晚白垩世松辽盆地嫩江组米兰科维奇旋回的识别及其古气候响应

发布时间：2018-06-11 22:03

本文选题：晚白垩世 + 松辽盆地　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：对白垩纪陆相沉积记录的研究有助于我们了解在温室气候的条件下,陆表沉积系统和生态系统对过去气候变化的响应,同时也有利于我们对未来气候变化的预测。位于中国东北地区的松辽盆地是世界上保存陆相白垩系地层最完整的地区之一,盆地内巨厚的湖相沉积物记录着古环境、古气候演变的信息。松辽盆地白垩纪大陆科学钻探计划为我们提供了独一无二的精细地质记录,有助于开展详尽的科学研究。本次研究利用钻取自松科2井东孔嫩江组一段(1182.74~1249.32m)和嫩江组二段(1086~1145.24m)岩心的高分辨率X射线荧光扫描数据Rb/Sr,K/Ti,Ti/Al和Zr/Rb进行米兰科维奇旋回的识别,并关于古气候对天文轨道参数的响应机制作初步探讨。通过观察陆源碎屑元素的相对变化,认为嫩江组沉积时期气候由嫩一段沉积期的湿润向嫩二段沉积期的半干旱、半湿润过渡。利用MTM(Multitaper Method of Spectral Analysis)分析、EHA(Evolutive Harmonic Analysis)分析、ASM(Average Spectral Misfit)分析和带通滤波分析在嫩江组的沉积序列中识别到了保存良好的米兰科维奇旋回,结果表明嫩江组一段沉积期间气候较为稳定,偏心率和斜率对气候的调控作用较为明显,但嫩江组二段沉积期间气候波动显著,其气候的变化主要受偏心率和岁差周期的共同调控,斜率周期的调控作用则表现的相对较差,并且越到后期调控作用越弱。松辽盆地晚白垩世嫩江组沉积期间的古气候响应机制主要表现为:(1)嫩一段沉积期间的气候变化主要受季风环流的影响,尤其在斜率显著增加和岁差振幅增大时季节性差异增强,此时夏季风强烈,降雨充沛;(2)嫩二段沉积早期气候仍较为湿润,但在向沉积中后期过渡的过程中斜率的调控作用减弱,岁差的调控作用增强,使得季节性降雨减少,平均经圈环流在北半球冬季南移的过程中强度增加,来自北大西洋的西风增强,季风减弱,气候干旱,夏季北移的过程中强烈的下沉气流使得水汽不易凝结,气候较湿润时期干旱。
[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.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P532;P542

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