A1: EFFECTS OF ADIRONDACK BASEMENT UPLIFT ON JOINTS AND FAULT DEVELOPMENT IN THE APPALACHIAN BASIN MARGIN, NEW YORK
Joshua D. Valentino
Department of Geosciences
Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061
David W. Valentino
Alex P. O’Hara
Hannah Valentino
Department of Earth & Environmental Sciences
State University of New York at Oswego
Oswego, NY 13126
Introduction
Recent development of unconventional shale gas plays in the Appalachian Basin has drawn considerable attention to basement structures, and joints and fracture zones in the Paleozoic cover rocks (Figure 1), and nowhere is this more apparent than in the region of central Pennsylvania through western and central New York State (Engelder and Lash, 2009; Engelder, 2008; Jacobi, 2002; Jacobi and Fountain, 1996). Two ubiquitous joint sets occur throughout this region (J1 and J2 of Engelder), in addition to significant domains of fracture intensification related to faults (Jacobi, 2002). It was demonstrated that the regional joint sets are largely the result of hydrocarbon maturation fluid pressure under late Paleozoic Alleghanian orogenic stress (Lash and Engelder, 2009), however domains of fracture intensification have been linked to faults in the underlying crystalline basement (Jacobi and Fountain, 1996; Jacobi, 2002). Basement structure controlled the distribution and orientation of brittle faults in the overlying Paleozoic strata (Jacobi, 2002), and in some cases the displacement on basement faults had a substantial influence on patterns of Paleozoic sedimentation (Jacobi and Mitchell, 2002).
The direct observation of basement faults that had control on the distribution and subsequent deformation of Paleozoic cover is limited to the exposure of Proterozoic rocks of the Adirondack dome (i.e. Isachsen, 1975; Isachsen, 1981; Roden-Tice et al., 2000; Jacobi and Mitchel, 2002). Roden-Tice et al. (2000) and Jacobi and Mitchel (2002) suggested that the Adirondack dome uplifted in segments that were accommodated by faults related to the Iaptian rift. Jacobi and Mitchel (2002) also discovered that the distribution of the Ordovician strata was controlled by fault bounded structural blocks, demonstrating fault activity during that period. Roden-Tice et al. (2000) and Roden-Tice and Tice (2009) demonstrated that the Adirondack region underwent differential uplift with the formation of the dome, and was controlled by change in bulk compression direction and reactivation of faults. Through apatite fission track dating, Roden-Tice et al. (2000) constrained the age of the dome uplift to mid-Jurassic through the Cretaceous. Wallach and Rheault (2010) suggested that the gentle southwestern incline of the Ordovician strata west of the Adirondacks, to be directly the result of basement faulting and uplift of the Adirondack dome. They further suggested that reactivation of the Carthage-Colton shear zone and movement on the Black River fault contributed to the formation of the Tug Hill plateau. Earlier, Isachsen (1981) reported on Adirondack fault zones that form small graben that contain remnants of the Paleozoic strata that covered the Adirondacks prior to uplift. Additionally, Isachsen (1975; 1981) proposed that neotectonic activity continues in the Adirondacks, and this is partially supported by seismic activity on the Saint Lawrence fault zone and in the Champlain Valley (Barosh, 1986; 1990; 1992; Faure et al., 1996; Mareschal and Zhu, 1989; Wallach, 2002). A statistical correlation between faults and seismic activity led Deneshfar and Ben (2002) to conclude that northwest striking faults in the Adirondacks are more likely to exhibit seismic activity.
It is apparent that faulting in the Proterozoic basement of the Adirondack dome exhibits a protracted history, ranging from late Proterozoic through the Cretaceous, and possibly even neotectonic in nature. Although it was demonstrated that basement faults penetrate the Paleozoic rocks adjacent to the Adirondack dome, the extent of joint and fracture zone development associated with rise of the dome has yet to be described. The intent of this investigation was to address this issue though a detailed study of joints and fracture zones in the Middle Ordovician rocks that directly overly the western flank of the Adirondack dome. This is the region of the Tug Hill plateau, where Wallach and Reault (2010) recently identified basement faults that extend into the Paleozoic strata (Figure 2), and where deformation associated with the Appalachian basin (i.e. Jacobi, 2002; Engelder, 2009) is most likely overlapped by deformation related to the uplift of the Adirondack dome.

A1: EFFECTS OF ADIRONDACK BASEMENT UPLIFT ON JOINTS AND FAULT DEVELOPMENT IN THE APPALACHIAN BASIN MARGIN, NEW YORK

STOP 1. Lake Ontario at SUNY Oswego
The field trip begins at the parking-lot for Mary Walker Health Center on the campus of SUNY Oswego. From the parking-lot, follow the path along the lake shore toward the east to the first metal stair case. The outcrop of interest is at the bottom and to the west of the stair case.
A. Thick to medium bedded Oswego sandstone.
B. Two prominent joint sets (east-northeast and southeast striking).
C. Sinistral fault in the pavement outcrop.
D. Evidence for minor sinistral displacement on individual east-northeast striking joints.
E. East-northeast striking en-echelon fracture zones with sinistral geometry.

STOP 2. Lake Ontario in East Oswego
From the parking-lot, walk east along the lake shore to the first large exposure of the Oswego sandstone.
A. Thick bedded Oswego sandstone.
B. Two prominent joint sets (east-northeast and southeast striking)
C. Fracture zone about 1 meter wide.

STOP 3. Salmon River Falls
From the parking-lot, follow the trail northeast to the top of the falls, and then follow the trail back toward the parking-lot to the entrance to the gorge trail.
A. Oswego sandstone at the top of the falls.
B. Pulaski formation in the gorge.
C. Joints and fracture zones in the Oswego sandstone.
D. Fracture cleavage in the shale beds of the Pulaski formation.
E. Normal fault on the southeast side of the base of the falls.

STOP 4. Mooney Gulf.
From the parking area, follow the gravel road into the gulf. There are excellent exposures on the north side of the gulf. See Figure 8 for a detailed joint map of Mooney and Totman Gulfs.
A. Whetstone Gulf formation.
B. East-northeast and southeast striking joints are present.
C. Some joints can be traced 10’s of meters.

STOP 5. Robert Wehle State Park at Stony Point.
From the parking-lot, walk northwest to the lake shore. There are several trails to the lake shore, but the closest is located behind the tennis court. Once on the lake shore trail, follow it toward the northeast and see the topographic map inset for reference. It will be necessary to traverse down the steep embankment to reach lake level. See Figure 19 for details.
A. Trenton Group limestone.
B. Minor normal faults with mineralized fractures.
C. Fault with no apparent displacement. The fault merges with bedding.
D. Large rock-fall that was controlled by two prominent joint sets.
Azimuthal Electrical Resistivity for Joint Analysis
Azimuthal ER (AER) involves a Wenner survey around a single point to look for directional variation, which can be impacted by the direction of groundwater-filled joints. The direction of the lowest ER values should correlate with the direction of the most prominent joints (Taylor and Flemming, 1988). At Stony Point, the limestone bedrock is very close to the surface with thin soil. In an attempt to locate joint patterns away from the lake shore, six azimuthal electrical resistivity (ARE) surveys were conducted (Figures 21 and 22). Each AER survey was completed with an automated 24 node system with the azimuthal increment of 30 degrees.

STOP 6. Whetstone Gulf State Park.
Excellent exposures of Utica black shale occur in the bed of the creek that parallels the park road into the gulf. As well, the Whetstone Gulf formation is exposed in numerous high-walls that can be accessed along the road side farther up the gulf.
A. Utica black shale.
B. Whetstone gulf shale and siltstone beds.
C. Complex joint sets in the Utica formation (see text for details).
D. Follow the trail into the gulf to view the transition from Whetstone Gulf formation to Pulaski formation.
E. Follow the Rim Trail to the head of the gulf to view thick sandstone beds on the lower Pulaski formation.