Geochemistry of a spring-dense karst watershed located in a complex structural setting, Appalachian Great Valley, West Virginia, USA |
| |
| Authors: | Dorothy J Vesper Rachel V Grand Kristen Ward and Joseph J Donovan |
| |
| Institution: | (1) Department of Geology and Geography, West Virginia University, Brooks Hall, Morgantown, WV 26506-6300, USA;(2) CH2M-HILL, St Louis, MO 63102, USA |
| |
| Abstract: | The distribution and chemistry of the springs in the Tuscarora Creek watershed is controlled by both geologic structure and
karst dissolution. The watershed is located in eastern West Virginia in the structurally complex Great Valley of the Appalachian
Valley and Ridge province. The upper portion of the stream parallels strike along a mapped fault zone and is bordered by clastic
rocks that comprise North Mountain. The lower reaches of the stream flow cross-strike through Cambro-Ordovician carbonates.
The controlling chemical signature in the spring water is carbonate dissolution. Little evidence was seen for the recharge
from adjacent clastic rocks although differences in the Ca/Mg molar ratio between springs indicated the presence of localized
spring basins in headwater reaches. Na, Cl and Ca generally increased from upstream to downstream in the cross-strike reaches.
Comparison of stream and cumulative spring discharge was consistent with significant groundwater base-flow contribution directly
to the creek, particularly in the strike-parallel region. The largest spring in the watershed (>162 L/s) was sampled during
and after a large storm event along with the adjacent creek. The creek displayed a typical dilution response with each flood
pulse, whereas the spring had only a limited or delayed response. The overall chemical and thermal stability of the spring,
relative to the creek, indicated the lack of significant direct hydraulic connection between the two. The conceptual model
for the area includes localized flowpaths in the headwater region where the stream flow is parallel to strike and a thrust
fault. In addition to the shallow localized flowpaths, a deeper, more regional flowpath likely exists for a large spring further
downstream. |
| |
| Keywords: | Karst Hydrogeology Carbonate hydrology Springs |
| 本文献已被 SpringerLink 等数据库收录！ |
|
