Term
| Magmatic Segregation Deposits |
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Definition
| Related to the emplacement of ultramafic to mafic magma bodies. |
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Term
| Layered Mafic Intrusion (LMI) |
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Definition
| Differential crystal settling w/in magma body. |
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Term
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Definition
Major source of:
Cr, Ni, Cu, P, Ti, Fe, Va, Sn, S |
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Term
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Definition
| Typically Precambrian in age; asso. w/ deep faults in rift zones. |
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Term
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Definition
| Thought to originate from plagioclase-rich fractional crystallization of ancient magma bodies in the lower crust. |
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Term
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Definition
Typically 90-100% plagioclase, w/ ~10% mafic minerals.
Ti-rich magnatite, hematite, rutile, ilmenite. |
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Term
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Definition
| Isolated vertical eruption column of ultramafic diamond-bearing magma. |
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Term
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Definition
Continental rift settings.
Usually occur as small plugs w/in zoned alkalic intrusive complexes. |
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Term
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Definition
Magma containing >50% carbonate minerals.
Rich in REE, U, Th, Va, Hf, Ta, etc. |
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Term
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Definition
| Thick wedge of oceanic crust emplaced on a subduction-active continental margin. |
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Term
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Definition
Deepest layer consists of serpentinized ultramafic rocks.
Rich in chrysotile asbestos. |
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Term
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Definition
1-2% of all Fe deposits.
Segregation of Fe-rich magma w/ 4-5% phosphorus. |
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Term
| Porphyry base metal deposits |
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Definition
| Related to the hydrothermal fluid systems of shallow-seated subduction-related magmatic intrusions. |
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Term
| Porphyry base metal deposits |
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Definition
| Important concentrations of Pb, Zn, MN, Au, Ag, Cu, Mo. |
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Term
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Definition
| Shallow-seated intermediate magmatic intrusion in to carbonate host rock. |
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Term
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Definition
| May be adjacent /extensions of porphyry base-metal deposits. |
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Term
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Definition
| Minerals that form are dependent on metasomatic fluid composition and host rock (limestone/sandstone/shale/etc.). |
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Term
| Hydrothermal iron deposits |
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Definition
Calc-alkaline plutonism related
Ring the Pacific Basin
Not as important as banded iron. |
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Term
| Cordilleran Vein Deposits |
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Definition
Convergent margin setting; shallow depth vein replacement.
Hydrothermal fluids carry and deposit ore components. |
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Term
| Cordilleran Vein Deposits |
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Definition
Major economic significance; similar ore minerals to porphyry copper deposits.
Ag, Cu, Pb, Zn. |
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Term
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Definition
| Slow crystallization of dikes/veins of alkali-rich igneous fluids. |
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Term
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Definition
| Important source of REE, Be, Li, Ru, Ce, Nb, Mo, W, Sn. |
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Term
| Epithermal Volcanic Deposits |
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Definition
Shallow volcanic rocks w/ warm hydrothermal activity.
Mineral replacement textures. |
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Term
| Epithermal Volcanic Deposits |
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Definition
Sulfosalt minerals are characteristic.
Compounds of Au, As, An, S, Ag common. |
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Term
| Epithermal Volcanic Deposits |
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Definition
| Typical iron oxide gossan cap of easily weathered pyrite. |
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Term
| Volcanogenic Massive Sulfides |
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Definition
Created from submarine volcanic-associated hydrothermal systems.
Straiform accumulation of sulfide minerals precipitated out of hydrothermal fluids. |
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Term
| Volcanogenic Massive Sulfides |
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Definition
| Cu-Zn rich deposits w/ S, Ni, Pb, Fe, Tu, An, Sn. |
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Term
| Volcanogenic Massive Sulfides |
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Definition
| Common lateral facies of the deposits are banded iron, exhalite gold. |
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Term
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Definition
| Volcanically heated water w/ convecting sea water and adjacent igneous rocks. |
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Term
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Definition
| Substantial proportion of worlds Pb-Zn sources. Galena-sphalerite dominant minerals. |
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Term
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Definition
Higher P/T conditions.
Redistribution of mineral components or ore constitutes mobilize and re-emplace. |
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Term
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Definition
| Important source of corundum, emerald, garnet, and uranium. |
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Term
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Definition
| Sedimentary ores formed at the same time as enclosing rocks. |
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Term
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Definition
| Deposits include those formed by chemical precipitates or placers. |
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Term
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Definition
| Ores introduced in to sedimentary rock after host rock has formed. |
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Term
| Chemical Sedimentation Deposits |
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Definition
| Include: sulfide deposits, marine black shale, sed. iron ores. |
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Term
| Chemical precipitation sulfide deposits |
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Definition
| Metal ions supplied to a depositional basin w/ reducing conditions. |
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Term
| Chemical sulfide deposits |
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Definition
Important concentrations of:
Cu, Pb, Zn
Minor constituents:
Ag, Ni, Co, Se, Va, Mo |
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Term
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Definition
| Marine or lacaustrine in environment, evaporation of sea water. |
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Term
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Definition
Mineral sequence:
Calcite, gypsum/anhydrite, halite, magnesium sulfates, sodium bromide. |
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Term
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Definition
| More varied water evaporating than seawater, leads to greater variety in produced minerals. |
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Term
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Definition
| Found in extensional fault block topographic low spots (inland basins). |
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Term
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Definition
| Nitrates, borax, lithium, sulfate, oil shales, sodium bicarb. |
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Term
| Clastic Sedimentation Deposits |
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Definition
| placer deposits, mechanical concentration of heavy mineral particles. |
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Term
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Definition
| Stream and marine action represent the most significant deposits of heavy minerals (Au/Pt). |
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Term
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Definition
| Tropical climate leaching creates Fe- and Al-oxide rich soils. |
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Term
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Definition
| Al-rich, Fe- and Si-poor laterites. |
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Term
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Definition
| Humid, (sub)tropical environs. cause feldspar decomposition, through kaolinite, to final product. |
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Term
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Definition
| Special case of weathering; element redistribution. |
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Term
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Definition
Ore mineral leached through pyrite-rich permeable strata followed by re-precipitation.
(Oxidizing to reducing zone) |
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Term
| Induced Polarization (IP) |
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Definition
Passes a current through the ground, shuts it off, measures remnant current.
Useful to find sulfide deposits, clays, zeolites, delineate clay aquitards. |
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Term
| Electromagnetic methods (EM) |
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Definition
Induction of alternating current to measure EM field.
Ideal for massive sulfide deposits. |
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Term
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Definition
Measures variations in Earths EM field.
Useful to several km depth. |
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Term
| Direct current resistivity |
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Definition
| Useful to identify highly conductive massive sulfide deposits, groundwater flow pathways. |
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Term
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Definition
Pos. gravitic anomalies: high density minerals i.e. chromite, barite, hematite.
Neg. gravitic anomalies: peat, halite, weathered kimberlite. |
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Term
| Aerial Photography reconnaissance |
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Definition
| Useful to delineate soil patterns/distribution, determine generalized lithology, physiography for locating ore deposits. |
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Term
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Definition
An area including rock, surrounding mineral deposit, and enriched elements that make up that deposit.
May extend by 10s to 100s of meters laterally and several km down strike. |
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Term
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Definition
| An area around a primary ore body where mobilized minerals/elements are present but at lower economic concentrations than the ore body, due to chemical/mechanical weathering methods and transportation (i.e. stream activity). |
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Term
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Definition
| A relatively mobile element whose geochem. properties are used to more easily find a deposit of greater value/importance. |
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