Late inception of a resiliently oxygenated upper ocean
Wanyi Lu1, Andy Ridgwell2,3, Ellen Thomas4,5
1Department of Earth Sciences, Syracuse University, Syracuse, NY, USA.
Abstract:
Rising oceanic and atmospheric oxygen levels through time have been crucial to enhanced habitability of surface Earth environments. Few redox proxies can track secular variations in dissolved oxygen concentrations around threshold levels for metazoan survival in the upper ocean. We present an extensive compilation of iodine-to-calcium ratios (I/Ca) in marine carbonates. Our record supports a major rise in the partial pressure of oxygen in the atmosphere at ~400 million years (Ma) ago and reveals a step change in the oxygenation of the upper ocean to relatively sustainable near-modern conditions at ~200 Ma ago. An Earth system model demonstrates that a shift in organic matter remineralization to greater depths, which may have been due to increasing size and biomineralization of eukaryotic plankton, likely drove the I/Ca signals at ~200 Ma ago.
Related Concept Videos
Arteries of the Upper Limbs
Veins of Upper Limbs
The deep venous system is primarily composed of the ulnar and radial veins. The ulnar vein, which drains the fingers through the superficial palmar venous arches, and the radial vein, which serves the palms via the deep palmar...
Bones of the Upper Limb: Humerus
Upper Respiratory Drugs: Decongestants
Most decongestants are readily available over-the-counter in...
Upper GI Series: Barium Swallow
Purpose and Procedure
Patients undergoing this procedure ingest a liquid containing barium sulfate with a chalky...
Bones of the Upper Limb: Ulna


