Tellurium Enrichment in Jurassic Coal, Brora, Scotland

Abstract

Mid-Jurassic pyritic coals exposed at the village of Brora, northern Scotland, UK, contain a marked enrichment of tellurium (Te) relative to crustal mean, average world coal compositions and British Isles Carboniferous coals. The Te content of Brora coal pyrite is more than one order of magnitude higher than in sampled pyrite of Carboniferous coals. The Te enrichment coincides with selenium (Se) and mercury (Hg) enrichment in the rims of pyrite, and Se/Te is much lower than in pyrites of Carboniferous coals. Initial pyrite formation is attributed to early burial (syn-diagenesis), with incorporation of Te, Se, Hg and lead (Pb) during later pyrite formation. The source of Te may have been a local hydrothermal system which was responsible for alluvial gold (Au) in the region, with some Au in Brora headwaters occurring as tellurides. Anomalous Te is not ubiquitous in coal, but may occur locally, and is detectable by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS).

Selenium and tellurium concentrations of Carboniferous British coals

“…Causes of thermal maturity in coal, such as igneous intrusions heating the strata, may also be accompanied by trace element‐carrying hydrothermal fluids percolating through coals, precipitating as pyrite. Dissolved metals in fluids can enhance Se and Te content of coals and have been suggested for Carboniferous coals in Ayrshire (Bullock et al, ) and Jurassic coals in Brora (Bullock et al, ). The close proximity of the South Wales, Cumberland, and Northumberland coalfields to granitic intrusions (e.g., Shap and Skiddaw granites of Cumberland, Dartmoor granite in southwest England, Weardale granite in northeast England), associated deformation which produced a series of faults through the coal strata (forming cleat systems), or later Variscan activity (in the case of South Wales), may have provided a source and/or flow pathway for hot metal‐rich fluids and subsequent increased maturity and trace element enrichment to these coals (see also Gayer et al, ; Turner & Richardson, ).…”

“…Dissolved metals in fluids can enhance Se and Te content of coals and have been suggested for Carboniferous coals in Ayrshire (Bullock et al, 2018) and Jurassic coals in Brora (Bullock et al, 2017 Gayer et al, 1996;Turner & Richardson, 2004). The Clackmannan…”

Gold in Irish Coal: Palaeo-Concentration from Metalliferous Groundwaters

“…As the global coal industry continues to grow [70], the necessity to find added value in the waste derivatives will become increasingly important. This is particularly pertinent for the recovery of critical trace elements used in nanotechnologies [71][72][73], or toxic trace elements that may impact the environment [74][75][76]. Siderite is mostly separated and removed during coal processing, meaning it is not burned with coal, and any associated trace elements would not reach the fly ash post-combustion stage.…”

Mapping of Trace Elements in Coal and Ash Research Based on a Bibliometric Analysis Method Spanning 1971–2017

“…2012) is not high, it has strong burst (see Table 7), indicating that it has striking study results and high level of attention in 2012, and therefore it can be used as a reference for research focuses and trends. The enrichment origin [26] and modes of occurrence [27,28] of trace elements in coal, especially those with highly environmental concerns such as Hg, As, F [5,6] and Se, Te [29], and those with highly economic added values [30] such as Ge, Ga, Nb and rare earth elements [31][32][33][34][35] are strongly concerned. X-ray diffraction is a common method for determination of minerals related to toxic and valuable (critical) elements in coal [36] (see Table 6).…”