潮汕地区全新世障壁海岸三角洲沉积演化与砂体展布

Sedimentary Evolution and Sand-Body Distribution of Holocene Period,Barrier-Coast Delta,Chaoshan Region

全新世我国华南沿海广泛发育障壁海岸,此环境下发育独特的障壁海岸三角洲沉积。基于对潮汕地区的现代地质考察,并总结前人的研究认识,得出该地区韩江三角洲形成演化的主要控制因素为海平面变化、障壁—潟湖体系、河流搬运能力;明确了不同时期三角洲演化的特征及砂体的展布规律;然后,结合螺河三角洲和万宁小海的发育特点,划分出障壁海岸三角洲演化的三大阶段,即形成期:障壁—潟湖体系形成,潟湖内开始形成三角洲;发展期:潟湖内水体稳定,三角洲前积较快,障壁沙坝向海迁移;改造期:潟湖逐渐消失,沉积物开始在障壁沙坝外侧沉积,三角洲向海推进;最后,建立了潮汕地区早期潟湖内河流作用为主、后期障壁外多种动力共同作用下的障壁海岸三角洲的沉积模式。

Since the Holocene, the barrier coast depositional system, and the special barrier-coast delta formed in this environment extensively development in south China coastal. Based on the modern geological investigation in the Cha- oshan region, and summarizing the former researches, we found that evolution of Hanjiang delta in this region mainly affected by sea level change, the development of barrier-lagoon system, the ability of river transportation, and clari- fied evolution characteristics of delta and regularity of sand-body distribution in different periods. Then, combined with the developmental characteristics of Luohe delta and Wanning Xiaohai, the evolution of barrier-coast delta can be di- vided into three stages： formation period, the barrier-lagoon system formed, delta began to develop in the lagoon; de- velopment period, with the high stability of the lagoon water, the delta rapidly prograde, at the same time, the barrier bars migration to the sea; reforming period, lagoon disappeared gradually, sediments began to deposit on the outside of barrier bars, delta seaward progradation; Finally, the barrier-coast delta depositional model has been established in the Chaoshan region, and the former period controlled by fluvial in the lagoon, the later period influenced by variety of dynamic interaction out of the barrier.