe/Ti, (Fe+Mn)/Ti, Al/(Al+Fe+Mn) ratios, As and Sb concentrating coefficients, U-Th relationship, REE distribution patters, and δEu, show that REE-containing samples of the Gezhongwu Formation have hydrothermal features. The comprehensive analysis shows that REE-rich samples have hydrothermal and weathering features, suggesting that the REE enrichment might be related to hydrothermal sedimentation and weathering reformation.
Keywords: phosphorite type rare-earth deposit; ore characteristics; REE accumulation; geochemical characteristics
ACTA MINERALOGICA SINICA Vol. 37, No. 6, 2017, Page 755-763
