Sedimentation differences and depositional model in slope‐controlled travertine precipitation stream in Huanglong, China

ABSTRACT Travertine, a unique continental carbonate deposit, forms a multitude of fantastic landscapes and changes morphology through continued deposition by hydrothermal water. This study explores the depositional differences of travertine under slope control through the local hydrochemical changes of travertine at different slopes in Huanglong (China), the analysis of flow patterns under hydrodynamics and its micro‐morphological features. The hydrochemical characteristics of low‐gradient sloped stream undergo regular changes along the flow, while contributing to calcium carbonate deposition as surface water reaches a supersaturated state. As the slope steepens, the water flow undergoes successive water jumps. In addition, the concentrations showed a decreasing trend of jagged fluctuations and the concentrations at the jumping parts were all lower than those at the neighbouring falling points. The unique hydrodynamic conditions of the cascade steep slopes lead to differences in the upward aggradation and forward progradation of the curved convex structure, which further regulates changes in the radius of curvature of the arc. This process in turn feeds back into changes in hydrodynamic conditions. The interplay of hydrodynamics and hydrochemistry with geomorphology results in a progradational and aggradational travertine growth. In the steep‐slope region, the travertine lamination structure consists of alternating deposition of dense calcite and sparse calcite–microbial assemblages. The balance between microbial growth rates and calcite precipitation rates is influenced by flow conditions that vary with topography, and then, it further controls the phase distribution and structure of travertine sediments. The aim of this study is to explore the depositional models and evolutionary trends of stream travertine systems under different slope controls through sedimentological characterization, combined with hydrodynamic modelling and regional hydrochemical variability patterns. These results may be useful in assessing patterns of morphological evolution that explain other continental carbonate depositional areas.