Comparison of metal enrichment in pyrite framboids from a metal-enriched and metal-poor estuary

Abstract

The accumulation of metals and metalloids in diagenetic pyrite framboids is of interest because framboids can be a sink for heavy metal contaminants, a source of metals in ore deposits, and a tool to interpret paleo-ocean chemistry. In this study, we have used laser ablation-inductively coupled plasmamass spectrometry (LA-ICPMS) to analyze pyrite framboids from both the contaminated Derwent Estuary and the uncontaminated Huon Estuary in Tasmania, Australia. While the enrichment of many trace metals in the Huon Estuary followed expected trends, the trends in the Derwent were quite different. In addition to the expected high contents of Pb, Zn, and Cu in the contaminated interval it was found that several elements are not as strongly incorporated into pyrite within the contaminated zone. It is suggested that this is due to over-competition for adsorption sites on the growing iron sulfides in the contaminated zone resulting in diffusion of several elements to deeper levels in the sediments. This results in an increase of these elements in pyrite below the zone of major contamination. The LA-ICPMS technique also provided the opportunity to obtain accurate data on gold, silver, and tellurium in pyrite, something rarely achieved in sequential leach extractions due to the low concentrations of these metals observed in nature.

The Boring Billion, a slingshot for Complex Life on Earth

“…Sedimentary pyrite analyses are preferred to whole rock shale analyses as the method is more sensitive to trace element concentrations, and trace elements are preferentially partitioned and concentrated into pyrite compared to whole rock 31 , 32 . The validity of the technique has been the subject of several publications 33 – 36 which includes the proof of concept paper 8 . Additional information is also provided in the SI.…”

Geochemical and micro-textural fingerprints of boiling in pyrite

“…Additionally, it has been noted that metal and metalloids can occur as structurally-bounded elements or forming micro-to nano-scale mineral inclusions within pyrite (Reich et al, 2005;Deditius et al, 2008Deditius et al, , 2009aDeditius et al, ,b, 2011Deditius et al, , 2014Deditius and Reich, 2016). Since pyrite composition is strongly influenced by environmental conditions, its geochemical signature reflects the selective partitioning of elements during pyrite growth and ultimately, the composition and physico-chemical nature of the ore-forming fluids and/or marine pore waters (e.g., Deditius et al, 2009a, 2014, Reich et al, 2013Gregory et al, 2014Gregory et al, , 2015aLarge et al, 2014Large et al, , 2015Tardani et al, 2017). Furthermore, the significant diversity of textural features in pyrite has been investigated in detail.…”

Distinguishing Ore Deposit Type and Barren Sedimentary Pyrite Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Trace Element Data and Statistical Analysis of Large Data Sets

“…Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) allows for the determination of the trace element content of individual minerals. These data are useful because different ore deposit types have different fluid sources, metal sources, and depositional mechanisms, all of which can significantly affect the trace element content of the minerals that precipitate from them (Gregory et al, 2014;Tardani et al, 2017). Furthermore, these trace elements can be preserved in their mineral hosts during successive hydrothermal and metamorphic events.…”