A Petrological Model of the Laminated Lower Crust in Southwest Germany Based on the Wide-Angle P- and S-Wave Seismic Data

  1. Robert F. Mereu,
  2. Stephan Mueller and
  3. David M. Fountain
  1. W. Steven Holbrook

Published Online: 9 APR 2013

DOI: 10.1029/GM051p0121

Properties and Processes of Earth's Lower Crust

Properties and Processes of Earth's Lower Crust

How to Cite

Holbrook, W. S. (1989) A Petrological Model of the Laminated Lower Crust in Southwest Germany Based on the Wide-Angle P- and S-Wave Seismic Data, in Properties and Processes of Earth's Lower Crust (eds R. F. Mereu, S. Mueller and D. M. Fountain), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM051p0121

Author Information

  1. Geophysics Department, Stanford University, Stanford, Ca 94305

Publication History

  1. Published Online: 9 APR 2013
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780875904566

Online ISBN: 9781118666388

SEARCH

Keywords:

  • Earth—Crust—Congresses;
  • Geophysics—Congresses

Summary

On seismic reflection sections in many areas, the continental lower crust consists of subhorizontal reflections, often in such abundance that the lower crust and Moho appear layered or laminated [e.g., Hale and Thompson, 1982; Meissner and Wever, 1986; Mooney and Brocher, 1987]. the cause of this lamination remains a puzzle, but proposed explanations include compositional layering [Meissner, 1973; Hale and Thompson, 1982], lenses of partial melt [Meissner, 1967; Hale and Thompson, 1982], ductile shear zones [Jones and Nur, 1982, 1984; Smithson et al., 1986], and the presence of fluid-filled cracks [Matthews and Cheadle, 1986; Hall, 1986; Klemperer, 1987]. the lamination is often visible on wide-angle (“refraction”) seismic data as highly reflective precursors to PmP, the wide-angle Moho reflection [e.g., Sandmeier and Wenzel, 1986; Gajewski and Prodehl, 1987].

So far, most array seismic studies of the laminated lower crust have been based solely on compressional (P) waves. Important new information on the reflectivity of the lower crust can be gained, however, by combining shear (S) and compressional wave observations. In this paper I present a brief summary of a recent study of wide-angle P- and S-wave data from Southwest Germany [Holbrook et al., 1988]. the coexistence of high-quality, wide-angle P- and S-wave data with deep seismic reflection data in Southwest Germany creates a unique opportunity to model the composition of a classic laminated lower crust. In this summary I will focus on the implications of the shear-wave data on the cause of the lower-crustal reflectivity.