| Popis: |
Surface and subsurface investigation of the spatial relationships between the Cambrian-age Glen Mountains Layered Complex, Mount Scott Granite, and Sandy Creek Gabbro in the Hale Spring Area of the Wichita Mountains, shows that the upper portion of the Sandy Creek gabbro pluton is largely steep-walled, with a blunt irregular subhorizontal roof capped by Mount Scott Granite. In the subsurface, the near vertical sidewalls of the gabbro are presumed to truncate an older subhorizontal contact of regional extent, between the Glen Mountains Layered Complex substrate and the Mount Scott Granite cap. This subhorizontal contact is interpreted as an angular unconformity that developed on the layered complex and was subsequently buried by volcanic deposits of the Carlton Rhyolite Formation prior to intrusion of the Mount Scott Granite sheet. The Sandy Creek Gabbro does contain xenoliths of Glen Mountains Layered Complex and Meers Quartzite, a metasedimentary unit associated with this unconformity. Locally, a thin ledge of gabbro, with an irregular floor, protrudes more than 0.5 km to the south from the main body of the intrusion presumably exploiting this subhorizontal contact. Thus, the Sandy Creek Gabbro is a stock, capped by the floor of the Mount Scott Granite sheet, and only locally spreads laterally along the older unconformity, the contact between the Mount Scott Granite sheet and the underlying Glen Mountains Layered Complex. |
