The geologic structure of part of the southern Franklin Mountains, El Paso County, Texas

Conference · Mon Feb 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5933031

Smith, W R; Julian, F E ^[1]

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1. Univ. of Texas, El Paso, TX (United States). Dept. of Geosciences

The Franklin Mountains are a west tilted fault block mountain range which extends northwards from the city of El Paso, Texas. Geologic mapping in the southern portion of the Franklin Mountains has revealed many previously unrecognized structural complexities. Three large high-angle faults define the boundaries of map. Twenty lithologic units are present in the field area, including the southernmost Precambrian meta-sedimentary rocks in the Franklin Mountains (Lanoria Quartzite and Thunderbird group conglomerates). The area is dominated by Precambrian igneous rocks and lower Paleozoic carbonates, but Cenozoic ( ) intrusions are also recognized. Thin sections and rock slabs were used to describe and identify many of the lithologic units. The Franklin Mountains are often referred to as a simple fault block mountain range related to the Rio Grande Rift. Three critical regions within the study area show that these mountains contain structural complexities. In critical area one, Precambrian granites and rhyolites are structurally juxtaposed, and several faults bisecting the area affect the Precambrian/Paleozoic fault contact. Critical area two contains multiple NNW-trending faults, three sills and a possible landslide. This area also shows depositional features related to an island of Precambrian rock exposed during deposition of the lower Paleozoic rocks. Critical area three contains numerous small faults which generally trend NNE. They appear to be splays off of one of the major faults bounding the area. Cenozoic kaolinite sills and mafic intrusion have filled many of the fault zones.

• OSTI ID: 5933031
• Report Number(s): CONF-9303212-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:1; Conference: 27. annual Geological Society of America (GSA) South-Central Section meeting, Fort Worth, TX (United States), 15-16 Mar 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC STRUCTURES
MAPPING
TEXAS
CARBONATE ROCKS
CONGLOMERATES
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
GRANITES
PALEOZOIC ERA
PRECAMBRIAN ERA
RHYOLITES
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FRACTURES
IGNEOUS ROCKS
NORTH AMERICA
PLUTONIC ROCKS
ROCKS
SEDIMENTARY ROCKS
USA
VOLCANIC ROCKS
580000* - Geosciences