松辽盆地嫩江组—二段岩相精细划分与古湖泊变化

发布时间：2018-07-10 06:09

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

【摘要】：温室气候问题已成为全球研究的热点问题。白垩纪代表地质历史时期的一种极端的温室气候。随着人类活动影响的加剧,大气CO2含量持续增加,可能在不远的将来突破该临界浓度,从而接近或达到白垩纪时期的浓度水平。所以白垩纪气候的研究与认识亟待于人们去了解与发现该段时间里气候变化的规律与控制因素。细粒沉积岩中保存了大量的古气候信息,往往对应了一种特殊的沉积环境。通过对松辽盆地晚白垩世嫩一二段泥岩岩相的刻划可以反演出其当时的沉积环境,为进一步揭示古环境变化提供重要依据。本文主要依托松科二井所采得的岩心,对其固定、切割、抛光、贴上深度标尺。之后对所得的岩心进行岩相描述。岩相描述主要从其颜色、结构、构造、成分、生物五个方面进行。并得到以下认识:1.通过对嫩一二段细粒沉积岩岩相的划分,我们得到了有关细粒沉积岩的9种岩相。其中嫩一段9种细粒沉积岩相岩相,嫩二段5种细粒沉积岩岩相。嫩一段岩相较多,主要与它的湖泊水体动荡有关。季节性的气候变化导致湖泊盐度不断变化,生成了以富钙质纹层与富粘土纹层的岩相。嫩二段湖泊水体在海侵之后基本处于稳定的状态,且距离物源距离适中,生成了以硅质/粘土质为主要成分的中泥岩。2.通过化学相的对比发现,嫩一段下段的古盐度相与我们划分的岩相比较拟合。这从侧面可能反应了整个嫩一段下部主要受盐度控制。通过对比分析发现嫩二段的氧化还原相与我们划分的岩相比较拟合。这从侧面可能反应了整个嫩二段的岩相与湖泊水体的氧化还原有很好的对应关系。3.嫩一二段曾经发生过海侵事件,且共计发生三次海侵,两次在嫩一段底部,一次在嫩二段底部。由于两次海侵导致湖泊水体迅速升高,沉积了一套以细泥岩为主的泥岩岩相。且有机质在还原的环境下容易保存下来,含量相对于其他段处于高值状态。
[Abstract]:Greenhouse climate has become a hot issue in global research. The Cretaceous represents an extreme greenhouse climate in geological history. With the intensification of the influence of human activities, the atmospheric CO _ 2 content continues to increase, which may break through this critical concentration in the near future, thus approaching or reaching the Cretaceous concentration level. Therefore, the study and understanding of Cretaceous climate is urgent for people to understand and discover the laws and controlling factors of climate change during this period. A large amount of paleoclimate information is preserved in fine sedimentary rocks, which often corresponds to a special sedimentary environment. The sedimentary environment of the mudstone facies of Nen1 and 2 member of late Cretaceous in Songliao Basin can be reversed, which provides an important basis for further revealing the change of paleoenvironment. This paper mainly relies on the core of Songke well, fixed, cut, polished, and affixed with depth ruler. The obtained core is then described by lithofacies. Lithofacies description mainly from its color, structure, composition, biological five aspects. And get the following understanding: 1. Through the division of fine grain sedimentary lithofacies of Nen1 and 2 member, we have obtained 9 kinds of lithofacies related to fine grain sedimentary rock. There are 9 kinds of fine grain sedimentary lithofacies and 5 kinds of fine grain sedimentary lithofacies in Nen first member. There are many lithofacies in a section of Nen, which is mainly related to the turbulence of lake water. The seasonal climate change leads to the constant change of lake salinity, resulting in the lithofacies of calcareous and clay-rich grain. After transgression, the lake water in the second stage of Nenjiang River is in a stable state, and the distance from the source is moderate, resulting in the formation of middle mudstone, which is mainly composed of siliceous / clayey. Through the comparison of chemical facies, it is found that the paleosalinity facies of the lower part of the first member of Nen is compared with the lithofacies of our division. This from the side may reflect that the lower part of the whole section is mainly controlled by salinity. Through comparative analysis, it is found that the redox phase of the second stage of Nen is similar to the lithofacies that we have classified. This may reflect that the lithofacies of the whole member of the Nen member have a good corresponding relation with the redox of the lake water. There have been three transgressions in the first and second member of Nen, twice at the bottom of one segment and once at the bottom of the second segment. Due to two transgressions, a set of mudstone facies dominated by fine mudstone was deposited. The organic matter is easily preserved in the environment of reduction, and the content of organic matter is higher than that of other segments.
【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】：P588.2;P531

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