Compositional variation and the origin of deep crustal reflections

Details Compositional variation and the origin of deep crustal reflections Compositional variation and the origin of deep crustal reflections

Oct 1987

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1987e%26psl..85..416h&link_type=abstract

Earth and Planetary Science Letters, Volume 85, Issue 4, p. 416-426.

Mathematics

Logic

58

Scientific paper

Identifying the sources of crustal reflections is essential for deriving more geological information from deep crustal reflection profiles. Theoretical and model studies help place constraints on the role of compositional variation in producing deep crustal reflections. Analysis of laboratory-derived velocities and densities of rock types typical for the continental crust indicates that reflection coefficients are generally small, but significantly, 17% of the possible reflection coefficients have magnitudes between 0.1 and 0.2. Comparison between reflection coefficients derived from well logs and reflections observed in associated seismic profiles indicates that constructive interference associated with geological layering is at least as important as the magnitude of the reflection coefficients for producing detectable reflections. Constructive interference can increase reflection amplitude by two to three times but is limited to a relatively narrow range of layer thickness. For a typical 10-40 Hz seismic wavelet and typical crustal velocities of about 6 km/s, constructive interference occurs for layer thickness ranging between about 35 and 80 m. Layers thinner than 35 m interfere destructively. If reflections result from compositional variation, seismic models of hypothetical and observed geologic relations provide analogs for interpreting complex reflection patterns observed in deep crustal reflection profiles. Such models show reflection patterns similar to those observed in the reflection profiles. The models indicate that the reflections could originate in the complexly deformed and intruded terranes that are common in the crystalline crust and it may not be necessary to appeal to unobserved phenomena such as special lamellae or fluid-filled fractures to explain the reflections.

Affiliated with

Also associated with

No associations

Rating

Compositional variation and the origin of deep crustal reflections does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Compositional variation and the origin of deep crustal reflections, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compositional variation and the origin of deep crustal reflections will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1774160