A range of geochemical and mineralogical factors trigger the weathering and influence the
stability of various silica phases under near-surface temperatures and pressures. Based on …

We know how most rocks are formed. Silcrete is something of an enigma, for although there
are many interpretations of the origins of individual silcrete bodies, such as those in the …

Detailed stratigraphic, petrographic, and zircon U–Pb geochronological data are provided
for surface outcrops and newly obtained, unweathered drillcore intersections of Earth's …

The great variety and abundance of chert deposits in Archean terrains constitute one of the
most unusual features that mark Earth's early geological history. Proposed explanations for …

Abstract The Earth's Critical Zone, where physical, chemical and biological systems interact,
extends from the top of the canopy to the underlying bedrock. In this study, we investigated …

Global carbon balances are increasingly affected by large fluctuations in productivity
occurring throughout semiarid regions. Recent analyses found a large C uptake anomaly in …

Silica enrichments resulting in up to~ 90 wt% SiO2 have been observed by the Curiosity
rover's instruments in Gale crater, Mars, within the Murray and Stimson formations. Samples …

Silcrete is a term first used by Lamplugh (1902) to describe the products of near-surface
processes by which silica accumulates in and/or replaces a soil, sediment, rock or …

This paper exposes the unique set of attributes explaining why precious opal has formed in
such abundance in central Australia, and almost nowhere else on Earth. The Early …

The Paleocene–Early Eocene carbonate successions of the Indus Basin in Pakistan formed
on the northwestern continental shelf margin of the Indian Plate in the eastern Tethys Ocean …