Association With Mass Extinction
Martma et al.. (2005) assign a Mid-Ludfordian (Upper Ludlow) age to the Burgsvik, which places the beds in close temporal proximity to the Lau event, a late Silurian mass extinction. They also note a positive δ13Corg excursion in the Burgsvik and underlying Eke beds. Such excursions are normally associated with the decrease in oceanic productivity caused by mass extinctions. However, it could also be interpreted as climate, mainly precipitation, controlling the distribution of facies; high δ13C is often observed in deposits formed in arid conditions.
Calner (2005) notes that anachronistic facies are observed in other strata spanning the Lau event, places the Burgsvik beds immediately after this mass extinction (Calner 2005b), noting the occurrence of flat-pebble conglomerates in the underlying Eke beds.
Correlation with the P-S episodes postulated by Jeppsson (1990) suggests that the beds were deposited during a wet period - a P episode.
Read more about this topic: Burgsvik Beds
Famous quotes containing the words association, mass and/or extinction:
“They that have grown old in a single state are generally found to be morose, fretful and captious; tenacious of their own practices and maxims; soon offended by contradiction or negligence; and impatient of any association but with those that will watch their nod, and submit themselves to unlimited authority.”
—Samuel Johnson (1709–1784)
“Commercial jazz, soap opera, pulp fiction, comic strips, the movies set the images, mannerisms, standards, and aims of the urban masses. In one way or another, everyone is equal before these cultural machines; like technology itself, the mass media are nearly universal in their incidence and appeal. They are a kind of common denominator, a kind of scheme for pre-scheduled, mass emotions.”
—C. Wright Mills (1916–62)
“Man is an over-complicated organism. If he is doomed to extinction he will die out for want of simplicity.”
—Ezra Pound (1885–1972)