Geoscience Reference
In-Depth Information
(b)
W E
0
10
20
SMB
30
MOHO
40
Figure 10.60.
(a) COCORP deep-seismic-reflection sections crossing the Rio Grande
Rift near Socorro, New Mexico, U.S.A., at 34
◦
N. Layered reflections in the top 2 s
include syn-rift deposits, offset by normal faults. F and H are reflections from a
major crustal fault. Gl is a reflection from the top of the Socorro magma body.
(b) Interpretation of the COCORP deep-reflection lines across the Rio Grande Rift.
Dotted blocks represent pre-rift sedimentary strata. Note the deep fault that
penetrates to mid-crustal depths. Horizontal shading represents the horizontal
compositional/deformational fabric of the lower part of the crust. SMB is the Socorro
magma body. True scale. (From de Voogt
et al
.(1988).)
Ideally, it is possible to determine the presence of a solid-liquid interface
by studying the polarity of its reflections. Unfortunately, it was not possible to
determine unequivocally the polarity of reflections recorded on these COCORP
lines, but they are consistent with a thin layer of magma in solid material. The
complexity of the reflections, however, indicates that the reflector is not a simple
continuous sill but may be layered in some way and/or discontinuous.
