定量模拟层序叠加模式对断陷盆地非均一构造沉降活动的响应

Discussion on the Response of Sequence Stacking Patterns to Asymmetrical Tectonic Subsidence Depending on the Sequence Quantitative Simulation

利用SEDPAK二维层序模拟软件,通过考虑控制层序沉积过程的不同参数,探讨层序叠加模式对断陷盆地非均一性构造沉降活动的响应。结果表明,在非均一构造沉降活动作用下,盆地两侧同期层序显示出同步和非同步的叠加模式。同步叠加模式即盆地两侧同期层序同为退积或进积特征,非同步叠加模式即盆地两侧层序叠加模式相反(一侧退积,另一侧则进积)。同期层序非同步叠加模式的形成机理是盆地一侧可容纳空间的增量(△A)小于沉积物供应(△S)(△A<△S),而另一侧盆地一侧可容纳空间的增量大于或等于沉积物供应(△A≥△S)。此外,二者可以控制非同步叠加模式的持续时间。同期层序非同步叠加模式的识别,对陆相层序地层研究提出新的认识,尤其是对我国东部新生代断陷盆地的层序研究,具有一定的参考价值。

On the Basis of stratigraphic modelling using the SEDPAK computer program, the response of sequence stacking patterns to asymmetrical tectonic subsidence within a rift basin was simulated by considering the various parameters controlling the deposition of a sequence. The simulation results indicate that isochronous sequence stratigraphy within a rift basin may exhibit both synchronous and non-synchronous stacking patterns at different part of the hasin. Synchronous stacking patterns refer to that at any part of the basin the same transgression, retrogression and aggression occurs concurrently. Non-synchronous stacking patterns refer to that within the same basin some part may exhibit the exact opposite stacking patterns as other parts concomitantly. The development of non-synchronous stacking patterns were found to be caused by the combination of both accommodation space increment（△A） more than sediment supply increment（△S） （△A 〈 △S）in one side of basin and accommodation space increment （△A）less than or equal to sediment supply increment （△S） （△A ≥ AS）in other sides of basin. Meanwhile, duration of non-synchronous stacking patterns was controlled by the interplay of accommodation space increment（△A） and sediment supply increment（△S）. Reeognition of non-synchronous stacking patterns of isochronous sequence stratigraphy provides a new insight into continental sequence stratigraphy, and might be widely applicable for the Cenozoic basins in the eastern China.