Taghanic event 386 million years ago in
Early Devonian period
Followed by
Taghanic event 386 million years ago in
Late Devonian period
The Taghanic event (Taghanic unconformity, Taghanic crisis or Taghanic onlap) was an
extinction event that occurred about 386 million years ago during the
Givetianfaunal stage of the
Middle Devonian geologic period in the
Paleozoic era.[1] It was caused by
hypoxia from an
anoxic event. The event had a period in which dissolved
oxygen in the Earth's
oceans was depleted. The Taghanic event caused a very high death rate of
corals. The loss of the
coral reefs caused a high loss of animals that lived in and around the reefs. The extinction rate has been placed between 28.5 and 36%, making the event the 8th largest extinction event recorded.[2][3][4] The reduced oxygen levels resulted from a period of global warming caused by
Milankovitch cycles. In the Taghanic event sea levels were higher.[5] After the Taghanic Event, sea life recovered in the
Frasnian faunal stage starting 382.7 million years ago. Two other events near this period were the
Kellwasser event (372 ma) and the
Hangenberg event (359 ma).[6][5][7]
The period of global warming that caused the Taghanic event melted
ice caps causing
sea levels to rise. This caused the Taghanic
onlap, the submergence of land by the advancing sea. The advancing sea laid down
strata deposits on the
seafloor. The flooding of what is now the southwestern United States created a shallow marine environment.[3][11][12]
The Taghanic event was just before the Late Devonian (Late D) event. The chart gives a comparison of the extinction event to other mass extinction events in
Earth's history. Plotted is the extinction intensity, calculated from marine
genera.
Marcellus Formation Shale from Middle Devonian sedimentary rock, location of the Taghanic event rocks