Emplacement age of the Cross kimberlite, southeastern British Columbia, by the Rb–Sr phlogopite method

Abstract

The Cross kimberlite diatreme, located in the Columbia Mountains, southeastern British Columbia, has an emplacement age of 240–250 Ma, obtained by the Rb–Sr method on phlogopite. The time of emplacement was earlier than the intensive eastward structural displacements that occurred in this part of the Canadian Cordillera during the Laramide Orogeny, and the kimberlite may be structurally displaced as well as dismembered at depth.