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Climate change and tectonic uplift triggered the formation of the Atacama Desert’s giant nitrate deposits

2014; Geological Society of America; Volume: 42; Issue: 3 Linguagem: Inglês

10.1130/g34969.1

1943-2682

Alida Pérez-Fodich, Martín Reich, F. Álvarez, Glen Snyder, Ronny Schoenberg, Gabriel Vargas, Yasuyuki Muramatsu, U. Fehn,

Chemical Analysis and Environmental Impact

Research Article| March 01, 2014 Climate change and tectonic uplift triggered the formation of the Atacama Desert's giant nitrate deposits Alida Pérez-Fodich; Alida Pérez-Fodich 1Department of Geology, Universidad de Chile, Plaza Ercilla 803, Santiago, Chile2Andean Geothermal Center of Excellence (CEGA), Universidad de Chile, Santiago, Chile Search for other works by this author on: GSW Google Scholar Martin Reich; Martin Reich * 1Department of Geology, Universidad de Chile, Plaza Ercilla 803, Santiago, Chile2Andean Geothermal Center of Excellence (CEGA), Universidad de Chile, Santiago, Chile *E-mail: mreich@ing.uchile.cl. Search for other works by this author on: GSW Google Scholar Fernanda Álvarez; Fernanda Álvarez 1Department of Geology, Universidad de Chile, Plaza Ercilla 803, Santiago, Chile2Andean Geothermal Center of Excellence (CEGA), Universidad de Chile, Santiago, Chile Search for other works by this author on: GSW Google Scholar Glen T. Snyder; Glen T. Snyder 3Department of Earth Science, Rice University, Houston, Texas 77251-1892, USA Search for other works by this author on: GSW Google Scholar Ronny Schoenberg; Ronny Schoenberg 4Department of Geoscience, University of Tübingen, Wilhelmstrasse 56, D-72074, 72074 Tübingen, Germany Search for other works by this author on: GSW Google Scholar Gabriel Vargas; Gabriel Vargas 1Department of Geology, Universidad de Chile, Plaza Ercilla 803, Santiago, Chile2Andean Geothermal Center of Excellence (CEGA), Universidad de Chile, Santiago, Chile Search for other works by this author on: GSW Google Scholar Yasuyuki Muramatsu; Yasuyuki Muramatsu 5Department of Chemistry, Gakushuin University, Tokyo 171-8588, Japan Search for other works by this author on: GSW Google Scholar Udo Fehn Udo Fehn 6Department of Earth and Environmental Sciences, University of Rochester, Rochester, New York 14627, USA Search for other works by this author on: GSW Google Scholar Geology (2014) 42 (3): 251–254. https://doi.org/10.1130/G34969.1 Article history received: 23 Jul 2013 rev-recd: 26 Nov 2013 accepted: 16 Dec 2013 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Alida Pérez-Fodich, Martin Reich, Fernanda Álvarez, Glen T. Snyder, Ronny Schoenberg, Gabriel Vargas, Yasuyuki Muramatsu, Udo Fehn; Climate change and tectonic uplift triggered the formation of the Atacama Desert's giant nitrate deposits. Geology 2014;; 42 (3): 251–254. doi: https://doi.org/10.1130/G34969.1 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 SocietyGeology Search Advanced Search Abstract The giant nitrate deposits of the hyperarid Atacama Desert (Chile) are one of the most extraordinary, yet enigmatic, mineral occurrences on Earth. These deposits are complex assemblages of highly soluble nitrates, chlorides, sulfates, perchlorates, iodates, and chromates, and their preservation is the result of prevalent hyperarid climate conditions in the Atacama Desert since the late Miocene, with average rainfall rates of <10 mm/yr in the past ∼3 m.y. Although several hypotheses have been proposed since the mid-1800s, the formation of these extensive deposits still remains highly controversial despite the fact that recent studies have argued toward an atmospheric source for the nitrate, sulfate, and perchlorate components. In this report, we focus on the often overlooked and poorly studied iodine and chromium components of Atacama's nitrates. We present the first cosmogenic iodine (129I) and stable chromium (δ53/52Cr) isotope data of nitrates showing that groundwater has played an unforeseen role in the formation of these massive deposits. The isotopic signature of I in the nitrates (129I/I ∼150–600 × 10–15) share similarities with deep sedimentary (marine) pore waters and shales, deviating significantly from atmospheric iodine (129I/I ∼1500 × 10–15), while the positive and highly fractionated δ53/52CrSRM979 values (+0.7‰ to +3‰) are indicative of intense Cr redox cycling due to groundwater transport. Our evidence points toward a multi-source genetic model for the Atacama Desert nitrate deposits, where these extensive accumulations were the result of long-lived, near-surface mineral precipitation driven by groundwater (i.e., chromates, iodates) coupled with dry atmospheric deposition (i.e., nitrates, perchlorates) and sea spray inputs (i.e., sulfates, chlorides), triggered by increasing aridity and tectonic uplift. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.