| Popis: |
Asteroid and comet impacts are important catastrophic events in the Earth history, and their recognition and timing allow us to document the rate of cosmic catastrophes and resultant environmental stress. Some of these events left their mark in geological record as the cause of very rapid (almost instantaneous) climate changes, biotic stresses, and extinctions. Geologically young impact events left their mark in topography as impact craters, whereas older events are preserved as impact structures without visible crater, but display impact-generated facies such as breccia lens and impact melt-rocks as erosional remnants. Most old impact structures are deeply eroded, but some are buried by younger sediments and unexposed. The island of Krk is site of proposed impact structure which is located in central part of the island and has reconstructed size of 11 x 14 km. The structure was drilled by Krk-1 exploration well in 1967, and recognized as a breccia lens. The well was drilled through breccia for 1500 m, and revealed significant stratigraphic incompleteness. |
