Cenozoic paleogeography and climatic change in the North Pacific Ocean

Gladenkov, Yu. B.

doi:10.1016/0031-0182(94)90239-9

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…The Arctic Ocean basin, in comparison, was very much smaller and certainly not connected to the extensive North Pacific at the time. It would appear that there are some Paleocene marine strata in the north-west Pacific region but the earliest records of gastropod genera that dominate coldwater molluscan assemblages of the North Pacific at the present day are from the Middle Eocene [90], [91].…”

Section: Discussionmentioning

confidence: 99%

Early Cenozoic Differentiation of Polar Marine Faunas

Crame

2013

PLoS ONE

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The widespread assumption that the origin of polar marine faunas is linked to the onset of major global cooling in the Late Eocene – Early Oligocene is being increasingly challenged. The Antarctic fossil record in particular is suggesting that some modern Southern Ocean taxa may have Early Eocene or even Paleocene origins, i.e. well within the Early Cenozoic greenhouse world. A global analysis of one of the largest marine clades at the present day, the Neogastropoda, indicates that not only is there a decrease in the number of species from the tropics to the poles but also a decrease in the evenness of their distribution. A small number of neogastropod families with predominantly generalist trophic strategies at both poles points to the key role of seasonality in structuring the highest latitude marine assemblages. A distinct latitudinal gradient in seasonality is temperature-invariant and would have operated through periods of global warmth such as the Early Cenozoic. To test this concept a second global analysis was undertaken of earliest Cenozoic (Paleocene) neogastropods and this does indeed show a certain degree of faunal differentiation at both poles. The Buccinidae, s.l. is especially well developed at this time, and this is a major generalist taxon at the present day. There is an element of asymmetry associated with this development of Paleocene polar faunas in that those in the south are more strongly differentiated than their northern counterparts; this can in turn be linked to the already substantial isolation of the southern high latitudes. The key role of seasonality in the formation of polar marine faunas has implications for contemporary ecosystem structure and stability.

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Section: Discussionmentioning

confidence: 99%

Early Cenozoic Differentiation of Polar Marine Faunas

Crame

2013

PLoS ONE

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“…We speculate that the drivers for separation there may be related to the cool water regime established along the North Pacific rim latest with the initiation of the northern hemisphere glaciation that started at about 3.0-2.5 Ma (Anderson Dahl 2009), while the wide Central Pacific deep-water gap is a much older permanent feature. Warm pulses that could have facilitated some exchange of warm-water biota along the North Pacific rim could potentially have occurred as late as 5.0-3.5 Ma that culminated in the mid-Pliocene Climate Optimum (e.g., Morley & Dworetzky 1991;Gladenkov 1994;Tsuchi 2002). The closing process of the adjacent East Pacific and Caribbean basins apparently also led to an increase of the upwelling in the East Tropical Pacific that induced an expansion of the oxygen minimum zone in the intermediate ocean layer, i.e.…”

Section: Ecology and Biogeographymentioning

confidence: 99%

Revision of the ‘dragon-head’ cusk eels of the genus Porogadus (Teleostei: Ophidiidae), with description of eight new species and one new genus

Schwarzhans

2021

Zootaxa

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The ophidiid genus Porogadus occurs between 800 and 5300 m in the tropical and subtropical world oceans. Fifteen nominal species have been described since 1878 and most of them until 1902. The genus has been highlighted as needing revision in recent compilations about ophidiiforms and here we present the first comprehensive review. Twelve of the previously described species are here accepted as valid with two being moved to the newly established genus Tenuicephalus n. gen. that encompasses fishes differing from those of Porogadus in the extremely weak ossification, the stout head, absence of head spines and absence of the “triple” lateral line system considered typical for Porogadus and a reduced dentition. In addition, eight new species are described: Porogadus caboverdensis, P. dracocephalus, P. lacrimatus, P. mendax, P. solomonensis, P. turgidus, Tenuicephalus multitrabs and T. squamilabrus. The species of Porogadus show a distinctive depth segregation with the majority of species having a demersal bathyal life-style between 800 and 3500 m and other species being more or less exclusively restricted to abyssal depths below 3000 m. The biogeographic distribution pattern of bathyal groups shows putative species pairs in the Atlantic versus the eastern Pacific and a clear separation of eastern Pacific from Indo-West Pacific species. The geographic effects and timing are being discussed that may have led to this speciation events. Generally, we found widely distributed species that are found far away from continental masses and others restrained to continental slopes and sometimes exhibiting regionalism. In abyssal depth, the Cabo Verde and Canary basins off NW-Africa have yielded three exclusive species, but it is uncertain at this stage whether this could represent a sampling bias with this area being extensively sampled by the Discovery research vessel (BMNH) over the years from 1970–1998. Another instance of a potentially endemic abyssal species is that of Porogadus melanocephalus in the Bay of Bengal. The latter has been caught with 45 specimens in a single trawl, representing the highest number of Porogadus specimens collected in any trawl and indicating that these fishes may actually not be as rare as one might assume from the literature.

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“…Sedimentation of the studied formations occurred in marine environments. The prevalence of planktonic diatoms, radiolarians, cold‐water molluscs and presence of dropstones (including clasts of varying sizes ranging from pebbles to boulders embedded in fine‐grained siltstones and argillites) suggests that the late Palaeogene to Neogene climate of Sakhalin was fairly cold (Gladenkov, 1994).…”

Section: Stratigraphy and Geological Position Of The Studied Unitsmentioning

confidence: 99%

Marine diagenesis of ikaite: Implications from the isotopic and geochemical composition of glendonites and host concretions (Palaeogene–Neogene sediments, Sakhalin Island)

et al. 2021

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Glendonites represent pseudomorphs after calcium carbonate hexahydrate (ikaite) and can be used as indicators of past cold climates, because ikaite only naturally occurs in cold environments (<7°C) in the modern. The results of a multi-proxy study of 11 glendonite and host concretion samples from Palaeogene (Gennoishi Formation) and Neogene (Bora and Vengeri formations) sediments from Sakhalin Island, Russian Far East are reported here. Petrographic, cathodoluminescence, powder X-ray diffraction and scanning electron microscope analyses reveal that glendonites are composed of several successive mineralogical phases: low-magnesium ikaite-derived calcite, highmagnesium acicular cement (calcite and dolomite) and blocky calcite or authigenic quartz filling the remaining pore space. Host concretions comprise sandy limestones cemented by high-magnesium calcite. The d 13 C and d 18 O values for host concretions and enclosed glendonites are very similar, with d 13 C ranging from -20.3 to +1.9& Vienna Pee-Dee Belemnite and d 18 O ranging from -3.4 to +3.4& Vienna Pee-Dee Belemnite. Such isotopic values suggest that seawater was the main source of oxygen, while dissolved inorganic carbon and decaying organic matter were the main carbon sources for ikaite growth, concretion and glendonite cementation. The 87 Sr/ 86 Sr values within the glendonites and host concretions are significantly lower compared with coeval Palaeogene-Neogene marine carbonates, suggesting an influence of continental runoff on their isotopic composition. Post Archean Australian Shale normalized rare earth element patterns display negative Ce anomalies and positive Eu anomalies, with a depletion in light rare earth elements or bulge in middle rare earth elements. Such spectra of rare earth elements indicate that ikaite growth and replacement occurred very close to the aerobic-anaerobic boundary, with pore waters derived from trapped seawater and/or ikaite dehydration. Since Mg/Ca ratios and alkalinity increase 2227

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Cenozoic paleogeography and climatic change in the North Pacific Ocean

Cited by 5 publications

References 2 publications

Early Cenozoic Differentiation of Polar Marine Faunas

Early Cenozoic Differentiation of Polar Marine Faunas

Revision of the ‘dragon-head’ cusk eels of the genus Porogadus (Teleostei: Ophidiidae), with description of eight new species and one new genus

Marine diagenesis of ikaite: Implications from the isotopic and geochemical composition of glendonites and host concretions (Palaeogene–Neogene sediments, Sakhalin Island)

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