SCEC Award Number 17205 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Understanding strain accumulation and transfer between the SSAF, San Gorgonio Pass and the ECSZ Part I. Re-evaluating fault geometry, fault activity and slip rate on the Mission Creek-Mill faults from the Coachella Valley through the San Gorgonio Pass
Investigator(s)
Name Organization
Kimberly Blisniuk San Jose State University Julie Fosdick University of Connecticut Seulgi Moon University of California, Los Angeles
Other Participants Jesse Waco, SJSU
Brittany Emmons, UCLA
SCEC Priorities 1a, 2e, 3a SCEC Groups SAFS, Geology
Report Due Date 06/15/2018 Date Report Submitted 06/18/2018
Project Abstract
 Abstract: Support from SCEC in 2017 provided funding to
(1) complete an integrated provenance study on the Mission Creek alluvial fan complex;
(2) conduct detailed mapping of active faulting adjacent to the restraining left-bend of the Mission Creek-Mill fault strands; and
(3) apply 10Be exposure, 36Cl/10Be burial and single-grain luminescence on post-IR IRSL dating on offset deposits along the Mission-Mill Creek faults.
Our data to date from new 36Cl/10Be burial dating and an integrated provenance analysis of conglomerate, sandstone, and detrital zircon collected from Deformed gravels of Whitewater River (Qd), the overlying flat-lying alluvial-fanglomerate (Qo, Cabezon Fanglomerate), and modern drainages within the San Bernardino Mountains (SBM) and Little San Bernardino Mountains (LSBM) show the fanglomerate at this location were deposited and laterally offset along the Mission Creek Fault. A statistical analysis of our integrated provenance approach from Qd and Qo alluvial deposits and modern drainages suggests Qo deposits are most compatible with a Mission Creek source and Morongo Valley source in the SBM. Qd deposits are incompatible with a SBM source and more closely match the eastern LSBM, where catchments expose mostly Cretaceous and Jurassic plutons of the Sierra Nevada batholith. These data challenge the paradigm suggesting the Mission Creek Fault is inactive in this region and provides evidence of continued dextral fault displacement along the MCF throughout its history into the present since ~100 ka. Presently, we are awaiting AMS analysis to determine final burial ages for the fan complex.
Intellectual Merit This proposal will directly address two long-term science priorities for SCEC4; namely, improving our understanding of (1) stress transfer from plate motion to crustal faults and (2) the structural evolution of fault zones and fault systems. In reference to the San Gorgonio Pass Science Plan specifically, we anticpate that data from this study will make important contributions to the following tasks and goals: (1) fill slip rate data gap, (2) provide validation for results of mechanical models that evaluate long term horizontal slip rates, and (3) provide slip rate data for rupture model refinement. We show with are new data that the Mission Creek Fault is likely active in a region where the fault is mapped as inactive.
Broader Impacts The broader impacts of this proposal permitted multiple institutions with 3 early career female scientists and their students to work together collaboratively. These people include PI Blisniuk (SJSU), co-PI Moon (UCLA), co-PI Fosdick(UConn), graduate student Jesse Waco from SJSU, and undergraduate student Brittany Emmons from UCLA. In addition, the project provided partnerships between these institutions. The research outcomes of this project improve our understanding of active faults and earthquakes in southern California and therefore directly affects society.
Exemplary Figure Figure 3