Depositional facies and Hohokam settlement patterns of Holocene alluvial fans, N. Tucson Basin, Arizona
The distribution of depositional facies on eight Holocene alluvial fans of varying dimensions is used to evaluate prehistoric Hohokam agricultural settlement patterns. Two facies are recognized: channel gravelly sand facies and overbank silty sand facies. No debris flow deposits occur. The channel facies is characterized by relatively well sorted stratified sands and gravels with common heavy mineral laminations. Overbank facies deposits are massive and very poorly sorted due to heavy bioturbation. Lithostratigraphic profiles from backhoe trenches and sediment size analysis document headward migration of depositional facies which results in fining upward sequences. Each sequence is a channel fan lobe with an underlying coarse grained channel sand which fines to overbank silty sands. Lateral and vertical variations in facies distributions show that depositional processes are affected by drainage basin area (fan size) and distance from fan head. Gravelly channel sands dominate at the headward portions of the fan and are more pervasive on large fans; overbank silty sands are ubiquitous at fan toes and approach closer to the fan head of smaller alluvial fans. When depositional facies are considered as records of water flow over an alluvial surface, the farming potential of each fan can be analyzed. Depositional models of alluvial fan sedimentation provide the basis for understanding Hohokam settlement patterns on active alluvial surfaces.
- Research Organization:
- Arizona State Museum, Tucson (USA)
- OSTI ID:
- 6613127
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARIZONA
ALLUVIAL DEPOSITS
SEDIMENTARY BASINS
STRATIGRAPHY
AMERICAN INDIANS
GEOLOGIC HISTORY
HABITAT
HISTORICAL ASPECTS
QUATERNARY PERIOD
SEDIMENTATION
CENOZOIC ERA
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
HUMAN POPULATIONS
MINORITY GROUPS
NORTH AMERICA
POPULATIONS
USA
580100* - Geology & Hydrology- (-1989)