RAO Can1, CHEN Han-lin1, LI Zi-long1, MENG Li-feng1, HU Yan-hua2
(1. Department of Earth Sciences, Zhejiang University, Hangzhou 310027, China;
2. Zhejiang Institute of Geological Survey, Hangzhou 311203, China)
Abstract: The Lizhu iron deposit in Zhejiang Province, China is a typical skarn-type deposit located in the east part of the Qinhang Metallogenic Belt in southern China. The ore bodies are lenticular, bedded, and irregular, and are located in skarn in a wide contact zone of Nanhua system of Sinian system, of the Cambrian and Ordovician periods along the external contact belts of the Guangshan granite complex. The main skarn minerals include diopside, garnet, Fe-rich edenite, phlogopite, chlorite and titanite. The main metallic minerals are magnetite, pyrite, galena, sphalerite and molybdenite. The skarn minerals discussed in this paper were studied using electron microprobe analyses. Results show that the Lizhu iron deposit experienced a period of skarnization and a period of hydrothermal alteration. The period of skarnization is divided into a pyroxene-garnet phase, a magnetite phase and a hornblende-phlogopite phase. As well, the hydrothermal alteration period includes a quartz-sulfide phase and a quartz-carbonate phase. The pyroxene end-member is dominated by diopside, and is altered into hedenbergite (Mg2+ to Fe2+); and garnet is altered from grossular into andradite (Al3+ to Fe3+). These features suggest a progressive concentration of Fe3+ ion and increasing oxygen fugacity f(O2) in mineralization fluids during the early period of skarnization. The Na-, K-, and F-bearing Fe-rich edenite, F-rich phlogopite and titanite, and fluorite phenomenon, indicate that ore-forming fluids are alkaline and enriched in F, which favour the migration, enrichment and mineralization of iron. The formation of the Lizhu iron deposit is related to multiple periods of magmatic hydrothermal activity in the Guangshan-Shanxi plutons.
Key words: skarn; mineralogy; mineralization stage; mineralization fluids; Lizhu iron deposit
ACTA MINERALOGICA SINICA Vol. 34, No. 3, 2014, Page 328-336
