潮汐沉积韵律计算新方法及其应用——以四川江油地区中三叠统雷口坡组藻白云岩为例

提出一种新的高精确度的方法来计算沉积旋回韵律，即以样品断面光学灰度参数作为韵律沉积变化的替代指标，利用数字图像分析软件，通过最小二乘法、一阶差分法等数据处理后，定量计算沉积旋回韵律。对采自四川江油西南部中三叠统雷口坡组的纹层藻白云岩样品进行研究，观察样品抛光面和薄片，确定藻白云石具有明显的潮汐沉积韵律纹层。应用此方法计算得出研究区样品共有217个潮汐层偶对，层偶对最大厚度为4.2mm，通过人工计数对比证明了该方法的可行性。这种技术方法与传统方法相比更省时、更高效，可推广性高，同时也可应用于其它类型频段韵律旋回中。

A new method for calculating tidal sedimentary rhythm and its application: a case study of the algal dolomite laminae from Middle Triassic Leikoupo Formation, Jiangyou area, Sichuan Province

This paper presents a new high-precision method for calculating sedimentary cycles. The grayscale values acquired from the sample section by digital image analysis software can be used as a substitute index of lamination rhythmic changes. Through least squares and first difference data processing, the sedimentary cycle rhythm can be quantitatively estimated. The algal dolomite laminae collected from Middle Triassic Leikoupo Formation in southwest Sichuan were studied. The obvious tidal sedimentary rhythm laminae displayed on polished sections were observed under microscope. The application of this method to the sample led to the discovery of 217 tidal cycles, with the maximum thickness being 4.2 mm. A comparison based on manual counting confirmed the feasibility of this method. Compared with traditional methods, this method is more time-saving, more efficient, and more easily extended. It can also be applied to other types of sedimentary cycles.