6. GEOLOGICAL SETTING

6.1 Tectonic Belts
6.2 Terrane
6.3 Physiographic Area
6.4 Metamorphisms
      6.4.1 Type
      6.4.2 Relationship
      6.4.3 Metamorphic Grade
6.5 Comment - Geological Setting

Tectonic belt is a mandatory field and only one may be input for any given occurrence. The Province of British Columbia contains five distinct tectonic belts listed in the adjacent table and the figure below:

6.2 TERRANE

(*)

A number of lithotectonic terranes have been identified in the Cordillera. Each terrane preserves a geological record different from those of its neighbours or from rocks deposited on or adjacent to cratonic North America. Terrane boundaries are discontinuities, generally major faults, across which the geological record changes abruptly. Many terranes are displaced in the sense that their original paleogeographic positions relative to the North American Craton are uncertain.

Thirty-nine terranes or equivalents have been identified within British Columbia for the requirements of the MINFILE database and these are listed in Appendix VI. The database will accept up to two terranes for any given occurrence.

For terranes use the recent compilation from J.O Wheeler et. al. (Wheeler, J.O., Brookfield, A.J., Gabrielse, H., Monger, J.W.H., Tipper, H.W. and Woodsworth, G.J. (comp.), 1991: Terrane Map of the Canadian Cordillera; Geological Survey of Canada, Map 1713A, scale 1:2 000 000). A comprehensive description of each terrane from the previous compilation by J.O Wheeler et. al. is also included in Appendix VI. For a more detailed description refer to Monger, J.W.H. & Berg, H.C. Part B of U.S.G.S. Open File Report 84-523 and G.S.C. Preliminary Manuscript Map "Cordilleran Orogen of Canada" prepared for DNAG Volume G6.

For information on tectonic assemblages refer to Wheeler, J.O. and McFeely, P. (comp.), 1991: Tectonic Assemblage Map of the Canadian Cordillera and adjacent parts of the United States of America; Geological Survey of Canada, Map 1712A, scale 1:2 000 000.

NOTE: See Figure 3.

The Province of British Columbia has been divided into physiographic areas according to distinctive physical characteristics, reflecting in part the gross underlying geological character (e.g., plateaus, trenches, mountain ranges, etc.) The boundaries of each physiographic area are derived from GSC Map 1701A "Physiographic Map of the Canadian Cordillera", by Mathews, W.H. (1986).

Only one physiographic area can be input for each occurrence. The physiographic areas are listed in the following table:

6.4.1 TYPE (R15) (E15) - The type of metamorphism associated with the occurrence is identified. This is a mandatory field if the Relationship and/or Grade fields are used. One or two types may be entered if appropriate.

TYPE CODE Contact 1 Regional 2 Unknown *

 

6.4.2 RELATIONSHIP (R17) (E17) - The age-relationship of metamorphism to hostrock mineralization is indicated here. Up to three categories may be selected if appropriate.

RELATIONSHIP CODE Pre-mineralization 1 Syn-mineralization 2 Post-mineralization 3 Unknown *

6.4.3 METAMORPHIC GRADE (R16) (E16) - The database will accept a maximum of two metamorphic grades and/or coal ranks from the following list:

 

GRADE/RANK CODE Zeolite ZL Greenschist GS Amphibolite AM Hornfels HF Granulite GL Blueschist BS Eclogite EC

GRADE/RANK CODE Anthracite AN Semi-Anthracite SA Low-Volatile Bituminous LV High-Volatile Bituminous HV Medium-Volatile Bituminous MV Sub- Bituminous SB Lignite LI Unknown **

One 70-character line of text is available to give a brief but pertinent comment on the overall geological setting of a given occurrence.