5.1 Dominant Hostrock
5.2 Formal/Informal Host
5.3 Stratigraphic Age
5.4 Isotopic Age
5.5 Material Dated
5.6 Dating Method
5.7 Rock Type/Lithology
5.8 Comments - Host rock
5.1 DOMINANT HOSTROCK
(*) (R03) (E03)
|This is a mandatory field identifying the most significant hostrock type. The hostrock is normally defined as the type of rock in which the mineralization occurs. Only one dominant hostrock is accepted by the system.
5.2 FORMAL/INFORMAL HOST
(*) (R23) (E23)
Each MINFILE occurrence requires at least one FORMAL or INFORMAL HOSTROCK. Both categories may be entered for any given occurrence; the system will accept a maximum of two FORMAL (groups and formations) and two INFORMAL (plutonic, metamorphic, etc.) hostrocks. The HOST units are entered into the database using the Group, Formation, Igneous-Metamorphic and Informal host names in Appendix IV. New names and their corresponding codes will be added to the master table periodically as required. The hostrock name(s) must be written out in full on the coding card.
FORMAL hostrocks are those with an officially established Group, Formation, or other stratigraphic name. INFORMAL hostrocks include formal names for igneous and metamorphic units as well as informal names or general terms which are not part of the stratigraphic nomenclature (e.g., plateau basalt).
Group and Formation names are entered in the FORMAL HOST category. Informal, igneous, or metamorphic units must be entered in the INFORMAL HOST category.
It is imperative that both the Group and corresponding Formation are identified. If an occurrence is hosted by the Telkwa Formation, the coding must identify it as part of the Hazelton Group. UNNAMED/UNKNOWN may be used in either category. If a Group or Formation is known but the corresponding Formation or Group is not identified then UNDEFINED GROUP or UNDEFINED FORMATION should be used to maintain data relations in the hostrock field.
In the MINFILE system, a stratigraphic unit identified as a member is assigned a code in the Formation category. Rock units identified as a Series or Supergroup are assigned codes in the Group category. The formal/informal host(s) along with its stratigraphic age(s) must be included in the Capsule Geology description.
5.3 STRATIGRAPHIC AGE
The stratigraphic age is a mandatory field identifying the geological age of the hostrock in terms of era, period or epoch. Appropriate ages are the same as for "Age of Mineralization" listed in Appendix V. Both FORMAL and INFORMAL HOST categories must have relevant ages.
Where only a stratigraphic age is identified it is not necessary to complete the MATERIAL DATED and the DATING METHOD fields. The most specific age information available should be used e.g., Hazelton Group, Mount Dilworth Formation date should be Lower Jurassic even though the Hazelton Group is Upper Triassic to Middle Jurassic in age.
5.4 ISOTOPIC AGE
(of Hostrocks) (R23)
|Isotopic Age is a 20-character, free-format field for a specific hostrock age, quoted in millions (Ma) or billions (Ga) of years. Associated age dating errors should be included (e.g., 48.7 Ma +/- 1.2 Ma). A Reference should be included in the Hostrock Comment field. The stratigraphic age and the isotopic age must correspond.
Okulitch, A.V. (1999): Geological Time Chart 1999, Geological Survey of Canada, Open File 3040
Grant, Brian (2003): Geoscience Reporting Guidelines
PDF version or JPG
5.5 MATERIAL DATED (R23)
When an ISOTOPIC age is given, the material used in the dating procedure must be identified. This is a 30-character, free-format field, listing material(s) used in the age determination (e.g., biotite, zircon, fossil, etc.).
5.6 DATING METHOD (R23) (E22)
The dating method used to determine the ISOTOPIC age must be identified. Refer to the Dating Method table located within the Mineral Occurrence section for appropriate dating methods (page 18).
5.7 ROCK TYPE/LITHOLOGY
(*) (R25) (E25) (E26)
At least one Rock Type/Lithology must be entered for each occurrence. A total of ten different rock types and up to three modifiers for each rock type may be identified for each occurrence. Appendix III is a listing of current rock names and modifiers. This table will be updated periodically as required. The rock types that host the significant mineralization should be listed in their order of importance and should correspond with the Dominant Hostrock category. Other lithologies identified should correspond with the FORMAL and INFORMAL hostrocks.
All rock types plus modifiers identified should be written out in full in the lithology field on the coding card. Care should be taken not to duplicate rock types by using synonyms (e.g., diabase dike and diorite dike). The Rock Type(s)/Lithologies must be included in the Capsule Geology description.
MODIFIER SEARCH CODE(S)
ROCK TYPE SEARCH CODE
Quartz Feldspar Porphyry
Two lines of text may be added to the comment field to clarify hostrock or age dating information.