Earth and Planetary Sciences ETDs

Publication Date

6-3-1968

Abstract

Several reeflike masses crop out in the upper part of the Upper member of the San Andres Formation in the Last Chance Canyon area, southeastern New Mexico. The reeflike masses are situated on the Northwest shelf adjacent to the Delaware basin of Permian age. Based on the compilation of the field and laboratory data, it was concluded that the reeflike masses are not reefs at all and such exposures are termed pseudoreefs. No criteria were found which could be used to differentiate the masses from surrounding, laterally equivalent strata since both consist of relatively unfossiliferous dolomitized mudstones and wackestones. The apparent calm-water depositional environment of the reeflike masses was not conducive to reef development. The masses possess none of the more distinctive structural or lithological features characteristic of known ancient reefs. The pseudoreefs do resemble true reefs, in that they seem to lack clearly defined beddedness in bold outcrop exposures. The massive boldness is superficial and is inferred to be related to weathering phenomena associated with the steep­walled, south- or southwestward-facing outcrops. In the course of the field studies in the Last Chance Canyon area, several channel-and-fill structures were noted in the Cherry Canyon sandstone tongue, which underlies the strata in which the pseudoreefs occur. Reconnaissance field studies were made in the Rocky Arroyo area, approximately 6 miles to the northwest of the Last Chance Canyon area, to determine if the reported anomalous dips in some of the strata of the Lower member of the San Andres Formation might also be related in origin to channel-and-fill structures. These anomalous dips, however, seem to be related to post-depositional folding of strata, as were the anomalous dips associated with some strata in the upper part of the Upper member of the San Andres Formation in the Last Chance Canyon area.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Vincent Cooper Kelley

Second Committee Member

Stuart Alvord Northrop

Third Committee Member

Sherman Alexander Wengerd

Language

English

Document Type

Thesis

Download

Included in

Geology Commons

Share

COinS