Continental red beds, widely formed at various geologic timescales, are sedimentary rocks and sediments with red as the main color. Geoscientists have analyzed the geomorphology, paleomagnetism, paleoenvironments, paleontology, energy, and minerals in continental red beds. Despite the agreement that fine-grained hematite is closely related to the color of continental red beds, controversies and problems still exist regarding the micro-mechanism of their formation. As a review, this paper details the composition and color properties of pigmentation in red beds, analyzes the existence and distribution of authigenic hematite, and summarizes the iron sources and the formation of hematite. In addition, we introduce the fading phenomenon observed in continental red beds, including three types of secondary reduction zones: reduction spots, reduction strips, and reduction areas. Lastly, this paper summarizes the evolution of color in continental red beds, emphasizes the relationship between authigenic hematite and the diagenetic environment, and proposes possible research directions for future red bed-related issues.

In the past two decades, algorithms for multiple‐point statistics (MPS) have been applied in many fields. However, 3D training datum or data (TD) is difficult to be obtained. Two‐dimensional geological cross‐sections from boreholes or geophysical data with high reliability are usually used to explain geological phenomena and are relatively easier to be acquired. In this study, a step‐wise algorithm that combines sequential process and global optimization is presented. Constructing 3D TD set and corresponding pattern databases that extended from 2D cross‐sections at each scale is one of the key steps after presetting the simulation parameters. The following step is constructing an initial model at the coarsest scale with the pattern databases. The iterative Expectation Maximum‐like (EM‐like) optimization process is implemented to obtain the final realization. Each iteration is conducted with a multiscale strategy. Simulation examples of the regional geological structures show that the stratigraphic sequence can be reasonably kept and reproduced. Also, the randomness and effectiveness of the microstructure model are verified by calculating the proportion of grains, fractal dimension and the curve of two‐point connectivity probability function.