Download Previous_Work - The Nevada Seismological Laboratory

Previous Work:
Klemperer, S.L., T.A. Hauge, E.C. Hauser, J.E. Oliver, C.J. Potter, 1986, The Moho in
the northern Basin and Range province, Nevada, along the COCORP 40N seismicreflection transect. GSA Bulletin, v.97, p. 603-618





Brought-up because may be imporant in discussion of the Basin and Range Moho.
In many tectonic provinces, there appears to be a pair of reflections at the base of
the crust, and until this paper, not discussed as widespread.
The Basin and Range, has a clear Moho relfection that is continuous, there is no
“prominent reflection Moho detected beneath the Sierra Nevada” (see Nelson, et
al paper).
Moho has a variable “origin or evolution” (Oliver, 1982).
General statement: in areas of recently rifted crust, there is a clear and continuous
Moho. and areas of thicker crust, possibly older, gradation crust-mantle boundary,
including the Sierras and Colorado Plateau (same observations of Prodehl 1977,
refraction)
(Personal note: If it’s contingent on the recently rifter/altered, then the southern
Sierra, has in a way, recently been rifted apart, and the central is rifting).
Zandt, G., H. Gilbert, T.J. Owens, M. Ducea, J. Saleeby, and C.H. Jones, 2004. Active
foundering of a continental arc root beneath the southern Sierra Nevada in California,
Nature, vol 431.






This experiment is just km south of the INC transect. This paper sees a crustal
welt where the slab is downgoing and then the missing Moho at the latitude of
visalia, just south of Fresno. Doesn’t make to many conjectures about areas to the
north (but recent AGU poster does). The papers crustal welt would appear deeper
on our transect.
Personal note: In areas with possible foundering root. No clear Moho reflections,
but maybe clear refractions.
20-station Passcal experiment, 5 permanent stations, recorded teleseismic waves,
reciever function seismology, P-S wave conversion (similar to reflection convert
to depth and make a cross-section
Concurs with Fliedner refraction experiments, thicker crust north of 36.5 (approx
40 km)
No PmP Moho reflection beneath the western foothills (brooadband stations show
not because of noise). Explanations: shear velocity contrast reduced by localized
zone of low S-wave velocity in uppermost mantle (serpentinization, like forearc
regions). The other and preferred, small-scaled topography on the Moho is
scattering away the coherent Ps conversion, as the active source of PmP
reflections).
Good for story telling
W.D. Mooney and C.S. Weaver, 1989, Regional crustal structure and tectonics of the
Pacific Coastal States; California, Oregon, and Washington, in Pakiser, L.C., and
Mooney, W.D., Geophysical framework of the continental United States: Boulder, CO,
GSA Memoir 172








30 +/- 2, crustal thickness in S. CA, due to crustal extension in the Mojave Desert
and ductile shear along plate boundary.
Central and northern CA, more due to volcanism and subduction, 20 km to 55 km
beneath the Sierra Nevadas. (Pakiser, this edition)
Contour map in Sierras, seems like one main root point and then just contoured
around that. So, maybe not correct for the Southern Sierras,
Sierra Nevada Mountains, 600 km long, 150 km wide, batholith, 180-80 Ma
(Bateman and Eaton 1967), Uplift cenozic time, Christensen, 1966, 10 my. 121800 m high, not much releif. Uplift began 10-35 Ma, more like 10.
Gravity, I think, suggests crustal thinning 54-40 km in Sierra near Lake Tahoe
(Oliver, 1977)
Velocity model beneath the Sierra Nevada, 6.2 to 25km, 6.9 to 50km, 7.9, from
Eaton 1966 and Prodehl, 1979.
Don’t believe Carder because un-reversed.
Long valley area, suggested Magmatic body at 7-8 km depth, not in Mono lake
however
**Several paper published from the SSCD project. Probably only need to talk about 1 or
2.
M.M. Fliedner, S.L. Klemperer, and N.I. Christensen, 2000, Three-dimensional seismic
model the Sierra Nevada arc, California, and its implications for crustal and upper mantle
composition. JGR, vol. 105, no. B5






Also see the northward thickening, 42 km depth.
Southern Sierra Contential Dynamics project, 50 km shot spacing, with 50
reciever spacing
Also inverts Savage et al., earthquake data (previous too sparse).
Does not have laminated crust that seperates Moho and crust.
Thinning north to south, symmetric