Earth has been habitable for 4.3 billion years, and the earliest rock record indicates the
presence of a microbial biosphere by at least 3.4 billion years ago—and disputably earlier …

This textbook is a complete rewrite, and expansion of Hugh Rollinson's highly successful
1993 book Using Geochemical Data: Evaluation, Presentation, Interpretation. Rollinson and …

Nitrogen is an essential nutrient for all life on Earth. It is, and likely has been, a critical
limiting nutrient controlling primary production rates in the oceans. The marine N budget is …

Abstract During the Marinoan Ice Age (ca. 654–635 Ma), one of the 'Snowball Earth'events
in the Cryogenian Period, continental icesheets reached the tropical oceans. Oceanic …

The colonization of emergent continental landmass by microbial life was an evolutionary
step of paramount importance in Earth history. Here we report direct fossil evidence for life …

Global warming, widespread oceanic anoxia and stagnation, and large perturbations of the
global carbon cycle characterized the end-Permian to Middle Triassic interval. Nitrogen …

Nitrogen (N) is a macronutrient essential to all living organisms and its availability in
Precambrian oceans may have played an important role in the early evolution and …

The later stages of Earth's transition to a permanently oxygenated atmosphere during the
Great Oxidation Event (GOE;∼ 2.43–2.06 Ga) is commonly linked with the suggestion of an …

Nitrogen isotope ratios in marine sedimentary rocks have become a widely used
biogeochemical proxy that records information about nutrient cycling and redox conditions in …

High-pH alkaline lakes are among the most productive ecosystems on Earth and prime
targets in the search for life on Mars; however, a robust proxy for such settings does not yet …