Landscape Evolution at an Active Plate Margin - Biological Science ...

D. R. Jessey and R. E. Reynolds
Figure 1-11. Generalized geologic cross section of the central Owens Valley. [D. R. Jessey]
lies along the east edge of the Alabama Hills and the
Owens Valley fault about 0.6 miles to the east of that.
The scarp of the Inyo Mountains is created by the
White–Inyo fault.
The Alabama Hills lie 0.6–1.2 miles west of the town
of Lone Pine, California. They form a prominent
ridge of Cretaceous plutons and Jurassic metavolcanic
and metasedimentary rocks separated from the
main Sierra massif by the Independence frontal fault.
Across the valley is the “famous” Union Wash ammonite
locality and the geologically complex Inyo
Mountains. The Owens Valley and Inyo Mountains
lie near the western margin of the North American
craton and at the center of the central Sierra Nevada
segment of the Cordilleran arc (Sorensen et al, 1998).
The emplacement of the Sierra Nevada batholith was
a result of the oblique subduction of the Farallon
oceanic plate beneath the North American plate from
210-80 Ma.
The late Cenozoic tectonic history of eastern California
is dominated by the Eastern California Shear
Zone (ECSZ). The ECSZ is the name applied to the
southern segment of the Walker Lane belt, a zone
of dextral shear that accommodates about 20–25%
of the total relative motion between the Pacific and
North American plates (Gan, et al., 2000). North of
the Garlock fault the ECSZ is 60 miles wide and comprised
of four separate north-northwest striking fault
zones; from east to west the Death Valley-Furnace
Creek, Fish Lake Valley, Hunter Mountain–Panamint
Valley, and Owens Valley (Frankel, 2008). The Owens
Valley fault is the only one of the four that has
recorded a major seismic event in the historic past.
Le, et. al. (2007) published a comprehensive study of
Sierra Nevada Frontal Fault (SNFF) system including
the Independence fault, 5 miles to the west of Lone
old as 10 Ma.
Pine. Their study reported that
movement along the Independence
fault was dip-slip, east side
down, at a rate of 0.2–0.3 mm/
yr. This rate is about one-half to
one-third that necessary to accommodate
the 5000–7000 feet
of vertical displacement between
the Sierra Nevada crest and the
Owens Valley. They suggested
this discrepancy indicates the Sierra
Nevada Mountains are older
than the generally agreed upon
figure of 3–5 Ma (Wakabayashi
and Sawyer, 2001), perhaps as
The Lone Pine fault lies immediately to the east of
the Alabama Hills. The Lone Pine fault appears to be
right, oblique-slip fault. Rates of vertical motion are
estimated at 0.12–0.25 mm/yr. Horizontal slip rates
are less well constrained, but Lubetkin and Clark
(1988) suggest rates ~1 mm/yr. The relationship between
the Lone Pine fault and the Owens Valley fault
to the east is enigmatic. Since both were displaced
by the 1872 Lone Pine earthquake they are clearly
interrelated, however, Le et. al (2007) suggest that
motion along the Owens Valley fault is almost pure
dextral shear. Estimates of slip rate are variable from
a high of 4.5 mm/yr (Kirby, et. al., 2008) to a low of
0.7 mm/yr (Lubetkin and Clark, 1988). No estimates
are available for the vertical component of movement
along the Owens Valley fault, which manifests itself
in the scarp created by the 1872 earthquake, but it is
undoubtedly small; < 0.1 mm/yr.
The White–Inyo fault strikes along the east side of the
Owens Valley, 5–7 miles east of Lone Pine. Its history
is complex. Bacon et. al. (2005) suggest that Holocene
motion along this fault is predominantly right
oblique–slip at a rate of 0.1–0.3 mm/yr. However,
Beiller and Zoback, (1995) argue that motion along
the White Mountains/Inyo Mountains fault system
underwent a change from predominantly dip-slip
(west side down) to oblique slip at 288 ka. This seems
reasonable as the vertical component in an obliqueslip
fault moving at a rate of 0.1–0.3 mm/yr would
be insufficient to account for the relief between the
White/Inyo crest and the valley floor.
Richardson’s (1975) Master’s thesis from the University
of Nevada–Reno was the first publication on the
stratigraphy of Alabama Hills. The Jurassic sedimen-
20 2009 Desert Symposium