柴达木盆地东部三湖地区四系米兰柯维奇旋回分析  

Analysis of milankovitch cycles of quaternary in sanhu area,eastern qaidam basin

作　　者：王永军[1] 郭泽清[2] 刘卫红[1] 徐小林[2] 曾富英[2] 

机构地区：[1]中国地质大学,北京10083 [2]中国石油勘探开发研究院廊坊分院天然气地质所,廊坊065007

出　　处：《地球物理学进展》2007年第2期544-551,共8页Progress in Geophysics

摘　　要：自然伽马曲线包含丰富的地质信息，能够很好地反映由气候变化引起的地层旋回．本文采用频谱分析对柴达木盆地三湖地区第四系自然伽马测井曲线进行了系统分析．作为频谱分析方法之一的快速傅里叶变换能够将自然伽马曲线从时间（深度）域转换为频率域，然后分析每一个峰值频率的波长及其相互之间的比率关系，寻找那些波长比率与米兰柯维奇周期比率相同或相似的频率，从而捕获高频旋回信息．研究结果表明第四系地层中很好地保存了高频的米兰柯维奇旋回，这样的沉积旋回主要由地球轨道的周期性变化而导致的古气候变化引起的．偏心率周期引起的地层旋回厚度变化范围在92．00～115．00m之间，黄赤交角引起的地层旋回厚度变化范围在24．55～63．43m之间，岁差引起的地层旋回厚度变化范围在16．8～26．35m之间．黄赤交角和岁差是影响该区米兰柯维奇旋回的主要因素，其中岁差的影响最大，而偏心率的影响最小．Natural gamma-ray curves that include great amount of geological information can well reflect stratigraphic cycles caused by climate changes. In this paper, the gamma-ray curves of the Quaternary of Sanhu area in eastern Qaidam Basin are analyzed using frequency spectrum analysis method. The time （depth） field of the natural gammaray curves can be transformed into the frequency field by the fast Fourier transform, and then the wavelength of every peak frequency and the ratios between these wavelengths are analyzed in order to find the frequencies whose wavelength ratios are the same as or similar to the Milankovitch cycles, and find out that the strata conserve well Milankovitch cycles and the main sedimentary cycles are 100, 54, 41, 29, 23 and 19 ka, corresponding with the eccentricity cycle, the obliquity cycle and the precession cycle of Milankovitch cycle. So it is reasonable to deduce that the sedimentary cycles are controlled by palaeoclimate which is caused by the eccentricity cycle, obliquity cycle and the precession cycle. The thickness range of sedimentary cycles caused by the eccentricity cycle is 92. 00 ～ 115.00 m, that caused by the obliquity cycle is 24.55～63.43 m and that cause by the precession cycle is 16.8～26.35 m. Among the three control factors, the obliquity and the precession have more important effect on Milankovitch cycle of the Quaternary in Sanhu area.

关 键 词：自然伽马曲线 米兰柯维奇旋回 频谱分析 沉积速率 柴达木盆地 第四系 

分 类 号：P631[天文地球—地质矿产勘探]