Whole-Rock Geochemistry and Mineralogy of Triassic Montney Formation, Northeastern British Columbia, Western Canada Sedimentary Basin

Abstract

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was used to analyze chemical elementsmajor, trace and rare earth elements (REE) concentrations, augmented with quantitative X-ray diffraction (XRD) analysis and thin-section petrography for mineralogical characterization of the Triassic Montney Formation in northeastern British Columbia, Western Canada Sedimentary Basin (WCSB). Results from this study indicate that integration of chemical elements with mineralogy shows affinity to the host lithologies. Evidently, chemical elements are the building blocks for minerals, thus, their significances in the interpretation of geological systems are unambiguous. Herein, major elements concentration such as Al, Fe, K, Mg, Ca, Mn in the samples analyzed from the Montney Formation are interpreted as: 1) indication of dolomitization and diagenesis; 2) trace elements-Rb, Th, U, and Cs are related to the organic matter-kerogen in the clay component of the Montney Formation source rock; and 3) transition metals-Sc, V, Co, Cr, Zn show strong affinity with diagenesis in the study interval.

Isotopes (<sup>13</sup>C and <sup>18</sup>O) Geochemistry of Lower Triassic Montney Formation, Northeastern British Columbia, Western Canada

“…Pyrite replaces organic matter in plate-D during decomposition of organic matter due to diagenensis; (e) Illustration of a very well formed palygorskite clay; a form of clay mineral growth, formed from the transformation of dickite to illite, and further transformation of illite to palygorskite due to severe temperature and pressure in a diagenetic regime. Adapted from [12]. −8.46‰) and it is related to oxidation of organic matter during diagenesis.…”

“…Evidently, Ca has enormously high concentration due to the stoichiometric co-existence with dolomite. Adapted from [12].…”

“…The succession was deposited in a west-facing, arcuate extensional basin on the western margin of Pangaea [23][24][25][26][27]. The Montney Formation consists of siltstone, very fine-grained sandstone, bioclastic packstone/grainstone (coquina, in Alberta) [19,20], interlaminated, interbedded, dolomitic silty-sandstone [12][13][14]22] and shale. The Triassic Montney Formation is separated by an unconformity from the underlying Permian Belloy Formation (Figure 2).…”

“…The Montney Formation is the basal stratigraphic unit of Triassic succession in the subsurface of western Canada [12][13][14]. It rests, unconformably in most areas, upon carbonate or mixed siliciclastic-carbonate strata of Carboniferous to Permian age [15][16][17][18][19][20][21][22].…”

“…This study of the Montney Formation in Fort St. John area (T86N, R23W and T74N, R13W), northeastern British Columbia ( Figure 1) utilized stable isotopes ( 13 C and 18 O), whole-rock geochemistry (Table 1) and mineralogical composition (Table 2) to interpret dolomitization of the Montney Formation because they are established methods for studying dolomitization and diagenesis in carbonates [11,12].…”