摘要
为了揭示侏罗纪柴达木盆地北缘泥炭聚集特征,对高泉露天矿7号煤层进行了煤岩学和频谱分析研究。结果表明,7号煤层有机组分变化大,镜质组平均含量为49.9%,以基质镜质体(平均含量19.1%)和结构镜质体(平均含量12.1%)为主;惰质组平均含量为41.1%,以半丝质体(平均含量19.3%)和碎屑惰质体(平均含量12.3%)为主;类脂组平均含量为2.8%,以孢子体(平均含量2.5%)为主。频谱分析识别出7号煤层内0.68 m、1.00 m和1.82 m三个有效厚度周期,其周期比值与泥炭地发育时期的岁差和黄赤交角周期比值相近,认为煤层V/I变化受到米兰科维奇天文周期中岁差和斜率的影响。利用MTM多窗谱分析重建了3个厚度周期的频谱信号,计算出7号煤层沉积时间约为371 ka,泥炭沉积速率约为0.2 mm/a,由于聚煤期泥炭的侵蚀和氧化等原因,该速率低于全新世全球低海拔相近纬度带的泥炭最高聚集速率(0.5~1.6 mm/a)。
To reveal peat accumulation characteristics of Jurassic coal seams in northern Qaidam Basin,coal petrology of the main coal seams and spectral analysis of coal seam No. 7 in Gaoquan open-pit mine were investigated. Results show that the volume of organic macerals varies considerably(120 samples),the average content of vitrinine and inertinite are 49. 9% and 41. 1% respectively,the former mainly comprises collodetrinite( ave. 19. 1%) and telinite( ave. 12. 1%),and the later primarily comprises semifusinite( ave. 19. 3%) and inertodetrinite( ave. 12. 3%). Sporinite( ave. 2. 5%) is the major component of liptinite( ave. 2. 8%). Three effective thickness periods of 0. 68 m,1. 00 m and 1. 82 m in coal No. 7 were recognized through the spectrum analysis,and the ratio of them is similar to that of the peat development period precession and obliquity cycle. As a result,the variation of coal vitrinite and inertinite is affected by the precession and slop of Milankovitch astronomical cycle. The spectrum signal of three thickness periods were reconstructed by the Multi Taper Method( MTM),from which the total deposition time( approximately 371 ka) and the average peat sedimentation rate( ave. 0. 2 mm/a)of coal No. 7 was obtained. The peat sedimentation rate of coal No. 7 is lower than the highest rate( about 0. 5 ~ 1. 6 mm/a) of Holocene deposited in lower altitude area with similar latitude.
出处
《矿业科学学报》
2018年第1期1-8,共8页
Journal of Mining Science and Technology
基金
国家自然科学基金(41472131
41772161)
教育部新世纪优秀人才项目(2013102050020)
