ABSTRACT
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, J. 1984. Chatham Fault Zone, Old Chatham-East Chatham, New
York: mesostructures and microstructures: their spatial and age
relationships. Unpublished MSc. thesis, State University of New
York at Albany. 78pp., +x; 2 folded plates (maps)
University at Albany Science Library call number: SCIENCE
Oversize (*) QE 40 Z899 1984 M67
thesis (scanned
text) - 2.5MB pdf file
Plate
1 - Geological Map of the Chatham Fault Zone: Old Chatham-East
Chatham, NY
Geological Map (uncoloured
outcrop map, scale 1: 6,000)
Plate 2 - Cross-Sections (Roadcut outcrop
profiles) A-A',
B-B', C-C',
D-D', E-E'
Return to MS Theses completed in the
Geological Sciences Program, University at Albany