Quartz-Rich Fault Rocks as Potential High Purity Quartz Source (I) in a Sequence of the Central Cameroon Shear Zone (Etam Shear Zone): Geology and Structure

Sigue, Cyrille; Moundi, Amidou; Mbongue, Jean Lavenir Ndema; Vishiti, Akumbom; Kedia, Arnold Chi; Suh, Cheo Emmanuel; Nzenti, Jean Paul

doi:10.1007/978-3-030-01455-1_16

Cited by 2 publications

(8 citation statements)

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“…These lithologies are associated with a mylonitic band ( Fig. 1c) oriented N030 to N045 [43] termed the Etam shear zone (ESZ) [44], which constitutes a segment of CCSZ. The mylonitization event has been attributed to a Pan-African age [40] and has reworked the gneissic foliation.…”

Section: Geology Of Etammentioning

confidence: 99%

“…This is a clear white rock with no other rock-forming minerals than quartz similar to the Serra de Santa Helena high-purity quartz rock. [43,44] suggested magmatic protoliths for the mylonitic rocks in Etam. These previous studies also indicated greenschist to amphibolitic metamorphic conditions between 300 and 450 °C in the surrounding country rocks, where epidote, neocrystallized quartz and chlorite minerals assemblage coupled with the albitization of K-feldspar and the formation of perthite were recorded.…”

Section: Geology Of Etammentioning

confidence: 99%

“…Other minerals include amphibole, muscovite, chlorite as well as iron oxide, pyrite and zircon. According to [44], the pervasive alteration in ESZ released K + , Na + , Ca + , Fe + and Al + ions that circulated in hydrothermal fluids saturated in Si, precipitated in fractures and enriched the quartz veins.…”

Section: Geology Of Etammentioning

confidence: 99%

“…Two quartz bodies are studied in this work: (1) quartzite body, showing blocks with variable dimensions (up to 20 m × 8 m) observed in the Etam Shear Zone (ESZ). The quartzite blocks are brecciated and can be traced along strike for over 2.5 km [44] in NNE-SSW to NE-SW direction. On some large blocks, joints and hydrothermal quartz veinlets (up to 15 cm wide) are observed arranged in subparallel arrays ( Fig.…”

Section: Petrography and Textural Studiesmentioning

confidence: 99%

“…Daughter crystals in fluid inclusions in this quartz are mostly salts, and therefore, Al is probably incorporated in the quartz structure added by hydrothermal fluid circulating during metamorphic events. Indeed, milky quartz in Etam was probably (re)crystallized under greenschist to amphibolitic metamorphic condition [44] in the shear zone. The relative low concentration of Na and K coupled with the low Al/Li ratio suggests that the charge balances are compensated mainly by H + [75] from hydrothermal fluid in milky and translucent quartz, since either a metamorphic event or the brittle nature of the rock has enhanced fluid flow in the area.…”

Section: Geochemistry and Fluid Inclusionsmentioning

confidence: 99%

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Assessment of shear zone-derived quartz from the Etam area, southwest Cameroon as potential high-purity quartz resource: petrography, geochemistry and technological studies

et al. 2020

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This study focuses on the evaluation of the high-purity quartz (HPQ) potential of a shear zone-hosted hydrothermal and metamorphic quartz deposit in Etam, southwest Cameroon. The shear zone quartz-rich rock is monomineralic and consists of both milky and translucent varieties. The combination of ICP-MS and LA-ICP-MS analytical techniques was used to assess the chemical purity of both quartz varieties. These compositional analyses show that all quartz samples have SiO 2 content of 98.46-99.75 wt% with very low concentrations of all the other elements. Translucent quartz when compared to the milky quartz variety shows low concentration of most of the elements including the following principal impurities: Al (mean 107 µg g −1 ), Ca (mean 27.85 µg g −1 ) and Fe (mean 26.05 µg g −1 ). Bubble generation in the samples after flame fusion over a silica plate was assessed to test the suitability of the quartz in industrial uses. The results obtained from the chemical analyses and bubble formation tests indicate that all the samples investigated do not meet the HPQ requirement. However, the translucent quartz shows characteristics of medium-purity quartz and can produce silica glass for some industrial manufacturing even without further purification. In this study, the fluid inclusions in the samples were examined as this bears information on the economic viability of the deposit and provides clues on the genesis of the quartz vein. Also tiny mineral inclusions within individual quartz grains were identified by SEM-EDS. The results of these studies show that the deposit is probably of metamorphic origin marked by crystal-plastic deformation in quartz grains. The veins were later modified by hydrothermal fluid input. The results also indicate that the majority of impurities are likely hosted by fluid inclusions and thus the quartz can be upgraded to HPQ after purification by suitable methods.

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Section: Geology Of Etammentioning

confidence: 99%

Section: Geology Of Etammentioning

confidence: 99%

Section: Geology Of Etammentioning

confidence: 99%

Section: Petrography and Textural Studiesmentioning

confidence: 99%

Section: Geochemistry and Fluid Inclusionsmentioning

confidence: 99%

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