12 Paleontology/Sedimentology/Stratigraphy

Thursday, 20 March 2008
8:00 AM - 12:00 PM

PRE-GLACIAL NITROGEN CYCLE IN THE LATE ORDOVICIAN VININI FORMATION

Paper number: 12-2
Program: Technical Sessions
Time: 8:20 AM – 8:40 AM

Authors

Abstract

The Late Ordovician is a time of extreme climate events. While most of the Ordovician climate was warm and equitable, the Late Ordovician culminated in a severe glaciation. The Vinini Formation in Central Nevada provides an excellent record of the Late Ordovician glacioeustatic events along the continental slope of Laurentia.

Denitrification in the oxygen-minimum zones along continental slopes of modern oceans plays an important role in the global N budget, and variation in rates of denitrification at the timescale of glaciations may represent an important forcing of global climate. Low δ15N values in the black shale unit of the Vinini Formation, ranging between +1 ‰ to -1‰, indicate nitrogen fixation and a lack of denitrification during the deposition of these deposits. This suggests that nitrogen denitrification might not have played a mayor role in controlling global climate dynamics in the Hirnantian.