Three-dimensional development of a buckle fold
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences
Many investigators have postulated that characteristics near a fold termination are equivalent to those during early amplification at the fold culmination. In essence, space along the hinge line from termination to culmination is traded for time back through the amplification history of the culmination. The purpose of this contribution is to test this postulate by examining a natural fold in three profiles across the hinge line from termination to culmination. The mechanical strut for this natural fold in easter West Virginia is a 9m thick quartz arenite that is preserved in a 300m long anticline. Near the termination, the fold has one narrow rounded hinge and two straight limbs. At the intermediate profile, the hinge is broader, and contraction faults have thickened the arenite, producing a second fold hinge. Near the culmination, the second fold hinge is dominant and sub-isoclinal, and is collapsed above a contraction fault. At the termination, the quartz arenite records a diagenetic compactional strain with about 30% volume loss, maximum principal strain axes (X axes) in a girdle parallel to bedding, and minimum principal strain axes (Z axes) normal to bedding. In the intermediate profile, the quartz arenite records a structurally modified compaction with a weak concentration of X axes about bedding strike. Near the culmination, a more intensely modified compactional strain is recorded with a strong clustering of X axes about bedding strike and an enhanced concentration of Z axes normal to bedding. The simple fold geometry, lack of early mesostructures and compactional finite strain near the fold termination are representative of early deformation at the fold culmination. The difference in subsequent deformation between the intermediate profile and the culmination means that the profiles should not be treated as literal time slices for each other.
- OSTI ID:
- 5936049
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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