Miocene Fluvial Facies and Vertebrate Taphonomy in Northern Pakistan
Published:January 01, 1987
Anna K. Behrensmeyer, 1987. "Miocene Fluvial Facies and Vertebrate Taphonomy in Northern Pakistan", Recent Developments in Fluvial Sedimentology, Frank G. Ethridge, Romeo M. Flores, Michael D. Harvey
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The deposits of the Potwar Plateau in northern Pakistan show large-scale changes in fluvial deposition during the period between 14 and 6 my BP in three superimposed formations (Chinji, Nagri, Dhok Pathan) approximately 2700 m in total thickness. Five cross sections spaced throughout this sequence document intervals 30-80 m thick over lateral distances of 3-5 km. These show the architectural relationships of sand bodies, fine-grained facies, pedogenic horizons, and vertebrate fossil occurrences within floodplain deposits between major channel belt sandstones. Vertebrate fossil localities are particularly frequent within the fine-grained fill of different scales of abandoned floodplain channels (crevasse-splay and/or tributary channels). Such channels are larger and more common in the lower part of the sequence where average rates of sediment accumulation were 0.14-0.32 m/1000 yrs. as determined from the Siwalik magnetostratigraphic time framework. Higher average accumulation rates of 0.46-0.48 m/1000 yrs for the upper part of the sequence correspond to fewer fine-grained channel fills and lower fossil abundance. Changes in type and frequency of floodplain channels are attributed to a combination of differences in the fluvial regimen and in sediment accumulation rates. The quality of the vertebrate record is linked to the frequency and/or magnitude of abandoned channels on the sub-Himalayan alluvial plain and thus to large-scale tectonic and climatic controls on the fluvial systems.
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Recent Developments in Fluvial Sedimentology
This volume brings together 36 of the manuscripts that were presented at the Third International Fluvial Sedimentology Conference hosted by Colorado State University in August, 1985. Fluvial systems and sedimentary rock sequences discussed range in age from Holocene to Precambrian and include many diverse areas. The principal objective of the volume was to document the recent developments in the application of facies analysis to the reconstruction of the architecture of fluvial systems. Reconstruction of architecture is an integral part of the overall process of basin analysis.