Late Neoproterozoic banded iron formation (BIF) in the central Eastern Desert of Egypt: Mineralogical and geochemical implications for the origin of the Gebel El Hadid iron ore deposit

Abstract We stated and solved three successive problems concerning automatization of geological mapping using the case of the Bolshetroitskoe high-grade iron ore deposit in weathered crust of Banded Iron Formation (Kursk Magnetic Anomaly, Belgorod Region, Russia). (1) Selecting a classification (clustering) method of geochemical data without reference sampling, i.e., solution of an “unsupervised clustering task”. We developed 5 rock classifications based on different principles, i.e., classification by visual description, by distribution of economic component (Fe2O3), by cluster analysis of raw data and centered log-ratio transformation of the raw data, and by artificial neural network (Kohonnen’s self-organized map). (2) Non-parametric comparison of quality of the classifications and revealing the best one. (3) Automatic 3D geological mapping in accordance with the best classification. The developed approach of automatic 3D geological mapping seems to be rather simple and plausible.

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Petrography, lithostratigraphy and major element geochemistry of Mesoarchean metamorphosed banded iron formation-hosted Nkout iron ore deposit, north western Congo craton, Central West Africa

Journal of African Earth Sciences ◽

10.1016/j.jafrearsci.2018.06.007 ◽

2018 ◽

Vol 148 ◽

pp. 80-98 ◽

Cited By ~ 8

Author(s):

Ekah Nzume Ndime ◽

Sylvestre Ganno ◽

Landry Soh Tamehe ◽

Jean Paul Nzenti

Keyword(s):

West Africa ◽

Iron Ore ◽

Major Element ◽

Iron Formation ◽

Banded Iron Formation ◽

Element Geochemistry ◽

Ore Deposit ◽

Iron Ore Deposit ◽

North Western

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Fluid Inclusion and Oxygen Isotope Characteristics of Vein Quartz Associated with the Nabeba Iron Deposit, Republic of Congo: Implications for the Enrichment of Hypogene Ores

Minerals ◽

10.3390/min9110677 ◽

2019 ◽

Vol 9 (11) ◽

pp. 677

Author(s):

Ebotehouna ◽

Xie ◽

Adomako-Ansah ◽

Pei

Keyword(s):

Iron Ore ◽

Early Stage ◽

Laser Raman Spectroscopy ◽

Iron Formation ◽

Iron Deposit ◽

Banded Iron Formation ◽

Republic Of Congo ◽

Ore Deposit ◽

Laser Raman ◽

Ore Mineralization

The Nabeba iron ore deposit is located at the northern part of Congo Craton, Republic of Congo. The ore deposit consists of supergene and hypogene ores, both of which are hosted in the Precambrian Nabeba banded iron formation (BIF). This study focuses on the hypogene iron ore mineralization associated with quartz veins in the Nabeba deposit, for which two hypogene ore stages have been recognized based on geologic and petrographic observations: early-stage high‐grade hematite‐rich ore (HO‐1) and late-stage magnetite‐rich ore (HO‐2). Based on microthermometric measurements and laser Raman spectroscopy of the fluid inclusions, the H2O‐NaCl ± CO2 fluids interacting with the Nabeba BIF at the HO‐1 stage evolve from high‐to‐moderate temperatures (203–405 °C) and contrasting salinities (moderate-to-low: 1–15 wt. % NaCl equiv.; high: 30–35 wt. % NaCl equiv.) to H2O‐NaCl fluids of moderate‐to‐low temperatures (150–290 °C) and salinities (1–11 wt. % NaCl equiv.) for the HO‐2 ore stage. Assuming equilibrium oxygen isotopic exchange between quartz and water, the δ18Ofluid values range from 4.7–8.1‰ for the HO‐1 stage and −2.3‰ to −1.5‰ for the HO‐2 stage. This implies the ore‐forming fluid of initially-mixed metamorphic–magmatic origin, later replenished by seawater and/or meteoric water during the formation of the HO‐2 stage. These mixtures of different fluids, coupled with their interaction with the BIF lithology followed by phase separation, are responsible for the enrichment of hypogene iron ore in the Nabeba deposit.

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