碳酸盐成岩作用在碳酸盐沉积学,尤其是在碳酸盐储层沉积学中具有十分重要的意义,近年在以下领域取得重要进展:(1)白云岩烃类储层的几何学和岩石成因学,尤其涉及到对已有白云化模式的评论和重新认识等。(2)碳酸盐储层热液改造的构造控制机理,涉及热液白云岩的成因及其对烃类储层的影响,尤其是深部热流体对碳酸盐成岩作用的影响。(3)对一些经典成岩理论的更新和对传统成岩理论的挑战,尤其是对混合水成岩作用带和对海水环境下的埋藏成岩作用的重新认识等。(4)锶同位素组成在海相碳酸盐研究中的广泛应用,涉及对地质事件的跟踪研究、海相地层的等时对比、定年和成岩过程中水一岩相互作用的研究等。然而,碳酸盐成岩作用研究中也存在一些问题值得我们思考:(1)深埋条件下碳酸盐最为重要的溶解介质可能是作为硫酸盐还原作用产物的H2S和CO2,但并非是温度越高,碳酸盐越溶解,相对较低的温度条件反而有利于溶解,这就是所谓的倒退溶解模式。(2)碳酸盐溶解需要有温度的降低(即必须要有足够的负△T),这可通过两种途径实现:其一是沿断层向上运移的流体,显示断层等构造作用在碳酸盐成岩研究中的重要性;二是构造抬升,显示与构造有关的埋藏历史在碳酸盐成岩研究中的重要性。(3)控制白云石锶含量最为重要的因素是其晶体化学习性,锶在白云石中的较低的分配系数导致了白云岩普遍较低的锶含量,因此,我们不能仅利用白云岩的锶含量来判断白云化流体的性质,白云岩较低的锶含量也不能说明相应的白云化流体与海水无关。(4)与硫酸盐还原作用有关的SO4^2-的带出会诱发白云化作用或白云石的沉淀,而与硫酸盐溶解有关的SO4^2-的引入则会加速白云石的溶解。
Carbonate diagenesis is an important branch in carbonate sedimentology, especially in carbonate reservoir sedimentology. Recently, there have been remarkable advances on carbonate diagenesis in the following aspects: 1) the geometry and petrogenesis of dolomite hydrocarbon reservoir, particularly referring to the review and reappraisal on dolomitization models cited by many sedimentologists for a long time; 2) the mechanism of structurally controlled hydrothermal alteration of carbonate reservoirs, concerning the origin of hydrothermal dolomite and its effects on hydrocarbon reservoir, especially the influences of hydrothermal fluids on carbonate diagenesis in deep-burial setting; 3) renewals of classic diagenesis theories of carbonate and challenges to past diagenesis theories that people have been using until now, some new sights of diagenesis in marine-meteoric mixing-zone and marine-burial environments should make us to reappraisal the understanding of carbonate diagenesis; 4) wide application of strontium isotope composition to marine carbonate sedimentology, including isochronous correlation of sedimentary sequences, directly dating marine sediments, and interaction of water-rock during diagenesis. However, some following questions existing in the carbonate diagenesis need us to pay more attentions to: 1) the most important dissolving fluids to carbonates are probably H2 S and CO2 as byproducts of sulfate reduction in deepburied setting with sulfate minerals, but carbonates are more soluble in relatively low temperature, which is so-called retrograde solubility; 2) a temperature difference (△T) for cooling water to dissolve carbonates can be implemented by following two geological processes: (1) fluids flowing upward along faults, showing the importance of faults in carbonate diagenesis; (2) tectonic uplift, suggesting the significance of burial history related to tectonics in carbonate diagenesis; 3) the first thing controlling Sr content in dolomite is the crystalline che