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The concentrations of Cd, Cr, Cu, Mo, Ni, Sb, U, V, and Zn were measured in early Quaternary sediment (1.32 to 1.08 Ma) from the Oki Ridge in the Japan Sea. The elements were partitioned between a detrital fraction, composed of terrigenous and volcaniclastic aluminosilicate debris, and a marine fraction, composed of biogenic and hydrogenous debris derived from seawater. The most important factors controlling minor-element accumulation rates in the marine fraction were (1) primary productivity in the photic zone, which largely controlled the flux of particulate organic-matter-bound minor elements settling through the water column and onto the seafloor, and (2) bottom-water redox, which determined the suite of elements...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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We reconstructed paleoclimate patterns from oxygen and carbon isotope records from the fossil estuarine benthic foraminifera Elphidium and Mg/ Ca ratios from the ostracode Loxoconcha from sediment cores from Chesapeake Bay to examine the Holocene evolution of North Atlantic Oscillation (NAO)-type climate variability. Precipitation-driven river discharge and regional temperature variability are the primary influences on Chesapeake Bay salinity and water temperature, respectively. We first calibrated modern ??18 Owater to salinity and applied this relationship to calculate trends in paleosalinity from the ??18 Oforam, correcting for changes in water temperature estimated from ostracode Mg /Ca ratios. The results indicate...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Coral skeletons are valuable archives of past ocean conditions. However, interpretation of coral paleotemperature records is confounded by uncertainties associated with single-element ratio thermometers, including Sr/Ca. A new approach, Sr-U, uses U/Ca to constrain the influence of Rayleigh fractionation on Sr/Ca. Here we build on the initial Pacific Porites Sr-U calibration to include multiple Atlantic and Pacific coral genera from multiple coral reef locations spanning a temperature range of 23.15–30.12°C. Accounting for the wintertime growth cessation of one Bermuda coral, we show that Sr-U is strongly correlated with the average water temperature at each location (r2 = 0.91, P < 0.001, n = 19). We applied the...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The Arctic cryosphere is changing and making a significant contribution to sea level rise. The Late Pliocene had similar CO2 levels to the present and a warming comparable to model predictions for the end of this century. However, the state of the Arctic cryosphere during the Pliocene remains poorly constrained. For the first time we combine outputs from a climate model with a thermodynamic iceberg model to simulate likely source regions for ice‐rafted debris (IRD) found in the Nordic Seas from Marine Isotope Stage M2 to the mid‐Piacenzian Warm Period and what this implies about the nature of the Arctic cryosphere at this time. We compare the fraction of melt given by the model scenarios with IRD data from four...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Geochemical analyses of authigenic carbonates, bivalves, and pore fluids were performed on samples collected from seep fields along the Queen Charlotte Fault, a right lateral transform boundary that separates the Pacific and North American tectonic plates. Samples were collected using grab samplers and piston cores, and were collected during three different research cruises in 2011, 2015, and 2017.
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In the southwestern New Jersey Coastal Plain, four drill holes contain continuous neritic sedimentation across the Paleocene/Eocene boundary (calcareous nannofossil Zone NP 9/NP 10 boundary). Significant lithologic and biotic changes occur in these strata near the top of the Paleocene. Global warming, increased precipitation, and other oceanographic and climatic events that have been recognized in high-latitude, deep-oceanic deposits of the latest Paleocene also influenced mid-latitude, shallow-marine, and terrestrial environments of the western North Atlantic. The diverse, well-preserved calcareous nannofossil flora that is present throughout the entire New Jersey boundary section accurately places these events...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The Cenozoic record of the Lomonosov Ridge (central Arctic Ocean) recovered during Integrated Ocean Drilling Program (IODP) Expedition 302 revealed an unexpected 26 Ma hiatus, separating middle Eocene (???44.4 Ma) from lower Miocene sediments (???18.2 Ma). To elucidate the nature of this unconformity, we performed a multiproxy palynological (dinoflagellate cysts, pollen, and spores), micropaleontological (siliceous microfossils), inorganic, and organic (Tetra Ether Index of lipids with 86 carbon atoms (TEX86) and Branched and Isoprenoid Tetraether (BIT)) geochemical analysis of the sediments from ???5 m below to ???7 m above the hiatus. Four main paleoenvironmental. phases (A-D) are recognized in the sediments encompassing...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Detailed planktonic foraminiferal biostratigraphy from eight measured sections of Cretaceous limestone near Laytonville, California, indicates a composite sequence that extends in age from late Albian to early Turonian. The sequence contains seven biozones and two subzones. Unequivocal biostratigraphic facing directions show four sections are right side up and four are reversed, and confirm the stratigraphic polarity employed in the paleomagnetic studies of Alvarez et al. (1980) and Tarduno et al. (1986). We propose that this complex of biogenic and lithogenic patterns records transit via oceanic plate motion from a depositional site in the southern part of the paleoequatorial zone of high productivity to the central...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The North American monsoon (NAM), an onshore wind shift occurring between July and September, has evolved in character during the Holocene largely due to changes in Northern Hemisphere insolation. Published paleoproxy and modeling studies suggest that prior to ∼8000 cal years BP, the NAM affected a broader region than today, extending westward into the Mojave Desert of California. Holocene proxy SST records from the Gulf of California (GoC) and the adjacent Pacific provide constraints for this changing NAM climatology. Prior to ∼8000 cal years BP, lower GoC SSTs would not have fueled northward surges of tropical moisture up the GoC, which presently contribute most of the monsoon precipitation to the western NAM...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The application of radiogenic isotopes to the study of Cenozoic circulation patterns in the South Pacific Ocean has been hampered by the fact that records from only equatorial Pacific deep water have been available. We present new Pb and Nd isotope time series for two ferromanganese crusts that grew from equatorial Pacific bottom water (D137-01, "Nova," 7219 m water depth) and southwest Pacific deep water (63KD, "Tasman," 1700 m water depth). The crusts were dated using 10Be/9Be ratios combined with constant Co-flux dating and yield time series for the past 38 and 23 Myr, respectively. The surface Nd and Pb isotope distributions are consistent with the present-day circulation pattern, and therefore the new records...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The sensitivity of the tropics to climate change, particularly the amplitude of glacial-to-interglacial changes in sea surface temperature (SST), is one of the great controversies in paleoclimatology. Here we reassess faunal estimates of ice age SSTs, focusing on the problem of no-analog planktonic foraminiferal assemblages in the equatorial oceans that confounds both classical transfer function and modern analog methods. A new calibration strategy developed here, which uses past variability of species to define robust faunal assemblages, solves the no-analog problem and reveals ice age cooling of 5??to 6??C in the equatorial current systems of the Atlantic and eastern Pacific Oceans. Classical transfer functions...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Although climate records from several locations around the world show nearly synchronous and abrupt changes, the nature of the inferred teleconnection is still poorly understood. On the basis of preserved laminations and molybdenum enrichments in open margin sediments we demonstrate that the oxygen content of northeast Pacific waters at 800 m depth during the Bölling-Alleröd warm period (15–13 kyr) was greatly reduced. Existing oxygen isotopic records of benthic and planktonic foraminifera suggest that this was probably due to suppressed ventilation at higher latitudes of the North Pacific. Comparison with ventilation records for the North Atlantic indicates an antiphased pattern of convection relative to the North...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Multiple paleoceanographic proxies in a zonal transect across the California Current near 42°N record modern and last glacial maximum (LGM) thermal and nutrient gradients. The offshore thermal gradient, derived from foraminiferal species assemblages and oxygen isotope data, was similar at the LGM to that at present (warmer offshore), but average temperatures were 3.3° ±1.5°C colder. Observed gradients require that the sites remained under the southward flow of the California Current, and thus that the polar front remained north of 42°N during the LGM. Carbon isotopic and foraminiferal flux data suggests enhanced nutrients and productivity of foraminfera in the northern California Current up to 650 km offshore. In...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The intensity of North Atlantic Deep Water (NADW) production has been one of the most important parameters controlling the global thermohaline ocean circulation system and climate. Here we present a new approach to reconstruct the overall strength of NADW export from the North Atlantic to the Southern Ocean over the past 14 Myr applying the deep water Nd and Pb isotope composition as recorded by ferromanganese crusts and nodules. We present the first long-term Nd and Pb isotope time series for deep Southern Ocean water masses, which are compared with previously published time series for NADW from the NW Atlantic Ocean. These data suggest a continuous and strong export of NADW, or a precursor of it, into the Southern...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The present upper water mass of the northeastern Pacific Ocean off California has a well-developed oxygen minimum zone between 600 and 1200 m wherein concentrations of dissolved oxygen are less than 0.5 mL/L. Even at such low concentrations of dissolved oxygen, benthic burrowing organisms are abundant enough to thoroughly bioturbate the surface and near-surface sediments. These macro organisms, together with micro organisms, also consume large quantities of organic carbon produced by large seasonal stocks of plankton in the overlying surface waters, which are supported by high concentrations of nutrients within the California Current upwelling system. In contrast to modern conditions of bioturbation, laminated sediments...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Proxy records from two piston cores in the Gulf of Mexico (GOM) provide a detailed (50-100 year resolution) record of climate variability over the last 14,000 years. Long-term (millennial-scale) trends and changes are related to the transition from glacial to interglacial conditions and movement of the average position of the Intertropical Convergence Zone (ITCZ) related to orbital forcing. The ??18O of the surface-dwelling planktic foraminifer Globigerinoides ruber show negative excursions between 14 and 10.2 ka (radiocarbon years) that reflect influx of meltwater into the western GOM during melting of the Laurentide Ice Sheet. The relative abundance of the planktic foraminifer Globigerinoides sacculifer is related...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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Biogenic opal, organic carbon, organic matter stable isotope, and trace metal data from a well-dated, high-resolution jumbo piston core (EW0408–85JC; 59° 33.3′N, 144° 9.21′W, 682 m water depth) recovered from the northern Gulf of Alaska continental slope reveal changes in productivity and nutrient utilization over the last 17,000 years. Maximum values of opal concentration (∼10%) occur during the deglacial Bølling-Allerød (B-A) interval and earliest Holocene (11.2 to 10.8 cal ka BP), moderate values (∼6%) occur during the Younger Dryas (13.0 to 11.2 cal ka BP) and Holocene, and minimum values (∼3.5%) occur during the Late Glacial Interval (LGI). When converted to opal mass accumulation rates, the highest values...
Categories: Publication; Types: Citation; Tags: Paleoceanography
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The Marine Isotope Stage 16–15 boundary (Termination VII) is the first deglacial warming step of the late Quaternary following the mid-Pleistocene transition (MPT), when 41 kyr climatic cycles shifted to strong 100 kyr cycles. The detailed structure of this important climatic event has remained unknown until now. Core MV0508-19JPC from Santa Barbara Basin, California, contains a decadal-scale climatic and geochemical sediment record of 4000 years duration that includes the early part of this deglacial episode. This record reveals that the climatic shift during the early deglacial occurred rapidly (<700 years), in a progression of three abrupt warming steps. The onset of Marine Isotope Stage (MIS) 15 was remarkably...
Categories: Publication; Types: Citation; Tags: Paleoceanography


map background search result map search result map Productivity and sedimentary δ<sup>15</sup>N variability for the last 17,000 years along the northern Gulf of Alaska continental slope Response of the North American monsoon to regional changes in ocean surface temperature Geochemical analysis of seeps along the Queen Charlotte Fault Geochemical analysis of seeps along the Queen Charlotte Fault Response of the North American monsoon to regional changes in ocean surface temperature Productivity and sedimentary δ<sup>15</sup>N variability for the last 17,000 years along the northern Gulf of Alaska continental slope