LATE ACADIAN FOLD TRAIN SHORTENING, MT ADAMS, PRESIDENTIAL RANGE, NH

           Shortening calculations were performed on D4 fold trains from the Devonian Littleton Formation in the Mt. Adams alpine region, Presidential Range, NH. The purpose was to evaluate the spatial variation of late stage Acadian linear strain and how that relates to major D4 fold traces, the bedrock rheology, and Acadian tectonic models.  The Littleton Formation contains variably bedded schist/quartzite couplets, ranging to massive schists, that were multiply deformed in the Acadian. The D4 folds are east vergent with west dipping axial planes and shallow, variably plunging axes. Linear strain shortening calculations were performed with ImageJ software at the meso-, macro- and microscales using the equation, e = ((lf-lo)/lo)*100. Fold train shortening was determined for 48 meso-scale outcrops, six micro-scale thin sections, and one macro-scale cross section. For each mesoscopic fold, the limbs (S0), axial plane (S4), hinge line (F4), wavelength, and double amplitude were measured. Mesoscopic folds have wavelengths that range from 5.5 cm to 7.82 m with a mean value of 98.6 cm, and double amplitude range from 210 cm to 1cm. The range of mesoscale shortening is 65% to .75% with a mean value 14.2%, consistent with previous studies of shortening in the Presidential Range.  Mesoscale shortening varies spatially with the lowest values in King Ravine area (0.75%-8.2%), slightly increasing along Sam Adams Ridge (1.4%-8.9%), increasing to the Mt. Adams summit (65.7%-2.3%) and John Quincy Adams (60.7%-1.7%). Macro- and micro-scale shortening calculations will be compared with the mesoscale to evaluate the scale dependence of the strain.