Stratiform Deposits

Stratiform Deposits


mineral deposits concentrated within one or more strata of volcano-sedimentary and sedimentary bedded rock formations. The most characteristic examples are deposits of lead and zinc ores in strata of carbonate rocks (the Missouri Valley deposits in the USA and similar deposits in the USSR, Canada, Poland, Austria, North Africa, and elsewhere) and copper ore deposits in sandstone-shale strata (the Copper Sandstone Deposits in Southern Africa, the German Democratic Republic, and Poland and in Kazakhstan and Central Siberia in the USSR).

In stratiform deposits, there is a predominance of stratified bodies that are conformable with the enclosing rocks. The ores in these bodies have simple mineral compositions determined by the dissemination of copper, zinc, and lead sulfides and the accompanying minerals in one or more strata of the ore-bearing rocks. Stratiform deposits are generally of large size, cover a broad area, and form vast ore regions or provinces (for example, the Mississippi Valley lead and zinc deposits).

Several hypotheses have been advanced on the origin of stratiform deposits. In the view of such geologists as E. Zakharov and K. Satpaev of the USSR, C. Behre of the USA, and C. Davidson of Great Britain, stratiform deposits are of hydrothermal origin. This hypothesis, however, is contradicted by the absence of mag-matic rocks in the areas where the stratiform deposits are found. Another hypothesis, whose adherents include V. Popov and V. Domarev of the USSR and H. Gruszczyk of Poland, regards stratiform deposits as sedimentary formations that arose from marine sediments on the bottoms of ancient seas together with the enclosing rock strata. This view is contradicted by the presence of cross-cutting ore veins along with the bedded ore bodies.

The second half of the 20th century has seen the development of the hypothesis of the protracted formation and complex origin of stratiform deposits. The ore minerals were initially deposited in the ore-bearing strata by sedimentation on the bottoms of ancient seas; extensive deposits of low-grade, noncommercial ores were thereby formed. Subsequently, under the action of hot, chemically active subterranean water that circulated through the strata, the sulfide material was dissolved and redeposited, so that secondary deposits of richer, commercial ores were formed. V. Smirnov of the USSR and P. Zuffardi of Italy are among the geologists supporting this hypothesis.

In the capitalist countries, stratiform deposits account for about 40–60 percent of the lead-ore reserves and 35–40 percent of the zinc-ore reserves.

The term “stratiform deposits” was introduced at a conference on the origin of such deposits held in New York in 1969.


Smirnov, V. I. “Faktor vremeni v obrazovanii stratiformnykh rudnykh mestorozhdenii.” Geologiia rudnykh mestorozhdenii, 1970, vol. 12. no. 6.


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For example, layered intrusions are subdivided into stratiform and contact deposits, with the stratiform deposits further subdivided into chromite and sulphide-associated deposits.
All cobalt produced in Katanga is taken from stratiform deposits.
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Carrollite is the principal primary cobalt mineral in the stratiform deposits.
Unlike carrollite from other stratiform deposits, the crystals from Luishia contain several percent nickel.
Not a single crystal visible to the naked eye has been found during more than 90 years of exploitation of the stratiform deposits.
The Shield is, however, the principal area of interest, and includes magmatic and late magmatic deposits, contact metamorphic deposits on the igneous boundaries, and stratiform deposits and veins.
An independent review has been commissioned, leading to a program to identify further commercially attractive stratiform deposits within the current known vein structure, and also aid in further exploration strategy elsewhere on the property.
In the stratiform deposits near Cave in Rock, the apparent origin of the mineralization can be stated in the following hypothesis (Grogan and Bradbury, 1967): fluorine was emplaced by convection of connate water driven by heat of magmatic origin.
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Contiguous assay results for the vein, stockwork and stratiform deposits have been included by MRDI in the calculation of the geological resource, other than those silver assays with grades in excess of 600 gm/tonne which have been included at that reduced figure.