本文選題：河套盆地 + 古環(huán)境　； 參考：《蘭州大學(xué)》2016年博士論文

【摘要】：亞洲內(nèi)陸沙漠的發(fā)育是新生代亞洲內(nèi)陸干旱化的直接結(jié)果,對(duì)其形成發(fā)展歷史的研究可以為認(rèn)識(shí)亞洲內(nèi)陸干旱化歷史和演化過(guò)程提供最直接的證據(jù)。在這些沙漠中,黃土高原近源沙漠是黃土高原粉塵沉積的重要源區(qū),在黃土高原形成過(guò)程中發(fā)揮了重要作用。位于河套盆地南部的庫(kù)布齊沙漠是黃土高原近源沙漠之一,由于其特殊的地理和地貌條件,庫(kù)布齊沙漠的形成不僅受控于亞洲內(nèi)陸干旱氣候的發(fā)展,同時(shí)也受黃河活動(dòng)和河套盆地古環(huán)境的影響,而河套盆地古環(huán)境重建則是認(rèn)識(shí)庫(kù)布齊沙漠和黃河形成演化過(guò)程的關(guān)鍵。本文對(duì)位于河套盆地的DR01鉆孔地層序列進(jìn)行了總結(jié),同時(shí)對(duì)鉆探于盆地中部的WEDP05鉆孔開(kāi)展了系統(tǒng)的沉積學(xué)和年代學(xué)研究。采用電子磁旋共振(ESR)和磁性年代學(xué)方法建立了WEDP05鉆孔地層的年代標(biāo)尺。通過(guò)地層巖性判識(shí)、古生物證據(jù)、顆粒形態(tài)掃描電鏡觀察和粒度分析等多種方法恢復(fù)了 WEDP05鉆孔地層的沉積相。在此基礎(chǔ)上,利用WEDP05鉆孔沉積物色度、磁化率、粒度、碳酸鹽碳氧同位素、有機(jī)質(zhì)碳氮同位素及總有機(jī)碳和總氮含量等環(huán)境代用指標(biāo)并結(jié)合包括DR01鉆孔在內(nèi)的盆地多個(gè)鉆孔沉積地層特征和年代序列重建了河套盆地新生代氣候和古環(huán)境演化歷史。最后,探討了庫(kù)布齊沙漠的形成時(shí)間及發(fā)育模式并討論了黃河活動(dòng)在盆地古環(huán)境演化和庫(kù)布齊沙漠形成方面的重要作用。主要得出以下結(jié)論:1.DR01鉆孔地層自底到頂可分為:晚白堊紀(jì)地層(2503.18-2125.45 m),下部主要為棕紅色泥巖夾淺灰色泥巖,上部主要為棕紅色泥巖、砂質(zhì)泥巖夾黃色砂巖和紫色薄層泥巖。上新世地層(2125.45-1834.55 m),棕色泥巖和砂質(zhì)泥巖、淡黃色、粉色砂巖偶夾紫色泥巖、砂質(zhì)泥巖,與白堊紀(jì)地層之間呈不整合接觸。第四紀(jì)地層(1834.55-0 m),淡黃色粉砂和細(xì)砂夾淡紅色泥巖、砂質(zhì)泥巖,部分層位出現(xiàn)青灰色、灰綠色、淺灰色泥巖,為典型的湖相沉積物。2.WEDP05鉆孔地層沉積相自頂?shù)降卓蓜澐譃?0-11.3m,河流和沙漠沉積,其中頂部5.5 m以粗顆粒河流砂為主;11.3-87.51 m,湖相沉積,以細(xì)粒粘土和粉砂質(zhì)粘土為主;87.51-141.63 m,風(fēng)成砂層夾湖相沉積層;141.63-183.35 m,湖相沉積為主,中間夾一套風(fēng)成砂層;183.35-268.14 m,風(fēng)成砂層為主,中部夾厚約30米湖相沉積層;268.14-274.60 m,湖相粉砂質(zhì)粘土沉積。3.WEDP05鉆孔B/M界限位于143.4m處,鉆孔底界年齡為～1.68 Ma。4.河套地區(qū)在新生代早期可能處于隆起狀態(tài)并接受剝蝕,至少在上新世后開(kāi)始沉降形成沉積盆地,盆地內(nèi)發(fā)育河湖相沉積環(huán)境,第四紀(jì)時(shí)河湖和沙漠沉積環(huán)境多次交替發(fā)育。自早更新世以來(lái)盆地經(jīng)歷了多次的湖泊和沙漠交替擴(kuò)張過(guò)程,其中～1.47-～1.30 Ma,～1.17-～1.07 Ma,～0.68-～0.60 Ma和～0.47 Ma至末次間冰期時(shí)湖泊擴(kuò)張、沙漠收縮,盆地內(nèi)氣候相對(duì)濕潤(rùn);在～1.30-～1.17 Ma,～1.07-～0.68 Ma、～0.60-～0.47 Ma和末次冰期時(shí)沙漠?dāng)U張、湖泊收縮,盆地以干旱氣候?yàn)橹��！?.47 Ma、～0.3 Ma和末次間冰期是盆地內(nèi)湖泊擴(kuò)張最為顯著的三個(gè)時(shí)期;末次冰期和全新世時(shí),湖泊萎縮消亡,庫(kù)布齊沙漠顯著擴(kuò)張并發(fā)育大型沙丘,逐步形成現(xiàn)代景觀格局。5.庫(kù)布齊沙漠至少在早更新世～1.65 Ma時(shí)已經(jīng)形成。近地面冬季風(fēng)對(duì)河套盆地內(nèi)裸露的河湖相沉積物的改造和搬運(yùn)分選是庫(kù)布齊沙漠物質(zhì)的主要來(lái)源方式。黃河活動(dòng)提供大量的碎屑物質(zhì)是導(dǎo)致庫(kù)布齊沙漠發(fā)育的重要原因之一,同時(shí)盆地內(nèi)湖泊萎縮及區(qū)域干旱氣候也發(fā)揮了重要作用。6.河套盆地內(nèi)黃河古河道可能至少在上新世時(shí)就已經(jīng)形成。黃河流入河套盆地并建立較為完整上游水系的時(shí)間可能發(fā)生在至少～1.6 Ma,并至少在～1.2 Ma時(shí)形成較為完整的串聯(lián)河套盆地、晉陜峽谷、汾渭盆地和三門(mén)峽的現(xiàn)代黃河水系。差異性構(gòu)造活動(dòng)造成盆地出水口抬升是導(dǎo)致黃河形成之后在河套盆地內(nèi)發(fā)育湖泊環(huán)境的主要原因,濕潤(rùn)的氣候條件對(duì)盆地內(nèi)大湖的形成起到一定的促進(jìn)作用,而黃河快速侵蝕下切是造成河套盆地湖泊消亡的主要原因。
[Abstract]:The development of the Asian inland deserts is the direct result of the droughts in the new generation of Asian inland. The study of its formation and development history can provide the most direct evidence for understanding the history and evolution process of the Asiatic droughts. In these deserts, the near source desert of the Loess Plateau is an important source of dust deposition on the Loess Plateau and is formed on the Loess Plateau. The reservoir in the southern part of the Hetao Basin is one of the near source deserts in the Loess Plateau. Due to its special geographical and geomorphic conditions, the formation of the desert is not only controlled by the development of the arid climate of the Asian inland, but also influenced by the the Yellow River activities and the palaeoenvironment of the Hetao Basin, and the ancient ring of the Hetao Basin. The reconstruction of the territory is the key to understanding the evolution process of the the Yellow River desert and the Yellow River. In this paper, the sequence of the drilling strata in the Hetao Basin is summarized, and the systematic sedimentology and chronological study of drilling in the WEDP05 borehole in the middle of the basin are carried out. The electronic magnetic rotation co vibration (ESR) and magnetic chronology are used to establish the WEDP0. The age scale of 5 borehole strata has recovered the sedimentary facies of WEDP05 drilling strata through stratigraphic lithology identification, paleontological evidence, particle morphology scanning electron microscope observation and particle size analysis. On this basis, using WEDP05 drilling sediment chromaticity, magnetic susceptibility, granularity, carbon and oxygen isotopes of carbonate salts, organic carbon and nitrogen isotopes and total organic matter. The climatic and paleoenvironment evolution history of the Cenozoic era of the Hetao Basin is rebuilt with the characteristics of the sedimentary strata of the basins, including the DR01 boreholes, including the carbon and total nitrogen content, and the history of the Paleoenvironment evolution. Finally, the formation time and development model of the cubqi desert are discussed, and the evolution of the Paleoenvironment of the Yellow River in the basin is discussed and the evolution of the Paleoenvironment in the basin is discussed. The main conclusions are as follows: the bottom to the top of the 1.DR01 borehole can be divided into the late Cretaceous (2503.18-2125.45 m), the lower part mainly of the brown red mudstone with pale gray mudstone, the upper part of the brown mudstone, the sandy mudstone with yellow sandstone and the purple thin mudstone. The Pliocene (2125.45- 1834.55 m), brown mudstone and sandy mudstone, pale yellow, pink sandstone and purple mudstone, sandy mudstone, unconformable contact with Cretaceous strata. Quaternary strata (1834.55-0 m), pale yellow silt and fine sand with pale red mudstone, sandy mudstone, gray green, gray mudstone, and typical lacustrine deposits. .2.WEDP05 sedimentary facies from the top to the end can be divided into: 0-11.3m, river and desert deposition, the top 5.5 m with coarse grain river sand; 11.3-87.51 m, lacustrine deposition, mainly fine clay and silty clay; 87.51-141.63 m, the aeolian sand layer lacustrine sedimentation layer; 141.63-183.35 m, lacustrine deposition, a set of wind in the middle. Sand formation, 183.35-268.14 m and aeolian sand layer are mainly in the middle, and the middle part is thicker than 30 Lake Myvatn sedimentary layers; 268.14-274.60 m, lacustrine silty clay deposits.3.WEDP05 borehole B/M boundary is located at 143.4m, and the age of drilling bottom boundary is 1.68 Ma.4. in the early Cenozoic, which may be in the early stage of uplift and denudation, at least after the Pliocene. The sedimentary basins are formed and the sedimentary environment of the river lacustrine facies is developed in the basin, and the sedimentary environment of the rivers and lakes and deserts develops alternately in the Quaternary period. Since the early Pleistocene, the basin has undergone several periods of alternation expansion of lakes and deserts, of which 1.47- to 1.30 Ma, to 1.17- to 1.07 Ma, to 0.68- to 0.60 Ma and to 0.47 Ma to the last interglacial period. Expansion, desert contraction, and relatively humid climate in the basin; from 1.30- to 1.17 Ma, to 1.07- to 0.68 Ma, to 0.60- to 0.47 Ma and in the last glaciation, the desert expands, the lakes shrink, the basin is dominated by arid climate. To 0.47 Ma, to 0.3 Ma and the last interglacial period is the most significant three period of Lake expansion in the basin; the last glacial and Holocene, The lake atrophy is dying out, and the reservoir desert has expanded and developed large sand dunes, and the modern landscape pattern is gradually formed in.5.. At least in the early Pleistocene to 1.65 Ma, the transformation and transportation of the bare River lacustrine sediments in the river basin are the main source of the material in the desert. The river activities provide a large amount of debris material which is one of the important reasons for the development of the the Yellow River desert. At the same time, the lake atrophy and regional arid climate also play an important role in the basin. The ancient river in the the Yellow River river basin may have been formed at least in the Pliocene. The Yellow River flows into the river set basin and establishes a more complete upstream water system. It may occur at least 1.6 Ma, and at least 1.2 Ma to form a relatively complete series of Hetao Basin, Shanxi Shaanxi Canyon, Fenwei basin and Sanmenxia's modern the Yellow River water system. Differential tectonic activities cause the basin outlet uplift is the main cause of the lake environment development in the river basin after the Yellow River formation, the humid climate. The conditions played a certain role in promoting the formation of the Great Lakes in the basin, and the rapid erosion and undercutting in the Yellow River was the main reason for the loss of lakes in the Hetao Basin.

【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：P941.73;P534.6
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本文編號(hào)：1785117