ABSTRACT: Sedimentology of the Castner Marble, Franklin Mountains, El Paso County, Texas
PITTENGER, MICHELLE A., and KATHLEEN M. MARSAGLIA, University of Texas at El Paso, El Paso, TX
The Castner Marble occurs within roof pendants in the Red Bluff Granite complex, and is the oldest Proterozoic unit exposed in the Franklin Mountains. This contact-metamorphosed metasedimentary unit consists of six lithologies: (1) stromatolitic limestone, (2) cryptalgalaminite, (3) massive limestone, (4) hornfels, (5) rhythmite, and (6) flat-pebble conglomerate. Based on the distribution of these lithologies, the Castner Marble can be divided into three distinct intervals: (1) lower section, consisting of stromatolitic, cryptalgalaminite and massive limestone, (2) middle section, characterized by thick hornfels and massive limestone beds, and (3) upper section, consisting of interbedded rhythmite and flat-pebble conglomerates. The lower section represents a shallow-water, intertidal o subtidal deposit, whereas the upper section was deposited in deeper water (below wave base) by turbidite or storm-related processes. The middle section may be a transition between the two, in that it contains lithologies found in the upper and lower sections. These three sections appear to record a transgression on a low-energy, carbonate ramp/platform. The contact between the Castner Marble and the overlying basaltic Mundy Breccia marks a catastrophic event or series of events in which megabreccias of deep-water, subtidal carbonate facies were deposited onto underlying rhythmite intervals.
AAPG Search and Discovery Article #91018©1992 AAPG Southwest Section Meeting, Midland, Texas, April 21-24, 1992 (2009)