Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China

Remobilization and mineralization of selenium–tellurium in metamorphosed red beds: Evidence from the Munster Basin, Ireland

“…In Such selenide mineralogical textures, and the overall anomalous occurrence of selenium within a red bed is comparable with known examples of selenium mineralization in other red bed basins, such as in roll front deposits (Reynolds & Goldhaber 1983, Min et al 2005). In other red bed basins this reflects the susceptibility of selenium to precipitation under subtle changes of redox conditions, such as the reduction of an oxidized aquifer or the oxidation of a reduced aquifer.…”

“…However, selenium may be partitioned within the reduced enclaves of the Old Red Sandstone, as is observed in biogenically-induced reduction within roll front deposits which commonly have a zoned mineralization envelope Min et al 2005). Selenide minerals occur in a 'selenium-rich band' close to the front of the alteration envelope beyond the oxidation-reduction interface (Fig.…”

Potential aquifer vulnerability in regions down-gradient from uranium in situ recovery (ISR) sites

“…He proposed that aerobic bacteria facilitated mineral oxidation and dissolution up-gradient of the roll front, and anaerobic bacteria such as sulfate-reducers were important in precipitating reduced minerals in the roll-front ore zone. More recently, Min et al (2005b) and Cai et al (2007) described textures consistent with bacterial activity and preservation in uranium roll-front ores in northwestern China. Many models (e.g., Granger and Warren, 1969;Harshman, 1972Harshman, , 1974Devoto, 1978;Harshman and Adams, 1980;Nash et al, 1981;Hobday and Galloway, 1999) for roll-front uranium deposit genesis include the concept that the roll fronts move down-dip in the host formation over time, as the redox boundary shifts due to the continuous incursion of oxidized groundwater.…”

Micro-textures and in situ sulfur isotopic analysis of spheroidal and zonal sulfides in the giant Jinding Zn–Pb deposit, Yunnan, China: Implications for biogenic processes

“…It is generally agreed that sulfate-reducing bacteria produce isotopically light reduced sulfur, whereas thermal sulfate reduction processes result in isotopically heavy sulfur (Lichtner and Biino, 1992;Canfield and Thamdrup, 1994;Spangenberg and Macko, 1998;Druschel et al, 2002;Bawden et al, 2003;Bazylinski and Frankel, 2003;Southam and Saunders, 2005;Min et al, 2005;Lengke and Southam, 2006;Mihály and Rafal, 2006;Rainbow et al, 2006;Cai et al, 2007;Barrie et al, 2009;Kucha et al, 2010;Greenwood et al, 2013). Therefore, the d 34 S values of sulfides are commonly used to distinguish BSR and TSR.…”