Quaternary evolution of the Rio Grande near Cochiti Lake, northern Santo Domingo Basin, New Mexico
David P. Dethier
Quaternary base-level change in the northernmost Santo Domingo basin records the effects of damming and knickpoint migration upstream in White Rock Canyon and the influence of middle Pleistocene climate change. Quaternary changes were superimposed on complex base-level responses to changes in upstream sediment delivery, volcanism in the western Cerros del Rio and movement along the La Bajada fault zone in the late Pliocene and early Pleistocene. During Quaternary time, the Rio Grande cut the modern White Rock Canyon, initially transporting large quantities of sediment into the northernmost Santo Domingo basin, then incising this fill and underlying bedrock, stranding a series of inset, mainly fill terraces. Two principal pulses of aggradation, separated by >40 m of incision, can be distinguished in the surficial geologic record near the southern end of White Rock Canyon: an early Pleistocene episode (Q1) that began with eruption of the upper Bandelier Tuff and another episode (Q2) in middle Pleistocene time. Base-level lowering of ~60 m, punctuated by relatively brief periods of aggradation (Q3 and Q4), dominated geomorphic changes in the northernmost Santo Domingo basin from about 300 ka to present. Middle and late Pleistocene incision records decreased sediment load or increased stream power that resulted from upstream drainage evolution and pluvial/interpluvial cycles of increased amplitude.
- Dethier, David P., 1999, Quaternary evolution of the Rio Grande near Cochiti Lake, northern Santo Domingo Basin, New Mexico, in: Albuquerque Country, Pazzaglia, Frank J.; Lucas, S. G.; Austin, G. S., New Mexico Geological Society, Guidebook, 50th Field Conference, pp. 371-378.