块状硫化物矿床与火山岩岩相的关系

块状硫化物矿床(黄铁矿型矿床、黑矿型矿床)与玄武岩-流纹岩建造的相互关系是由矿石与围岩形成的近似性所决定的,更确切地说,是矿石有规律地产在火山岩一定的岩相中。近年来,火山岩系的岩相分析已成为火山岩地区区域地质调查、块状硫化物矿床普查勘探工作中最重要的方法之一。这是因为,一方面岩相分析和古火山恢复方法,可以对火山体、火山岩系的喷发沉积旋回,以及火山岩的层序进行详细的研究,从而较为客观地总结出

The Relationship Between Massive Sulfide Deposits And Volcanic Rock Facies

The genetic relationship between massive sulfide deposits and volcanic rock facies finds its expression in three aspects: 1. Ore-bearing portions lie mostly at the transitional positions between different volcanic rock facies. In the volcanic sedimentation section, ore beds occur where lithological characters alter in each cycle, especially where relatively basic volcanic rocks are replaced by relatively acid ones. 2. Ore deposits of different types are distributed regularly in specific volcanic, rock facies: volcanic-sedimentary deposits, volcanic exhalative-hydrothermal sedimentary deposits and volcanic ore-magmatic effusive deposits, all formed in sea-floor environment, are found respectively in sedimentary volcaniclastic rocks of distant zone, volcaniclastic rocks of intermediate zone and highly alkalic and sodium-rich basic volcanic rocks closely around the crater; volcanic ore magma-filled deposits and volcanic hydrothermal metasomatic deposits, produced at very shallow depths, are observed respectively in highly alkalic and sodium-rich basic lava of volcanic vent facies and acid volcanic rocks of volcanic vent facies and explosion facies; volcanic porphyry type deposits, formed at certain depths below the surface, mostly occur in subvolcanic and hypogene volcanic facies. The formation of different industrial types of massive sulfide deposits seem also to have been obviously under the domination of volcanic rock facies: copper-bearing pyrite type deposits and pyrite type copper-zinc deposits occur chiefly in volcanic rocks of vent or near vent facies; pyrite-polymetallic deposits and kuroko deposits exist primarily in tuff of transitional facies and distant carbonatite-terigenous rocks-tuffaceous facies. 3. Ores are noticed to occur in certain volcanic rock facies which have some distinctive characteristics in constituent, chemical composition of near-ore country rocks, texture and structure as well as mechanical properties.