本文選題：長江三角洲 + 上新世��； 參考：《中國地質(zhì)大學》2017年博士論文

【摘要】：長江三角洲地區(qū)地質(zhì)環(huán)境條件比較脆弱,松散層中孔隙水發(fā)育,軟土層廣布。充分認識上述與國民經(jīng)濟建設(shè)密切相關(guān)的地質(zhì)條件,脫離不了中國東部,乃至全球新生代以來氣候演化的框架認識。上新世以來,現(xiàn)長江河口地區(qū)堆積了近500 m的松散沉積。在這一較厚的松散層中,沉積環(huán)境的改變和演化不是偶然的,而是氣候等因素作用下的必然現(xiàn)象。然而受制于測年手段、沉積環(huán)境變化復(fù)雜等因素的影響,對長時間尺度內(nèi)的氣候事件及其對區(qū)域、全球氣候變化的響應(yīng)研究比較薄弱、爭論較大。因此,本文針對長江口橫沙島松散層厚395.4 m的LZK1孔開展了古氣候演化沉積響應(yīng)的綜合研究工作。本次針對磁化率、粒度等傳統(tǒng)指標進行了較高密度的采樣,并引入了粒徑—標準偏差、粒度端元組分模擬、軌道調(diào)諧、數(shù)字濾波、R/S分析、功率譜和小波分析等線性、非線性的數(shù)學處理方法開展了嘗試研究,建立了天文年代標尺,綜合對比了氣候事件的沉積記錄,并初步進行了氣候周期變化研究,分析了沉積環(huán)境與氣候之間的耦合關(guān)系。結(jié)果顯示,相關(guān)方法在具有短時間尺度沉積缺失的持續(xù)沉降地區(qū)具有適應(yīng)性,并能取得比較有效的成果。本次主要成果和認識有:1、沉積旋回清楚,沉積物特征復(fù)雜,沉積環(huán)境多樣,沉積速率階段性明顯。研究剖面可劃分為213個小層,15個大層。沉積物類型有粘土質(zhì)粉砂、砂質(zhì)粉砂、粉砂質(zhì)砂、粘土—粉砂—砂、細砂、中砂、粗砂和含礫粗砂、礫質(zhì)粗砂、砂質(zhì)礫、泥質(zhì)砂質(zhì)礫等。上新世以來,先后發(fā)育了沖積扇、辮狀河、曲流河、湖泊、曲流河、湖泊—河口灣、曲流河、河口灣、淺海、三角洲等多個沉積體系。沉積速率變化呈現(xiàn)明顯的階段性。晚更新世以來沉積速率較高,晚全新世達到最大,平均可達4.1~8.5 m/ka;晚更新世以前,平均沉積速率整體波動不大。在1076~1787 ka和5232~6033 ka間極低,約0.011 m/ka。2、質(zhì)量磁化率、頻率磁化率的粒度效應(yīng)差別較大,氣候指示意義不同。質(zhì)量磁化率、頻率磁化率總體上呈中等的負相關(guān)性,但局部層位無相關(guān)性,都以13~15 m、80~90 m、220~230 m、290~295 m為界發(fā)生四次顯著變化,其中前三者與平均粒徑、粒度組成含量的突變深度相一致。質(zhì)量磁化率受粒度控制明顯,多與250μm以下粒極正相關(guān)。頻率磁化率除局部層位外,受粒度控制不明顯。磁化率的氣候指示意義不確定性較大,高磁化率可指示干冷氣候,也可指示暖濕氣候,而頻率磁化率的氣候意義較明確,高值指示暖濕氣候,低值指示冷干氣候。3、建立了剖面約6.3 Ma以來的年代標尺,識別了16次可能存在的極性漂移、亞時事件,且研究表明在有短時間沉積缺失的持續(xù)沉降區(qū),可以通過軌道調(diào)諧方法建立總體可靠的年代框架。全新統(tǒng)、上更新統(tǒng)、中更新統(tǒng)、第四系和Gi/Ga界線、Gilbert底界分別約在41.6 m、107.1 m、143 m、219 m、296.6 m、369.6 m。可能記錄了全新世I、全新世II、哥德堡、Mono lake、Laschamp、Blake、M/B Precursor、Kamicatsura、Santa Rosa、Jaramillo-cobb mountain、Olduvai、Feni-Reunion、Keana、Mammoth、sidufjall、Thvera等16個極性飄移和極性亞時事件。調(diào)諧后的頻率磁化率在軌道周期上與ETP曲線高度相關(guān),相關(guān)性超過了95%檢驗標準。100ka、41ka和23ka周期的帶通濾波曲線與偏心率、斜率和歲差在振幅和相位上吻合較好,但局部時間段有差異,可能與低沉積速率、沉積速率突變或短時間尺度的地層缺失等因素有關(guān)。研究表明,在具有短暫沉積缺失的持續(xù)沉降區(qū)域,只要保證樣品分辨率,可以通過軌道調(diào)諧方法建立可靠的年代框架4、通過粒徑—標準偏差分析和端元組分模擬方法,提取了剖面的敏感粒徑和端元組分,構(gòu)建了兩個組合端元組分分別作為夏季風和冬季風的替代指標。全剖面提取的敏感粒徑和分段提取的敏感粒徑差別較大,包含關(guān)系較差;但全剖面提取的端元組分與分段提取的端元組分基本相近,且能被后者包括。考慮粉塵堆積中懸浮組分通常的上限粒徑,認為EM1(2.7~3.9μm)、EM2(10.8~14.3μm)、EM3(33.1~36.2μm)、EM4(76.7~83.9μm)四個端元組分直接或間接含有氣候信息。以長期懸浮粉塵堆積的上限為界,構(gòu)建了EM1+EM2、EM3+EM4兩個組合端元,認為分別具有夏季風和冬季風氣候演化指示意義,且與靈臺黃土剖面平均粒徑階段具有明顯可對比性。5、粒度端元組分、平均粒徑、質(zhì)量磁化率、頻率磁化率的H值與區(qū)內(nèi)現(xiàn)代氣候指標值十分接近,可以很好地指示氣候環(huán)境的變化。EM1+EM2粒度端元組分、平均粒徑、質(zhì)量磁化率、頻率磁化率的H值較接近,且接近1。它們與現(xiàn)代夏季日照數(shù)、年最低日氣溫的H值相近,這表明其與夏季風的強弱密切相關(guān)。EM3+EM4粒度端元組分H值與其他四個差別較大,但大于0.5。與冬季平均氣溫、日照數(shù)基本相當,表明與冬季風的強弱密切相關(guān)。6、各類氣候代用指標具有可比性,綜合相關(guān)指標提出了上新世以來的氣候框架,5.2 Ma、3.5 Ma、2.7 Ma、2.2 Ma、1.5 Ma、1.1 Ma、0.6 Ma等氣候轉(zhuǎn)化時間節(jié)點,與區(qū)域和全球尺度上的研究成果相一致。6.3~5.2 Ma,以暖濕氣候為主,冬、夏季風作用均較強,但都逐漸減弱。5.2~3.5Ma間,仍以暖濕氣候為主。以約4.7 Ma、4.2 Ma為界,夏季風呈減弱—增強—減弱的過程,而冬季風相對穩(wěn)定。在約5.0 Ma同時發(fā)生冬、夏季風的強化事件。約3.5~2.7 Ma,氣候較前一階段明顯變涼、變干,波動加大。夏季風輕微增強的同時,冬季風迅速增強并主導(dǎo);但在3.0~3.1 Ma,冬、夏季風發(fā)生大幅波動。約2.7~2.2 Ma,冬、夏季風的同時顯著加強,但冬季風仍占主導(dǎo),氣候變暖偏干。約2.2~1.5 Ma,氣候仍較暖,但波動加大。夏季風總體穩(wěn)定并略增強,冬季風較前明顯減弱,兩者呈反相關(guān)系。約1.5~1.1 Ma,氣候較前階段偏涼干,大幅波動。夏季風占主導(dǎo),以1.2~1.3 Ma為界,由大幅波動轉(zhuǎn)為逐漸減弱,與此同時,冬季風開始增強。約1.1~0.6 Ma,氣候暖濕與干冷交替明顯,波動進一步加大。夏季風繼續(xù)減弱,而冬季風繼續(xù)增強,兩者呈繼續(xù)反相關(guān)。約0.6~0.2 Ma,氣候仍表現(xiàn)為暖濕與干冷交替的大幅波動,但總體呈暖濕特征�？傮w上,夏季風減弱,冬季風增強,兩者呈反相關(guān)系。0.2 Ma以來,氣候的暖濕與干冷交替波動加劇,冬、夏季風呈反相關(guān)系,表現(xiàn)為大幅度的增強(減弱),但夏季風總體上有所減弱,冬季風加強。MIS5期,氣候暖濕,發(fā)育MIS5e、MIS5d、MIS5c三個階段。MIS4期,氣候變冷,MIS3期(本剖面僅保留48~29 ka階段沉積),氣侯略回暖,夏季風強度相對MIS4應(yīng)變化不大,但波動明顯,而這個階段的氣溫轉(zhuǎn)暖可能與冬季風的相對明顯減弱有關(guān)。末次冰消期始于16 ka,在14 ka附近氣候迅速轉(zhuǎn)暖,可能指示B/A暖氣的開始。全新世氣候呈三分的特征,約11ka~5.5 ka間以夏季風占主導(dǎo)。約5.5~2.0 ka,氣候明顯變干。約2.0 ka以來,呈降溫和變冷過程。7、初步的氣候周期表明,不同指標記錄的氣候周期有一定差異,但總體都表現(xiàn)出了強烈的歲差和半歲差周期。周期數(shù)值波動性較大,具有一定規(guī)律性。頻率磁化率、EM1+EM2粒度端元組分、Rb/Sr指標的頻譜分析表明,區(qū)內(nèi)氣候周期主要呈準長偏心率(330 ka)、準200 ka(200 ka、250 ka、166-185ka)、準短偏心率(72~125 ka)、準斜率(38~50 ka和26~33 ka)、準歲差(16~23 ka)和半歲差(10~13 ka)等周期特征。除長周期外,其他周期都波動性較大,尤其是歲差周期,可能與沉積速率較小或短時間尺度的沖刷侵蝕等因素有關(guān)。600 ka、1100ka前后存在偏心率、斜率周期發(fā)育的區(qū)別,可能與中更新世氣候革命有關(guān)。8、沉積環(huán)境變化與氣候演化密切相關(guān),清楚記錄了區(qū)內(nèi)在MIS5、MIS3、MIS1期間在氣候控制作用下發(fā)生的三次海侵事件。氣候轉(zhuǎn)型階段會缺失部分短時間尺度的沉積記錄。
[Abstract]:The geological environment conditions in the Yangtze River Delta are relatively fragile, the pore water in the loose layer is developed and the soft soil layer is widely distributed. The geological conditions that are closely related to the national economic construction are fully understood, which can not be separated from the framework of the climate evolution in the eastern China and even the global Cenozoic era. Since the upper Miocene, the Yangtze River Estuary has accumulated nearly 500 m In this thicker loose layer, the change and evolution of the sedimentary environment is not accidental, but the inevitable phenomenon of climate and other factors. However, it is influenced by factors such as the means of dating, the complex environmental changes, and the response to the climate events in the long time scale and its response to the region and the global climate change. It is relatively weak and controversial. Therefore, this paper has carried out a comprehensive study on the paleoclimate evolution deposition response to the LZK1 hole of 395.4 m loose layer thickness in the Changjiang Estuary. This time, the traditional indexes such as magnetic susceptibility and grain size were sampled at a high density, and the particle size standard deviation, particle end tuple component simulation, orbit tuning, and numbers were introduced. The linear and nonlinear mathematical processing methods, such as filtering, R/S analysis, power spectrum and wavelet analysis, have been studied. The astronomical dating scales are established, the sedimentary records of climatic events are compared, and the climatic cycle changes are preliminarily studied and the coupling relationship between the sedimentary environment and the climate is analyzed. The results show that the related methods are related. The region with short time scale deposition loss is adaptive and can achieve more effective results. The main achievements and understanding are as follows: 1, the sedimentary cycle is clear, the sediment characteristics are complex, the sedimentary environment is diverse and the deposition rate is distinct. The research section can be divided into 213 small layers, 15 large layers. Sediment types have clay. Silty sand, sandy silt, silty sand, clay silty sand, fine sand, medium sand, coarse sand and gravel sand, gravel coarse sand, sandy gravel, and sandy gravel, and so on. Since Pliocene, the alluvial fan, braided river, meandering river, lake, lacustrine estuary, meandering river, estuarine, shallow sea, Delta and other depositional systems have been deposited. In late Pleistocene, the rate of deposition was higher, the maximum in the late Holocene, the maximum in the late Holocene, up to 4.1~8.5 m/ka, and the average fluctuation of the average deposition rate before the late Pleistocene. It was very low between 1076~1787 Ka and 5232~6033 Ka, about 0.011 m/ka.2, and the particle size effect of the mass magnetic susceptibility and frequency susceptibility was very different. The quality magnetic susceptibility and frequency susceptibility are generally negative correlation, but there are no correlation between the local layers and the four significant changes in 13~15 m, 80~90 m, 220~230 m and 290~295 m. The first three are in accordance with the average particle size and the depth of the grain size composition. Most of them are positively related to the particle size below 250 m. The frequency magnetization is not obviously controlled by the grain size except the local layer. The climatic indication of the magnetic susceptibility is uncertain. The high susceptibility can indicate the dry cold climate and the warm wet climate. The Climate Significance of the frequency magnetization is clearer, the high value indicates the warm wet climate, and the low value indicates the cold dry climate.3. The chronological ruler since about 6.3 Ma has been established to identify 16 possible polar drifting and subtemporal events, and the study shows that the overall and reliable age frame can be established through the orbit tuning method in the continuous subsidence area with short time deposition missing. Holocene, upper Pleistocene, Middle Pleistocene, Quaternary and Gi/Ga boundaries, and Gilbert bottom boundary 41.6 m, 107.1 m, 143 m, 219 m, 296.6 m, 369.6 M. may record the Holocene I, 16 Polar drift and polarity sub events such as the Holocene II, Mono lake, Laschamp, Blake. The magnetic susceptibility is highly related to the ETP curve on the orbit cycle, and the correlation exceeds the 95% test standard.100ka. The band pass filter curve of the 41ka and 23ka cycles is in good agreement with the eccentricity, the slope and the precession of the amplitude and phase, but there are differences in the local time period, which may be associated with the low deposition rate, the deposition rate mutation or the short time scale loss of the strata. The study shows that a reliable age frame 4 can be established by track tuning method in the persistent subsidence area with short deposition loss. The sensitivity particle size and end components of the section are extracted by the particle size standard deviation analysis and the end tuple component simulation method, and two combined end tuples are constructed. The sensitive particle diameter of the total section and the sensitive particle size of the segmented extraction are very different, and the inclusion relationship is poor, but the end tuples extracted from the whole section are almost similar to the end components extracted by the sections, and can be included in the latter. The four end tuples of EM1 (2.7~3.9 mu m), EM2 (10.8~14.3 mu m), EM3 (33.1~36.2 u m) and EM4 (76.7~83.9 micron) contain the climatic information directly or indirectly. With the limit of the long suspended dust accumulation, two combinatorial endpoints are constructed, and they are considered to have the significance of the climate evolution of the summer monsoon and the winter monsoon, respectively, and the loess section of Lingtai. The average particle size phase has obvious contrast.5. The H value of the grain end tuple, the average particle size, the mass susceptibility and the frequency susceptibility is very close to the modern climate index in the region. It can well indicate the changes in the.EM1+EM2 grain end components of the climate and environment, the average particle size, the mass susceptibility and the frequency susceptibility, and the connection of the H value of the frequency susceptibility. Nearly 1. of them are similar to the H value of the modern summer sunshine and the annual minimum daily temperature, which indicates that the H value of the.EM3+EM4 granularity end group is closely related to the intensity of the summer monsoon, but it is larger than the average temperature of 0.5. and winter, which is closely related to the strength and weakness of the winter wind, which is closely related to the.6 of the winter wind. The climatic framework since the Pliocene, 5.2 Ma, 3.5 Ma, 2.7 Ma, 2.2 Ma, 1.5 Ma, 1.1 Ma, 0.6 Ma and other climatic transformation time nodes, is proposed by the comprehensive correlation index, which is consistent with the regional and global scale research results.6.3~5.2 Ma, which is dominated by warm and wet climate, winter and summer wind are all stronger, but they are gradually weakened between.5.2~3.5Ma, still between.5.2~3.5Ma, still between.5.2~3.5Ma, still be weakened between.5.2~3.5Ma, still between.5.2~3.5Ma, still to weaken between.5.2~3.5Ma, still between The warm and wet climate is the main. With about 4.7 Ma and 4.2 Ma as the boundary, the summer wind is weakening - weakening process, and the winter wind is relatively stable. At about 5 Ma, the winter, the summer wind intensification event. About 3.5~2.7 Ma, the climate is obviously cooler, dry and fluctuant. The summer monsoon is slightly enhanced and the winter wind is rapidly enhanced and dominated. But in 3.0~3.1 Ma, winter, summer wind fluctuates significantly. About 2.7~2.2 Ma, winter and summer wind are significantly strengthened, but the winter wind still dominate, the climate warming is dry. The climate is still warmer, but the climate is still warmer, but the fluctuation increases. The summer wind is generally stable and slightly stronger, the winter wind is obviously weaker than before, and the relationship between the two is inverse relationship. About 1.5~1.1 Ma, climate is earlier than before. At the same time, the winter wind began to strengthen. At the same time, the winter wind began to strengthen. At the same time, the wind began to increase. About 1.1~0.6 Ma, the climate warm and dry cold alternated obviously, the fluctuation further increased. The summer wind continued to weaken, and the winter wind continued to strengthen, the two continued to reverse correlation. About 0.6~0.2 Ma, climate of about 0.6~0.2 Ma, climate. On the whole, the summer wind weakened and the winter wind was enhanced. Since the relationship between the two was.0.2 Ma, the climate warming and the dry and cold alternating fluctuation intensified, the winter and the summer wind showed a negative relationship, showing a significant increase (weakening), but the summer monsoon weakened in general. The wind strengthened.MIS5 period, climate warm and wet, developed MIS5e, MIS5d, MIS5c three stages,.MIS4 period, climate cold, MIS3 period (this section only retained 48~29 Ka stage deposition), gas slightly warm, the summer wind intensity relative MIS4 should not change little, but the fluctuation is obvious, and this stage of temperature warming may be relative to the relative decrease of winter wind. The period begins at 16 Ka and warm rapidly near 14 Ka, which may indicate the beginning of B/A heating. The Holocene climate is characteristic of three points, about 11ka~5.5 Ka is dominated by summer monsoon. About 5.5~2.0 Ka, the climate is obviously dry. Since about 2 Ka, the cooling and cooling process is in.7. The preliminary climatic cycle shows that the climatic cycles of different indexes are certain. The difference, but the whole show a strong precession and semi precession cycle. The cycle numerical volatility is larger, with a certain regularity. Frequency susceptibility, EM1+EM2 granularity end components, Rb/Sr index spectrum analysis shows that the climate cycle in the region is mainly quasi long eccentricity (330 KA), quasi 200 kA (200 kA, 250 Ka, 166-185ka), quasi short eccentricity (72~125). KA), the periodic characteristics of the quasi slope (38~50 Ka and 26~33 KA), the quasi precession (16~23 KA) and the semi precession (10~13 KA). Except for the long period, the other cycles are very volatile, especially the precession period, which may be related to the.600 Ka, which may be related to the less deposition rate or the short time scale erosion erosion. There is a difference between the eccentricity and the slope cycle development before and after the 1100ka. .8 may be related to the climate revolution of the Middle Pleistocene, and the sedimentary environment changes closely related to the climate evolution. It clearly records the three transgression events that occur during the climate control during the period of MIS5, MIS3 and MIS1 in the region.

【學位授予單位】：中國地質(zhì)大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：P512.2;P532
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本文編號：1792846