应用自然伽马曲线反演陇东地区延安组沉积旋回  

Use of natural gamma-ray well log to study sedimentary cycles of Yan'an Formation in Eastern Gansu, Ordos Basin, China

作　　者：李凤杰[1] 王多云[1] 程微 

机构地区：[1]中国科学院兰州地质研究所气体地球化学重点实验室,兰州730000 [2]辽宁工程勘察院

出　　处：《成都理工大学学报（自然科学版）》2004年第5期473-477,共5页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国科学院资源环境领域知识创新工程重要方向项目资助(KZCX3-SW-128-04)

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。采用频谱分析对鄂尔多斯盆地陇东地区延安组湖沼相自然伽马测井曲线进行反演,可以得出地层中很好地保存了高频的米兰科维奇旋回,认为研究区延安组地层中的沉积旋回主要受古气候变化的控制,其中偏心率周期引起的地层旋回厚度变化范围为7.86～16.75m;地轴倾角周期引起的地层旋回厚度变化范围为2.34～6.36m;岁差周期引起的地层旋回厚度变化范围为1.14～2.96m。频谱分析法可用于测井曲线进行高频沉积旋回分析。Natural gamma\|ray well log that include a great amount of geological information can well reflect stratigraphic cycles caused by climate changes. In this paper, the authors use frequency spectral analysis method to analyze the gamma-ray curves of liminetic facies of Yan'an Formation in Longdong area, Ordos Basin and find out that the strata conserve well Milankovitch cycles and the main sedimentary cycles are 123, 46.8, 36.7, 21.8 and 17.9 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, the obliquity cycle and the precession cycle. The thickness range of sedimentary cycles caused by the eccentricity cycle is 7.86～16.75 m, that caused by the obliquity cycle is 2.34～6.36 m and that caused by the precession cycle is 14～2.96 m. (Frequency) spectral analysis can be used to study the high frequency with well log.

关 键 词：自然伽马曲线 米兰科维奇旋回 快速傅立叶变换 鄂尔多斯盆地 延安组 

分 类 号：P631.817[天文地球—地质矿产勘探] TE121.34[天文地球—地质学]