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The Laba Yanshanian Porphyry Mo(‐Cu) Deposit in Shangri‐ La, NW Yunnan, China: Alteration, Mineralization and its Genesis
Author(s) -
XIANG Kun,
XUE Chuandong,
LI Shilei,
QURESHI Javed Akhter,
NGUYEN Ba Da
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 - 10.1111/1755-6724.12374_61
Subject(s) - china , chinese academy of sciences , library science , rare earth , geography , archaeology , geology , earth science , computer science
The Laba porphyry molybdenum (-copper) polymetallic deposit lies in the western margin depression belt of the Yangtze landmass and is adjacent to the southern connection part of Zhongdian island arc, which belongs to the southern part of the Late Triassic Yidun magmatic arc. The Zhongza block and Jinsha River suture are located in the northwest along the Geza faults zone, and the GarzeLitang suture zone to the northeast. The ore field covering an area of 10 square kilometres is located in Laba valley of Loji town in ShangriLa county, northwestern Yunnan province, southwestern China. Some little copper-, lead-, and zincpolymetallic occurrence in the southeastern The deposit has two ore blocks termed the Tongchanggou ore block and the Laba ore block. Tongchanggou ore block has been discovered in 1985. Till to 2010, the No. KT1 Mo (Cu) orebody was firstly explored by Geology Investigation Institute of Yunnan Bureau of Geological Survey sponsored by Yunnan Copper Industry Group Company(e.g., Li et al., 2012). After that, a number of Mo(Cu) orebodies in the Laba ore block to the northwestern have been explored successively. The investigation confirmed that there is a superlarge porphyryskarn hydrothermal type Mo (Cu) polymetallic metallogenic system with resources reserves of 63.5 mt Mo @ 0.11%, associated with 33.7kt Co@ 0.22% and Au 14.7t @ 0.65ppm. The porphyry intrusions contributed to the mineralization closely, the superficial vein type Mo (Cu, Pb, Ag) orebodies are usually located in faults and secondary fractures, and the deep porphyry type orebodies occurred in the granodiorite porphyries, the skarn type orebodies occurred in the contact zone intruded into limestone and/ or basalts in a certain range. Some intrusions have been wholly mineralized in the Laba deposit, show great prospecting potential. The ore-bearing porphyry age measured by zircon SHRIMP UPb dating is from 83.0 Ma to 86.0 Ma(Li et al., 2012; and this study). It provides some clues for studying Yanshanian mineralization processes in this region. The oreforming elements are rich in Mo mainly in the Laba deposit, however, the surrounding deposits are rich in Cu. Owing to these difference, it may be that they have different tectonic controlling, orebearing magma source and evolution, geological characteristics, oreforming fluid source and evolution (Seedorff et al., 2005; Yang et al., 2008) and so on. The characterization about mineralization processes becomes extremely important. The alteration and mineralization, as the postmagmatic hydrothermal fluid flow record (Sillitoe, 1972), is also macroscopic performance of orebearing magma fluid evolution, its general characteristics and zonation studying is always the basic research of porphyry deposits.