RELATIONSHIP OF THE GONIC FORMATION AND NONSUCH RIVER FAULT TO THE NORUMBEGA FAULT ZONE IN BERWICK, MAINE
Located in southwestern Maine the Gonic Formation abuts the Nonesuch River Fault of the Norumbega Fault System. The rock types of the Gonic Fm. consist
predominantly of micaceous schist and lesser amounts of quartzite. Fieldwork suggests that the units have undergone transposition and thus appear to be
interlayered and pinch-out along strike. Granitoid rocks have also been observed and are interpreted as related to either the Lyman Pluton or White Mountain
Complex and serve as the backbone to the line of low-lying hills within the Gonic Formation.
The unit is entirely within the amphibolite zone of metamorphism. Hand specimens show reaction rims of staurolite and muscovite around andalusite
crystals suggesting a localized secondary metamorphism, most likely due to the intrusion of the Lyman Pluton during the Carboniferous period.
Large scale F1 recumbent folding is evident from stereonet plots of the primary schistosity (S1). F2 folding is observable at the outcrop scale as a folding
of S1. F2 related folding and structures show dominantly southwest trending plunges. Evidence of F3 folding is observable at the map scale as a variation of S1
strike and F2 trend directions.
Kinematic indicators such as: asymmetric and rotated porphyroclasts and S-C fabric throughout the field area indicate sinistral deformation occurred within
the Gonic Fm. This is contrary to regional deformation displacement along the Norumbega Fault System and may support evidence for off shore deflection of the
Norumbega Fault System as a dextral transpression system.
Renda, J.F., 2004. Structural analysis of the Gonic Formation in
Unpublished MSc. thesis, State University of New York at Albany. 99 pp., +vii; 1 folded plate (map)
University at Albany Science Library call number: SCIENCE Oversize (*) QC 869 Z899 2004 R46
MS thesis text pdf - 2.3MB pdf file
- Geological map of Structural detail within the Gonic
Formation, Berwick, Maine
(coloured line map, scale ~1:13,150, with detailed insets) - 6MB pdf file
Return to MS Theses completed in the
Geological Sciences Program, University at Albany