Mineralization and Divergent Boundary (Mid-oceanic ridge)
Submarine hydrothermal vent or “Black Smoker”
Cyprus type: associated with tholeiitic basalts in ophiolite sequences copper rich withgold. e.g. Troodos Massif (Cyprus). Besshi-type: associated with volcanics and continental turbidites, copper/zinc with gold and silver.e.g. Sanbagwa (Japan). Kuroko-type: associated with felsic volcanics particularly rhyolite domes copper/zinc/lead with gold and silver, e.g. Kuroko deposits (Japan).
Ophiolites are pieces of oceanic plate that have been thrusted (obducted) onto the edge of continental plates. They provide models for processes at mid-ocean ridges.
Ophiolites are thought to represent slices of oceanic crust that have been thrust or obducted onto a continental margin during collision. They are characterised by a sequence of rock types, consisting of deep sea sediments overlying basaltic pillow lavas, sheeted dykes, gabbros and peridotites.
Podiform chromite deposits are irregular but fundamentally lenticular chromite-rich bodies that occur within Alpine peridotite or ophiolite complexes. Thus, they generally occur in orogenic settings.
Podiform chromite deposit, Cyprus Chromite: FeCr 2 O 4
Mineralization at Convergent Boundaries Calcalkaline Magma Series Volcano-plutonic complexes Subaerial / Submarine volcanism Porhyry / Massive sulphide deposits Plutonism: Granitic batholiths / Stocks Pegmatitic/ Hydrothermal / Skarn / Greisen/ deposits Regional Metamorphism (High P/ Low T and Low P/High T ) Some gemstone deposits e.g. jade and corundum Geological Processes
The ASARCO Mission Mine near Tucson, Arizona
Detailed Cross - Section of a Porphyry Copper Deposit
Schematic model of a fully grown kimberlite pipe
J - Manto K - Skarn L - Porphyry M - Ultramafic / Mafic N - Carbonatites O - Pegmatite P - Metamorphic-hosted Q - Gems and Semi-precious Stones R - Industrial Rocks S - Other A - Organic B - Residual/Surficial C - Placer D - Continental Sediments and Vocanics E - Sediment-Hosted F - Chemical Sediment G - Marine Volcanic Association H - Epithermal I - Vein, Breccia and Stockwork MASTER LIST OF ALL DEPOSIT GROUPS
Hydrothermal/Pegmatitic mineral deposits form in association with hot water- or gas-rich fluids Magmatic mineral deposits concentrated in igneous rocks; Metamoprhogenic mineral deposits concentrated by metamorhism / metasomatism Sedimentary mineral deposits are precipitated from a solution, typically sea water; Placer minerals are sorted and distributed by flow of water (or ice); Residual mineral deposits formed by weathering reactions at the earth's Classifications Based on Geological Processes
Unconsolidated Deposits Sedimentary Rocks Volcanic Rocks Intrusive Rocks Regionally Metamorphosed Rocks Classifications Based on Host Lithology