LEAD-ZINC MINERALIZATION IN THE CRETACEOUS SEDIMENTS OF BENUE TROUGH OF NIGERIA

In the Lower Benue Trough of Southeastern Nigeria, lead-zinc-barium mineralization occurs as widely distributed epigenetic fracture-controlled vein deposits which are restricted to Albian – Turonian sediments. Detailed field studies carried out in Ishiagu, Enyigba-Ameki-Ameri, Wanikande-Wanakom, and Gabu-Oshina which together constitute the four main areas of mineralization in the Lower Benue Trough, show that mineralization appears restricted to NW-SE and N-S fractures while the more common NE-SW fractures are barren. Apart from the Enyigba area, igneous bodies are found in the vicinity of the ore deposits while in the Wanikande area, barite veins and veinlets were observed to be closely interwoven with intrusive bodies. The host lithologies are highly varied, ranging from shales to siltstones, sandstones and occasionally igneous bodies. The ore assemblage also varies remarkably, with lead:zinc:barium ratios ranging from approximately 3:1:0 at Ishiagu, to 2:1:0 at Enyigba, 1:0:2 at Wanikande and nearly 100% barite at Gabu-Oshina. Thus, there is a remarkable increase in barite content from the southwest (Ishiagu) to the northeast (Gabu). The characteristics of the ore deposits roughly fit the base metal type mineralization known as clastic dominated lead-zinc-barium deposits. This study forms part of a mineral potential database which is invaluable for any detailed exploration venture in the area. Contraste de estilos de mineralización de plomo-zinc-bario en la parte baja de la Formación Benue Trough, en el sudeste de NigeriaResumenEn la parte baja de la Formación Benue Trough, en el sudeste de Nigeria, la mineralización de plomo-zinc-bario ocurre en depósitos epigenéticos de fractura controlada ampliamente distribuidos pero que se restringen a sedimentos Albian-Turonian. Estudios de campo detallados realizados en Ishiagu, Enyigba-Ameki-Ameri, Wanikande-Wanakom y Gabu-Oshina (que conforman las cuatro áreas principales de mineralización en la parte baja de Benue Trough) muestran que la mineralización aparece restringida a fracturas NW-SE y N-S, mientras que las fracturas NE-SW, que son más comunes, aparecen estériles. Aparte del área Enyigba, los cuerpos ígneos se encontraron junto a los depósitos de minerales, mientras en el área Wanikande se observaron vetas y vetillas de baritina que están prácticamente entretejidas con cuerpos intrusivos. Las litologías sede son ampliamente variadas, y van desde esquistos a limolitas, areniscas y ocasionalmente cuerpos ígneos. El ensamble de la mena también varía con proporciones de plomo:zinc:bario que van aproximadamente desde 3:1:0 en Ishiagu, 2:1:0 en Enyigba, 1:0:2 en Wanikande y cerca del 100 % de baritina en Gabu-Oshina. Por ende, hay un incremento importante en el contenido de baritina desde el suroeste (Ishiagu) hacia el noroeste (Gabu). Las características de los depósitos minerales se enmarcan aproximadamente en el tipo de mineralización de base metálica, conocido como depósitos plomo-zinc-bario de dominación clástica. Este estudio hace parte de una base de datos de minerales potenciales que es invaluable para una exploración detallada en el área.

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Origin of lead-zinc mineralization in the southern Benue Trough, Nigeria ? Fluid inclusion and trace element studies

Mineralium Deposita ◽

10.1007/bf00204313 ◽

1985 ◽

Vol 20 (2) ◽

Cited By ~ 23

Author(s):

M.A. Olade ◽

R.D. Morton

Keyword(s):

Fluid Inclusion ◽

Trace Element ◽

Benue Trough ◽

Lead Zinc

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Implementing Digital Edge Enhancers on Improved High-Resolution Aeromagnetic Signals for Structural-Depth Analysis around the Middle Benue Trough, Nigeria

Minerals ◽

10.3390/min11111247 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1247

Author(s):

Eko Gerald Ejiga ◽

Noer El Hidayah Ismail ◽

Ismail Yusoff

Keyword(s):

High Resolution ◽

Mineral Exploration ◽

High Amplitude ◽

Tectonic Structures ◽

Near Surface ◽

Benue Trough ◽

Depth Analysis ◽

Lead Zinc ◽

Deep Depth ◽

Depth Ranges

Digital edge detector operations using magnetic derivatives in conjunction with spectra depth analysis were performed on high-resolution aeromagnetic signals to enhance the delineation and interpretation of depth, structural, and intrasedimentary features within the Middle Benue Trough (MBT) of North Central Nigeria, which could serve as a guide for mineral exploration. The derivatives revealed high-amplitude and short-wavelength anomalies over areas underlain by crystalline basement complexes, major volcanic zones, and aggregates of intrasedimentary volcanic and plutonic rocks. Geologic lineaments trending predominantly NE–SW and NW–SE, as well as minor trends of E–W and N–S, suggest that the area has undergone differential stress regimes across geologic time. The spectral depth analysis indicates a two-source depth model. The deep depth ranges from 1.9 to 6.1 km with an average of 3.9 km, whereas the shallow depth ranges between 0.3 and 1.9 km with an average of 0.8 km and is found to emanate from magnetic signals of post-Cretaceous near-surface igneous intrusions as well as other magnetized bodies embedded within the sediments. The spatial distribution of various hydrothermal minerals such as lead–zinc–barite deposits, as well as salt mineralization, is associated with the widespread Tertiary–recent magmatism and governed by pre-existing tectonic structures in the region.

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