Did the Mjølnir Asteroid Impact Ignite Barents Sea Yydrocarbon Source Rocks?

Henning Dypvik¹, Wendy S. Wolbach², Valery Shuvalov³, and Susanna L. Widicus Weaver^4
1University of Oslo, Oslo, Norway
²De Paul University, Chicago, IL
³Russian Academy of Sciences, Moscow, Russia
⁴University of Illinois, Urbana, IL

The Late Jurassic, organic-rich shales of the Barents Sea make up one of the main petroleum source rocks in the Arctic. These sediments covered the target area of the Late Jurassic Mjølnir impact. We suggest that the extreme richness of organic matter and highly volatile components in the target rock resulted in colossal and intense fires in the impact area, both in the air and on the seafloor. This theory is supported by numerical simulations and explains the large quantities of soot that have been found in samples associated with the Mjølnir impact.
The soot formation occurred just after impact (due to shock heating of target material and ejecta heating in impact plume) and probably had an initial distribution similar to that of other ejecta. The soot size and distribution are consistent with a combustion origin.
At the time of impact the paleogeographic position of the impact site was hundreds of km from the closest forest, making wildfires on surrounding land not very probable. An extraterrestrial carbon source seems less likely, since geochemical analysis indicates an iron-nickel rich impactor. We consequently find it most likely that the soot particles came from organic rich, partly volatile, dark clays of the sea bed. The soot grains have an appearance comparable to those of combustion origin from oils or hydrocarbons. The fires in the air and on the seafloor must have started immediately at impact and were on and off in periods, partly controlled by the wash and back wash into the crater.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece