REMOTE SENSING AND GIS AS A CYBERRECONNAISANCE TOOL IN NORTHERN ETHIOPIA AND SOUTHERN ERITREA

The Neoproterozoic Tambien Group of northern Ethiopia and southern Eritrea is the focus of an ongoing study to evaluate the Snowball Earth hypothesis and its impact on the geologic evolution of the Arabian-Nubian Shield. Fieldwork in developing countries, such as Ethiopia, presents unique challenges, including sensitive political boundaries, limited road networks, and a general lack of high resolution geologic data (particularly in digital format). Here we demonstrate how satellite imagery provides an opportunity to partially surmount these challenges. We generated a mosaic of ASTER scenes, combined with DEM data and geographic shapefiles of the area, to show existing sample locations and better guide future field studies. Remote evaluation of gross geologic structure and stratigraphy and the ability to identify access points along road and stream cuts makes fieldwork more efficient. For example, stratigraphic tops and bases of prospective structures can be evaluated in advance to identify optimal transect localities. Many carbonate units with unique isotopic characteristics are nicely displayed in the ASTER scenes. The GIS also allows feasibility of fieldwork near politically sensitive areas, such as the Ethiopia-Eritrea border, to be explored proactively. However, development of the GIS also revealed the challenge posed by integrating ASTER images taken during contrasting seasons (wet season = abundant vegetation; dry season = little vegetation). Lower resolution Landsat TM and ETM+ scenes are more useful for showing the region without distractions of seasonal vegetation changes along many scene boundaries. Finally, the GIS can also be of interest to local university, industry, and government agencies, often for nongeologic purposes.