THE JOGGINS AND SPRINGHILL MINES FORMATIONS FACIES MODEL AND INTERPRETATION OF THE PALED-ENVIRONMENT

Abstract

The type section of the Joggins Formation is located along the eastern shore of Chignecto Bay, Nova Scotia. A bed-by-bed measurement of the Carboniferous strata within a 200m stratigraphic zone encompassing the Joggins and Springhill Mines boundary is performed and classified into lithological units and facies types and finally, a conceptual model of the depositional paleo-environment is suggested. Facies types observed within the study area include large, moderate and minor-scale sandstone channel-fill facies; undulating, thin sheet, and tabular planar sandstone facies; grey friable, grey platy, red friable, and red platy mudstone facies; a coarsening-upwards bay-fill facies; and limestone, shale and coal organic facies. A prominent feature of the lithology found in the stratigraphic section, is a repetative cyclicity. Cyclicity can be observed as sm,all-scale coarsening-upward or fining-upward packages (<l0 rn) and as larger-scale grey and red assemblages (<40 m). The smaller-scale cycles are divided by sharp erosional boundary layers, designated as flooding surfaces, while larger-scale cycles generally have gradational boundaries. Grey assemblages reflect wetland environments, whereas, red assemblages reflect arid environments. Both these trends can be used to synthesize facies types by association. Successive environments, resulting as a response to variations in base-level, can then be classified as either belonging to a progradational or retrogradational parasequence set. This establishes a contemporaneous link between facies types, and allows for modeling of paleo-environmental cyclical trends. Keywords: Carboniferous, progradational parasequence sets, retrogradational parasequence sets, base-level, and facies types, sequences, and associations