title: Revealing the climate of snowball Earth from Δ17O systematics of hydrothermal rocks.
abstract: The oxygen isotopic composition of hydrothermally altered rocks partly originates from the interacting fluid. We use the triple oxygen isotope composition ((17)O/(16)O, (18)O/(16)O) of Proterozoic rocks to reconstruct the (18)O/(16)O ratio of ancient meteoric waters. Some of these waters have originated from snowball Earth glaciers and thus give insight into the climate and hydrology of these critical intervals in Earth history. For a Paleoproterozoic [∼2.3-2.4 gigayears ago (Ga)] snowball Earth, δ(18)O = -43 ± 3‰ is estimated for pristine meteoric waters that precipitated at low paleo-latitudes (≤35°N). Today, such low (18)O/(16)O values are only observed in central Antarctica, where long distillation trajectories in combination with low condensation temperatures promote extreme (18)O depletion. For a Neoproterozoic (∼0.6-0.7 Ga) snowball Earth, higher meltwater δ(18)O estimates of -21 ± 3‰ imply less extreme climate conditions at similar paleo-latitudes (≤35°N). Both estimates are single snapshots of ancient water samples and may not represent peak snowball Earth conditions. We demonstrate how (17)O/(16)O measurements provide information beyond traditional (18)O/(16)O measurements, even though all fractionation processes are purely mass dependent.
authors: Abteilung Isotopengeologie, Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, 37073 Göttingen, Germany; d.herwartz@uni-koeln.de.
authors: Daniel
authors: D
authors: Herwartz
authors: Abteilung Isotopengeologie, Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, 37073 Göttingen, Germany;
authors: Andreas
authors: A
authors: Pack
authors: Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, 199034 St. Petersburg, Russia;
authors: Dmitri
authors: D
authors: Krylov
authors: CAS Key Laboratory of Crustal-Mantle Materials and Environments, School of Earth and Space Science, University of Science and Technology of China, Hefei, 230026, China; and.
authors: Yilin
authors: Y
authors: Xiao
authors: Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E3.
authors: Karlis
authors: K
authors: Muehlenbachs
authors: Abteilung Isotopengeologie, Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, 37073 Göttingen, Germany;
authors: Sukanya
authors: S
authors: Sengupta
authors: Abteilung Isotopengeologie, Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, 37073 Göttingen, Germany;
authors: Tommaso
authors: T
authors: Di Rocco
keywords: climate; hydrothermal alteration; paleo-temperatures; snowball Earth; triple oxygen isotopes