Estimates of Physical Parameters in Sedimentary Environments by Means of Ancient Ripple Marks--Case of Changchengian quartz sandstones in Xuanhua Area, Northwest Hebei
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摘要: 从20 世纪70 年代开始，沉积学步入了定量和半定量的阶段，欧洲学者在20 世纪80 年代对阿尔卑斯地区海相沉积和英国的设得兰地区的陆相沉积的波痕构造作了大量的开创性工作，建立了一系列的数学表达规律。本文利用了他们的研究成果，在宣化地区长城系下部石英砂岩中进行了应用研究。结果表明，处于特殊沉积环境下的石英砂岩A、B、C 的环境物理参数有规律地变化，石英砂岩A!石英砂岩B!石英砂岩C，水质点的运动速度由大到小，再由小变大；运动周期（T）由长变短，又由短变长；水深由深至浅，又由浅至深；波浪的高度由大变小；又由小变大；水体的能量由大到小，又由小到大。计算结果与实际观察较吻合。结合粒度分析，三层石英砂岩中砂质颗粒在水体中主要作跳跃运动，其次是跳跃运动与悬浮运动的转换运动，部分质点作悬浮运动，反映了水体浅，能量较高。Abstract: Since the 1970~s, sedimentology has entered into a quantitative study era. The Europe an sedimentologist creatively did a lot of quantitative study on ancient ripple marks in the marine sediments in Alps and lacustrine sediments in Shedland of England in the 1980s. A series of mathematical formulae have been established. A number of physical parameters of sedimentary environments of Changchengian quartz sandstones A, B, and C in the Xuanhua area, northwest Hebei are estimated based on the mathematical formula in this study. The calculation results show the velocities of water particles of sedimentary environments from sandstones A via B to C becom smaller, then bigger; the motion periods for water particles become shorter, then longer; the water depths of environments become shallower, then deeper; the wave heights of waters become lower, then higher; the energy of waters becomes smaller, then larger. These estimations are in fair harmony with the observations in the field. The grain size analyses demonstrate the jumping population of sandstones dominated in sedimentary environments and the suspension population at 20～40% of the total grains. No tractive population is present in the analyzed samples. So,the grains are transport in the form of jumping and suspension. in shallower water bodies.
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Key words:
- Xuanhua Area /
- quartz sandstone /
- ripple mark /
- physical parameter /
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