کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5779954 1634690 2017 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Oxygenation history of the Neoproterozoic to early Phanerozoic and the rise of land plants
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Oxygenation history of the Neoproterozoic to early Phanerozoic and the rise of land plants
چکیده انگلیسی


- Cerium anomalies in marine carbonates are used to track oceanic oxygenation.
- Neoproterozoic to Phanerozoic oxygenation is not unidirectional.
- Change to a modern-like oxygenated Earth occurs during the Devonian.
- Evolution of landplants and trees is a significant driver of Phanerozoic oxygenation.

There has been extensive debate about the history of Earth's oxygenation and the role that land plant evolution played in shaping Earth's ocean-atmosphere system. Here we use the rare earth element patterns in marine carbonates to monitor the structure of the marine redox landscape through the rise and diversification of animals and early land plants. In particular, we use the relative abundance of cerium (Ceanom), the only redox-sensitive rare earth element, in well-preserved marine cements and other marine precipitates to track seawater oxygen levels. Our results indicate that there was only a moderate increase in oceanic oxygenation during the Ediacaran (average Cryogenian Ceanom = 1.1, average Ediacaran Ceanom = 0.62), followed by a decrease in oxygen levels during the early Cambrian (average Cryogenian Ceanom = 0.90), with significant ocean anoxia persisting through the early and mid Paleozoic (average Early Cambrian-Early Devonian Ceanom = 0.84). It was not until the Late Devonian that oxygenation levels are comparable to the modern (average of all post-middle Devonian Ceanom = 0.55). Therefore, this work confirms growing evidence that the oxygenation of the Earth was neither unidirectional nor a simple two-stage process. Further, we provide evidence that it was not until the Late Devonian, when large land plants and forests first evolved, that oxygen levels reached those comparable to the modern world. This is recorded with the first modern-like negative Ceanom (values <0.6) occurring at around 380 Ma (Frasnian). This suggests that land plants, rather than animals, are the 'engineers' responsible for the modern fully oxygenated Earth system.

106

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 466, 15 May 2017, Pages 12-19
نویسندگان
, , , , , ,