© ICDP, the International Continental Scientific Drilling Program, 1996-2020

www.icdp-online.org

Deep Dust: Probing Continental Climate of the Late Paleozoic Icehouse-Greenhouse Transition

North America, U.S.A., Oklahoma, Utah, Arizona, Europe, France, Paris Basin

new workshop-proposal: ICDP-2018/13
for the funding-period starting 2018-01-15
by Gerilyn S. (Lynn) Soreghan, Nicholas G. Heavens, Stephane Pochat, Laurent Beccaletto, Kathleen Counter Benison, Michael A. Hamilton, Wan Yang, Natsuko Hamamura, Cynthia V. Looy, Linda Alide Hinnov
Abstract
The tectonic, climatic, and biotic events of the Permian are amongst the most profound in Earth history. Global orogeny leading to Pangaean assembly culminated by middle Permian time, and included multiple orogenic belts in the equatorial Central Pangaean Mountains, from the Variscan-Hercynian system (east) to the Ancestral Rocky Mountains (west). Earth’s penultimate global icehouse peaked in early Permian time, transitioning to full greenhouse conditions by late Permian time, archiving our only example of icehouse collapse while the Earth had an expansive terrestrial biosphere. The Late Paleozoic Icehouse was the longest and most intense glaciation of the Phanerozoic, with hypothesized low-moderate-elevation glaciation posited for both eastern and western tropical Pangaea during early Permian time. The atmosphere during this icehouse experienced the lowest CO2 and highest O2 levels of the Phanerozoic, but average CO2 levels were comparable to our present, rapidly warming climate. Fundamental shifts occurred in atmospheric circulation: a global megamonsoon developed and the tropics became anomalously arid with time. Extreme environments are well documented in the form of, e.g., voluminous dust deposits, acid lakes, extreme continental temperatures, and major extinctions/extirpations, ultimately culminating at the Permo-Triassic boundary with the largest extinction of Earth history. We have assembled expertise in sedimentary and planetary geology and paleoclimatology, climate modeling, structural geology, geochronology, paleobotany, geomicrobiology, and quantitative cyclostratigraphy. We seek to elucidate paleoclimatic conditions and forcings through the Permian at temporal scales ranging from the sub-millennial to the Milankovitch and beyond by acquiring continuous core in continental lowlands known to harbor stratigraphically complete records dominated by loess and lacustrine strata, and adjacent upland-proximal sites hypothesized to have hosted glaciation. We have identified locales in the western U.S. and France as the key sites globally to achieve our objectives, as these represent the western and eastern limits, respectively of the Pangaean tropics. Additionally, the Anadarko Basin (Oklahoma) and Paris Basin (France) archive arguably the most complete continental Permian sections at the paleoequator, and their adjacent paleo-uplands are the only sites globally for which Permian tropical glaciation has been hypothesized. We will also address the nature and character of the modern and fossil microbial biosphere, Mars-analog conditions, and exhumation histories of source regions. Our project connects the dusty climates of the late Paleozoic and the late Cenozoic, North America with Europe, and the Earth with Mars— all potent themes for international education/outreach.
Scientific Objectives
  • Our overarching objective is to clarify tropical continental paleoclimate and climate forcings of Earth’s penultimate icehouse and icehouse-greenhouse transition. Key questions: How did tropical climate, vegetation, and surface hydrology evolve through the Permian, from western to eastern Pangaea, and what were the drivers? What is the record of atmospheric dust loading and how did this affect tropical climate? Did glaciation extend to relatively low elevations in tropical regions, and if so, what drove such extreme conditions? How can we explain the apparent hyperaridity and extreme temperatures of later Permian time? What was the nature of iron cycling on the Permian Earth and how did this affect biogeochemical cycling and climate?
  • To address these objectives we will collect and analyze lithologic, geochemical, rockmagnetic, fluid-inclusion, and geochronological indicators that archive climatic parameters preserved in continental (loess-paleosol, lacustrine, periglacial) and epeiric successions. We will collect palynological and paleobotanical data to reconstruct vegetational changes. We will use a combination of approaches to date and correlate sections. We will integrate the results with climate modeling to better address climate forcings. Auxiliary objectives achievable only by coring include 1— Investigations of the modern and fossil microbial biosphere, by testing the limits of the modern microbial biosphere, and, using fluid inclusions to assess the presence and character of the fossil microbial biosphere. 2— Analysis of pristine red-bed and evaporite strata as analogs to Martian climate and paleoclimate. 3— Continuous thermochronology of lowland sediments to gain insight to exhumation of sources.
Keywords
DEEP-DUST, Europe, France, Geomicrobiology, Greenhouse, ICDP-2018/13, Ice, North america, Oklahoma, Paleoclimate, Permian, U.S.A.
Location
North America, U.S.A., Oklahoma, Utah, Arizona, Europe, France, Paris Basin: 34.83944, -98.80361

© ICDP, the International Continental Scientific Drilling Program, 1996-2020

www.icdp-online.org