An inclination-only fold test

The fold test is inevitably used to determine whether a remanence is acquired prefold. The remanence declinations recorded in rocks may be affected by local rotation. Thus, it is difficult to restore the structure correction’s original orientation, leading to a possible incorrect conclusion of the fold test. However, the tilt correction of inclination is immune to the influence of local rotations. Therefore, we propose a more straightforward fold test based on the inclination-only mean. Examples are given to verify the validity of the inclination-only fold test, which can be applied to data affected by a possible local rotation. The inclination-only fold test should be used to determine the contribution of inclinations. The combined use of the 3-D and inclination-only fold tests is required to evaluate paleomagnetic results from the orogen or sampling sections with unrecognizable plunging folds or near the faults.