Date of Award
Master of Science (MS)
Detailed studies in rocks of Mettawee (Late Precambrian? to Early Cambrian) and Walloomsac (Middle Ordovician) slates between Old Chatham and East Chatham, New York, have shown that these rocks were intensely deformed during the Taconic orogeny and a later deformation event(?). Two generations of structures are clearly recognized in the area. The first generation (G1) includes tight west-verging folds whose axial plane foliation is the regional foliation slaty cleavage (S1). These structures are considered synchronous with the regional metamorphism of the Taconic orogeny and correlative with those structures belonging to the D2 deformation event proposed by Ratcliffe (1979) and Rowley (1983). The second generation of structures (G2) is represented by NE-trending kink bands, concentric folds and their associated crenulation cleavage (S2) which overprint the pre-existing regional foliation (S1). This kind of deformation seems to be localized in the metapelitic rocks and is, at least partially, synchronous with the development of the Chatham fault zone. These structures are considered here to be correlative with those belonging to the D3 deformation event of Rowley (1983) and the F5 generation of folds of Ratcliffe (1979). Their overprinting relationships relative to the faulting are consistent with the Rowley idea about the generation of the crenulation cleavage during thrusting (c.f. T3, Rowley 1983).
Evidence of an earlier deformation event (e.g. dismembered intrafolial folds in the metapsammites) in rocks of Mettawee slate has been sporadically observed, and is correlated with the D1 deformation event of Rowley (1983). Other structure present in the Chatham area and not included in the above generations is a NW-trending macrofold in the regional foliation, which reflects the geometry of the Chatham fault zone. This fold has been correlated with the NW-trending folds belonging to the F4 generation of Ratcliffe (1979).
Mora, Jorge M., "Chatham Fault Zone, Old Chatham-East Chatham, New York: mesostructures and microstructures: their spatial and age relationships" (1984). Geology Theses and Dissertations. 62.
Plate 1 - Geological Map of the Chatham Fault Zone: Old Chatham-East Chatham, NY Geological Map (uncoloured outcrop map, scale 1: 6,000)
moraprofile1.pdf (2790 kB)
Plate 2 - Cross-Sections (Roadcut outcrop profiles) A-A', B-B'
moraprofile2.pdf (3184 kB)
Plate 2 - Cross-Sections (Roadcut outcrop profiles) C-C', D-D'
moraprofile3.pdf (2181 kB)
Plate 2 - Cross-Sections (Roadcut outcrop profiles) E-E'