【摘要】 在详细研究各类沉积体系的相序构成和沉积演化过程的基础上,采用动态成因及地层分析的方法,恢复了已遭受严重构造破坏的滇黔桂伸展裂谷海盆地的成因地层格架。根据各类等时地层界面的性质和地层序列划分出了5个沉积幕,详细解剖了各沉积幕的三维空间构成。同时以沉积体系域为单位,恢复了各沉积幕中相应阶段的构造古地理环境,将伸展裂谷盆地的演化历史划分为陆壳初始裂陷和洋壳化阶段、盆地伸展扩张阶段、洋壳俯冲和盆地分化阶段以及盆地聚合碰撞阶段。盆地封闭后,留下了北北东向延续的陆内软碰撞带。更多还原

【Abstract】 On the basis of researches on the facies sequences and depositional evolution of various depositional systems in detail, the genetic stratigraphic framework of a rif-ted oceanic basin due to lithospheric stretching, which had undergone strong structural distortion, has been established by means of dynamic genetic stratigraphic analysis. The evolution history of this ancient sedimentary basin may be subdivided into four stages according to the features of isochronous stratigraphic boundary planes and the stratigraphic pattern.(1) Initial rifting and oceanization stage of continental crust (P2)A NNE trending rifted valley system has been recognized in the basin center. "Submarine volcanic basalt rocks, volcanic debris flow system and pelagic siliceous radiolarian fossils are found in the deep-water rifted valley. The basin-fill sequence formed in this stage includes two depositional episodes controlled by the sea-level change cycle.(2) Stretching and spreading stage of basin basement (T1)The main diagnostic markers are an intracontinental soft collision zone and some remnants of the pelagic depositional system in the central part of the basin. For example, both the basic volcanic rocks with a pillow structure and the volcanic debris flow system may be interpreted as deep marine environments. Because the spatial configuration of depositional systems is discontinuous on both sides of the soft ’collision zone, the authors believe that the oceanic crustal basement and the greater part of the pelagic system were destroyed and covered during the basin convergence and collision stage. Only one depositional episode controlled by sea level change cycle occurred in this stage, so the time range for stretching and spreading of the basin basement might be short, and the basin central pelagic system small.(3) Subduction and basin diversification stage (T2)Two depositional episodes occurred in this stage. The lower depositional episode consisted of three depositional system associations in space: a trench system association with the subaqueous gravity flow system in the central part of basin, a passive continental margin association with the shelf break in the west part, and an .active continental margin system association with the volcanic island and backarc basins in the east part. The soft collision zone is located between the trench association and passive continental margin association. The intermediate-acid volcanic rock, and associated volcanic debris flow system are recognized in the acitve continental margin association. The genetic stratigraphic pattern of this depositional episode might respond to a process of subduction and basin diversification stage. The genetic stratigraphic pattern of the upper depositional episode is simple. There are two continental-margin depositional system asociations only, which represent an initial convergent process of the basin.(4) Convergence and collision stage (T3)A remnant embayment-foreland basin on the passive continental margins and a orogenic fold belt on the active continental margins developed during this stage. Consequently, a soft collision zone which separated the gentle stratigraphic complex of the passive continental margin from the strongly folded stratigraphic complex of the active continental margin was formed as a result of obduction of the active contine ntal margin upon the passive continental margin.更多还原