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Only 10% of the 150 or so known impact craters on Earth date from the early Precambrian Era, a time period covering some 88% of the Earth's history. Yet this Era encompasses fundamental events in the origin and evolution of our planet from the origin of life itself to the development of continents. The papers in this volume were presented at a workshop sponsored by the European Science Foundation Scientific Network on Impact cratering held in Cambridge, UK, in December 1998. The papers outline the present state of scientific understanding of the role impacts may have played in the biological and geological evolution of the Early Earth.
List of contents
Exobiology: Laboratory tests of the impact related aspects of Panspermia.- Macromolecular organic materials in carbonaceous chondrites: A review of their sources and their role in the origin of life on the early earth.- Effects of atmospheric heating on infalling meteorites and micrometeorites: Relevance to conditions on the early earth.- Search for petrographic and geochemical evidence for the late heavy bombardment on earth in early archean rocks from Isua, Greenland.- The oldest impact deposits on earth - First confirmation of an extraterrestrial component.- Early archean spherule beds in the Barberton mountain land, South Africa: Impact or terrestrial origin?.- Particles in late archean carawine dolomite (Western Australia) resemble muong nong-type tektites.- Fossil micrometeorites from Finland - Basic features, scientific potential, and characteristics of the mesoproterozoic host rocks.- Impact diamonds as indicators of shock metamorphism in strongly-reworked Pre-Cambrian impactites.- Deeply exhumed impact structures: A case study of the Vredefort structure, South Africa.- Identification of ancient impact structures: Low-angle faults and related geological features of crater basements.- Basic remote sensing signatures of large, deeply eroded impact structures.- The terrestrial cratering rate over the last 125 million years.- Impact melting of carbonates from the Chicxulub crater.- The Gallejaur structure, Northern Sweden.- Neugrund structure - the newly discovered submarine early Cambrian impact crater.- Impact-induced replacement of plagioclase by K-feldspar in granitoids and amphibolites at the Kärdla Crater, Estonia.
