Publications

From a geological viewpoint, Papua is well-known as a frontier area in Indonesia. Less detailed geological information and fewer reports are available compared to other parts of the country due to its limited accessibility as well as its complex geological setting. At the same time, the tectonics and structure in Papua is challenging in part due to its very long geological history with various rock types spanning a very large time period from at least as far back as the Devonian (Paleozoic) through to the Holocene (Cenozoic). This paper aims to describe and provide more information about the tectonic features which have been formed on Mesozoic to Cenozoic era boundary age rocks, and in particular on the Cretaceous to Paleogene age formations through responses of major river basins around the Enarotali area. This was carried out by studying three areas: (i) lithostratigraphy of the basins, (ii) morphometry of river basins, (iii) lineament features. Geologic mapping and measured sections on the main course of rivers were carried out to create the stratigraphic column. Drainage patterns of major rivers and their tributaries were mapped to measure bifurcation ratio (Rb) and drainage density (Dd). DEM/SRTM was combined with Landsat TM Images to delineate the lineaments on the surface as indicators of geological structures or tectonic features. Statistical analysis was used to differentiate the morphotectonic features on both formations. The Cretaceous Ekmai Formation (Kue) is predominantly composed of glauconitic quartz sand, whilst the Paleogene Waripi Formation (KTew) is * University of Padjadjaran ** Office of Mining & Energi – Papua, Jayapura carbonaceous quartz sand. However, the statistical values of Rb and Dd as morphometric variables between both formations were not significantly different. In addition the azimuth of lineaments and river segments between both formations does not vary significantly. This result suggests that there was a continuity of sedimentation with no signature of an unconformity between these formations, thus, inferring that tectonic activity was uninterrupted from the Cretaceous to Paleogene. Keywords: Tectonic Geomorphology, Central Papua, River Basin, Cretaceous, Paleogene