摘要
山东七宝山隐爆角砾岩型Cu-Au矿床位于郯庐断裂带东侧,矿体主要赋存在七宝山杂岩体中。通过显微学观察,发现在深部蚀变斑岩的重结晶石英斑晶中发现了含子晶包裹体（Type 1型）,同时伴生有气相（Type 2型）和富气相水溶液（Type 3型）包裹体。浅部矿坑石英脉中的流体包裹体主要为气液两相包裹体,并对较为发育的石英晶柱进行了详细的阴极发光特征和显微学观察研究。从其根部到末端可以划分为三个期次,其中第一期次石英环带中主要发育富液相包裹体（Type4型）,另外还发育少量的负晶形气液两相包裹体（Type 5型）,第二期石英环带中主要发育Type 5型包裹体,第三期石英环带中主要发育形态各异的气液两相包裹体（Type 6型）。显微测温结果显示,Type 1型包裹体均表现为子晶熔化均一特征,均一温度介于375-450℃之间,计算获得的盐度为43.8%-52.2%NaCleqv;Type 3型包裹体表现为临界均一特征,均一温度介于347-420℃之间,估算盐度为0.8%-7.1%NaCleqv;Type 4,5和6型包裹体均均一至液相,均一温度分别为221-327℃、199-379℃以及109-193℃,相应的盐度为2.4%-7.8%NaCleqv、10.2%-16.8%NaCleqv以及0.3%-4.0%NaCleqv。热力学计算获得Type 1型包裹体均一压力为623.46-1111.82bar,平均855.70bar。Type 3型包裹体均一压力范围为139.18-362.47bar,平均为250.70bar。由此可以认为,尽管富气相包裹体和含子晶包裹体共存,并且具备相近的均一温度范围,但是压力相差极为明显,所以这种共存特征并不能表征流体沸腾作用。根据前人实验研究结果,本文认为Type 2和3型包裹体代表了斑岩体结晶早期由于上覆地层隐爆而导致的压力降低条件下分异出来的流体,由于角砾岩筒后续固结引起压力增加,由Type 1型含子晶包裹体所代表的高盐度流体逐渐从成矿岩体中分异出来。当这两种流体沿裂隙通道向上运动时,被同期石英包裹体�
The Qibaoshan deposit is a large Cu-Au deposit located in southwest of Shandong Province,China. Three types of fluid inclusions are recognized in recrystallized quartz phenocrysts of the deep located altered porphyry： Type 1,halite-bearing inclusions;Type 2,pure vapor inclusions; and Type 3,vapor-rich inclusions. They commonly show coexistence in samples. Two types of fluid inclusions in quartz veins with different ore minerals representing different hydrothermal stages,and in quartz crystal column collected from the shallow open pit are identified in this study： Type 4,liquid-rich inclusions with vapour volume fraction of 5% - 8%; Type 5,aqueous inclusions with vapour volume fraction of 10% - 20%,which can be subdivided into 5a and 5b according to their differential occurrences. Microthermometric analyses indicate that Type 1 inclusions homogenized via halite dissolution at temperatures of 375 to450℃ with calculated salinities of 43. 8% to 52. 2% Na Cleqv; Type 3 inclusions displayed a critical homogenization mode based on the comparison between homogenization pressures and critical pressures at the same homogenization temperatures（ 347 to 420℃） with calculated salinities of 0. 8% to 7. 1% Na Cleqv; Type 4,5a and 5b inclusions homogenized to liquid phase at temperatures of 221 to327℃,199 to 379℃ and 109 to 193℃,respectively,with calculated salinities of 2. 4% to 7. 8% Na Cleqv,10. 2% to 16. 8%Na Cleqv,and 0. 3% to 4. 0% Na Cleqv,respectively. Type 2 inclusions were not analyzed in this study due to high vapor volume fraction（ 〉80%）,which makes observation of homogenization behaviors difficult. The coexistence of Type 1,2 and 3 inclusions is not caused by fluid immiscibility,because the homogenization pressures（ Ph） of Type 1 inclusions（ Ph = 623. 46 to 1111. 81bar） are much higher than those of Type 3 inclusions（ Ph = 139. 18 to 362. 47bar）. According to previous experimental researches,fluids represented by Type 2 and 3 inclusions are believed to be directly exsolved from the
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第4期1015-1030,共16页
Acta Petrologica Sinica
基金
国家自然科学基金项目(41172083)资助
