本文選題：全新世早中期 + 杭嘉湖平原��； 參考：《華東師范大學(xué)》2015年碩士論文

【摘要】：21世紀(jì)海平面加速上升是目前人類不能忽視的問題。地質(zhì)歷史時(shí)期中得到的經(jīng)驗(yàn),將有助于預(yù)測(cè)本世紀(jì)末及未來海平面加速上升如何影響河口海岸帶沉積地貌的演化。世界各地學(xué)者研究得出,全新世是最后一次冰期結(jié)束、氣候轉(zhuǎn)暖時(shí)期。全新世的早中期全球海面迅速上升,到距今6000年前接近現(xiàn)今位置,其后僅有微小的變化。因此,研究全新世早中期海平面上升過程及河口地貌響應(yīng),可指導(dǎo)我們?nèi)绾螒?yīng)對(duì)海平面快速上升所帶來的海岸帶環(huán)境變化。前人研究顯示,因長(zhǎng)江三角洲平原的特殊性,重建全新世相對(duì)海平面曲線用基底泥炭和地層學(xué)方法較為可行。本論文通過對(duì)長(zhǎng)江三角洲南部的杭嘉湖平原10個(gè)全新世鉆孔的巖性、粒度特征以及微體古生物(孢粉、藻類)分析來精細(xì)識(shí)別全新世地層,并尋找適合本區(qū)海平面定量重建的有效指示物。通過對(duì)有效指標(biāo)(基底鹽沼泥炭和高潮灘沉積相)進(jìn)行測(cè)年與古海平面定量分析,重建杭嘉湖平原全新世早中期相對(duì)海平面曲線,并通過對(duì)鉆孔沉積相演變研究揭示海岸帶沉積地貌對(duì)海平面變化的響應(yīng)。研究顯示,本區(qū)在9600 cal a BP左右海平面還處在現(xiàn)今海平面以下29m處,到6800 cal a BP,海平面已上升到與現(xiàn)今海平面相差不大的高度。且9600-8700 cal a BP,其海平面上升速率達(dá)到11mm/a; 8700-8400 cal a BP,海平面上升速率更是達(dá)到18mm/a; 7800-7400 cal a BP短短400年上升了5.2m之多,杭嘉湖平原地區(qū)海平面上升速率達(dá)到13.2mm/a。由于水均衡和沉積物均衡調(diào)整等作用的影響,研究區(qū)早中全新世相對(duì)海平面與世界各地同時(shí)期相對(duì)海平面不同,且高于太湖平原東部鉆孔所得的相對(duì)海平面。杭嘉湖平原全新世早中期主要為潮灘環(huán)境,隨海平面上升速率的改變而發(fā)生退積或加積和進(jìn)積。9600-7750 cal a BP,海平面上升速率略微大于研究區(qū)沉積速率,潮灘發(fā)生退積,杭嘉湖平原由高位鹽沼向高潮灘演化；而7750-7450 cal a BP期間,沉積速率遠(yuǎn)小于海平面上升速率,杭嘉湖平原潮灘繼續(xù)退積,普遍演變?yōu)橹械统睘?直到7450-6800 cal a BP時(shí)期,海平面上升速率下降,杭嘉湖平原又開始加積形成高潮灘。
[Abstract]:The accelerated rise of sea level in twenty-first Century is a problem that human beings cannot ignore at present. The experience gained in geological history will help to predict how the sea level acceleration at the end of the century and in the future will affect the evolution of sedimentary geomorphology in the estuary and coastal zone. Scholars around the world have concluded that the Holocene was the last ice period and the climate warming. In the early and middle period of the Holocene, the global sea level rose rapidly, approaching the present position 6000 years ago and only minor changes. Therefore, the study of the sea level rise process and the estuarine geomorphic response in the early Holocene can guide us to cope with the coastal environment changes caused by the rapid rise of sea level. Previous studies have shown that the Yangtze River is three. It is more feasible to reconstruct the Holocene relative sea level curve with the method of base peat and stratigraphy to reconstruct the Holocene relative sea level. In this paper, the lithology, grain size characteristics and micropaleontology (sporopollen, algae) of the 10 Holocene boreholes in the hang Jia Lake Plain of the south of the Changjiang Delta were analyzed to identify the Holocene strata and find the suitable one. The effective indicator of regional sea level quantitative reconstruction is to reconstruct the relative sea level curve of the early and middle Holocene in the Hangzhou Jiagan Lake Plain by quantitative analysis of the effective index (base salt marsh peat and high tide beach sedimentary facies) and the paleo sea level, and to reveal the response of the sedimentary geomorphology of the coastal zone to the sea level change through the study of the evolution of the borehole sedimentary facies. The study shows that the sea level in the area around 9600 cal a BP is still at 29m below the present sea level, and to 6800 cal a BP, the sea level has risen to a high altitude of the present sea level. And the sea level rise rate of 9600-8700 cal a BP is up to the 11mm/a; the rate of sea level rise is reached more than that of the sea level; 7800-7400 A BP has risen more than 5.2m in just 400 years. The sea level rise rate of the hang Jia Lake Plain has reached 13.2mm/a. due to the effect of water balance and sediment balance adjustment. The relative sea level in the early Middle Holocene is different from the relative sea level in the world at the same time in the world, and is higher than the relative sea level in the east of the Taihu plain. The early and middle Holocene epoch of the Jiahu plain is mainly the tidal flat environment. With the change of the sea level rising rate, the accretion or accumulation and accumulation of.9600-7750 cal a BP, the sea level rising rate is slightly greater than the deposit rate in the study area, the tidal flat is degrading, the hang Jia Lake Plain evolves from high salt marsh to the high tide beach, while the deposition of 7750-7450 cal a BP is deposited. The rate is far less than the rising rate of the sea level. The tidal flat of the hang Jia Lake Plain continues to deceit and generally evolves into the middle and low tidal flat. Until the 7450-6800 cal a BP period, the rise rate of the sea level drops, and the hang Jia Lake Plain begins to accumulate to form a high tide bank.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P534.632;P736.22

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 李琳;太湖平原全新世沉積物TS/TOC和鐵硫化物的分布及其沉積環(huán)境指示意義[D];華東師范大學(xué);2013年

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本文編號(hào)：1996900