Zn-, Mn- and Co-rich chromian spinels from the Bou-Azzer mining district (Morocco): Constraints on their relationship with the mineralizing process

Fossil black smoker yields oxygen isotopic composition of Neoproterozoic seawater

“…As previously shown by Hodel et al 18 , the hydrothermal alteration of the North Aït Ahmane serpentinites also drastically affected the Cr-spinels they host. Ferritchromite and Cr-magnetite rims resulting from this alteration are highly enriched in Mn, up to 5.41 wt.% of MnO 18 , 33 , which is once again exclusive to black smoker-related serpentinites 32 . Finally, samples presenting the highest LREE enrichments and the strongest Eu anomalies are characterized by a high abundance of sulphides and can be analogous to the sulfide-rich serpentinites and stockworks of modern black smoker systems 23 , 24 .…”

The importance of trace element analyses in detrital Cr‐spinel provenance studies: An example from the Upper Triassic of the Barents Shelf

“…The relative depletion of Al, Ga, Ni and Mg, together with the relative enrichment of Zn, Co, Mn, Fe and Cr, is likely the result of metamorphic alteration of Cr‐spinel, with individual detrital grains representing varying degrees of chemical alteration (Colás et al., 2014; Fanlo et al., 2015; Rui et al., 2019). As documented by Colás et al.…”

“…The composition of metamorphically altered Cr-spinel depends on factors such as primary composition, pressuretemperature conditions during metamorphism, composition of fluids and the composition of the host rock (Colás et al, 2014;Fanlo, Gervilla, Colás, & Subías, 2015;Suita & Strieder, 1996), and may also be used to indicate metamorphic grade (Colás et al, 2014;Suita & Strieder, 1996). Alteration of Cr-spinel during metamorphism commonly includes textural alteration and mineral/chemical zoning between core and rim (Colás et al, 2014;Fanlo et al, 2015). The chemical composition of Cr-spinel rims may be significantly altered compared to the cores, commonly with depletion of Al and Mg giving a composition closer to Cr-magnetite (Colás et al, 2014;Suita & Strieder, 1996).…”

“…The relative depletion of Al, Ga, Ni and Mg, together with the relative enrichment of Zn, Co, Mn, Fe and Cr, is likely the result of metamorphic alteration of Cr-spinel, with individual detrital grains representing varying degrees of chemical alteration (Colás et al, 2014;Fanlo et al, 2015;Rui et al, 2019). As documented by Colás et al (2014), the trace element compositions in Cr-spinel vary within each mineral grain, depending on the metamorphic history and the type of host rock (Rui et al, 2019; Anna Pryadunenko personal communication).…”

Cr-spinels in carbonate veins of the Onguren Complex (Western Baikal Region)

“…От обычных хромшпинелидов из мантийных перидотитов (Barnes, Roeder, 2001;Kamenetsky et al, 2001; субферриалюмохромит отличается крайне низкой магнезиальностью, а также обогащенностью ZnО, MnO и TiO 2 . Такие изменения состава первичного магнезиального хромшпинелида могли произойти либо в результате реакций с высокотемпературным флюидом (Johan, Ohnenstetter, 2010), либо в результате наложенных гидротермальных процессов (Fanlo et al, 2015). Хромшпинелиды с повышенным содержанием Zn и низкими содержаниями Mg и Al были обнаружены во включениях в алмазах из кимберлитов (Meyer, Boyd, 1972).…”