See more from this Division: Topical Sessions
See more from this Session: Recent Advances in the Understanding of Adirondack and Southern Grenville Province Tectonics I: In Honor of James McLelland
Abstract:
This study focuses on an area around the Black Lake Ductile Shear Zone (BLDSZ) in order to understand Lowlands deformation in this area. The dominant foliation, S1, strikes NE, has a steep to vertical dip, is formed by the transposition of isoclinal folds (F1) of compositional layering and increases in intensity toward the BLDSZ. F1 axes have a moderate plunge to the SW. A stretching lineation, L1, plunges steeply to the north. Preliminary dating of a syn-kinematic tourmaline-bearing granite (1062+/-45 Ma) indicates that S1 is Ottawan in age. A weak schistosity defines S2 and is axial planar to F2 folds of S1. S2 appears to fan and cross-cuts a late-Ottawan (1035+/-77 Ma) granite. Southeast of the BLDSZ the interference of F1 and F2 produces Type III fold interference patterns. Fabric within the BLDSZ strikes north-south to northeast-southwest, dips steeply, contains strong down-dip stretching lineation and is cut by S2. Kinematic indicators show conflicting senses of shear suggesting multiple motions or transpression. S1 and BLDSZ fabrics may be associated; however there is evidence that BLDSZ fabric overprints an earlier fabric (S1?). Evidence for pre-Ottawan deformation has yet to be identified.
See more from this Division: Topical Sessions
See more from this Session: Recent Advances in the Understanding of Adirondack and Southern Grenville Province Tectonics I: In Honor of James McLelland