全新世以来珠江三角洲快速沉积体的初步研究

A preliminary study on rapid deposition bodies in the Zhujiang Delta since Holocene

根据珠江三角洲代表性钻孔资料以及PRD-LTMM长周期"动力-沉积-形态"模型分析了珠江三角洲形成发育过程中的快速沉积现象,提出了珠江三角洲快速沉积体的概念,并且对典型快速沉积体的成因进行了初步分析。快速沉积体有明确的沉积环境和特定的沉积动力成因,沉积速率为每年厘米级,研究它可以深入地揭示珠江三角洲基本沉积单元的形成过程,为探索珠江三角洲的形成、发育机制打下基础。初步发现的快速沉积体有古汇潮点快速沉积体、古涨潮射流快速沉积体和台地周边快速沉积体。研究结果表明,快速沉积体的形成多与特定的地形边界条件下形成的中、小尺度动力结构有关,具有高度的时空变化。掌握珠江三角洲地形边界的特点、变化过程及其作用下的中、小尺度动力结构是研究珠江三角洲快速沉积体的关键。

Based on the typical bore holes of the Zhujiang Delta and the long-term morphodynamic model PRD-LTMM, rapid deposition body （RDB） is examined. The RDB is defined, and the formations of typi- cal RDBs in the Zhujiang Delta are analyzed initially. The RDBs hold the specific sedimentary environment and particular sedimentary dynamics with the annual deposition rate of centimeters; so, the research on the RDBs can help disclose the mechanism of the basic sedimentary units in the Zhujiang Delta, providing a basis for the study of mechanism of the Zhujiang Delta evolution. The initially discovered RDBs include depositions at the paleo-tide convergent flow and the paleo-flood tidal jet, fringing deposition around the palco- terrance. A study result shows that the formation of RDBs, with being highly variable in time and space, is related to the small- to medium-scale dynamic structures under particular morphologic boundaries. Understanding the morphologic boundary,its evolution process and medium- to small-scale dynamic structures under corresponding morphologic boundaries in the Zhujiang Delta is key to the research of the RDBs.