The Greenland analogue project. Geomodel version 1 of the Kangerlussuaq area on Western Greenland

During the 2nd annual Greenland Analogue Project modelling workshop in Toronto, November 2010, the hydrological modellers requested an updated geological map and structural model of the field area around Kangerlussuaq, Western Greenland. This report presents an updated GAP Geomodel which utilizes all available information in order to improve the accuracy of the model, especially beneath the ice-sheet. The modelling area was divided into two scales: The regional scale area and the site scale area. The site scale refers to the area were surface mapping has been performed, and where two drillholes (DH-GAP01 and DH-GAP03) were drilled during 2009. Geological and topographical maps from GEUS (sub-model 1) and data extracted from the Geophysical map, GEUS, (sub-model 2) were used in the process to develop GAP Geomodel version 1. These two interpretations were independent from each other and in the final stage these sub-models were integrated and developed into GAP Geological model version 1. The integration resulted in a total of 158 lineaments. These lineaments are referred in the final model as deformation zones and faults, where deformation zones are larger features and faults are single fractures indicating some sense of movement. Four different sets of deformation zones and faults were identified in the regional area. The most prominent feature is the ductile/brittle roughly ENE-WSW trending zones crosscutting the whole area; referred as Type 1. Type 2 and Type 3 zones are in general smaller scale than Type 1 and mostly dominated by brittle deformation. The Type 2 system generally trends NW-SE, while the Type 3 system generally trends NE-SW. The Type 4 features are a brittle and roughly N-S orientated younger system, thus crosscutting all other types. Confirmation and validation of the regional model is based on detailed surface-based examination of fractures within the site area, although the scale is different the same orientations were also identified in the regional lineament interpretation. The site area lineament model is coupled with major tectonic events in Western Greenland to further improve the certainty of our interpretation. This report describes solely a structural 2-D model and the data produced in this report were developed into a 3-D model that together with hydrological properties serves as basis for the future hydrological modelling within the GAP project, however this work is described in a separate report. (orig.)