摘要
层序地层分析为当代沉积学的重大进展领域和研究热点,主要来自北美边缘海盆地的经验不能简单的用于性质极不相同的、在我国占重要比例的内陆盆地和近海盆地。为此本文从更广泛意义上讨论了层序地层单元和各级建造块的地质涵意,并以在我国不同类型板内盆地中的实践进行了论证,提出了在我国进一步开展层序地层分析的主要问题。
Sequence stratigraphy erected by Northern American geologists has established a relatively perfect concept system and research methodology, based on the investigation of continental margin basins. It has a great influence upon the development of sedimentary basin analysis, biostratigraphy and other fields of geology. Economically important Mesozoic oil and coal-bearing basins and Late Palaeozoic coal-bearing ba sins in China, however, are mostly continental basins or paralic basins characterized by epeiric sea environments, it is impossible to mechanically use the model from continental margin study in the sequence stratigraphic analysis of thses basins. Several key points' that should be stressed are as follows: 1) Unconformities identified in the basins mentioned above are mainly related to tectonic movements, most of them are minor-dip unconformable contacts. Such surfaces have been recognized in Sichuan and Ordos basins mainly by palaeogeological mapping beneath the surfaces. 2) Although it may be impossible to figure out the influence of sea level changes in continental basins, polyphasic major lake level change episodes are usually basin-wide identifiable in large lacustrine basins such as Songliao, Ofdos and Jungar. 3) Even if in paralic basin the low sea level events can not generate unconformities because of very gentle palaeoslop in the basin. 4) The integrated study of seismic stratigraphy and outcrop or core examination should be emphazied in reconstruction of sequence stratigraphic framework. On the basis of integrated analysis, the mapping of depositional section network is neccessary and effective for correlation. 5) High resolution event stratigraphy, particularly the event markers such as volcanic ash beds, coal seams related to the abundance of regional clastic systems, and palaeoweathering residue or surfaces, have been verifies to be very useful in the reconstruction of chronostratigraphic framework.
It is evident that the concept system of sequence stratigraphy should be reconsidered in a broad sense so that to widely use in the study of different types of sedimentary basin. Based on our investigation of Mesozoic
出处
《沉积学报》
CAS
CSCD
北大核心
1992年第4期11-22,共12页
Acta Sedimentologica Sinica
