《柴达木盆地西部上、下干柴沟组湖平面变化程式及控制因素》由会员分享，可在线阅读，更多相关《柴达木盆地西部上、下干柴沟组湖平面变化程式及控制因素（90页珍藏版）》请在金锄头文库上搜索。
1、成都理工大学 硕士学位论文 柴达木盆地西部上、下干柴沟组湖平面变化程式及控制因素 姓名：武向峰 申请学位级别：硕士 专业：地质学（沉积学） 指导教师：伊海生 20100501 摘 要 柴达木盆地西部上、下干柴沟组湖平面变化程式 柴达木盆地西部上、下干柴沟组湖平面变化程式 及控制因素 及控制因素 作者简介：武向峰，男，1984 年 12 月生，师从成都理工大学伊海生教授， 2010 年 6 月毕业于成都理工大学地质学（沉积学）专业，获得理学硕士学位。 摘摘 要要 柴达木盆地第四纪气候演变受全球变化影响与控制， 因而其气候变化记录在 长周期、大尺度上与全球变化基本一致并可进行对比。湖相沉积主要由物
2、源、气 候和区域的古地貌特征共同决定。当物源和区域古地貌特征相对稳定时，气候是 湖相沉积的主控因素。气候条件的周期性变化可引起湖平面、沉积物供给和沉积 物类型的变化,从而控制湖盆沉积充填和湖平面的变化。 本文以沉积学理论、层序地层学理论为指导，以长尾台剖面为研究重点，通 过野外露头剖面、磁化率与测井资料相结合，野外宏观观测与室内微观分析相结 合，重点利用磁化率和自然伽马曲线对整个目的地层进行系统的分析，力图解析 上、下干柴沟组湖平面变化样式及其驱动机制，进而为青藏高原内部气候变化及 隆升对全球气候影响效应的研究提供参考和借鉴。 首先，结合野外剖面测量及室内薄片观察，从岩石学特征、沉积构造特征以
3、 及遗迹化石等相标志的识别，总结出了研究区地层主要发育了扇三角洲相、湖泊 相两种沉积相类型，并在此基础上划分了 6 个亚相类型。垂向上分析沉积环境演 变特征，从老到新，整体上呈现出湖水面先上升后下降的态势，同时反映出气候 由湿润向干旱变化的趋势。 其次， 以露头岩石磁化率和测井自然伽马作为反映古气候及古环境的替代指 标，并通过数据预处理中线性回归、一阶差分等新的计算方法来划分沉积旋回。 论证了不同岩性、不同砂岩粒度和不同泥岩颜色对磁化率的影响：沉积物由泥岩 -砂岩-砾岩，磁化率的峰值呈高低变化；砂岩粒度从中-粗砂岩到细-中砂岩、 粉-细砂岩，磁化率值呈现出由低到高的趋势，与粒度变化呈相反关系；
4、泥岩颜 色呈现红色等氧化色，磁化率峰值较高，说明地层沉积时的气温较高，气候比较 干燥， 盆地水体较浅； 若呈现灰绿， 青灰等还原色， 对应磁化率的峰值相对较低， 代表一种较为温湿的气候环境。 再次，利用磁化率和自然伽马数据划分的旋回地层，用 Fischer 图解分别绘 制了上、下干柴沟组湖平面变化曲线，直观反映了高频湖平面变化特征和长周期 湖平面变化趋势。 两个曲线都显示了从下干柴沟组底部到上干柴沟组的湖平面变 I 成都理工大学硕士学位论文 化程式为浅-深-浅的过程。这与通过岩相沉积环境分析的结果不谋而合，这很好 的证明了磁化率和自然伽马也可以作为湖平面变化的一个替代指标。 最后，利用滤波选定
5、沉积速率相对稳定段沉积，通过磁化率和自然伽马两 组数据的频谱分析后，上、下干柴沟组地层识别出 4 个周期长度不同的频率带。 主要频率带为第一和第三频率带。 通过详细比对地层所包含的各种旋回与米氏旋 回周期比率关系，认为斜率周期（主要为 40.984ka）对应 5-10m 的旋回厚度， 岁差周期（22.327ka 和 20.456ka）对应 2-4m 的旋回厚度。由米兰科维奇旋回周 期中斜率和岁差控制的气候变化是控制上、 下干柴沟组高频沉积旋回和湖平面变 化的主要因素。 关键词：柴西地区 上、下干柴沟组 沉积旋回 频谱分析 米兰科维奇旋回 II Abstract Lake level fluct
6、uation pattern and controlling factors of Shangganchaigou Formation and Xiaganchaigou Formation ,Western Qaidam Basin Introduction of the author:Wu Xiangfeng, famale, was born in December 1984, whose tutor was Professor Yi Haisheng. He graduated from Chengdu University of Technology in geology (sedi
7、mentology) major and was granted the Master Degree in June, 2010. Abstract The Quaternary climate of the Qaidam Basin is impacted and controlled by global changes, so its climate change record can be consistented with and compared with global change in the long-period and large-scale. Provenance, cl
8、imate and the feature of palaeogeomorphology combined to effect the lacustrine sedimentation. When the provenance and palaeogeomorphology are pediocratic, the climate become the main factor.Cyclical changes in climate conditions could cause the changes of lake level,sediment supply and sedimentation
9、 types, then impact the lake basin deposit and the lake level fluctuation. With sedimentology and sequence stratigraphy theory, this paper focus on Changweitai section, combined with magnetic susceptibility,outcrop section and logging data, through field observation and laboratory micro-macro analys
10、is, trying to resolve the lake level change style and its driving mechanism in the Shangganchaigou formation and Xiaganchaigou formation.then, provide reference and help for the study of the relationship between climate change and uplift of the Tibetan Plateau and global climate. First of all, based
11、 on field survey and thin section analysis, identify sedimentary structures and fossil lebensspur indicant,The sedimentary facies of Shangganchaigou formation and Xiaganchaigou formation is divided into alluvial fan and lacustrine facies,and then subdivided into 6 subfacies.Form old to new,vertical
12、evolution characteristics of sedimentary environment indicate the lake surface increased and then decreased, meanwhile, reflecte the climate change form humid to arid. Secondly, taking magnetic susceptibility and gamma logging data as a proxy index of the paleoclimate and paleoenvironment, using the
13、 methods of linear III 成都理工大学硕士学位论文 regression and first differences to divide sedimentary cycles. Demonstrate different lithologies, different sandstone size and different mudstone colors on the effects of magnetic susceptibility:form mudstone to sandstone then to conglomerate, the peak of magnetic
14、 susceptibility was form high to low; the grain of sandstone change form coarse sandstone to sandstone , siltstone, the value of susceptibility alter form low to high;the susceptibility show opposite relationship with the grain size; when red or somethis oxidation colours appeared in mudstone, the p
15、eak of susceptibility always come to high value, intend the sedimentary temperature relatively higher, the climate towards aridity, and the level of water maybe lower in this situation; if the colour turns up to graygreen or balsam green, as these reducible colours, it represents a relatively warm a
16、nd humid climate, meanwhile, the peak of susceptibility comes to lower value. Thirdly, using the cycle formation divided by magnetic susceptibility and gamma logging data, the lake level curve of Shangganchaigou formation and Xiaganchaigou formation drawed by Fisher diagram can visual infect high frequency lake level variations and long-period trend of lake level change.Both of the curves show the lake level changing from low to high, this
