滨海相沉积压实量研究与深沪湾海底古森林及晚更新世古牡蛎滩遗迹  

The Research of Compaction Measure of Littoral Sediment and Vestiges of the Ancient Submarine Forest and Ancient Oyster Belt in Late Pleistocene of Shenhuwan Bay

作　　者：徐起浩[1] 

机构地区：[1]广东省地震局,广东 广州

出　　处：《地球科学前沿（汉斯）》2020年第4期346-364,共19页Advances in Geosciences

基　　金：中国地震局2018年老专家科研基金(2018-05)。

摘　　要：本文是笔者多年来对福建深沪湾距今7500 a左右海底古油杉森林和距今25,000~15,000 a晚更新世古牡蛎滩遗迹在今天潮间带浅滩同存成因研究导致滨海相沉积压实量研究的过程及所获最新认识的综合论述。笔者对东南沿海古气候和古海平面进行了研究,结果指出距今8000~7200 a古气候比今天凉,今天生长在福建500 m以上至1200 m丘陵山上的古油杉森林当年在相对低海拔的深沪湾陆地也能生长。古海平面研究结果表明距今45,000年以来滨海相沉积是连续的,水动型海平面是渐进上升的。设定滨海相沉积无压实,论证场址距今45,000 a以来地壳稳定,提出了《广东中山石岐距今45,000 a以来的渐进上升水动型海平面变化曲线》。根据该曲线,距今21,000~15,000年的海平面相应在今天海拔约?8.2~?4.7 m之间。利用滨海相沉积,结合该曲线,通过多手段研究揭示:深沪湾及沿岸今天地貌景观主要是由大约距今12,000 a以来当地3次大古地震造成。距今47,500 a以来深沪湾经历了三次陆变海和二次海变陆的过程。沿岸地堑边缘古河流的生成及后来被堵塞,形成龙湖前港湖等地震断塞湖也可能是由深沪湾全新世距今大约7000 a和距今2400 a两次大古地震先后造成的。这些研究结果催生了晚更新世中晚期以来的滨海相沉积压实量研究。本文介绍了笔者沉积压实研究的起因,与研究相关的经验及研究的路径。研究结果显示滨海相沉积渗水不好,地表下40 m以浅或晚更新世中晚期以来滨海相沉积无明显压实作用。在用滨海相沉积研究古海平面研究海岸带地壳运动和古地震时一般可不考虑沉积压实影响。本文还指出现代黄河三角洲的大速率缓慢下沉不是由沉积压实造成,而可能主要是由地震构造作用造成。The paper is a comprehensive discussion on the course of that the research cause of the formation of the paleo-keteleeria forest about 7500 a.BP and the paleo-oyster belt of 25,000~15,000 a.BP exist in the tide belt of Shenhuwan Bay at the same time today, which led to the research of compaction measure of littoral sediment and new knowledge are acquired of the writer for many years. The author had studied the palaeo-climate and palaeo-sea-level change of the south-east coast of China. The results show that the climate in 8000~7200 a.BP is cooler than that today and led to that the keteleeria forests of growth in hills of 500 to 1200 m above sea level today can grow in the area of lower sea level land of Shenhuwan Bay. The research of paleo-sea-level shows that the sediments of littoral facies have been almost continuous and the “eustatic” sea level was raised with gradual advance since 45,000 a.BP. “Guangdong Zhongshan Shiqi related curve of ‘eustatic’ sea level changes with gradual advance since 45,000 a.BP” has been built, which supposes that the deposits of littoral facies are not compacted and the crust at the site has been stable since 45,000 a.BP that has been proved. The curve shows that the sea levels were roughly ?8.2 m to ?4.7 m for 21,000 a.BP to 15,000 a.BP. The research reveals that today landform of Shenhuwan Bay and along the coast is created because three times great earthquakes occurred since 12,000 a.BP in the location and the process was undergone of land changes to the sea of three times and the sea changes to the land of two times in Shenghuwan Bay since 47,500 a.BP in samples of littoral facies deposits and linked the curve and some methods of the research. The original ancient rivers occurred and stopped up later and 4 earthquake-faulted-dammed lakes of Long Hu Lake, Qian Gang Lake et al. were formed due to two earthquakes occurring before and later in Holocene of Shenhuwan Bay. The result of these researches presses the writer for the study of compaction measure of littoral se

关 键 词：海底古森林 海底古牡蛎礁 潮间带海底共存 古海平面变化与古地震 催生研究 滨海相沉积 无明显沉积压实 现代黄河三角洲 

分 类 号：P61[天文地球—矿床学]