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Articles 1 - 9 of 9
Full-Text Articles in Paleobiology
Aptian To Santonian Foraminiferal Biostratigraphy And Paleoenvironmental Change In The Sverdrup Basin As Revealed At Glacier Fiord, Axel Heiberg Island, Canadian Arctic Archipelago, Claudia J. Schröder-Adams, Jens O. Herrle, Ashton F. Embry, James W. Haggart, Jennifer M. Galloway, Adam T. Pugh, David M. Harwood
Aptian To Santonian Foraminiferal Biostratigraphy And Paleoenvironmental Change In The Sverdrup Basin As Revealed At Glacier Fiord, Axel Heiberg Island, Canadian Arctic Archipelago, Claudia J. Schröder-Adams, Jens O. Herrle, Ashton F. Embry, James W. Haggart, Jennifer M. Galloway, Adam T. Pugh, David M. Harwood
ANDRILL Research and Publications
Exceptional exposures of a High Arctic Cretaceous sedimentary record were studied at Glacier Fiord, Axel Heiberg Island. The succession reveals a complex Aptian to Santonian paleoenvironmental history of the Sverdrup Basin that documents several global events. Foraminiferal faunas in combination with rare macrofossil occurrences permit the distinction of nine zones that facilitate biostratigraphic correlations to other High Arctic locales, the Beaufort Mackenzie Basin and the Western Interior Sea. The depositional environment as exposed in the Christopher, Hassel, Bastion Ridge and Kanguk formations changed frequently from a shelf to a shoreface setting. Most sequence boundaries appear to be conformable where shoaling …
New Insights Into Skeletal Morphology Of The Oldest Known Silicoflagellates : Variramus, Cornua And Gleserocha Gen. Nov. = Nouvelles Connaissances Sur La Morphologie Du Squelette Des Plus Anciennes Silicoflagellés Connus : Variramus, Cornua Et Gleserocha Gen. Nov., Kevin Mccartney, Jakub Witkowski, David M. Harwood
New Insights Into Skeletal Morphology Of The Oldest Known Silicoflagellates : Variramus, Cornua And Gleserocha Gen. Nov. = Nouvelles Connaissances Sur La Morphologie Du Squelette Des Plus Anciennes Silicoflagellés Connus : Variramus, Cornua Et Gleserocha Gen. Nov., Kevin Mccartney, Jakub Witkowski, David M. Harwood
ANDRILL Research and Publications
Two of the oldest known silicoflagellate-bearing sediments, lower Albian at Ocean Drilling Program Site 693 in the Weddell Sea of Antarctica and Santonian in the Devon Island sequence of the Canadian Archipelago, are re-examined with a focus on silicoflagellate genera Variramus, Cornua, and Gleserocha that lack basal rings, a feature appearing during late Santonian/early Campanian time within the genus Corbisema. The extraordinary variability of Variramus aculeifera is studied, and a new genus Gleserocha is proposed for taxa with apical structures made of three struts, but without pikes. This new genus includes previously described Variramus wisei and Cornua …
Rapid Fluctuations In Mid-Latitude Siliceous Plankton Production During The Middle Eocene Climatic Optimum (Odp Site 1051, Western North Atlantic), Jakub Witkowski, Steven M. Bohaty, Kirsty M. Edgar, David M. Harwood
Rapid Fluctuations In Mid-Latitude Siliceous Plankton Production During The Middle Eocene Climatic Optimum (Odp Site 1051, Western North Atlantic), Jakub Witkowski, Steven M. Bohaty, Kirsty M. Edgar, David M. Harwood
ANDRILL Research and Publications
The Middle Eocene Climatic Optimum (MECO; ~ 40 million years ago [Ma]) is one of the most prominent transient global warming events in the Paleogene. Although the event is well documented in geochemical and isotopic proxy records at many locations, the marine biotic response to the MECO remains poorly constrained. We present new high-resolution, quantitative records of siliceous microplankton assemblages from the MECO interval of Ocean Drilling Program (ODP) Site 1051 in the subtropical western North Atlantic Ocean, which are interpreted in the context of published foraminiferal and bulk carbonate stable isotope (δ18O and δ13C) records. …
Chemostratigraphy Of The Early Pliocene Diatomite Interval From Mis And-1b Core (Antarctica): Paleoenvironment Implications, Giovanna Scopelliti, Adriana Bellanca, Donata Monien, Gerhard Kuhn
Chemostratigraphy Of The Early Pliocene Diatomite Interval From Mis And-1b Core (Antarctica): Paleoenvironment Implications, Giovanna Scopelliti, Adriana Bellanca, Donata Monien, Gerhard Kuhn
ANDRILL Research and Publications
The AND-1B drill core (1285 m-long) was recovered, inside the ANDRILL (ANtarctic geological DRILLing) Program, during the austral summer of 2006/07 from beneath the floating McMurdo Ice Shelf. Drilling recovered a stratigraphic succession of alternating diamictites, diatomites and volcaniclastic sediments spanning about the last 14 Ma. A core portion between 350 and 480 mbsf, including a 80 m-thick diatomite interval recording the early Pliocene warming event, was investigated in term of opal biogenic content and element geochemistry. Across the diatomite interval, in spite of the lithological uniformity, a fluctuating biogenic opal profile mirrors the δ18O record, testifying a decrease in …
Fragilariopsis Tigris Sp. Nov., A New Late Pliocene Antarctic Continental Shelf Diatom With Biostratigraphic Promise, Christina R. Riesselman
Fragilariopsis Tigris Sp. Nov., A New Late Pliocene Antarctic Continental Shelf Diatom With Biostratigraphic Promise, Christina R. Riesselman
ANDRILL Research and Publications
Anew species within the genus Fragilariopsis, F. tigris, is described and illustrated using light microscopy and scanning electron microscopy. This species is restricted to a single 8-meter-thick diatom unit within the 585-meter-long section of alternating diatomites and diamictites recovered in the upper portion of the ANtarctic geological DRILLing (ANDRILL) McMurdo Ice Shelf Project (MIS) AND-1B marine sediment core. This new taxon from a diverse, well-preserved diatom assemblage is inferred to be the youngest member of the well-documented, biostratigraphically useful F. praeinterfrigidaria – F. interfrigidaria – F. weaveri lineage and may represent a near-shore corollary to the open-ocean species …
Diatom Evidence For The Onset Of Pliocene Cooling From And-1b, Mcmurdo Sound, Antarctica, Christina R. Riesselman, Robert B. Dunbar
Diatom Evidence For The Onset Of Pliocene Cooling From And-1b, Mcmurdo Sound, Antarctica, Christina R. Riesselman, Robert B. Dunbar
ANDRILL Research and Publications
The late Pliocene, ~3.3–3.0 Ma, is the most recent interval of sustained global warmth in the geologic past. This window is the focus of climate reconstruction efforts by the U.S. Geological Survey’s Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) Data/Model Cooperative, and may provide a useful climate analog for the coming century. Reconstructions of past surface ocean conditions proximal to the Antarctic continent are essential to understanding the sensitivity of the cryosphere to this key interval in Earth’s climate evolution. An exceptional marine sediment core collected from the southwestern Ross Sea (78° S), Antarctica, during ANDRILL’s McMurdo Ice Shelf Project …
A Diatom Record Of Late Pliocene Cooling From The Ross Sea Continental Shelf, And-1b, Antarctica, Charlotte Sjunneskog, Diane Winter
A Diatom Record Of Late Pliocene Cooling From The Ross Sea Continental Shelf, And-1b, Antarctica, Charlotte Sjunneskog, Diane Winter
ANDRILL Research and Publications
A late Pliocene – early Pleistocene, 2.9–2.0Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitally paced climate cycles and are punctuated by glacial advances. Extant diatom assemblages have limited presence in the late Pliocene record, which makes environmental interpretation less straight forward. We employ modern ecological data in combination with late Pliocene to present variation in diatom assemblages across the …
Fragilariopsis Diatom Evolution In Pliocene And Pleistocene Antarctic Shelf Sediments, Charlotte Sjunneskog, Christina R. Riesselman, Diane Winter, Reed Scherer
Fragilariopsis Diatom Evolution In Pliocene And Pleistocene Antarctic Shelf Sediments, Charlotte Sjunneskog, Christina R. Riesselman, Diane Winter, Reed Scherer
ANDRILL Research and Publications
The late Pliocene – early Pleistocene sediment record in the AND-1B core from the McMurdo Sound, Ross Sea, Antarctica, displays a rich diversity and high abundance of diatoms, including several new morphologies within the genus Fragilariopsis. These new morphologies exhibit similarities to the extinct late Miocene/early Pliocene species Fragilariopsis aurica Gersonde and Fragilariopsis praecurta Gersonde, as well as to the modern sea ice-associated species Fragilariopsis ritscheri Hustedt and Fragilariopsis obliquecostata van Heurck. From the diverse morphologies present, we use light microscopy and scanning electron microscopy to identify and describe the characteristics of three new taxa, Fragilariopsis laqueata Riesselman, Fragilariopsis …
Significance Of The Trace Fossil Zoophycos In Pliocene Deposits, Antarctic Continental Margin (Andrill 1b Drill Core), Molly F. Miller, Ellen A. Cowan, Simon H. H. Nielsen
Significance Of The Trace Fossil Zoophycos In Pliocene Deposits, Antarctic Continental Margin (Andrill 1b Drill Core), Molly F. Miller, Ellen A. Cowan, Simon H. H. Nielsen
ANDRILL Research and Publications
Zoophycos is a complex three dimensional trace fossil that is abundant in deep ocean sediments worldwide, but has not been described previously from Cenozoic continental margin deposits of Antarctica. In the ANDRILL 1B core drilled through the north-west McMurdo ice shelf, Zoophycos occurs in a 17m thick unit of interglacial sediments bounded above and below by glacial surfaces of erosion. This unit was deposited during the transition from the relatively warm Early Pliocene characterized by productive open waters to the cooler Late Pliocene with fluctuating subpolar ice sheets. Globally, Late Cenozoic Zoophycos are most abundant at great depths (.1000 m), …