Poster Number 238
See more from this Division: Topical Sessions
See more from this Session: The Future of Sedimentary Geology: Student Research (Posters)
Abstract:
New geologic mapping, measured stratigraphic sections, and provenance of Upper Triassic strata from the Chulitna terrane reveal a continuous record of competing volcaniclastic, siliciclastic, and carbonate sedimentation. Red bed units are defined by interbedded successions of poorly-sorted and matrix-supported volcaniclastic and siliciclastic sandstone and conglomerate. Individual beds are typically 0.252 m thick and exhibit tabular geometries. Well-sorted sandstone occurs sporadically throughout red bed units and is characterized primarily by trough cross-stratification. Red bed units are laterally extensive for up to 150 m and only rarely exhibit evidence of basal erosional scour.
Upper Triassic volcaniclastic, siliciclastic, and carbonate units in the Chulitna terrane were originally thought to represent three distinct successions that were stratigraphically separate from each other. However, measured sections and modal composition reveal that carbonate and red bed successions are interbedded throughout the Chulitna terrane, suggestive of multiple distinct source areas and varying styles of sedimentation. Sedimentation is interpreted to represent a combination of subaerial and submarine gravity flow processes, limited fluvial processes, and carbonate precipitation. These new findings may imply mixed source areas that include a dissected arc and continental margin. Upper Triassic strata of the Chulitna terrane are interpreted to represent sedimentation associated with limited exhumation of a volcanic arc and continental margin and periods of tectonic quiescence where carbonate precipitation persisted.
See more from this Division: Topical Sessions
See more from this Session: The Future of Sedimentary Geology: Student Research (Posters)