Thermochronology of sandstone-hosted secondary Fe- and Mn-oxides near Moab, Utah: Record of paleo–fluid flow along a fault

Research Article| August 15, 2017 Thermochronology of sandstone-hosted secondary Fe- and Mn-oxides near Moab, Utah: Record of paleo–fluid flow along a fault Victor H. Garcia; Victor H. Garcia † 1Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721, USA †vhgarcia4@email.arizona.edu Search for other works by this author on: GSW Google Scholar Peter W. Reiners; Peter W. Reiners 1Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar David L. Shuster; David L. Shuster 2Department of Earth and Planetary Science, University of California–Berkeley, 307 McCone Hall, Berkeley, California 94720, USA3Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA Search for other works by this author on: GSW Google Scholar Bruce Idleman; Bruce Idleman 4Department of Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, Pennsylvania 18015, USA Search for other works by this author on: GSW Google Scholar Peter K. Zeitler Peter K. Zeitler 4Department of Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, Pennsylvania 18015, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Victor H. Garcia † 1Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721, USA Peter W. Reiners 1Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721, USA David L. Shuster 2Department of Earth and Planetary Science, University of California–Berkeley, 307 McCone Hall, Berkeley, California 94720, USA3Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA Bruce Idleman 4Department of Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, Pennsylvania 18015, USA Peter K. Zeitler 4Department of Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, Pennsylvania 18015, USA †vhgarcia4@email.arizona.edu Publisher: Geological Society of America Received: 30 Jul 2016 Revision Received: 02 May 2017 Accepted: 17 Jun 2017 First Online: 28 Dec 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2017 Geological Society of America GSA Bulletin (2018) 130 (1-2): 93–113. https://doi.org/10.1130/B31627.1 Article history Received: 30 Jul 2016 Revision Received: 02 May 2017 Accepted: 17 Jun 2017 First Online: 28 Dec 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Victor H. Garcia, Peter W. Reiners, David L. Shuster, Bruce Idleman, Peter K. Zeitler; Thermochronology of sandstone-hosted secondary Fe- and Mn-oxides near Moab, Utah: Record of paleo–fluid flow along a fault. GSA Bulletin 2017;; 130 (1-2): 93–113. doi: https://doi.org/10.1130/B31627.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Secondary Fe- and Mn-oxides are locally common near faults and fractures within sandstones of the Colorado Plateau in the form of cements, concretions, and fracture-fill material. However, little is known about how and why these oxides formed, and less is understood about when they formed. In this study, we integrated field observations, detailed scanning electron microscope and petrographic observations, and (U-Th)/He and 40Ar/39Ar dating to better understand the formation of Fe- and Mn-oxides from three fault zones in Flat Iron Mesa, Utah. Most Fe- and Mn-oxide (U-Th)/He ages range from 0.50 to 3.4 Ma, which are much younger than 40Ar/39Ar ages of 25–20 Ma from a previous study. Current 40Ar/39Ar ages on a Mn-oxide sample from this study yielded a plateau age of 3.6 ± 0.08 Ma. 4He/3He diffusion data from Fe- and Mn-oxides are consistent with the presence of multiple diffusion domains with varying He retentivity. Predicted fractional radiogenic He retention over 3.6 m.y. at near-surface temperatures for the bulk samples, with domain proportions of the diffusion experiments, is ∼90% for Fe-oxide and ∼45% for Mn-oxide. The multidomain behavior exhibited by the oxides and the variability observed in (U-Th)/He ages among aliquots are consistent with variable amounts of diffusive loss of He within dated aliquots. Using 4He/3He data and He bulk ages, step-age plots indicate a high fractional release plateau at ca. 3.6 Ma, concordant with 40Ar/39Ar dating and most of the oldest (U-Th)/He ages observed. Taken together, these results are most consistent with formation of Flat Iron Mesa Fe- and Mn-oxides near the surface (<0.5 km) at 3.6 Ma, due to hydrologic changes, fault activity, or both. Our data and interpretations suggest that erosional exhumation rates over ∼1–4 m.y. time scales may be variable in the central Colorado Plateau, possibly driven by local effects, and they are not spatially uniform over large regions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.