Paleostructural Interpretation, Eastern Great Basin, Nevada and Utah: An Update

E. L. Howard

In 1976, this author proposed a general paleostructural interpretation for the eastern Great Basin. This interpretation was largely derived from the field-observed relationship between variously eroded older rocks of mostly Paleozoic age and overlying sequences of lower Tertiary lacustrine sediments, volcanic ash flows, or both.

The author has continued to collect data that have confirmed much of the earlier work. The net results of integrating this new work with the original study has been the development of some refined uses of this information further to reconstruct the central part of the eastern Great Basin to its setting just prior to the deposition of the lower Tertiary cover. Once a semblance of reconstruction was achieved in a range or over an area of ranges, through the use of present day dip attitudes and steronet restoration, we can make one or more of the following deductions:

(1) Several more subtle anticlinal and synclinal undulations that were present in the Paleozoic rocks at the pre-Tertiary erosion surface can be detected and defined.

(2) Most early Tertiary (Eocene-Sheep Pass Formation) lacustrine clastics and carbonates were deposited in an environment very much controlled by the erosional configuration of these older beds.

(3) A reasonable prediction can be made as to where additional sections of these sediments might have been deposited once a depositional model for the relationship of these Tertiary sediments to their structurally controlled setting has been established.

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