AAPG Bulletin, Vol.85, No.10, 1759-1770, 2001
Quick-look techniques for evaluating two-dimensional cross sections in detached contractional settings
For more than 30 yr, geologists and geophysicists have used balancing techniques to constrain their cross-sectional interpretations in detached contractional settings. The quality of the resulting interpretations commonly directly correlates to the quality of the data, the balancing and interpretational experience of the interpreter, and the time allotted for the interpretation. We demystify the balancing process and present quick-look techniques for quickly and effectively detecting and preventing common cross section balancing errors in detached contractional settings. Common balancing problems are highlighted through close scrutiny of hanging-wall and footwall ramps and flats; such analysis helps identify inconsistencies in the numbers of ramps and flats, in the strata and stratal thicknesses in corresponding ramps, and in displacement along the fault. These techniques possess the additional advantages of being useful at any stage of the interpretational process for time or depth sections and being easily comprehensible by students, geologists, geophysicists, and managers alike. The quick look techniques, however, are not an all-encompassing panacea. They do not guarantee a unique and/or correct cross-sectional interpretation; instead, they serve to focus the interpreter's attention on potentially problematic areas in the cross section that might require explanation and/or reinterpretation.