Category
page 1Isotope excursions
δ13C
In geochemistry, paleoclimatology, archaeology, and paleoceanography '''δC''' (pronounced "delta carbon thirteen") is a normalized ratio of the two stable isotopes of carbon—C and C—reported in parts per thousand (per mille, ‰).

Cenomanian-Turonian boundary event
anoxic extinction events in the Cretaceous period, occurring at 91.5 ± 8.6 Ma

δ18O
In geochemistry, paleoclimatology and paleoceanography '''δ18O or delta-O-18''' is a measure of the deviation in ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O).
It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis.
In paleosciences, 18O:16O data from corals, foraminifera and ice cores are used as a proxy for temperature.
Lau event
mass extinction event in the Ludfordian age of the Silurian period, ca. 424 Ma
oxygen isotope ratio cycle
cyclical variations in the ratio of the abundance of oxygen
Ireviken event
first of three relatively minor extinction events (the Ireviken, Mulde, and Lau events) during the Silurian period; occurred at the Llandovery/Wenlock boundary
Mulde event
anoxic event causng mass extinctions, coinciding with a global drop in sea level, and is closely followed by an excursion in geochemical isotopes, during the Silurian period