Editing Paleogene (section)

== Geology ==

=== Stratigraphy ===
The Paleogene is divided into three [[Series (stratigraphy)|series]]/[[Epoch|epochs]]: the Paleocene, Eocene, and Oligocene. These stratigraphic units can be defined globally or regionally. For global stratigraphic correlation, the [[International Commission on Stratigraphy]] (ICS) ratify global [[Stage (stratigraphy)|stages]] based on a [[Global Boundary Stratotype Section and Point]] (GSSP) from a single [[Geological formation|formation]] (a [[stratotype]]) identifying the lower boundary of the stage.<ref>{{Cite web |title=International Commission on Stratigraphy |url=https://stratigraphy.org/chart |access-date=2024-07-15 |website=stratigraphy.org |archive-date=2014-05-30 |archive-url=https://web.archive.org/web/20140530005940/http://www.stratigraphy.org/index.php/ics-chart-timescale |url-status=live }}</ref>

==== Paleocene ====
The Paleocene is the first series/epoch of the Paleogene and lasted from 66.0 Ma to 56.0 Ma. It is divided into three stages: the [[Danian]] 66.0 - 61.6 Ma; [[Selandian]] 61.6 - 59.2 Ma; and, [[Thanetian]] 59.2 - 56.0 Ma.<ref name=":0">{{Citation |last1=Vandenberghe |first1=N. |title=Chapter 28 - The Paleogene Period |date=2012-01-01 |work=The Geologic Time Scale |pages=855–921 |editor-last=Gradstein |editor-first=Felix M. |url=https://www.sciencedirect.com/science/article/pii/B9780444594259000287 |access-date=2024-07-15 |place=Boston |publisher=Elsevier |isbn=978-0-444-59425-9 |last2=Hilgen |first2=F. J. |last3=Speijer |first3=R. P. |last4=Ogg |first4=J. G. |last5=Gradstein |first5=F. M. |last6=Hammer |first6=O. |last7=Hollis |first7=C. J. |last8=Hooker |first8=J. J. |editor2-last=Ogg |editor2-first=James G. |editor3-last=Schmitz |editor3-first=Mark D. |editor4-last=Ogg |editor4-first=Gabi M. |archive-date=2015-09-24 |archive-url=https://web.archive.org/web/20150924145807/http://www.sciencedirect.com/science/article/pii/B9780444594259000287 |url-status=live }}</ref> The GSSP for the base of the Cenozoic, Paleogene and Paleocene is at Oued Djerfane, west of [[El Kef]], [[Tunisia]]. It is marked by an [[iridium anomaly]] produced by an [[asteroid]] impact, and is associated with the Cretaceous–Paleogene extinction event. The boundary is defined as the rusty colored base of a 50 cm thick [[clay]], which would have been deposited over only a few days. Similar layers are seen in marine and continental deposits worldwide. These layers include the iridium anomaly, [[Tektite|microtektites]], [[nickel]]-rich [[spinel]] crystals and [[shocked quartz]], all indicators of a major extraterrestrial impact. The remains of the crater are found at [[Chicxulub crater|Chicxulub]] on the [[Yucatan Peninsula]] in [[Mexico]]. The extinction of the [[Dinosaur|non-avian dinosaurs]], [[Ammonoidea|ammonites]] and dramatic changes in [[Plankton|marine plankton]] and many other groups of organisms, are also used for correlation purposes.<ref name=":0" />

==== Eocene ====
The Eocene is the second series/epoch of the Paleogene, and lasted from 56.0 Ma to 33.9 Ma. It is divided into four stages: the [[Ypresian]] 56.0 Ma to 47.8 Ma; [[Lutetian]] 47.8 Ma to 41.2 Ma; [[Bartonian]] 41.2 Ma to 37.71 Ma; and, [[Priabonian]] 37.71 Ma to 33.9 Ma. The GSSP for the base of the Eocene is at Dababiya, near [[Luxor]], [[Egypt]] and is marked by the start of a significant variation in global [[Isotopes of carbon|carbon isotope]] ratios, produced by a major period of global warming. The change in climate was due to a rapid release of frozen [[Methane clathrate|methane clathrates]] from seafloor sediments at the beginning of the Paleocene-Eocene thermal maximum (PETM).<ref name=":0" />

==== Oligocene ====
The Oligocene is the third and youngest series/epoch of the Paleogene, and lasted from 33.9 Ma to 23.03 Ma. It is divided into two stages: the [[Rupelian]] 33.9 Ma to 27.82 Ma; and, [[Chattian]] 27.82 - 23.03 Ma. The GSSP for the base of the Oligocene is at [[Massignano]], near [[Ancona]], [[Italy]]. The extinction the ''[[Hantkeninoidea|hantkeninid]]'' planktonic [[foraminifera]] is the key marker for the Eocene-Oligocene boundary, which was a time of climate cooling that led to widespread changes in fauna and flora.<ref name=":0" />