Cretaceous / Paleogene Extinction Flashcards
What occurred in the aftermath of K/Pg?
Evolution of life
What were some victims of the K/Pg mass extinction?
Belemnites- bivalves
Ammonites
Dinosaurs pterosaurs and marine dinosaurs
What was used by the Alvarez’s to hint at the driver of the K/Pg?
Iridium found in cosmic dust flux within a clay layer in Italy caused by rapid sediment change usually thought to be unconformity but high level of cosmic dust in layer meant there was change to constant flux
What profound organism change was seen by both Smit and Alvarez around the K/Pg
Change in small marine organisms
End cretaceous diverse micro fossils (multi chambered)
Bottom Cenezoic little diversity
What are microtektites?
Tiny glass spherules found in land environments
What are microtektites associated with?
Molten rock being flung into atmosphere and cooling as it falls to surface
What is the problem with Spherules from around the K/Pg boundary being found?
These areas are not located near volcanoes
Where can examples of Microtektite locations associated with the K/Pg?
Raton, Colorado
Caravaca, Spain
Why is shocked quartz an example of a high impact event having occurred at the K/Pg?
Quartz is very string and resistant it would need strong and instantaneous pressure to be altered
What is the change form quartz to shocked quartz?
Quartz - undulating extinction, no good cleavages conchoidal fractures with no internal layers
Shocked quartz - distinct planar features, coloured birefringence
What within the clay layer of the K/Pg shows there was massive global wildfires?
High levels of soot
What idea tried to rebuke the impact theory?
Uniformitarianism (present key to past) as impact theory shows something outside of system can have a fast and dramatic impact
Where was the K/Pg impact crater located?
In the Yucatan
What evidence was there for massive tsunamis from the K/Pg impact?
metre thick sand deposits from a relatively small time period
What environmental evidence is there for the impact direction of K/Pg being NW?
Fern spike” in North America due to lack of competition and Higher flora extinctions in North America
What gravitational and seismic evidence is there for the K/Pg impact direction being NE?
Elongate central structure
Widening of the 180 km ring
“Twin peaks” alignment
Asymmetry in inner ring and peak ring
Thrusting downrange
Downrange depression
NE compressional shearing
What was the size of the impactor for K/Pg?
~12km Bolide (what remains when enters atmosphere)
What is the size of the K/Pg crater?
35km deep and 100km wide
What was the timeframe to produce the K/Pg crater?
300 to 600 seconds
Why was a double peak created in the k/Pg event crater?
the crater went so deep it reached rock undergoing flow which rebounded
How many atomic bombs was K/Pg equivalent to?
100 million
What was the energy distribution of the K/Pg impact?
1% of energy turned into (200 m) tsunamis and hurricane force winds
99% of energy caused melting, vaporization, ejecta & magnitude 13 earthquakes
What was the problem caused by ejecta from K/Pg?
Hot molten material in the atmosphere essentially cooked life from above
What was the selectivity/ bias from the K/Pg event?
Larger animals which couldn’t hide and have high metabolic requirements less favoured to survive
What was the climate impact of K/Pg?
Sulphur rich rocks burnt releasing sulphur dioxide into the atmosphere causing a nuclear winter
What was the effect on ozone after K/Pg?
Increased sulphate created hole in ozone increasing UV reaching surface
What occurred at the same time as K/Pg some some try to argue was a potential driver of extinction like PTME?
Deccan traps (Large igneous province)
Why did avian dinosaurs survive the K/Pg?
evolution of small body size (~1kg) over at least 60 million years
prior to K/Pg
What is the Lilliput event and why is it common among mass extinctions?
Effect that smaller organisms most commonly survive mass extinctions - widespread dwarfing can change efficiency of energy use within and among taxa
What was the major earth system perturbation of K/Pg?
~93% species extinction in the calcifying marine algae (coccolithophores) which affected bio pump and food chain
