【摘要】 不整合是地层记录中最显眼的最壮观的地质现象之一,这种表现为地层的不协调接触关系的地层面具有复杂的地质学涵义。上世纪60年代以前,地质学家对不整合的地质涵义主要集中在构造地质学方面,因为角度不整合明显包含着褶皱幕,这不但产生了构造旋回或构造地层学的概念,而且产生了繁杂混乱的不整合名称。在沉积岩地层中,不整合常常表现为两种:角度不整合面和平行不连续面;前者表明存在明显的构造作用,后者可能意味着构造上升,而且均包含有明显的地层缺失。早期的学者将不整合面所限定的地层序列定义为"层序",代表只是由不整合面所限定的地层单位;随着地震地层学的兴起和广泛应用,地层体内部各种终止现象的发现、以及它们的地层学和沉积学解释,导致了层序地层学的出现,从而产生了"层序"这一术语的变化,即"不整合面及其可以对比的整合面所限定的相对整合的地层序列"为新的"层序"概念。新的定义不但使层序地层学进入了地层学实践的主流,而且赋予了层序地层学新的活力。但是,在基于地震资料的层序地层学模式中,把可以对比的整合面被刻画为等同于基准面上升的时间面。这种将概念性的时间面作为层序界面一部分的使用,导致了层序地层学等同于年代地层学,而且这种解释导致了一系列的误解和问题,这些问题主要包括层序地层学中单元的定义和界面的识别。特别有趣的是,基于地震反射终止所提供的地层体内部各种复杂的终止现象,在建立"沉积层序"的地震地层学模式时,地质学家们展现了极为精妙的地层穿时性的实际几何形态。所以,追索不整合面的复杂地质涵义来了解层序地层学的发展和存在问题自然就成为层序地层学的重要科学命题之一,解读前辈学者对这个科学命题的长期探索将有助于层序地层学的进一步发展。更多还原

【Abstract】 As a conspicuous geological phenomenon that mark the discordant contact relationship between strata,unconformity is an important stratigraphic surface with complex geological meanings.In the 1960s,most studies focused on the tectonic meaning of unconformity because an angular unconformity signifies a folding episode,which led to both the important concept of tectonic cycle or tectonic stratigraphy and the confusing nomenclatures of unconformities.In depositional strata,there are mainly two types of unconformities that are the angular unconformity and the leurodiscontinuity.An angular unconformity indicates an obvious tectonic event and a leurodiscontinuity implies a crustal uplift,both of which mark distinct stratigraphic hiatuses.In early times,a stratigraphic succession bound by unconformities was defined as a "sequence",or an "Unconformity"-bounded Unit.With the rise and broad application of seismic stratigraphy,both the discovery of many stratigraphic terminations within strata and their stratigraphic and sedimentological interpretations led to the emergence of an important and new stratigraphic discipline:sequence stratigraphy.Further,the term "sequence" has been modified to refer to a unit "bounded by unconformities or their correlative conformities".This new definition made sequence stratigraphy a mainstream of stratigraphic practice.However,correlative conformities were portrayed as time surfaces equivalent to the start of base level rise on their sequence stratigraphic model which was based on the seismic data.The use of conceptual time surfaces as part of the sequence boundary made sequence stratigraphy equated with chronostratigraphy.This interpreted equivalence between sequence stratigraphy and chronostratigraphy has led to a number of misconceptions and problems associated with boundary recognition and unit definition in sequence stratigraphy.More interestingly,during the construction of a depositional sequence model on the basis of the complex termination of seismic reflections within strata geologists have recognized excellent geometrical pattern of stratigraphic diachronism.Therefore,it is important to further understand the problems and development of sequence stratigraphy to untangle the complex geological meanings of unconformity,which is the most important scientific problem of sequence atratigraphy.Furthermore,a thorough understanding of the accumulated research by the founding scholars on the complex geological meanings of the unconformity is very helpful to further the field of sequence stratigraphy in decades ahead.更多还原