Sedimentary Basin Development in Extensional Settings

To better understand the relationship between extensional deformation and sedimentary basin development, we have been mapping in the Mohawk Mountains of Arizona. Coarse-grained siliciclastic deposits in this mountain range contain the record of mid-Tertiary basin development associated with displacement along a regional detachment fault. The lack of mylonitic fabrics along this well exposed detachment fault suggests smaller amounts of displacement relative to the more highly extended terranes associated with metamorphic core complexes in other parts of the Cordillera. Structural and sedimentological analysis of deformed Tertiary sedimentary rocks in the Mohawk Mountains, therefore, provides an opportunity to study deformation and basin development at the higher structural levels of a detachment fault system. Working with Paul Layer (Univ. of Alaska, Fairbanks), we have dated several tuffs found during the last field season.

Jeff Trop collecting data from proximal conglomerates in Mohawk Mtns. Jeff Trop standing on detachment fault in Arizona. Proximal alluvial fan deposits in Tertiary basin of southwestern Arizona.