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One of the World's premier field geologists, Kristjan Saemundsson led immense geological mapping programs and authored or co-authored nearly all geological maps of Iceland during the past half century, including the first modern bedrock and tectonic maps of the whole country. These monumental achievements collectively yield the most inclusive view of an extensional plate boundary anywhere on Earth. When Kristjan began his work in 1961, the relation of Iceland to sea-floor spreading was not clear, and plate tectonics had not yet been invented. Kristjan resolved key obstacles by demonstrating that the active rifting zones in Iceland had shifted over time and were linked by complex transforms to the mid-ocean spreading ridge, thus making the concept of sea-floor spreading in Iceland acceptable to those previously skeptical. Further, his insights and vast geological and tectonic knowledge on both high- and low-temperature geothermal areas in Iceland yielded a major increase in knowledge of geothermal systems, and probably no one has contributed more than he to Icelandic energy development. Kristjan's legacy is comprised by his numerous superb maps on a variety of scales, the high quality papers he produced, the impactful ideas generated that were internationally diffused, and the generations of colleagues and younger people he inspired, mentored, or otherwise positively influenced with his knowledge and generous attitude.

The Krishna-Godavari basin is a rifted passive margin basin that developed orthogonally to the NW-SE trending Pranhita-Godavari graben along the central Eastern Continental Margin of India in response to the continental rifting process and the subsequent seafloor spreading between India and eastern Antarctica during the early Cretaceous period. The 3-D gravity interpretation of both the onshore and offshore sections of the basin integrated with detailed seismic reflection and refraction data provided significant new information about the crustal architecture and the early breakup history of the basin. The gravity-derived crustal models indicate that the crust at the eastern Indian shield margin is 39-41 km thick and thins to as much as 20-23 km at the Ocean Continent Transition (OCT) in the offshore. There is a significant variation in the nature of crust and the configuration along the margin between the three crustal domains encompassing the basin: the Cuddapah basin, Pranhita-Godavari Graben, and the Eastern Ghat Mobile Belt that indicates the lateral segmentation of the margin. A zone of high density (3.0 g/cm(3)) crustal material at the OCT separates the pure continental and oceanic crusts on either side. The Moho is shallowest along this zone and brought the upper mantle notably close to the surface, which indicates that it could be comprised of Proto-Oceanic Crustal rocks. Furthermore, the present study highlights a major basement structural high in the deep offshore area of the margin. The geophysical signatures over this structure suggest that it is a crustal scale feature that is characterized by intrusive volcanic rocks, comprised of low density crust, and lies close to the OCT towards offshore. Based on the inferred tectonic reconstruction, we believe that this structural high could be a continental fragment that was left behind during the process of breakup between India and the Elan Bank. (c) 2012 Elsevier Ltd. All rights reserved.