Mineral system

Mississippi Valley-type system

Also known as MVT system

A low-temperature system in which brines expelled from a sedimentary basin migrate through platform carbonates and precipitate lead and zinc sulfides where fluids mix or conditions change. It involves no magmatism at all, which is precisely why it belongs in the canon.

A schematic left-to-right chain of seven linked stages above a separate dashed band labelled observable expressions, with arrows running down from three of the stages into that band. — SchematicThe seven stages Lithoen records for every system: source, mobilisation, transport, pathway, trap, modification, preservation — with the observable expressions drawn as a separate band beneath, because only some stages leave anything to see. The order is the claim; nothing here is to scale in space or time, and the deposit, where there is one, is a very small part of the whole.

system class: basinal
model provenance: publishedModel

System architecture

The chain from source to what may be observed. A limb is shown only where Lithoen has recorded it from a source; nothing here identifies a place, ranks ground or implies that a deposit exists.

Source
Where the system draws its components from. Each edge names the component it refers to; source differs between systems and is never generalised.
- Continental crustestablished
  component
  Metals and sulfur, both from crustal sources rather than from a magma.
- Limestoneestablished
  component
  The carbonate host that is replaced by sulfides and dissolved to make the space they occupy.
Transport
What moves the components, and under what conditions. What a medium can carry depends on temperature, pressure, salinity and redox state, so every edge states the conditions it holds under.
- Basinal brineestablished
  conditions
  Basinal brine of about 10 to 30 weight percent salts at ore-deposition temperatures typically between 75 and about 200 degrees Celsius.
Pathway and focusing
What concentrated the flow. The presence of a structure is never on its own evidence that it focused anything, so each edge states the basis for the claim.
- Chemical weatheringinferred
  precisionNote
  Dissolution collapse breccias are named among the most important ore controls; the process entity available in the corpus for carbonate dissolution is chemical weathering, and the identification is recorded as inferred rather than asserted.
- Faultinginferred
  precisionNote
  The model treats faults and fractures as factors in fluid transmissivity that focus flow. Each such feature has an unmineralised counterpart in the same district, so the edge records a role where it operated, and the presence of a fault is never on its own evidence of mineralisation.
Deposition
Why the components stopped moving. A system may use more than one mechanism, and different mechanisms leave different signatures.
- Coolingestablished
- Fluid mixingestablished
- Redox processesestablished
  precisionNote
  Redox reactions of sulfate, named by the model alongside fluid mixing and changes in pH and temperature.
Minerals, in their role here
Mineral role is a property of a mineral in a system, not of the mineral. The same species is an ore mineral in one system and gangue in another.
- Dolomiteestablished
  role
  alteration mineral
Modification and preservation
What happened after the system finished. Formation is not preservation, and what is observed today is the sum of both.
- Dolomitisationestablished
  precisionNote
  Dolomitisation is the principal alteration of these systems; whether it precedes, accompanies or follows mineralisation varies between districts.
Commodity association
A geological association only: a commodity characteristically won from this class of system where one is developed and preserved. No statement about any occurrence, and none about value.
- Lead (commodity)established
- Zinc (commodity)established
Tectonic and geological context
The settings in which this system has been DOCUMENTED. Tectonic context is a necessary or common component of some models; it is not proof that mineralisation is present anywhere. Every entry states what else the setting contains.
- Orogenyestablished
  What else the setting contains
  Orogenic forelands accompany every mountain belt and have throughout the Phanerozoic. Being in one is not a distinguishing observation.
  precisionNote
  A documented context, not a prediction. The setting is vastly more extensive than the systems found in it, and this edge asserts only that sources place the system here.
Observable expressions
Features commonly associated with this system — and, for each, what else produces the same observation. None of these demonstrates that a system operated anywhere, and Lithoen ranks nothing.
- Dolomitisationinferred
  What else produces this
  Dolomitisation of carbonate platforms is ordinary and almost entirely barren; the model records explicitly that each ore-controlling feature has an unmineralised counterpart in the same district.

How this record is known

12
Settled consensus: Cited as the accepted position of the discipline.; 1
Interpretation: Reached by reasoning from evidence, or produced by a named model.

13 of 13 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.

What Lithoen records

Each claim states how it is known and cites its evidence.

InferredA structure is a pathway when it focused flow, which has to be shown rather than assumed.

Ore controls are best understood as factors in fluid transmissivity that focus flow and create opportunities for deposition — which means a structure matters when it did that, and the presence of a fault is not by itself evidence that it did.

method: Follows from the cited treatment of ore controls as transmissivity factors, together with the observation that the same features occur barren.