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Onset of the Laramide orogeny and associated magmatism in southern New Mexico based on U-Pb geochronology

2017; Geological Society of America; Linguagem: Inglês

10.1130/b31629.1

1943-2674

Jeffrey M. Amato, Greg H. Mack, Tara N. Jonell, William R. Seager, Garland R. Upchurch,

Geochemistry and Geologic Mapping

Research Article| May 11, 2017 Onset of the Laramide orogeny and associated magmatism in southern New Mexico based on U-Pb geochronology Jeffrey M. Amato; Jeffrey M. Amato † 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA †amato@nmsu.edu Search for other works by this author on: GSW Google Scholar Greg H. Mack; Greg H. Mack 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar Tara N. Jonell; Tara N. Jonell 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar William R. Seager; William R. Seager 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar Garland R. Upchurch Garland R. Upchurch 2Department of Biology, Texas State University, San Marcos, Texas 78666, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Jeffrey M. Amato † 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Greg H. Mack 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Tara N. Jonell 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA William R. Seager 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Garland R. Upchurch 2Department of Biology, Texas State University, San Marcos, Texas 78666, USA †amato@nmsu.edu Publisher: Geological Society of America Received: 02 Aug 2016 Revision Received: 03 Jan 2017 Accepted: 25 Mar 2017 First Online: 23 Jun 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2017 Geological Society of America GSA Bulletin (2017) 129 (9-10): 1209–1226. https://doi.org/10.1130/B31629.1 Article history Received: 02 Aug 2016 Revision Received: 03 Jan 2017 Accepted: 25 Mar 2017 First Online: 23 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jeffrey M. Amato, Greg H. Mack, Tara N. Jonell, William R. Seager, Garland R. Upchurch; Onset of the Laramide orogeny and associated magmatism in southern New Mexico based on U-Pb geochronology. GSA Bulletin 2017;; 129 (9-10): 1209–1226. doi: https://doi.org/10.1130/B31629.1 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 The Laramide orogeny is a classic yet controversial mountain-building event that resulted, in the southwest United States, in uplifts, sedimentation, and magmatism that can be used to constrain the onset of this event in the region and expand our knowledge of Late Cretaceous to Paleogene tectonism. The McRae Formation marks the onset of deposition in the Laramide Love Ranch Basin, which was located to the northeast of the west-northwest–trending coeval Rio Grande uplift in south-central New Mexico, but its age is not well constrained. A previously published late Maastrichtian age for the McRae Formation was based on the presence of dinosaur bones in the upper of two members of the formation. We obtained new U-Pb dates from one dacite clast and three ash-fall tuffs from the lower Jose Creek Member and from one ash-fall tuff from the lower part of the overlying Hall Lake Member of the McRae Formation. The clast yielded a date of 75.0 ± 1.1 Ma, whereas the ages of the tuffs, in ascending stratigraphic order, are 74.9 ± 0.7 Ma, 74.7 ± 0.6 Ma, 75.2 ± 1.3 Ma, and 73.2 ± 0.7 Ma. These dates indicate that the onset of Laramide deposition in the Love Ranch Basin must have occurred earlier, in late Campanian time, similar to deposition in the Laramide Ringbone Basin in southwestern New Mexico. In addition, U-Pb zircon dates of 75.7 ± 1.3 Ma and 75.0 ± 2.8 Ma were obtained on the Twin Peaks stock and on a dacite sill, respectively, in the Burro Mountains of southwestern New Mexico. These dates are similar to those of other Laramide arc magmatic centers in southern New Mexico, which have a limited range of ages from 75 to 70 Ma, including the Hidalgo Formation in the Little Hatchet Mountains, the Silver City–Pinos Altos region, and the Copper Flat porphyry system. These new and previously published dates indicate that during the onset of Laramide deformation in southwestern and south-central New Mexico, the angle of subduction of the Farallon plate may have been steep enough to allow partial melting of an asthenospheric wedge, resulting in arc magmatism far inboard of the trench. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.