Dynamic interaction between basin redox and the biogeochemical nitrogen cycle in an unconventional Proterozoic petroleum system.

Precambrian hydrocarbons and their corresponding source rocks are distinctly different from their Phanerozoic counterparts, having been deposited in persistently anoxic environments in ecosystems dominated by bacteria. Here, we show that cyclic enrichment of organic matter in the world's oldest hydrocarbon play (ca. 1.38 Ga), is not associated with flooding surfaces and is unrelated to variations in mineralogy or changes in the relative rate of clastic to biogenic sedimentation-factors typically attributed to organic enrichment in Phanerozoic shales. Instead, the cyclic covariation of total organic carbon, δ15N, δ13C and molybdenum are explained by the feedback between high levels of primary productivity, basin redox and the biogeochemical nitrogen cycle. These factors are important in constraining productivity in the marine biosphere, the development of Precambrian hydrocarbon source rocks, and more generally in understanding oxygenation of the ocean and atmosphere through Earth history; as all are ultimately related to organic carbon burial.

Data analysis of the U-Pb geochronology and Lu-Hf system in zircon and whole-rock Sr, Sm-Nd and Pb isotopic systems for the granitoids of Thailand.

This data article provides zircon U-Pb and Lu-Hf isotopic information along with whole-rock Sm-Nd, Sr and Pb isotopic geochemistry from granitoids in Thailand. The U-Pb ages are described and the classification of crystallisation and inherited ages are explained. The petrography of the granitoid samples is detailed. The data presented in this article are interpreted and discussed in the research article entitled "Probing into Thailand's basement: New insights from U-Pb geochronology, Sr, Sm-Nd, Pb and Lu-Hf isotopic systems from granitoids" (Dew et al., 2018).