FRACTURE INTENSIFICATION DOMAINS, FRACTURE FLOW, AND TRENTON-BLACK RIVER FAULTS IN THE FINGER LAKES REGION, NYS

That fault zones can be the pathways for accelerated fluid flow has been understood for quite some time. More recently, we have established that fracture intensification domains (FIDs) mark faults in the Appalachian Basin of New York State (NYS). In eastern and western NYS, we found that FIDs, soil gas anomalies, and lineaments are all coincident with faults observed in seismic and well logs. The location of potential fracture flow along faults, then, can be identified by our integrated studies.

This report presents data from the central part of NYS (Finger Lakes region), where Trenton/Black River faults are observed on proprietary seismic. Fracture flow along the Trenton-Black River faults (possibly in Taconic times) caused dissolution of the Black River carbonates and the precipitation of dolomite. The resulting porosity along these faults forms gas reservoirs presently driving the gas exploration boom in NYS.

We measured 9 characteristics of over 2550 fractures in a N-S swath along the eastern shore of Seneca Lake and over 3000 fractures along the western shore of Cayuga Lake. Additionally, we collected soil gas measurements along a 30 km N-S transect (at 10m intervals) between the two lakes. We found that N-striking fracture intensification domains (FIDs) typify the southern parts of the lakeshore of both lakes, whereas ENE-striking FIDs characterize the central part of the lakeshore of both lakes. This change in fracture patterns corresponds to soil gas anomalies, Landsat, topographic and aeromagnetic lineaments, as well as the approximate location of ENE-trending Trenton-Black River faults observed in seismic. Thus, the general location of reservoirs and faults more than a mile below the surface can be inferred from surface fractures, soil gas anomalies, and lineaments.

That deep faults are marked by surficial lineaments, FIDs, and soil gas anomalies suggests that the fracture intensification was guided by reactivation of these faults. It is probable that the FIDs associated with the faults promote fracture flow, even in sections where actual faulting may be absent, based on soil gas anomalies and our studies to the east in Otsego County, where dissolution of Siluro-Devonian carbonates and consequent tuffa deposition occur along FIDs.