摘要
红透山块状硫化物矿石主要成分为黄铁矿、磁黄铁矿、黄铜矿、闪锌矿和石英、角闪石、黑云母等脉石矿物。切成长40mm 直径17mm 的矿石圆柱用20wt%NaCl 溶液浸泡260小时后装入长江500型活塞-圆筒式三轴应力试验机,在362℃414MPa 围压下加1342MPa 轴压,13小时后于空气中自然冷却。实验后试样长度压缩为32.3mm,算得应变速率为4.1×10^(-6)/s。实验产物中出现大量垂直应力轴的松弛裂缝。黄铁矿强烈脆性破裂,而磁黄铁矿、黄铜矿和闪锌矿以塑性变形为主,局部也发生脆性破裂。再活化黄铁矿、磁黄铁矿和黄铜矿分别充填同种矿物的碎粒间隙。再活化产物也呈细脉穿插脆性变形的黄铁矿碎斑,细脉中以黄铜矿为主,其次是磁黄铁矿,有时含极少量闪锌矿,在磁黄铁矿、黄铜矿和闪锌矿的塑性变形区内,以及变形的石英和其它脉石矿物中均无再活化硫化物产出。实验结果表明在构造应力作用下强干性矿物和地质体容易发生脆性变形,从而为再活化成矿流体的运移和析出矿质提供通道和空间,而韧性变形区较难提供流体通道和矿质沉淀空间。所以,再活化成矿作用容易发生在脆性变形区和韧-脆性转换部位。原生矿石中的黄铜矿在实验条件下比其它三种硫化物更容易再活化。脆性变形的黄铜矿和黄铁矿比起其它矿物来更容易接受含铜流体的叠加,因此地层中的含铜黄铁矿矿胚层最容易受叠加流体作用而形成层控富矿床。
The ore as starting material for the experiment was taken from the Hongtoushan massive sulphide deposit, and is composed predominantly of pyrite, pyrrhotite, chalcopyrite, sphalerite, quartz and silicate minerals. The ore was cut into a cylinder 40 mm in length and 17 mm in diameter, immerged in a NaC1 solution of 20 wt% for 260 hours, and then was mounted in the 3-axes rock stress machine Changjiang 500. After the experiment performed for 13 hours at temperature of 362℃, confining pressure of 414 MPa and axial pressure of 1342 MPa, the sample was cooled at room temperatures for 24 hours Determination indicates that the sample has compressed to a length of 32.3 mm. The strain ratio is calculated at 4.1 × 10^-6/s. A set of relax fractures perpendicular to the long axis of the sample is observed. Pyrite has been intensely cataclastically deformed, while pyrrhotite, chalcopyrite and sphalerite are dominated by plastic deformation with local cataclastic textures. Remobilized pyrite, pyrrhotite and chalcopyrite are tound to fill fractures of the same minerals, or occur as veinlets cutting cataclastically deformed pyrite porphyroelasts. Minerals in the veinlets are dominated by pyrite with less pyrrhotite, while sphalerite is only locally seen. However, no remobilized sulphides occur in plastically deformed areas in pyrrhotite, chalcopyrite and sphalerite, and in deformed gangue minerals, such as quartz. The experimental results show that, in contrast to plastic minerals and geological bodies, cataclastieally deformed competent minerals and geological bodies will provide more conduits and spaces for fluid transport and metal precipitation. Chaleopyrite will be more easily remobilized than pyrite, pyrrhotite and sphalerite by NaCl-rich fluids under conditions for this experiment. Cataclastically deformed chalcopyrite and pyrite are more favorable than other minerals for overprinting of Cu-bearing remobilizing fluids, Therefore, embryo ore beds containing sedimentary. Cu-bearing pyrite in the strata will be easily overprinted bv metal-bearing fluids to form enriched strata-bound ore deposit.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第5期1429-1434,共6页
Acta Petrologica Sinica
基金
本文为国家自然科学基金项目(No.40172034
40234051
40221301.40472042)成果
关键词
流体
再活化
变形
块状硫化物矿床
层控矿床
Fluid, Remobilization,Detbrmation, Massive sulphide deposit, Strata-bound ore deposit
