Phase-specific nitrogen and carbon isotopes reveal progressive marine oxygenation during the early Great Ordovician Biodiversification Event

This dataset compiles high-resolution chemos tratigraphic records from the Early Ordovician interval of LCD1 drill core on the North Chian Block. It includes carbonate content, total organic carbontal nitrogen, carbon and oxygen isotopes, bulk-rock nitrogen isotopes, and silicatebound nitrogen abundance and isotopic composition,complemented by biogenic silica and Al-normalized trace-elementratios(Cu/Al, Ba/Al, Ni/Al) as nutrient/productivity=related proxies.