Principle and geomorphological applicability of summit level and base level technique using Aster Gdem satellite-derived data and the original software Baz (original) (raw)

This article presents principle and geomorphological applicability of summit level technique using Aster Gdem satellite-derived topographic data. Summit level corresponds to the virtual topographic surface constituted by local highest points, such as peaks and plateau tops, and reconstitutes palaeogeomorphology before the drainage erosion. Summit level map is efficient for reconstitution of palaeosurfaces and detection of active tectonic movement. Base level is the virtual surface composed of local lowest points, as valley bottoms. The difference between summit level and base level is called relief amount. These virtual maps are constructed by the original software Baz. The macro concavity index, MCI, is calculated from summit level and relief amount maps. The volume-normalised three-dimensional concavity index, TCI, is calculated from hypsometric diagram. The massifs with high erosive resistance tend to have convex general form and low MCI and TCI. Those with low resistance have concave form and high MCI and TCI. The diagram of TCI vs. MCI permits to distinguish erosive characteristics of massifs according to their constituent rocks. The base level map for ocean bottom detects the basement tectonic uplift which occurred before the formation of the volcanic seamounts.