July 16, 2002 - Geology Report By Gordon "Oz" Osinski Ph.D. Candidate, Planetary and Space Science Centre, University of New Brunswick Despite the slow start to the field season due to the snowy weather conditions, the HMP geology program is now in full swing. One of the key goals of this season is to complete the systematic mapping and sampling of the entire crater. By mapping the crater in a systematic fashion, we hope to gain a better understanding of the distribution and mode of occurrence of several important impact-related features: (1) post-impact hydrothermal deposits, (2) carbonate impact melt rocks, (3) impact-generated faults, and (4) the central uplift. In addition, we hope to answer a longstanding question: How big is the Haughton impact structure? It may seem surprising that this apparently simple question has yet to be conclusively answered. Indeed, estimates of the diameter of Haughton range from 18 to 24 km! These differences are in part due to the different methods employed (e.g., geophysics, regional mapping), and due to problems about where exactly to define the outer rim of the crater. It is only through our detailed mapping that we will finally be able to answer this question. During the first few days of the 2002 field season, we have been focusing our field studies in the western and northern regions of the Haughton impact structure. These areas represent some of the most remote and least explored regions of the crater. Our mapping is yielding important insights into the distribution of impact-generated faults around the crater. These faults were formed when the initially steep (and unstable!) crater walls collapsed under the action of gravity. Mapping the distribution of these faults will also enable us to accurately determine the actual diameter of the Haughton impact structure. Basically, the diameter can be determined by the position of the last major collapse fault outwards from the crater center. In a continuation of the work from previous field seasons, we are also mapping the location and nature of hydrothermal deposits related to the impact event. Hydrothermal systems will develop anywhere in the Earth's crust where water coexists with a heat source. Most hydrothermal systems on Earth are sustained by magmatic or volcanic heat sources (e.g., Yellowstone National Park). However, during the last few summers, we have found evidence for the existence of a hydrothermal system formed by the interaction of water with hot, impact-generated melt rocks at the Haughton impact structure (see paper in Meteoritics and Planetary Science by Osinski et al., 2001). This work adds to a growing body of evidence which suggests that impact-induced hydrothermal activity is commonplace after the impact of a meteorite or comet, with a planetary surface. This is important because hydrothermal systems may have provided warm, wet sites suitable for the origin of life on Earth and other planets (e.g., Mars). [For larger images and description please click on the image.] (Photo NASA Haughton-Mars Project 2002 / Gordon 'Oz' Osinksi)