Paleontology, paleoecology, and depositional history of the Miocene-Pliocene Verde Formation, Yavapai County, Arizona
Nations JD, Hevly RH, Blinn DW, Landye JJ. 1982. Paleontology, paleoecology, and depositional history of the Miocene-Pliocene Verde Formation, Yavapai County, Arizona. Arizona Geological Society Digest. 23:133-149
The Verde Formation is a nonmarine basin-fill sequence of fluvial and lacustrine clastic, volcaniclastic, evaporite, and carbonate sediments. It was deposited within the Verde basin after drainage at the southeastern end of the basin was interrupted by faulting and volcanism during the Miocene and early Pliocene. During that time drainage was internal, dissolved salts were concentrated, and evaporite minerals were deposited in the southern portion of the basin, with some carbonates in the northern portion. The absence of aquatic mollusks in Miocene rocks of the southern portion of the basin further attests to the high salinity of the ponded water. The dominance of limestone with abundant freshwater mollusks in Pliocene rocks indicates improved drainage and freshening of the water that periodically flooded the basin. Aquatic plants grew in abundance, causing the precipitation of Ijmestone by photosynthetic removal of CO2. Fine-grained clastic sediments were deposited across the basin floor during periods of low carbonate sedimentation. The pollen record of terrestrial plants indicates savannalike vegetation in the vicinity and climatic conditions more mesic than at present. It also suggests elevation changes of plus 330 m of the plateau and minus 660 m in the basin, due to tectonic movements since the Miocene. Cessation of volcanism and overflow of the volcanic-tectonic dam in late Pliocene and a complete breaching of the dam in early Quaternary has resulted in the erosion of much of the Verde Formation from the Verde basin. (Copied verbatim from the journal article.)
- Type
- Journal Article
- Authors
- Nations, J.; Hevly, Richard; Blinn, Dean; Landye, J.
- Units
- MOCA
- Keywords
- 1, Core, depositional history, Fossils, History (Geologic), Invertebrates, Montezuma Well (MOCA), non-marine basin, NRCA, Paleoecology, Paleontology, Plants, Sediments, Verde basin (AZ)geology, Verde formation, Vertebrates