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:
In order to investigate the likelihood of such models, an area across the CCMZ within the ca. 1164 Ma Diana Syenite between Harrisville and Dutton Corners, New York, was investigated. This area is dominated by a southeast striking, northwest dipping mylonitic fabric with a north-northwest plunging stretching lineation. Kinematic indicators consistently indicate south-southeast directed oblique thrusting of the Adirondack Lowlands over the Adirondack Highlands. Microstructures of the mylonitic fabric, plus kinematics and structural patterns of other ductile structures in the area are consistent with this oblique thrusting. These results appear to contradict the models that require the CCMZ to be a significant extensional structure, though it can be possible to explain these ductile structures by a rotated and warped crustal detachment. However, peak metamorphic conditions were approximately 700-800 degrees C throughout the area, which indicates that these ductile fabrics probably developed during compression of the Shawinigan Orogeny at ca. 1150-1130, when both the Lowlands and Highlands were last at these metamorphic conditions. Further, the character of Lowlands and Highlands time-temperature cooling paths indicate that extension must occur along the CCMZ late in its history. Therefore, late brecciated lineaments found throughout the area may accommodate extension in this portion of the CCMZ.
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