Muhammad Bilal Department of geology university of Peshawar

1. Muhammad Bilal (23)
MISSISSIPPI VALLEY TYPE DEPOSITS
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2. CONTENT
• Introduction
• Host rock
• Source rock (fluid flow)
• 3 sub types
• Origin factors
• Occurrence in Pakistan
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3. INTRODUCTION
• Leading source of Lead and Zinc
• Type locality: Mississippi valley mines southeast USA
• The first exploration and mining of such deposits was by Roman Empire 200BC
• Lead was there major source of metal especially used for water transportation by Lead
pipes, which is also considered the major Cause of fall of the Empire, as Lead particles
dissolved in water are poisonous (Gilfillan, 1965).
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4. INTRODUCTION
• These are Lead-zinc deposits of epigenetic nature.
• Hosted in Carbonate Rock (Dolostone, Limestone).
• They are rarely found in Precambrian Lithology while abundant in Phanerozoic time
associated with reef carbonate.
• Tectonically associated with Intra-Cratonic Settings.
• Zn and Pb are major ore minerals, with fluorite is also some time Dominated.
• They are of chemical sedimentary nature (Chemical precipitation of ore from fluids).
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5. HOST ROCK
• Reefal limestone is the host for MVT deposits while dolomite is also found regionally.
• The host rock lithology has three important features
1. Relative importance of Dolomite
2. The presence of erosional surfaces
3. The significance of lateral facies change
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6. SOURCE ROCK
• Shale plus other sedimentary rock containing Pb-Zn-F as traces are deep buried in Intra
Cratonic setting that produces over pressured Situation. Hot pore fluid escape from shale
Basin and move up aquifers to form deposits in cooler Strata, filling fractures or forming
other type of Ore bodies Sangster (1993).
• Other hypothesis indicated Gravity driven fluids flowing from a hydraulic head in a
highland are flush through a basin drinking out and replenishing the formation waters
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7. SUB TYPES
• MVT deposits are classified into sub types on the basis of primary ore association
• Zinc Dominant
• Lead Dominant
• Fluorite Dominant
Mineral Association: +Sphalerite ±Galena
±Ag ±Ni ±Co ± Cu (chalcopyrite)
Mineral Association: +Galina ±Sphalerite
±Ag ±Ga ±Gr ±In [±Ni ±Co] by-products
Mineral Association: +CaF2 ±Galina [±Gr
±Cadmium] by-products-> ±Sphalerite
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Metcalfe et al (1994)

8. ORIGIN FACTOR
• Porosity of Host Rock
• Sufficient quantity of trace element in migrating Fluid
• Release of Solution Depend on;
1. Compaction
2. Aquifer puncture
3. Faulting and Slopping
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9. OCCURRENCE IN PAKISTAN
• Anderson et.al, (1990) Reported MVT in Jurassic carbonates of Pakistan
• Jankovic (1986) reported at Gunga, Khuzdar district, Baluchistan
• Jones (1995) reported The Duddar Ge-Zn-Pb-Ba deposit, Balochistan
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