AbstractsEarth & Environmental Science

Geology of the Antone district of Wheeler County, Oregon

by Joseph Porter Dobell




Institution: Oregon State University
Department: Geology
Degree: MS
Year: 1948
Keywords: Geology  – Oregon  – Wheeler County
Record ID: 1487158
Full text PDF: http://hdl.handle.net/1957/9242


Abstract

The area studied in detail, known as the Antone District, is located in the southeast corner of Wheeler County, Oregon, , between longitude 119 37. and 119°54 east, and latitude 44°23 and 44°3O' north. Surface elevations range from 3050 feet above sea level in the northeast corner of the district, to 6M5 feet on Spanish Peak. The Miocene Columbia Biver lavas outcrop over 48 of the 68 square miles in the district. Older rocks exposed include Pre- Cretaoeous mota-sedimente and metamorphosed intrusives, Cretaceous conglomerates and sandstones, a granite porphyry pluton, and the brilliantly colored rooks of the upper 011goe.ne and lower Miocene John Day. The early Tertiary formation known as the Clarno does not outcrop in this district. Younger formations include the gravels and tuffs of the upper Miocene Mascall formation, extensive outcrops of the Pliocone Rattlesnake, and limited accumulations of undifferentiated Quaternary alluvium. A horublende andesite extrusive, which is probably of Pleistocene age, occurs in the western part of the district. Eaoh of the above stratigraphic units is discussed under the following headings: Distribution and Topographic Expression; Lithology; Thickness; Age and Stratigraphic Relations. A section of the "Dayville Quadrangls, issued by the U. S. aeologioal Survey, was used as a base for a detailed map showing the distribution of the various formations. Special attention was devoted to the study of the Pre-Cretaceous rooks. Approximately 8000 feet of ohloritic schist, argillite, caleareous sohist, phyllie, marble, and quartzite are included in this older series. Basic Intrusives, largely altered to serpentine, cut the meta-sediments. The structure of the Antone District is discussed under the following subheadings: John Day Valley Syncline; Ochoco Escarpment and Highland; Pre-Cretaceous Folding and Faulting; Cretaceous Monocline; and, Fracturing and Slumping of the Rattlesnake Formation. Special sections have been devoted to historical and economic geology. The report is adequately illustrated with photomicrographs of representative rooks and with numerous pertinent detail photographs. Also included is a plate showing the structural details of a north-south section through the middle of the Antone District.