--> ABSTRACT: Discriminant Analysis of Components of El Paso Group Rocks in Southern Hueco Mountains, Hudspeth County, Texas--Approach to Depositional Environments, by I. J. Aluka; #91040 (2010)

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Discriminant Analysis of Components of El Paso Group Rocks in Southern Hueco Mountains, Hudspeth County, Texas--Approach to Depositional Environments

I. J. Aluka

The El Paso Group of the Southern Hueco Mountains, Hudspeth County, Texas, crops out over an area of about 57 km2 (22 mi2) and is divided into three informal units--lower, middle, and upper. The lower contains the lower calcareous sandstone member and an overlying sandy limestone member; the middle is cherty limestone; and the upper unit contains two members: sandy dolomite and an upper silty dolomite.

The El Paso Group rocks are classified into seven microfacies based on thin section studies of the rocks' components. These are organic allochems (peloids, gastropods, trilobite fragments, pelmatozoan ossicles, algae, and unidentifiable bioclasts); inorganic allochems (glauconite, stylolites, quartz grains, voids, lithoclasts, and ooids); matrix (micrite, microspar, recrystallized sparite, micritic size dolomite, microsparitic size dolomite, and sparitic size dolomite). Discriminant analysis of the components of the rocks tests the classification of the rocks into seven microfacies. Six discriminant functions, discriminant function scores for each sample, and probability of the sample's membership in each classification group are calculated during the study to discriminate among the g oups. The eigenvalues, plots of discriminant scores, chi-square tests, Wilk's lambda, and the territorial map proved effective in classifying the components of the El Paso Group rocks; 100% of the grouped cases are correctly classified into seven microfacies. The components/microfacies indicate that the rocks of El Paso Group were deposited in shelf lagoon with open circulation, restricted circulation in shelf, subtidal, intertidal, and tidal flat environments.

AAPG Search and Discovery Article #91040©1987 AAPG Rocky Mountain Section Meeting, Boise, Idaho, September 13-16, 1987.