Premium
The Maximum Effective Moment Criterion (MEMC) and Its Implications in Structural Geology
Author(s) -
Yadong ZHENG,
Tao WANG,
Xinshe WANG
Publication year - 2006
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2006.tb00797.x
Subject(s) - crenulation , geology , shear (geology) , terrane , deformation (meteorology) , geometry , shear zone , petrology , seismology , tectonics , mathematics , oceanography
The Mohr‐Coulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which is mathematically expressed as M eff = (σ 1 — σ 3 ) L · sin 2α sin α)/2, where σ 1 ‐σ 3 represents the yield strength of the related rock, L is a unit length and α is the angle between σ 1 and deformation bands. This criterion demonstrates that the maximum value appears at angles of ±54.7° to σ 1 and there is a slight difference in the moment in the range of 55°±10°. The range covers the whole observations available from nature and experiments. Its major implications include: (1) it can be used to determine the stress state when the related deformation features formed; (2) it provides a new approach to determine the W k of the related ductile shear zone if only the ratio of the vorticity and strain rate remains fixed; (3) It can be used to explain (a) the obtuse angle in the contraction direction of conjugate kink‐bands and extensional crenulation cleavages, (b) formation of low‐angle normal faults and high‐angle reverse faults, (c) lozenge ductile shear zones in basement terranes, (d) some crocodile structures in seismic profiles and (e) detachment folds in foreland basins.