Premium
Comparisons on Alteration and Mineralization Paragenesis between the Qiaoxiahala and the Laoshankou Fe‐Cu‐Au Deposit
Author(s) -
LIANG Pei,
CHEN Huayong,
BAO Zhiwei
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12372_12
Subject(s) - metallogeny , chinese academy of sciences , paragenesis , beijing , china , geochemistry , mineralization (soil science) , geology , archaeology , geography , sphalerite , soil science , metamorphic rock , soil water , pyrite
belt, which is located in the Sawur Late Paleozoic island arc at the northern margin of the Junggar Terrane and hosted by the Middle Devonian Beitashan Formation volcanic and sedimentary rocks, currently incorporates the Fe-Cu-Au mineralization at Qiaoxiahala (1.44 Mt at 43% ~ 53% Fe, 0.55% ~ 2.21% Cu and 0.13 ~ 2.4 g/t Au) (Li, 2002; Wei, 2002) and at Laoshankou (3.26 Mt at 33.5% ~ 36.42% Fe, 9800 t at 0.19% ~ 0.41% Cu, 1400 t at 0.49 ~ 1.31 g/t Au) (Cheng, 2004; Lv et al., 2012). The Qiaoxiahala deposit is located 30 km to the southeast of Fuyun county, Xinjiang, China, and geologically on the southern margin of the Irtysh Fault. Alteration types mainly include garnetization, amphibolization, epidotization, chloritization, k-feldspathization, silicification and carbonatization. Based on field observations and micro-petrography, the paragenetic sequence can be established as (Fig. 1a): (1) early skarn, (2) late skarn, (3) magnetite stage, (4) magnetite-pyrite stage, (5) Cu (-Au) mineralization stage, and (6) late veins. The Laoshankou deposit is located 41 km to the southwest of Qinghe county and at the intersection between the Irysh Fault and Ertai Fault. Although the wall-rock alteration is similar to Qiaoxiahala, a slightly different paragenetic sequence was identified as (Fig. 1b): (1) early skarn, (2) late skarn, (3) magnetite-epidote stage, (4) pyrite-epidote stage, (5) Cu (-Au) mineralization stage, and (6) late veins. At Qiaoxiahala, the typical skarn alteration minerals, such as garnet and amphibole, are more widely present before magnetite mineralization compared with those in Laoshankou, at which the early skarn alteration is characterized by dominant Hypersthene. Magnetite at Qiaoxiahala is associated with quartz, apatite, sphene and K-feldspar in stage Q-III and with pyrite in stage Q-IV, respectively. However at Laoshankou, magnetite is closely associated with epidote in stage-L-III but not in sulfide mineralization stages. Chalcopyrite, probably associated with Au mineralization, usually replaced early-stage magnetite and pyrite in both Qiaoxiahala and Laoshankou, indicating a possible different hydrothermal fluid system.