發(fā)布時間：2018-06-11 22:03

  本文選題：晚白堊世 + 松遼盆地��； 參考：《中國地質(zhì)大學(北京)》2017年碩士論文

【摘要】：對白堊紀陸相沉積記錄的研究有助于我們了解在溫室氣候的條件下,陸表沉積系統(tǒng)和生態(tài)系統(tǒng)對過去氣候變化的響應,同時也有利于我們對未來氣候變化的預測。位于中國東北地區(qū)的松遼盆地是世界上保存陸相白堊系地層最完整的地區(qū)之一,盆地內(nèi)巨厚的湖相沉積物記錄著古環(huán)境、古氣候演變的信息。松遼盆地白堊紀大陸科學鉆探計劃為我們提供了獨一無二的精細地質(zhì)記錄,有助于開展詳盡的科學研究。本次研究利用鉆取自松科2井東孔嫩江組一段(1182.74~1249.32m)和嫩江組二段(1086~1145.24m)巖心的高分辨率X射線熒光掃描數(shù)據(jù)Rb/Sr,K/Ti,Ti/Al和Zr/Rb進行米蘭科維奇旋回的識別,并關于古氣候?qū)μ煳能壍绤?shù)的響應機制作初步探討。通過觀察陸源碎屑元素的相對變化,認為嫩江組沉積時期氣候由嫩一段沉積期的濕潤向嫩二段沉積期的半干旱、半濕潤過渡。利用MTM(Multitaper Method of Spectral Analysis)分析、EHA(Evolutive Harmonic Analysis)分析、ASM(Average Spectral Misfit)分析和帶通濾波分析在嫩江組的沉積序列中識別到了保存良好的米蘭科維奇旋回,結(jié)果表明嫩江組一段沉積期間氣候較為穩(wěn)定,偏心率和斜率對氣候的調(diào)控作用較為明顯,但嫩江組二段沉積期間氣候波動顯著,其氣候的變化主要受偏心率和歲差周期的共同調(diào)控,斜率周期的調(diào)控作用則表現(xiàn)的相對較差,并且越到后期調(diào)控作用越弱。松遼盆地晚白堊世嫩江組沉積期間的古氣候響應機制主要表現(xiàn)為:(1)嫩一段沉積期間的氣候變化主要受季風環(huán)流的影響,尤其在斜率顯著增加和歲差振幅增大時季節(jié)性差異增強,此時夏季風強烈,降雨充沛;(2)嫩二段沉積早期氣候仍較為濕潤,但在向沉積中后期過渡的過程中斜率的調(diào)控作用減弱,歲差的調(diào)控作用增強,使得季節(jié)性降雨減少,平均經(jīng)圈環(huán)流在北半球冬季南移的過程中強度增加,來自北大西洋的西風增強,季風減弱,氣候干旱,夏季北移的過程中強烈的下沉氣流使得水汽不易凝結(jié),氣候較濕潤時期干旱。
[Abstract]:The study of Cretaceous continental sedimentary records helps us to understand the response of surface sedimentary systems and ecosystems to past climate changes under greenhouse climate conditions, and also to predict future climate change. The Songliao Basin located in northeast China is one of the most complete areas in the world where the continental Cretaceous strata are preserved. The very thick lacustrine sediments in the basin record the information of paleoenvironment and paleoclimate evolution. The Cretaceous Continental Scientific drilling Program in Songliao Basin provides us with a unique fine geological record, which is helpful for detailed scientific research. In this study, the Milankovich cycle was identified by using high-resolution X-ray fluorescence scanning data taken from the cores of the first member of the Nenjiang formation, No. 1182.74 (1249.32m) and the second stage of the Nenjiang formation (1086, 1145.24m), from the core of the Nenjiang formation in the east of Songke 2 well, using the high resolution X-ray fluorescence scanning data of RB / Srr / K / Ti / Ti / tial and ZrRb. The response mechanism of paleoclimate to astronomical orbit parameters is discussed. By observing the relative changes of terrigenous clastic elements, it is considered that the climate of Nenjiang formation changed from wetting of Nenjiang formation during depositional period to semi-arid and semi-humid during depositional period of Nenjiang formation. Using MTMN Multitaper method of Spectral Analysis (MTM) analysis, the ASMU average Spectral Misfit-analysis and bandpass filter analysis were used to identify the well-preserved Milankovich cycle in the sedimentary sequence of the Nenjiang formation. The results showed that the climate of the Nenjiang formation was relatively stable during a period of deposition. Eccentricity and slope play a more important role in regulating climate, but climate fluctuation is obvious in the second stage of Nenjiang formation. The climate change is mainly controlled by eccentricity and precession period, but the slope period is relatively poor. And the later stage of regulation is weaker. The paleoclimate response mechanism of Nenjiang formation during late Cretaceous in Songliao Basin is mainly manifested as follows: (1) the climate change in the first member of Nen formation is mainly affected by the monsoon circulation, especially when the slope increases significantly and the precession amplitude increases. At this time, the summer monsoon is strong, and the rainfall is abundant. The early climate of the second stage of Nen is still relatively humid, but in the process of transition to the middle and late sedimentary period, the effect of slope regulation is weakened, and the regulating effect of precession is enhanced, which makes the seasonal rainfall decrease. The mean meridional circulation increases during the northern hemisphere winter southward migration, the westerly wind from the North Atlantic increases, the monsoon weakens, the climate is dry, and the strong downdraft during the summer northward movement makes the water vapor difficult to condense. The climate is dry during humid periods.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P532;P542

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