Unlocking the Secrets of the Doushantuo Formation

Scientists have uncovered new data from the Upper Doushantuo Formation in South China that sheds light on a significant event known as the Shuram Excursion. This event, marked by a steep drop in carbon isotopes, is one of the largest in geological history. But until now, its exact age has been a mystery. Using Re-Os geochronology, researchers found that the sediments from this formation are around 568 million years old, placing the event in the middle to late Ediacaran period. This age matches up with similar findings from Canada and Oman. Interestingly, these researchers also noticed that during this time, continental weathering was on the rise. When rocks break down, they release nutrients that can boost primary productivity, like plant and algae growth. This increase in organic matter being buried led to more oxygen in the oceans. Plus, the breakdown of rocks also sent oxidants, such as sulfates, into the oceans, temporarily boosting oxygen levels. The study shows that measuring the Re-Os age and initial Os isotope composition of organic-rich shale can help us understand when these weathering events happened and how they affected ocean oxygen levels. This method could be a powerful tool for exploring the Neoproterozoic era, a time filled with dramatic changes in Earth’s climate and life forms.