Matt Fantle
Title: High vs. low fidelity: The impact of stable mineral recrystallization on proxy archives
Abstract:
Stable mineral recrystallization is a recently identified process by which minerals exchange with ambient solution without overt mineralogical, compositional, or morphological changes. It is a phenomenon that has significant implications for the interpretation of geochemical proxies, and thus can impact mineral-based biosignatures and paleoclimatic reconstructions. Recent experimental work has suggested that significant mass fractions of minerals (i.e., as much as ~90-100%), such as iron oxides, exchange with ambient solutions over extremely short time scales. Similar behavior has also been observed in non-redox active minerals, such as calcite and barite.
The talk will focus on recent experimental and modeling work that clearly indicates the general mechanism by, and the extent to, which goethite reacts with aqueous Fe(II) over short time scales. The talk will also discuss the importance of the interpretive framework in deducing extents of reaction, and revisit experimental data from the literature. Ultimately, the talk will present a unifying framework for understanding stable mineral recrystallization, and discuss implications for proxy archives, which are used to reconstruct the past over a range of time scales.
