Quaternary history of sea ice and paleoclimate in the Amerasia basin, Arctic Ocean, as recorded in the cyclical strata of Northwind Ridge

Abstract

Research Article| September 01, 1997 Quaternary history of sea ice and paleoclimate in the Amerasia basin, Arctic Ocean, as recorded in the cyclical strata of Northwind Ridge R. Lawrence Phillips; R. Lawrence Phillips 1U.S. Geological Survey, 345 Middlefield Road, M.S. 910, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Arthur Grantz Arthur Grantz 2Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1997) 109 (9): 1101–1115. https://doi.org/10.1130/0016-7606(1997)109<1101:QHOSIA>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation R. Lawrence Phillips, Arthur Grantz; Quaternary history of sea ice and paleoclimate in the Amerasia basin, Arctic Ocean, as recorded in the cyclical strata of Northwind Ridge. GSA Bulletin 1997;; 109 (9): 1101–1115. doi: https://doi.org/10.1130/0016-7606(1997)109<1101:QHOSIA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The 19 middle-early Pleistocene to Holocene bipartite lithostratigraphic cycles observed in high-resolution piston cores from Northwind Ridge in the Amerasia Basin of the Arctic Ocean, provide a detailed record of alternating glacial and interglacial climatic and oceanographic conditions and of correlative changes in the character and thickness of the sea-ice cover in the Amerasia Basin. Glacial conditions in each cycle are represented by gray pelagic muds that are suboxic, laminated, and essentially lacking in microfossils, macrofossils, trace fossils, and generally in glacial erratics. Interglacial conditions are represented by ochre pelagic muds that are oxic and bioturbated and contain rare to abundant microfossils and abundant glacial erratics.The synglacial laminated gray muds were deposited when the central Amerasia Basin was covered by a floating sheet of sea ice of sufficient thickness and continuity to reduce downwelling solar irradiance and oxygen to levels that precluded photosynthesis, maintenance of a biota, and strong oxidation of the pelagic sediment. Except during the early part of 3 of the 19 synglacial episodes, when it was periodically breached by erratic-bearing glacial icebergs, the floating Arctic Ocean sea-ice sheet was sufficiently thick to block the circulation of icebergs over Northwind Ridge and presumably other areas of the central Arctic Ocean. Interglacial conditions were initiated by abrupt thinning and breakup of the floating sea-ice sheet at the close of glacial time, which permitted surges of glacial erratic-laden icebergs to reach Northwind Ridge and the central Arctic Ocean, where they circulated freely and deposited numerous, and relatively thick, erratic clast-rich beds. Breakup of the successive synglacial sea-ice sheets initiated deposition of the interglacial ochre mud units under conditions that allowed sunlight and increased amounts of oxygen to enter the water column, resulting in photosynthesis and biologic productivity, and strong oxidization of the pelagic sediment.The lithostratigraphy of Northwind Ridge suggests that during at least late Pleistocene time, glacial conditions in the Arctic Ocean were initiated abruptly and continued unabated until terminated, also abruptly, by onset of the succeeding interglacial warming. Variations in abundance of glacial erratics within the interglacial units of the late Pleistocene indicate that during at least most interglacial episodes northern North America was glaciated, but with generally diminishing severity, until onset of the succeeding continental glaciation.Magnetostratigraphy suggests that the glacial-interglacial cycles on Northwind Ridge had an average periodicity of approximately 93.5 k.y. during the Brunhes normal and approximately 105 k.y. during the latter part of the Matuyama reverse polarity zone. These average periodicities are close to the 100 k.y. temperature cycles found in North Atlantic deep-water sediments of the Brunhes normal polarity chron, which have been ascribed to forcing by a Milankovitch eccentricity cycle. They are also close, however, to the average interval (101 k.y.) between the aperiodic glacial terminations in the 500 k.y. Pleistocene continental climate record from Devil's Hole, Nevada, which have been ascribed to nonlinear feedbacks within the Earth's atmosphere-ice sheet-ocean system. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.