The Mineral System Ingredients

The Mineral System approach to exploration targeting concerns the identification of the key processes required to form mineral deposits. The ingredients include:

  • Sources of metals. These can be either distant or local to the deposit.

  • Mobilisation of the metals - There needs to be a mechanism that liberates the metals from the source rocks.

  • Pathways - the metalliferous fluids derived from diffuse sources must have a means of moving to the final deposition site.

  • Traps - There needs to be a means by which metals can drop out of solution to form mineral deposits in a focused manner.

  • Preservation - Any deposits that are formed, must be protected from subsequent destructive geological processes

Eastern Greenland meets all the above criteria at both macro, and local scales.  Potential sources for metals include a portion of Norway that was forced under Greenland in a collisional event with Europe . Such subduction zones are well known for being sources of metals. On a local scale, metals can be sourced out of sediments known as 'red-beds'. In east Greenland there is an 8 km thick pile of red-bed sediments from which metals are a potential source of metals.  

Metals may be liberated from their sources in east Greenland by three likely processes. The burial of the Norwegian slab may have resulted in melting. When Greenland began to separate from Europe, the Icelandic mantle plume ('hot spot') appeared. This deep, sustained source of magma represents a metal source, as well as mechanism for melting the lithosphere and subducting crust. Within the sediments, highly salty fluids derived from evaporitic sediments may have mobilised metals from their sources.

The deep potential sources of metalliferous fluids may be transported to near surface either as diapirs (think of a lava lamp), or followed the Jan Mayan Fault Zone. The Jan Mayen microcontinent to the east of Greenland and north of Iceland, is a control on the fault zone that extends deep into the Earth. Local sources of metals are readily transported through permeable sediments, but may be focused by aquitards (impermeable sedimentary layers).

The two basins that underlie Greenfields' license applications have layers of chemically contrasting sediments. As fluids pass through oxidised sediments into reduced sediments, the change in the surrounding chemical environment can trigger metals to drop out of solution. Additionally, as intrusions associated with the subduction zone and mantle plume rise to the surface, they can undergo processes of degassing and expulsion of volatile elements as the rocks begin to cool and depressurise.

Finally, any deposits formed in eastern Greenland may be preserved due to it being a passive margin. Since Greenland separated from Europe, it has been relatively free of compressional forces that can destroy deposits.

 
Thanks to  Wikimedia  for the image.

Thanks to Wikimedia for the image.

Hot spot

The Icelandic mantle plume appeared at the separation of Greenland and Europe. It resulted in about 30 million years of subvolcanic activity and a diverse range of melt types ranging from mafic to felsic. The mafic magmas are prospective for nickel-copper-cobalt sulphide mineralisation, while the felsics are known to contain molybdenum, as well as uranium.

Thanks to  Wikimedia  for the image.

Thanks to Wikimedia for the image.

Jan MayEn Fault Zone

This major crustal break is partially controlled by the Jan Mayen micro-continent. This zone runs sub-perpendicular to the palaeo-subduction zone and associated ~north-south faults in eastern Greenland. Both mafic and felsic intrusions are known to be associated with these structures.

Thanks to  John Goodge and Wikimedia  for the image

Thanks to John Goodge and Wikimedia for the image

Rodinia triple junction

As part of the Rondinia super-continent, Central eastern Greenland was located at a triple junction between Baltica, Amazonia and Laurentia. Such junctions create opportunities for metaliferous fluids to migrate to the surface. The break-up of Rodinia occurred during the Neoproterozoic, a time associated with the formation of the world's greatest sediment-hosted copper deposits in the African Copperbelt.

"The greatest obstacle to discovery is not ignorance - it is the illusion of knowledge" - Daniel J. Boorstin