Seismic reflection results from Precambrian crust.

S. B. Smithson, W. R. Pierson, S. L. Wilson, R. A. Johnson

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Results of crustal reflection profiling in the Precambrian can provide decisive information on such features as faulting, extension vs. compression and crustal scale deformation in general, vertical vs. horizontal movements, intrusions, mafic differentiates, underplating, and plate tectonics even though targets in the Precambrian are complex. Mylonite zones are probably the best crustal reflectors so that a moderately dipping reflector separating the ancient Archean gneiss terrain from younger Archean greenstone belts in Minnesota is probably a thrust fault marking the suture zone between the 2 terrains. This structure implies the operation of plate tectonics at least by the late Archean. The 3.6b.y. Minnesota gneiss terrain is underlain by a thick (10km) sequence of layered deformed rocks, whose presence restricts early Archean events. A Proterozoic suture in SE Wyoming is marked by a thick mylonite zone and a change in crustal structures that has persisted through time. The Adirondack anorthosite and granulite terrain is underlain by a thick layered sequence in the lower crust. Formation of a late Proterozoic basin filled with 10-12km of interlayered sedimentary rocks in Texas and Oklahoma may have been accompanied by crustal underplating.-Authors

Original languageEnglish (US)
Pages (from-to)21-37
Number of pages17
JournalUnknown Journal
DOIs
StatePublished - Jan 1 1985
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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