發(fā)布時(shí)間：2018-04-22 00:32

  本文選題：白洋淀地區(qū) + 晚更新世��； 參考：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：河北白洋淀地區(qū)晚更新世以來處于東亞季風(fēng)區(qū),是古環(huán)境演變的敏感區(qū)。第四紀(jì)沉積物分布廣泛、連續(xù),沉積厚度大,是古氣候環(huán)境變化的良好記錄。區(qū)域古氣候研究多集中在巖性和孢粉分析,而本文利用粒度和磁化率進(jìn)行精細(xì)分析。本文主要研究了白洋淀周邊三個(gè)有代表性剖面,通過分析巖性、磁化率和粒度特征,結(jié)合光釋光和14C測年結(jié)果,揭示河北白洋淀地區(qū)的環(huán)境演變規(guī)律。主要結(jié)論如下:1.通過光釋光和14C年代數(shù)據(jù)確定了剖面時(shí)代,同時(shí)經(jīng)過14C年代校正、結(jié)合沉積環(huán)境的變化分析了年代的合理性和可靠性。通過擬合計(jì)算得到底部年齡為121.843ka BP,屬于晚更新以來地層。2.在測年數(shù)據(jù)的基礎(chǔ)上,結(jié)合巖性分析,建立了末次間冰期以來三個(gè)階段的地層層序。下層從121ka BP至75ka BP,沉積相為河流相,沉積物以中粗砂和極細(xì)砂為主;中層從75ka BP至10ka BP,沉積相以河流相和濱湖相為主,沉積物粒徑較為分散,以粘土、粉砂為主,含有少量極細(xì)砂;上層從10ka BP至現(xiàn)代:沉積物以粘土、粉砂細(xì)粒物質(zhì)為主,湖沼相與河流相交替,發(fā)育黑色、灰褐色泥碳層,較多層位發(fā)現(xiàn)底棲生物類化石。3.根據(jù)磁化率和粒度的階段特征和環(huán)境指示意義分析,發(fā)現(xiàn)晚更新世早期,氣候溫暖濕潤;晚更新世晚期氣候較干冷,該階段內(nèi)氣候又經(jīng)歷了冷-暖-冷的階段性波動(dòng);全新世向暖濕轉(zhuǎn)變,中期溫暖濕潤,該區(qū)域生物生長狀況較好且湖泊經(jīng)歷擴(kuò)張與收縮的演進(jìn)過程。該區(qū)域晚更新世以來的氣候環(huán)境演變對(duì)應(yīng)深海氧同位素MIS5a,MIS4,MIS3,MIS2,MIS1。
[Abstract]:Since the late Pleistocene the Baiyangdian area in Hebei Province is located in the East Asian monsoon region and is a sensitive area for paleoenvironmental evolution. Quaternary sediments are widely distributed, continuous and thick, which is a good record of paleoclimate environment change. The study of regional paleoclimate is mainly focused on lithology and sporopollen analysis, but the fine analysis is based on particle size and magnetic susceptibility. In this paper, three representative sections around Baiyangdian are studied. By analyzing lithology, magnetic susceptibility and granularity characteristics, combined with the results of photoluminescence and 14C dating, the environmental evolution law of Baiyangdian area in Hebei Province is revealed. The main conclusions are as follows: 1. The age of section is determined by the data of photoluminescence and 14C, and the rationality and reliability of the age are analyzed by the correction of 14C and the change of sedimentary environment. By fitting calculation, the bottom age is 121.843ka BP, which belongs to stratum. 2. 2. On the basis of dating data and lithologic analysis, the stratigraphic sequence of three stages since the last interglacial period was established. From 121ka BP to 75ka BP, the sedimentary facies are fluvial facies, medium coarse sand and very fine sand, while from 75ka BP to 10ka BP, the sedimentary facies are mainly fluvial facies and lakeside facies, and the grain size of sediment is dispersed, mainly of clay and silt. It contains a small amount of very fine sand, the upper layer from 10ka BP to the modern: the sediment is mainly clay, silt fine grained material, the lake and marsh facies alternate with the river facies, develop black, grayish brown muddy carbon layer, the benthos fossils. 3 are found in many layers. According to the phase characteristics of magnetic susceptibility and granularity and the analysis of environmental indicators, it is found that in the early late Pleistocene, the climate was warm and humid, and in the late late Pleistocene the climate was dry and cold, during which the climate experienced a period of cold, warm and cold fluctuations. With the transition from Holocene to warm and wet and warm and humid in the middle of the period, the living conditions of the region are relatively good and the lakes have experienced the process of expansion and contraction. The evolution of the climate environment since the late Pleistocene in the region corresponds to the deep-sea oxygen isotope MIS5a4 (MIS3) MIS2 (MIS1).
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P532

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