Print this pageRocks in the vicinity of Mosca Creek have never been mapped up in detail, and the direction of fault movements whether modern or ancient have not been studied very well either. Modern fault movements that have been developed in Oligocene to recent time are being studied here in order to understand the possible effects the Rio Grande Rift Valley is having on the horst block of the Sangre De Cristo mountains and the major fault systems on the west side of the range.
The proposed area is a good lab to obtain a better understanding of the regional tectonics and structural history of this ancient foreland thrust area and the modern rift valley beside it.
An important aspect of the study area that has been looked into in detail is the Pennsylvanian sediments (located within a fenster or window), and the fault that bounds them. Granite gneiss and Precambrian metasediments have been misidentified as Pennsylvanian sedimentary rock. New geologic mapping will show correct contacts and proper structural style in this area and how it relates to the regional tectonic picture of the Rocky Mountains.
AAPG Search and Discovery Article #90925©1999 AAPG Foundation Grants-in-Aid