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The sedimentary appearance of the thin laminations led to early interpretations that the deposits formed exclusively or mainly by exhalative processes onto the seafloor, hence the term SEDEX. However, recent study of numerous deposits indicates that shallow subsurface replacement is also an important process, in several deposits the predominant ...
Sedimentary exhalative (SEDEX) deposits account for 40% of total world zinc production, 60% of lead and a significant proportion of silver. Despite their economic importance however, sedex deposits are relatively rare. A worldwide compilation of sedex deposits indicates that about 70 are known, of which 24 have been or are being mined.
For example, sedimentary exhalative deposits (SEDEX), are a class of ore deposit formed on the sea floor (sedimentary) by exhalation of brines into seawater (exhalative), causing chemical precipitation of ore minerals when the brine cools, mixes with sea water, and loses its metal carrying capacity.
Volcanogenic massive sulfide deposits are distinctive in that ore deposits are formed in close temporal association with submarine volcanism and are formed by hydrothermal circulation and exhalation of sulfides which are independent of sedimentary processes, which sets VMS deposits apart from sedimentary exhalative (SEDEX) deposits.
Economic geology: sedimentary rocks host large deposits of SEDEX ore deposits of lead-zinc-silver, large deposits of copper, deposits of gold, tungsten, Uranium, and many other precious minerals, gemstones and industrial minerals including heavy mineral sands ore deposits
The key criteria for BHT ore deposits are; [11] Association with major sedimentary packages of sandstone and siltstone protoliths sequences in highly disturbed metamorphic terranes. A Proterozoic age is considered important, as no other major SEDEX lead-zinc deposits of this style are known from the Phanerozoic or Archean.
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VMS deposits are a major source of zinc (Zn), copper (Cu), lead (Pb), silver (Ag), and gold (Au). [33] Gold ore (size: 7.5 × 6.1 × 4.1 cm) Sedimentary exhalative sulphide deposits (SEDEX) are a copper sulphide ore which form in the same manor as VMS from metal rich brine but are hosted within sedimentary rocks and are not directly related to ...