AbstractsEarth & Environmental Science

Stratigraphy and structure of the Horseshoe Gulch area, Etna and China Mountain quadrangles, California

by Ted Andrew Zdanowicz

Institution: Oregon State University
Department: Geology
Degree: MS
Year: 1971
Keywords: Geology  – California  – Horseshoe Gulch Area
Record ID: 1540832
Full text PDF: http://hdl.handle.net/1957/45788


The Horseshoe Gulch area includes 16 square miles in the Eastern Paleozoic Belt of the Klamath Mountains geologic province north of Callahan, California. Fossiliferous Late Ordovician and Silurian limestones and unfossiliferous greywackes, arkoses, shales, mudstones, schists, and phyllites, and other terrigenous clastic rocks are exposed in a broad fault zone in the area of study. It is concluded that the limestones represent a clear, stable, and relatively shallow water environment of deposition. These limestones are found associated with a geosynclinal sequence of rock units. Eleven mappable units grouped into upper and lower thrust plates, are recognized. The fault zone in the Horseshoe Gulch area, approximately one mile wide, is characterized by a prominent folded thrust fault that is part of the Mallethead Thrust. The Mallethead Thrust, whose age is at least post-Late Silurian in the area, has placed upper plate unfossiliferous, pre-Cretaceous age chlorite grade metamorphic rocks over the Early Paleozoic unmetamorphosed limestones and clastics of the lower plate. The trace of the Mallethead Thrust is very sinuous and irregular.