Steptoean positive carbon isotope excursion
Encyclopedia
The Steptoean Positive Carbon Isotope Excursion (SPICE) was a geological event which occurred about 500 million years ago at the end of the Cambrian
era. The SPICE event was a sudden reversal of the anoxia
(lack of oxygen
) that had steadily spread throughout the oceans during the Cambrian which also affected the atmosphere. After the SPICE event, oxygen levels recovered and levels in the atmosphere may have risen as high as 30%, higher than the 21% of the atmosphere that prevails today. The sudden increase in oxygen led to an explosion of life across the globe.
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
era. The SPICE event was a sudden reversal of the anoxia
Anoxia
The term anoxia means a total decrease in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts:* Anoxic waters* Anoxic event* Dead zone or hypoxic zones...
(lack of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
) that had steadily spread throughout the oceans during the Cambrian which also affected the atmosphere. After the SPICE event, oxygen levels recovered and levels in the atmosphere may have risen as high as 30%, higher than the 21% of the atmosphere that prevails today. The sudden increase in oxygen led to an explosion of life across the globe.