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Scientific Value of Coring the Proposed Southern Appalachian Research Drill Hole (1987) / Chapter Skim
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DEFORMATIONAL HISTORY
Pages 19-23

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From page 19...
... . Experimental deformation studies under controlled conditions have succeeded in reproducing many of the microstructures observed in naturally deformed rocks, and they show how textures vary as a function of lithology, finite strain, presence of water, and other parameters.
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From page 20...
... has convincingly shown that the Glarus thrust in the Alps was emplaced on a 1-meter thick layer of calcite mylonite that underwent grain boundary sliding and behaved in SL macroscopically superplastic fashion. This mechanism allowed for extremely sharp strain localization.
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From page 21...
... These involve strain markers, such as grain, pebble, and fossil shapes, or foliations and lineations. Deformation under some conditions, such as dislocation creep accompanied by syntectonic recrystallization, produces equigranular textures that do not indicate any strain; in such cases, measurement of the preferred crystallographic orientation of quartz can be useful in determining the type of strain and its approximate magnitude.
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From page 22...
... DEFORMATION OF THE SOUTHERN APPALACHIAN OROGEN Given that information on deformation mechanisms, amounts of strain, and stress parameters can be provided by study of deformation textures in core samples, what are some of the important geologic problems to be solved or processes to be studied in an ultra-deep drill hole in the southern Appalachians? One of the most important functions of a cored hole will be to provide calibrations of surface geophysical and down-hole logging techniques that are at present poorly known for crystalline rocks.
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From page 23...
... Continuous core through these zones and representative core samples from less strained sections will be needed. Furthermore, only through coring will there be exact positional control on samples, not only to place rocks in proper sequence in the hole but, equally important, to allow determination of the spatial orientations of structural features.
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Key Terms

  • dislocation creep
  • deformation mechanisms
  • drill hole
  • finite strain
  • grain boundary

  • recrystallized grain
  • southern appalachian
  • grain size
  • southern appalachians
  • thrust sheets

  • core samples
  • boundary sliding
  • pressure solution
  • sole thrust
  • rock samples

  • physical conditions
  • understanding deformation
  • state dislocation
  • deformation studies
  • experimental deformation

  • fibers precipitated
  • fault zones
  • chief mechanisms
  • mation textures
  • sharp strain

  • underwent grain
  • dominant mechanism
  • deep drill
  • mechanism allowed
  • dolomite layers


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