Grain-Size Characteristics Of Quaternary Sediments And Its Sedimentary Environment Implication In Langfang City

Langfang City, Which located at the border of the northern margin of the North China Plain and Yanshan Nan slope, tectonic belonging to the North China Platform, and its base, Archean and Proterozoic metamorphic rocks, on top of the accumulation of Early Paleozoic and Late Paleozoic sedimentary cover, Cenozoic rifting in the development of extensional structures, localized deposition of a few kilometers thick. Secondary structure in the settlement with the North China Plain area-the northern part of Jizhong Depression, Langgu rift basin. Genetic types of Quaternary alluvial, alluvial, lacustrine, and their transition type between the sea product, aeolian type. In this paper, laser particle size analysis methods, combined with the lithological characteristics, particle size characteristics of the controlling sediment cores analyzed in detail, and the hole pollen analysis results were analyzed. Meanwhile, the characteristics of the Langfang Quaternary deposition and depositional environment were analyzed.Controlled drilling, with an average particle size of sediments of the District, the average particle size distribution1.4-7.8φ, and mainly concentrated in the4-7.8φ, indicating that the deposition type silt, a small amount of sand, the overall performance of drilling hole the lower part of the coarse particles, the upper part of the particles relative partial fine; quartile and more from the difference in the0.67-1.4between sorting the majority, a small number of medium, a very small part sorting; skewness, negative bias, followed by nearly symmetrical, a few were highly negatively skewed, very positively skewed, indicating that the sediments most sorting is better, overall the small components of the main; kurtosis values are mainly concentrated within the0.9-1.56range, mainly between0.9-1.11, followed by1.11-1.56between kurtosis indicate that sediment characteristics in wait until the narrow, a few broad peaks. All the values are distributed in1.4-7.6φ, grain component to silty clay, clay and silty sand. And with different drilling depth and lithology changes. According to each parameter, the characteristic values of each parameter distribution of the characteristic curve, obtained by the comprehensive analysis and comparison of particle size analysis indicated by the integrated interpretation of the depositional environment characteristics:alluvial-Lakeside, Lake-shallow lake, shallow lake-deep lake phase.Through various methods, including particle size, pollen and dating data, including analysis of the sedimentary environment evolution characteristics of drilling holes representation. Gallery Quaternary climate change is characterized by:1) pollen reflect the warm and cool dryâ†'warm wet theâ†'warm and cool dry theâ†'warm moistâ†'cool dryâ†'warm and humid.2) dating data analysis of a representative section of the sedimentary environment evolution characteristics.3)comprehensive analysis of lithology, grain size, pollen, dating, controlled drilling deposition.Environmental features of study area were analyzed. The controlling sexual drilling is located at the fan delta of the river, the lake began to expand-river deposition-the Alluvial role-fluvial deposits-lake basin retreat-Lake into the enhanced role of the river; the late Pleistocene:Lake-red The alluvial role-the lake basin retreat-red, the alluvial role; Holocene:lake basin retreat-red, alluvial role.