Tectonically-controlled drainage fragmentation in the southern Great Basin, SW USA (Geological Society of America Bulletin PDF here)
In this paper, we establish latest Miocene to Pliocene fluvial connections (black arrows to right) that predated the modern system of internally-drained basins.
We utilized a multidiscplinary approach that included field work, mapping, detrital zircon U/Pb, detrital K-feldspar 40Ar/39Ar dating, 40/Ar/39Ar dating of lava flows, and major element geochemical analyses.
Pliocene faulting and volcanism fragmented the fluvial connections, leading to formation of internal drainages and isolated springs. The springs host endemic species of fish and snails that evolved in Pliocene time. We believe that fault-controlled isolation drove endemism.
Conceptual model
for fault-controlled drainage fragmentation in the southern Great Basin, SW USA
Click on images of figures below to enlarge them…
Fig. 2 shows an overview of the fluvial courses documented by this study.
Paired detrital K-feldspar & zircon
Age probability spectra indicate source areas for grains in alluvial fans around Death Valley.
Fans were derived in part from the Cottonwood Mountains (see figs. above), and two lie east of Death Valley. Thus, the fans pre-date the formation of Death Valley.
Age spectra from lava flows
help constrain the ages of fluvial courses that predated the modern Basin and Range topography.
Click on images to enlarge.
Stratigraphic correlation diagrams…
of Mio-Pliocene sections show the age of fluvial connections that predated the modern endorheic basins (e.g., Saline, Panamint, Death valleys).
Collaborators on this project:
Jeffrey Knott (California State University, Fullerton)
Fred Phillips (New Mexico Tech)
Jim Calzia (USGS)
Diane Clemens-Knott (California State University, Fullerton)
Matt Heizler (New Mexico Bureau of Geology and Mineral Resources)