Rare-earth-elements characteristics of the hydrothermal sulfide in the Central Indian Ridge

 A new method is proposed to identify automatically the foot of the continental slope (FOS) based on the integrated analysis of topographical profiles. First, it simplifies the topographic profiles based on second derivative extremum points and the Douglas-Peucker algorithm, and calculates a second-order derivative of the original profiles and the D-P profiles. Then, seven steps are used to simplify the original profiles and determine the slope gradient, water depth and second derivative values of data points. By combining with multiple identification factors, like the curve concave and convex, continuity and segmentation properties, the automatic identification of the FOS points is realized. This method can comprehensively and intelligently analyze the topographic profiles and their derived slopes, second derivatives and D-P profiles, based on which, it is able to analyze the essential properties of every single data point in the profile. Furthermore, it is proposed to remove the curve’s concave points and in addition, to implement six exact FOS judgment bases.