What is ‘dark oxygen’, found 13,000 feet under the sea? – Al Jazeera English

What is ‘dark oxygen’, found 13,000 feet under the sea?  Al Jazeera EnglishScientists may have discovered ‘dark oxygen’ being created without photosynthesis  NPR‘Dark Oxygen’ Discovered Coming from Mineral Deposits on Deep Seafloor  Scientific AmericanScientists find ‘dark oxygen’ being produced from metals on the seafloor  The Washington PostMystery oxygen source discovered on the sea floor — bewildering scientists  Nature.com