191 / 2019-06-12 22:19:20

火山作用对碳酸盐岩的影响（Influence of volcanism on carbonate rocks）

火山作用；碳酸盐岩；沉积环境；生物演化；成岩作用（volcanism; carbonate rocks; sedimentary environment; biological evolution; diagenesis）

火山作用是熔岩（岩浆）、火山碎屑和火山气体通过火山口喷出到地球表面的现象。火山爆发可以将大量的火山碎屑或火山灰喷射到大气、水生和陆地环境系统中，这将对其中碳酸盐沉积物的成分、结构、沉积构造、相序及沉积演化过程产生重要影响。火山物质含量的增加不仅会干扰碳酸盐沉积从而影响碳酸盐岩纯度，还能够改变其物理化学性质等，在空间上遵循粒度分异的规律。在组合方式上往往出现火山岩-碳酸盐岩双层结构，可以揭示火山活动的演化。碳酸盐岩主要形成于海洋、湖泊等环境中，火山作用可以通过影响台地的差异沉降/隆起、基底形态、热液喷涌、输入不同性质的火山碎屑物质和分布等，影响生物、沉积水体性质等古环境参数。然而在生物方面，这种影响通常具有破坏性和建设性等双面作用机制。例如火山灰的埋藏以及释放有毒物质会导致生物死亡，然而后期悬浮灰溶解又会释放PO3-、Fe3+、Mn2+等营养离子利于生物生长。就成岩作用及成岩流体性质而言，不同类型的火山物质所含不同元素、矿物等，导致流体性质的变化，进而影响碳酸盐成岩作用类型等，例如硅质交代、燧石结核、白云石化以及多期硅质胶结等等。在火山灰的沉积影响下，沉凝灰岩储层内部多种孔隙的形成说明了火山作用对碳酸盐岩储层物性改善具有积极作用，因此研究火山作用对碳酸盐岩的影响在油气勘探方面具有重大意义。
Volcanism is a phenomenon in which lava(magma), pyroclastics and volcanic gases are ejected through the vent to the surface of the earth. Volcanic eruptions can inject large amounts of pyroclastics or volcanic ashes into atmospheric, aquatic, and terrestrial environmental systems, which can have an important impact on the composition, structure, sedimentary structure, facies sequence, and sedimentary evolution of carbonate deposits. The increase of volcanic material content not only affects the purity of carbonate rock by interfering with carbonate deposition, but also change its physicochemical properties, etc., and follow the law of particle size differentiation in space. The volcanic-carbonate double-layer structure often appears in combination, which can reveal the evolution of volcanic activity. Carbonate rocks are mainly formed in marine, lacustrine and other environments. Volcanism can affect paleo-environmental parameters such as biological and sedimentary water properties by affecting differential subsidence / uplift of the platform, basement morphology, hydrothermal spurt, input of different characteristic pyroclastic materials and distribution, and so on. On the biological side, however, the effects are usually double-sided mechanisms, such as disruptive and constructive. For example, the burial of volcanic ash and release of toxic substances from ash will lead to the death of organisms. However, the dissolution of suspended ash at the later stage will release PO3-, Fe3+, Mn2+ and other nutrient ions, which are beneficial to the growth of organisms. In terms of diagenesis and diagenetic fluid properties, different types of volcanic materials contain different elements, minerals, etc., which lead to changes in fluid properties, which in turn affect carbonate diagenesis types, such as siliceous metasomatism, vermiculite nodules, dolomitization, and multi-stage siliceous cementation and so on. Under the influence of volcanic ash deposition, the formation of various pores in the sedimentary tuff reservoir indicates that volcanism has a positive effect on the improvement of carbonate reservoir physical properties. Therefore, it is of great significance to study the influence of volcanism on carbonate rocks in oil and gas exploration.