浙江杭州东苕溪平原全新世沉积地貌环境演变及与新石器文明关系的初探

发布时间：2018-05-03 10:29

本文选题：全新世 + 杭州东苕溪平原　；参考：《华东师范大学》2012年硕士论文

【摘要】：末次冰消期结束后,进入全新世大暖期,随着东亚季风环流的扩张,持续增暖的气候使本区文明得以重新发展,从而促进了新石器文化的发展。据不完全统计,太湖-宁绍平原已发现140处新石器文化遗址,研究史前文明和古环境演变规律,对本区经济发展和未来人地关系有着深远的意义。为了弄清楚杭嘉湖平原的环境演化过程及与良渚古文明兴衰的关系,本文在浙江杭州东苕溪流域的安溪镇取得XL钻孔,全长29m,该孔位于杭嘉湖平原西部南北向的古湖州-杭州河谷西侧谷坡上。本文对XL钻孔进行了粒度、磁性、有孔虫的分析,结合其岩性的特征,表明该区全新世沉积环境经历了五个阶段,依次为滨海平原相-潮滩相-河口湾相-潮滩相-泛滥平原相,沉积物的年龄和高程反映了该区环境的演变受控于海平面的变化。沉积环境演化详细阐述如下： (1)25.4-29m(全新世以来到9000cal.BP),在此层位沉积物粒度偏细,磁性偏弱,并含有少量的不完整含铁磁性矿物,不含有孔虫化石,反映钻孔所在地没有受到海水的影响,为滨海平原相沉积。 (2)21.55-25.5m (9000-8800cal. BP),其岩性表现为上部泥沙互层,向下出现灰色均质泥,变化较为剧烈,为水动力较强的潮滩相沉积。热磁曲线显示了硫复铁矿的存在,表明其沉积环境逐渐变为海水作用下的还原环境。此层有孔虫化石开始出现,但数量不多,其组合以分布在近内陆架的九字虫、卷转虫和希望虫为主。 (3)10-21.55m (8800-7300cal. BP),沉积物岩性反映沉积环境由潮滩相演变为河口湾相,有孔虫的丰度达到了全孔的最大值,其组合中仍以九字虫、卷转虫和希望虫为主,但出现了少量的河口种属如筛九字虫、五块虫和花朵虫及抱球虫。此层受海水影响增强,水深加大,物质来源丰富,沉积厚度较大。 (4)5-10m (7300-4300cal. BP),沉积顶部出现了侵蚀接触,推测被侵蚀。此层为典型的潮滩相沉积,砂泥互层且植物碎屑丰富；HARD值在全孔达到了最大值,沉积环境的氧化性增强；有孔虫的丰度明显减小,反映此层受海水影响明显减弱、水位变浅,而其所含的河口区种属的花朵虫和筛九字虫则可能为潮汐带来。 (5)0-5m (4300cal. BP以来),此层岩性为棕黄色、灰色泥质粉砂,成块状层理,含有大量铁锰结核,硬剩磁偏高,为典型的氧化环境。粒度变粗,沉积层中不含有孔虫,不再受海水影响,为陆相沉积。与前人的钻孔对比显示此时该孔东侧的湖州-杭州间的湖海通道逐渐淤浅,距今2500年以来,已逐渐淤积成陆,沉积环境已和现代相差不大,发育了粉砂粘土为主的平原河流相沉积。在侵蚀接触的下面(4.85-5m)测年结果为4320cal. BP,出现了一层决口扇相的粗砂质沉积,推测为东苕溪改道所致,并且推测此事件和良渚文化衰亡有联系。钻孔研究结果显示,距今约7000余年前以来,东苕溪平原逐渐演变为滨海沼泽湿地,应是该区新石器文明发展的环境基础。但由于该孔新石器文明时期的沉积物基本被侵蚀,无法判断淡水沼泽湿地的形成时间。
[Abstract]:After the end of the last deglaciation, it entered the Holocene warm period. With the expansion of the East Asian monsoon circulation and the continuous warming climate, the civilization of the region was redeveloped, thus promoting the development of the Neolithic culture. According to incomplete statistics, 140 Neolithic sites have been found in the Taihu Ningshao plain, and the evolution of the prehistoric civilization and the Paleoenvironment has been studied. It has far-reaching significance to the economic development of this area and the future human land relationship.
In order to clarify the environmental evolution process of the hang Jia Lake Plain and the relationship with the rise and fall of Liangzhu ancient civilization, this article has made XL drilling in Anxi town of the East tiuxi River Basin in Hangzhou, Zhejiang, with a full length of 29m, which is located on the Western Valley Slope of the ancient Huzhou Hangzhou River Valley in the western North and south of the hang Jia Lake Plain. The grain size, magnetism, and foraminiferal points of the XL borehole were carried out in this paper. In accordance with the characteristics of its lithology, it is shown that the Holocene sedimentary environment in this area has undergone five stages, in turn the facies of the coastal plain - tidal flat - estuarine - estuarine facies - tidal flat facies and flood plain facies. The age and elevation of the sediments reflect the change of the controlled Yu Hai plane of the environment evolution in this area.
The evolution of the sedimentary environment is described in detail as follows:
(1) 25.4-29m (from the Holocene to 9000cal.BP), the sediments in this layer are fine and weak in grain size and weak in magnetic properties, and contain a small amount of incomplete ferromagnetic minerals, which do not contain fossilized fossils, which reflect that the site of the borehole is not affected by the sea water and is deposited in the coastal plain.
(2) 21.55-25.5m (9000-8800cal. BP), its lithology shows the upper sediment interbedding, the downward appearance of gray homogeneous mud, which is more violent, is a strong tidal flat facies deposit. The thermal magnetic curve shows the existence of thiorenatite, indicating that the sedimentary environment gradually changed into the reduction environment under the action of seawater, but the fossils of foraminifera are beginning to appear in this layer. The number is not large, and its combination is mainly distributed in the nine character insects near inland shelf.
(3) 10-21.55m (8800-7300cal. BP), the sedimentary lithology reflects the sedimentary environment that evolves from tidal flat to estuarine facies, and the abundance of foraminifera has reached the maximum value of the whole pore. In its combination, there are still nine word worms, coiling worms and hope insects, but a small number of estuaries are like sieved nine word worms, five insects and flower insects and coccidiosis. The influence is enhanced, the water depth is increased, the material source is abundant, and the deposit thickness is larger.
(4) 5-10m (7300-4300cal. BP), erosion contact is found at the top of the deposit, which is eroded. This layer is typical tidal flat facies deposit, sand mud interbed and plant debris rich; HARD value reaches the maximum value in the whole hole, the oxidation of the sedimentary environment is enhanced; the abundance of foraminifera decreases obviously, reflecting the obvious weakening of the influence of sea water and shallow water level in this layer. The flowers and insects of the estuarine areas and the nine worm can be brought to the tides.
(5) 0-5m (since 4300cal. BP), the lithology of this layer is brown yellow and gray muddy silt, and has massive iron and manganese nodules. It has a large number of iron and manganese nodules, and the hard remanence is high. It is a typical oxidation environment. The granularity is coarser, the sedimentary layer does not contain orifellal and is no longer affected by the sea water, which is the Lu Xiangchen product. Compared with the previous drilling, the Huzhou Hangzhou on the east side of the hole is shown. The lake and sea channel has gradually silted up, and since 2500, it has gradually silted into land, and the sedimentary environment has been different from the modern, and the silt clay based plain fluvial deposits have been developed. The result of 4.85-5m dating is 4320cal. BP. And it is speculated that this event is related to the decline and fall of Liangzhu culture.
The results of borehole research show that, since about 7000 years ago, the East trial has gradually evolved into a coastal marsh wetland, which should be the environmental basis for the development of the Neolithic civilization in this area. However, the formation time of fresh marsh wetland can not be judged because of the erosion of the sediments in the period of the Neolithic civilization.

【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：K871.13;P931

【参考文献】