Paper No. 12
Presentation Time: 11:30 AM
REACTIVATED PRECAMBRIAN FAULTS IN THE APPALACHIAN BASIN OF NYS
In the Appalachian Basin of NYS, faults in the Precambrian basement have a profound effect on the distribution of seismicity and the "hot" fracture-related gas plays in the Trenton/Black River. Yet, until recently, only a few faults had been identified in either the Precambrian basement or the Phanerozoic section. By integrating Landsat and topographic lineaments with 1) detailed fracture analyses, 2) soil gas analyses, 3) sporadic deep well data and 4) seismic lines, we are able to identify and trace numerous Precambrian fault systems across NYS. Analayses of well log and seismic reflector intervals show that these faults were reactivated several times, including Iapetan opening, Taconic extension followed by Taconic thrusting, and motion in the Silurian and Devonian. In the Finger Lakes region, we have measured 12 attributes of over 5000 fractures and have collected over 50 km of soil gas data at 10m spacings. We can demonstrate that fracture intensification domains (FIDs) in outcropping Devonian thinly-interbedded sandstones and shales correspond to Landsat lineaments and to fault systems imaged in seismic reflection profiles. FIDs are characterized by a relatively high frequency of fractures that parallel the fault, and these fractures commonly are the master set. High ethane soil gas anomalies in the Finger Lakes region commonly correspond to faults associated with deep structure, rather than the shallow structures related to thrusts above the Silurian salt section. Recent deep drilling has confirmed the faults proposed on the basis of this integrated approach for the detection of faults.