Depositional age and tectonic environment of the Gouap banded iron formations from the Nyong group, SW Cameroon: Insights from isotopic, geochemical and geochronological studies of drillcore samples

摘要: Abstract The discovery of the Gouap banded iron formations (BIFs)-hosted mineralization in northwestern Nyong Group (Ntem Complex) southwestern Cameroon provides unique insights into geology this region. In contribution, we firstly report detailed study geochemistry, isotopic and geochronology well preserved samples BIFs collected from diamond drillcores. consist mainly amphibole amphibole–pyrite characterized by dominant Fe2O3 ​+ ​SiO2 contents variable CaO, MgO SO3, consistent with presence amphibole, chlorite, epidote pyrite, formed during amphibolite facies metamorphism overprinted hydrothermal event. are typically enriched trace rare earth elements (REE) compared to BIFs, suggesting influence detrital materials as secondary alteration. Post Archean Australian Shale (PAAS)-normalized REE–Y profiles display positive La, Eu anomalies, weak negative Ce indicating a mixture low-temperature fluids relatively oxic conditions probably under relative shallow seawater. We present here first data within Ntem Complex. δ30SiNBS28 values quartz vary −1.5‰ −0.3‰ −0.8‰ −0.9‰ for respectively. has δ18OV-SMOW 6.8‰–9.5‰ (amphibole BIFs) 9.2‰–10.6‰ (amphibole–pyrite BIFs). magnetite shows δ18O ranging −3.5‰ −1.8‰ −3‰ −1.7‰ Moreover, pyrite grains δ34S 1.1‰–1.8‰. All confirm that they might have precipitated input distant volcanic activity. According their geochemical characteristics, propose belong Superior type. situ U–Pb zircon dating was conducted assess BIF depositional age based on strong evidence thin section. were deposited at 2422 ​± ​50 ​Ma region where sediments extended continental shelf deep-water environments along craton margins like Caue Formation Minas Supergroup, Brazil. studied experienced regional activity 2089 ​± ​8.3 ​Ma Eburnean–Transamazonian orogeny. These findings suggest physical continuity between protocratonic masses both Sao Francisco Congo continents Rhyacian Period.