PALEOFLOW PATTERNS OF DOLOMITIZING FLUIDS AND PALEOHYDROGEOLOGY OF THE SOUTHERN CANADIAN ROCKY-MOUNTAINS - EVIDENCE FROM DOLOMITE GEOMETRY AND NUMERICAL MODELING

Massive dolomites, hosted in the Cambrian-Ordovician of the southern C anadian Rocky Mountains, form strata-bound sheets over broad platforms , except near the margin, where they also form dikes that crosscut sed imentary bedding planes. Field evidence indicates that the two kinds o f dolomite bodies were formed by pervasive, formation-parallel how and fracture-channeled, cross-formational flow, respectively, Fluid-inclu sion data indicated that the primary dolomitizing fluids were warm to hot (100 to 200 degrees C) saline brines (13-25 wt%). The timing of do lomitization (Silurian to Late Devonian) coincided with the timing of the early Paleozoic contractional deformation in the west, Finite elem ent modeling showed that the observed dolomite geometry and geochemist ry are consistent with miogeocline-scale ground-water flow driven by w est-to-east topographic relief.