【作者】 张天文；

【导师】 王建力；

【作者基本信息】 西南大学 ， 第四纪地质学， 2011， 硕士

【摘要】 粒度分析资料一是个传统的划相指标；沉积相及其沉积环境分析一般从形成条件(古构造,古地形,古气候与古水流)；岩石特征(岩石类型,结构,构造)：储集条件(砂体类型及亚相划分,含油气性)等特征入手进行综合分析,粒度作为结构特征中的一种也起着关键性的作用,随着粒度资料在沉积相划分中逐渐成熟的应用,利用多方式进行划相成为常用手段。通过对甘肃临夏盆地王家山剖面21.4Ma.BP以来的沉积物粒度特征及参数利用常用的判定方式进行了判断：通过对粒度参数的分析发现临夏盆地各个沉积相分选都趋向差,说明沉积环境多变；湖泊相和辫状河流相偏度跨度较大,洪积扇和三角洲相偏粗；辫状河流相沉积负偏最大,且呈现多峰；峰度和物源成分辫状河流相大于洪积扇和湖泊相窄大于三角洲；对正态概率累计曲线的分析发现辫状河流相沉积组合总体水动力逐渐变弱；但是后期沉积环境极不稳定,水流沉积变化明显且分选差。洪积扇相组合沉积体现出动力条件极强的特点,其分选好于其他三种沉积组合相,但还是属于分选较差范畴；湖泊三角洲组合相由典型的重力流沉积(洪水水道沉积物)和非洪水期沉积组成,分选相对较差；扇三角洲与湖泊三角洲很相似,扇三角洲颗粒较大,动力较湖泊三角洲强；对粒度参数的C-M图分析得出湖泊相沉积组合落在了S-R段(悬浮组分),处于均匀悬浮范围,且越是颗粒物越小,沉积物分选也越好,有少量粗颗粒沉积物,初步认为可能是构造运动的产物。辫状河流相组合样品投点显示出分选相对较差；大量递变悬浮的样点验证了辫状河流相的成立。洪积扇沉积样点散落于N-O-P-Q-R段其中NO(滚动组分)段和OP(滚动-跳跃组分)段含量较多,指示滚动和悬浮滚动两较大,搬运动力极强,沉积粗颗粒较多且分选差验证了该沉积是有强搬运动力及杂乱沉积为主；对粒度参数的弗里德曼散点图分析得出辫状河流相沉积组合的大部分落在了的样品点分布在弗单德曼分界线左上部,体现了河流、沉积粒度分布较粗、分选很差的特点；洪积扇沉积相组合样点投在从图中可看出洪积扇的样品点分布在弗单德曼分界线右上部,分选大于2偏度0.2左右的范围,以体现了洪积扇的沉积物与辫状河流、三角洲环境的沉积相比,粒度分布更粗、分选更差的特点；湖泊和扇三角洲样品投在分选大于1偏度0.2以下的区域,说明其分选较洪积扇较好但偏度也较小的特点,扇三角洲环境总体分选及偏度值都较湖泊三角洲的大,这说明扇三角洲比湖泊三角洲相动力条件略强,动能分选更大的特点,为判别扇三角洲和湖泊三角洲提供有效的方式；对偏度与峰度离散图分布分析发现湖泊相沉积组合图示反映看到峰度不确定性很大,因此用该图用来确定湖泊沉积的地层识别有不确定成分；而辫状河流相在图中偏度和峰度分布范围最广,峰度范围广说明其分选较差,偏度也分布广泛且趋向于负偏说明其粒径偏小,说明其水动力条件中悬浮沉积存在且有贡献。洪积扇主要特点是偏度处于近似正态与正偏范围,表示其沉积物颗粒较大,相对水动力条件比其他沉积相组合强,其峰度范围占全部分类范围,代表其分选很差,能够代表洪积扇相沉积特点。湖泊三角洲和扇三角洲也具有洪积扇的偏度特点,但其峰度中扇三角洲可能有极大值出现,总体印证了三角洲沉积相颗粒较粗,扇三角洲分选比湖泊三角洲分选更差的特点。综合上述分析,归纳出了临夏盆地湖相沉积中滨湖浅水微相和湖沼微相的粒度概率累计曲线特征以及湖泊三角洲的两种沉积模式的概率累计曲线特征以及C-M图散点模式；完善临夏盆地了洪积扇判别模式；湖泊三角洲沉积相可以根据其概率累计曲线判断古洪水与非洪水沉积但方法不完善。对王家山剖面沉积环境判别模式中五种沉积相可以进行粒度资料的多方式的判断,说明粒度资料可以作为临夏盆地五种沉积相划相指标进行应用并具有可行性,对其他地区的划相工作也有一定参考意义。更多还原

【Abstract】 One of the traditional particle size analysis data of the program relative to targets. For Sedimentary facies in the environment to determine inter-site identification of the particle size data can be used in addition to a number of ways to supplement their determination, through the Mount Royal Linxia Basin Since the grain size profile 21.4Ma.BP characteristics and parameters determined by commonly used methods were judged:Through the analysis of grain size parameters in various sedimentary facies Linxia Basin tend to poor sorting, indicating unstable sedimentary environment; lakes, braided fluvial facies and span a larger skewness, alluvial fan and delta coarse; braid fluvial deposits form the largest negative deviation, and the present multi-peak; peak level and source components than braided fluvial and lacustrine alluvial fan narrower than Delta.;Through the cumulative normal probability curve analysis combined braided fluvial deposits gradually weakened the overall hydrodynamic; but the latter unstable sedimentary environment, significant changes in water flow and sediment sorting poor. Deposition of alluvial fan facies association reflects the characteristics of highly dynamic conditions, the sub-selected combination of the other three sedimentary facies, but still are sorting poor areas; lake delta phase from the typical combination of gravity flow deposits (flood channel deposits material) and non-flood sediment composition, the relatively poor sorting; fan-delta and the lake is very similar to the delta, fan delta large particle size, power stronger than the lake delta.;Through the analysis of grain size parameters of the C-M diagram derived lacustrine sedimentary assemblage fell SR section, in the range of uniform suspension, and the more the smaller the particles, the better sorted sediments, a small amount of coarse sediment, the preliminary view that may be the product of tectonic movement. Braided fluvial investment point composite sample showed relatively poor sorting; a large number of graded suspension of the samples proved the establishment of braided fluvial. Alluvial fan deposits scattered in N-O-P-Q-R section samples paragraph in which NO-OP segment content and more, indicates the two large roll rolling and suspension, handling highly dynamic, large and coarse sediment sorting is poor to verify the deposit has a strong messy deposits in the power and handling.;Through the analysis of grain size parameters of the Friedman plot obtained combination of braided fluvial deposits fell most of the sample point located in the upper left Front line single Goldman, reflecting the river, sediment particle size distribution coarse, poor sorting characteristics; alluvial fan facies investment portfolio samples can be seen from the diagram of sample points alluvial fan located in the upper right Front line single Goldman, sorting skewness greater than 2 the range of about 0.2 to reflect the alluvial fan and braided river sediments, the deposition of delta compared to more coarse particle size distribution, sorting worse characteristics; lakes and fan delta invested in sorting samples skewness greater than 1, the area below 0.2, indicating that separation is better than the alluvial fan, but also smaller skewness characteristics of the overall fan-delta environment sorting and skewness values are relatively large lake delta, indicating that deltaic fan-delta dynamic conditions than the lake slightly, greater separation characteristics of the kinetic energy for discrimination fan delta and lacustrine delta provide an effective way.;Through the skewness and kurtosis of the discrete map the distribution of lake sediments that reflect the combination of icons that kurtosis great uncertainty, hence the lake sediments of the figure used to determine the identification of uncertain composition of formation; and;Braided river facies in the figure the distribution skewness and kurtosis the widest range of wide range of kurtosis on its poor sorting, skewness is also widely distributed and tend to explain the size of small negative bias, indicating that hydrodynamic conditions the existence and contribution of suspended sediment. Alluvial fan is characterized by skewness in the approximate range of the normal and positively skewed, indicating the larger sediment particles, the relative hydrodynamic conditions stronger than any other combination of sedimentary facies, the peak classification of degrees of total range, on behalf of their separation is poor, can represent the characteristics of alluvial fan facies. Lake delta and alluvial fan-fan delta also has a partial degree, but its peak level in the fan delta has a maximum value may occur, generally confirms the delta facies coarse, fan-delta lakes than sorting Delta sorting worse characteristics.The above analysis, summarized the Linxia basin lake sediments in the shallow water facies and lakeshore lake facies of the cumulative probability curves of grain size characteristics and lake delta depositional model of the probability of two cumulative curves and the C-M diagram scatter pattern; Linxia basin, the alluvial fan complete determination mode; lake delta facies cumulative curves can be judged according to their probability and non-flood deposition of ancient floods, but way incomplete. Royal Hill section of the sedimentary environment of five sedimentary facies discrimination mode data can be more granular way to judge, that granular materials can be used as Linxia basin planning phase of five sedimentary facies and feasible application of indicators to other areas phase work plan has certain reference value.更多还原