GEOL-1021EL Lecture Notes - Lecture 11: Planetary System, Pseudotachylite, Tektite
16 Jun 2018
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Department
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November 23, 2017
GEOL-1021
Meteoritic Impacts
•Near Earth Objects (NEO)
•Comets and asteroids are nudged y the gravitational attraction of nearby planets into
orbits that allow them to enter the earth’s neighbourhood
•comets are composed mostly of water ice with embedded dust particles and formed in the
cold outer planetary system
•Jupiter, saturn, uranus, neptune, etc, are formed by an agglomeration of billions of
comets
•Asteroids are rocky material formed in the warmer inner solar system between the orbits of
mars and Jupiter
•comets and asteroids may contain unique info about the origin of the solar system
•Meteorite is any of these objects impacting the earth
•Meteroitic impacts
•two main groups of geologic processes:
•slow processes (erosion, sedimentation)- effects require long periods of time
•Catastrophic processes (volcanic eruptions, earthquakes)- effects are immediate
•Meteoritic impacts are clearly catastrophic processes
•effects of large meteoritic impacts can be much larger than any geological process
•they are essential for the formation of all planets
•the earth itself formed by an accretion of material
•the moon formation is thought to be a collision event
•Meteor Information
•Meteorites first postulated by Ernst FF Chladni shortly before 1800
•his hypothesis was strongly supported by witnessed meteorite impact in 1795 and a
spectacular fireball even in 1803
•most recently, the origin of lunar craters was disputed between volcanic features and
meteorites as late as the late 40’s
•Meteorite composition
•sub classified in 3 major groups
•stony meteorites
