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Lithofacies and environmental analysis of clastic depositional systems (view source)
Revision as of 21:01, 3 March 2014
, 21:01, 3 March 2014→Braided and meandering fluvial deposits
===Braided and meandering fluvial deposits===
===Braided and meandering fluvial deposits===
Downdip from alluvial fans, rivers typically grade first into braided channels then, farther down the alluvial valley toward the coastal plain, into meandering channels. These different channel types can occur in the same river system and produce distinctly different kinds of sandstone bodies.
[[Dip|Downdip]] from alluvial fans, rivers typically grade first into braided channels then, farther down the alluvial valley toward the coastal plain, into meandering channels. These different channel types can occur in the same river system and produce distinctly different kinds of sandstone bodies.
''Braided rivers'' and ''braidplains'' form elongate, tabular, sandy and gravelly deposits composed of braided, sand-filled channels and sand and gravel bars (Figure 3c). They typically consist of coarse sand and gravel with relatively minor amounts of clay. Vertical sequences are composed of stacked, upward-fining channel sands and sand and gravel bars. Lateral trends in these deposits are dominated by an overall tabular geometry bounded by floodplain muds with an internally complex geometry of cross-cutting sands and gravels with subordinate mud-rich beds of varying thickness and dimension. Bar and channel deposits are typically elongate in the paleocurrent direction.
''Braided rivers'' and ''braidplains'' form elongate, tabular, sandy and gravelly deposits composed of braided, sand-filled channels and sand and gravel bars (Figure 3c). They typically consist of coarse sand and gravel with relatively minor amounts of clay. Vertical sequences are composed of stacked, upward-fining channel sands and sand and gravel bars. Lateral trends in these deposits are dominated by an overall tabular geometry bounded by floodplain muds with an internally complex geometry of cross-cutting sands and gravels with subordinate mud-rich beds of varying thickness and dimension. Bar and channel deposits are typically elongate in the paleocurrent direction.