Scientists Trace Triassic Ocean Oxygen Loss to 8 Million Years Before 201-Million-Year Extinction
Updated
Updated · Earth.com · Jun 5
Scientists Trace Triassic Ocean Oxygen Loss to 8 Million Years Before 201-Million-Year Extinction
1 articles · Updated · Earth.com · Jun 5
Summary
Alaska rock layers show ocean oxygen loss began about 8 million years before the end-Triassic mass extinction, pushing the crisis well ahead of the giant eruptions long blamed as the trigger.
Chemical signals from iron and nitrogen in sediments from Grotto Creek indicate deep Panthalassa waters were already oxygen-poor, while low-oxygen zones climbed upward through the water column during the late Triassic.
Around the extinction interval, the deep ocean appears to have turned toxic—likely hydrogen-sulfide rich—while prolonged oxygen loss also drained usable nitrogen from surface waters, threatening plankton and the wider food web.
The timeline matches marine declines seen in fossils, including ammonoid losses, and suggests the extinction that killed roughly 60% of species was the culmination of a long deterioration rather than a sudden collapse.
Published in Communications Earth & Environment, the study leaves the early trigger unresolved but sharpens parallels with modern ocean deoxygenation and today’s expanding dead zones.
If volcanoes weren't the initial killer, what suffocated Earth's oceans for 8 million years before the great extinction?
How can scientists identify the tipping point for ocean collapse before it is too late for marine life today?
Earth's oceans are losing oxygen again. Is history repeating a slow-motion catastrophe that we are currently ignoring?
Ancient Ocean Deoxygenation Began 8 Million Years Before End-Triassic Mass Extinction: New Geochemical Evidence and Modern Climate Warnings
Overview
This report reveals that significant ocean deoxygenation began about 209 million years ago, starting a slow suffocation of marine life well before the end-Triassic mass extinction. The process was triggered by a warmer global climate, which caused rocks on land to break down faster and release more nutrients into the oceans. Combined with warmer seawater that holds less oxygen, these changes led to the formation of vast 'dead zones' where marine life struggled to survive. Increased nutrient runoff also contributed to ocean acidification, creating a deadly combination that set the stage for one of Earth's greatest extinction events.