THE SEDIMENTOLOGY, COAL PETROLOGY, AND TRACE ELEMENT GEOCHEMISTRY OF COAL BEARING SEQUENCES FROM JOGGINS, NOVA SCOTIA, CANADA, AND SOUTHEASTERN NEBRASKA, USA

Coal-bearing sequences from Joggins, Nova Scotia, and southeastern Nebraska are selected as depositional end-members of coal deposition; the continental-fluvial, and brackish-water nearshore association. Verification of the fluvial depositional environment for the Joggins section is accomplished by a detailed description of a portion of the sequence between McCairn's Brook and Peter's Point. Significant features present in the Joggins sequence include lateral and vertical accretion deposits, lag conglomerate, convoluted lamination, and scoured surfaces. No marine fossils are encountered in this section. Several fossil plant-rich horizons are located above larger sandstone units. In contrast, the distinctive offshore paleoecology of the limestones overlying the coal beds described in Nebraska confirms their nearshore environment of deposition.;Following the establishment of the geographic end-member positions of these two sequences, an examination of their coal petrology, previously undescribed, and their trace element geochemistry is conducted. Coals from both localities have a dominant vitrinite maceral component. Alginite is the dominant liptinitic maceral present in the Nebraska-Kansas coals while sporinite and cutinite predominate in the coals from the Joggins sequence. Although the coals from Nova Scotia were collected at only one site, the high concentration of trace elements in both the Joggins and Nebraska coals suggests their deposition near a source area rich in igneous and/or meta-sedimentary rocks. Major conclusions of this study include (1) the documentation of a continental-fluvial origin for the coal beds located south of McCairn's Brook near Joggins, (2) refinement of the contact between Divisions 3 and 4 of the Cumberland Group, (3) ascertaining the liptinite dominance of sporinite and cutinite for the Joggins coals and alginite for the Nebraska-Kansas coals, (4) the origin near the source area for both coal sequences based on their higher than normal trace element concentrations in a basinward direction, and (5) that the physical characteristics defined by the sedimentary structures and the paleoecology of the surrounding rock units best describe the environment of deposition for a selected coal bed. The concentration of trace elements in a coal is a function not of environment but of proximity to the provenance area. An understanding of depositional environments derived from sedimentology and paleoecology can explain differences in the coal petrology and trace element geochemistry of coals.