Cenozoic mass accumulation rates in the equatorial Pacific based on high-resolution mineralogy of Ocean Drilling Program Leg 199

2004 ◽  
Vol 19 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
Michael D. Vanden Berg ◽  
Richard D. Jarrard
Keyword(s):  
High Resolution ◽  
Equatorial Pacific ◽  
Accumulation Rates ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Mass Accumulation Rates ◽  
Mass Accumulation

scholarly journals Late Miocene to Holocene high-resolution eastern equatorial Pacific carbonate records: stratigraphy linked by dissolution and paleoproductivity

2019 ◽  
Vol 15 (5) ◽  
pp. 1715-1739 ◽  
Author(s):  
Mitchell Lyle ◽  
Anna Joy Drury ◽  
Jun Tian ◽  
Roy Wilkens ◽  
Thomas Westerhold
Keyword(s):  
High Resolution ◽  
Primary Production ◽  
Late Miocene ◽  
Equatorial Pacific ◽  
Ocean Drilling Program ◽  
Regional Patterns ◽  
Ocean Drilling ◽  
Eastern Equatorial Pacific ◽  
Compensation Depth ◽  
Carbonate Compensation Depth

Abstract. Coherent variation in CaCO3 burial is a feature of the Cenozoic eastern equatorial Pacific. Nevertheless, there has been a long-standing ambiguity in whether changes in CaCO3 dissolution or changes in equatorial primary production might cause the variability. Since productivity and dissolution leave distinctive regional signals, a regional synthesis of data using updated age models and high-resolution stratigraphic correlation is an important constraint to distinguish between dissolution and production as factors that cause low CaCO3. Furthermore, the new chronostratigraphy is an important foundation for future paleoceanographic studies. The ability to distinguish between primary production and dissolution is also important to establish a regional carbonate compensation depth (CCD). We report late Miocene to Holocene time series of XRF-derived (X-ray fluorescence) bulk sediment composition and mass accumulation rates (MARs) from eastern equatorial Pacific Integrated Ocean Drilling Program (IODP) sites U1335, U1337, and U1338 and Ocean Drilling Program (ODP) site 849, and we also report bulk-density-derived CaCO3 MARs at ODP sites 848, 850, and 851. We use physical properties, XRF bulk chemical scans, and images along with available chronostratigraphy to intercorrelate records in depth space. We then apply a new equatorial Pacific age model to create correlated age records for the last 8 Myr with resolutions of 1–2 kyr. Large magnitude changes in CaCO3 and bio-SiO2 (biogenic opal) MARs occurred within that time period but clay deposition has remained relatively constant, indicating that changes in Fe deposition from dust is only a secondary feedback to equatorial productivity. Because clay deposition is relatively constant, ratios of CaCO3 % or biogenic SiO2 % to clay emulate changes in biogenic MAR. We define five major Pliocene–Pleistocene low CaCO3 % (PPLC) intervals since 5.3 Ma. Two were caused primarily by high bio-SiO2 burial that diluted CaCO3 (PPLC-2, 1685–2135 ka, and PPLC-5, 4465–4737 ka), while three were caused by enhanced dissolution of CaCO3 (PPLC-1, 51–402 ka, PPLC-3, 2248–2684 ka, and PPLC-4, 2915–4093 ka). Regional patterns of CaCO3 % minima can distinguish between low CaCO3 caused by high diatom bio-SiO2 dilution versus lows caused by high CaCO3 dissolution. CaCO3 dissolution can be confirmed through scanning XRF measurements of Ba. High diatom production causes lowest CaCO3 % within the equatorial high productivity zone, while higher dissolution causes lowest CaCO3 percent at higher latitudes where CaCO3 production is lower. The two diatom production intervals, PPLC-2 and PPLC-5, have different geographic footprints from each other because of regional changes in eastern Pacific nutrient storage after the closure of the Central American Seaway. Because of the regional variability in carbonate production and sedimentation, the carbonate compensation depth (CCD) approach is only useful to examine large changes in CaCO3 dissolution.

scholarly journals Quartz OSL dating of late quaternary Chinese and Serbian loess: A cross Eurasian comparison of dust mass accumulation rates

2019 ◽  
Vol 502 ◽  
pp. 30-44 ◽  
Author(s):  
Zoran Perić ◽  
Emma Lagerbäck Adolphi ◽  
Thomas Stevens ◽  
Gábor Újvári ◽  
Christian Zeeden ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Osl Dating ◽  
Accumulation Rates ◽  
Dust Mass ◽  
Mass Accumulation Rates ◽  
Mass Accumulation

Late Neogene–Quaternary Planktic Foraminiferal Biostratigraphy and Biochronology from ODP Site 807A, Ontong Java Plateau, Western Equatorial Pacific

2020 ◽  
Vol 50 (2) ◽  
pp. 111-127
Author(s):  
Tushar Kaushik ◽  
Ashutosh Kumar Singh ◽  
Devesh Kumar Sinha
Keyword(s):  
Equatorial Pacific ◽  
Ocean Drilling Program ◽  
Ontong Java Plateau ◽  
Faunal Turnover ◽  
Ocean Drilling ◽  
Late Neogene ◽  
Western Equatorial Pacific ◽  
Globorotalia Truncatulinoides ◽  
Oceanographic Conditions ◽  
Foraminiferal Biostratigraphy

ABSTRACT A biostratigraphic and biochronological study from the late Neogene–Quaternary section of Ocean Drilling Program (ODP) Site 807A, located on the Ontong Java Plateau, western equatorial Pacific, revealed 50 planktic foraminiferal events, enabling the identification of eight late Neogene–Quaternary biozones, from the Globorotalia plesiotumida Interval Zone to the Globorotalia truncatulinoides Interval Zone. A significant faunal turnover (17 events) from late Pliocene identified in cores 7 and 8, between 70 and 55 meters below seafloor (mbsf), and spanning 0.67 million years (Myr). This noteworthy turnover may be the result of a shift in oceanographic conditions pertaining to the closure of the Indo–Pacific Seaway, followed by the Northern Hemisphere Glaciation. This study provides a high resolution biostratigraphic and biochronological framework for ODP Site 807A that will aid in correlation and timing the various paleoceanographic changes over the last 6 million years in the western equatorial Pacific.

scholarly journals Phosphorus burial in the ocean over glacial-interglacial time scales

2009 ◽  
Vol 6 (4) ◽  
pp. 501-513 ◽  
Author(s):  
F. Tamburini ◽  
K. B. Föllmi
Keyword(s):  
Primary Productivity ◽  
Deep Sea ◽  
Interglacial Period ◽  
Accumulation Rates ◽  
The World ◽  
Mass Accumulation Rates ◽  
Mass Accumulation ◽  
Selection Of ◽  
The Last Glacial

Abstract. The role of nutrients, such as phosphorus (P), and their impact on primary productivity and the fluctuations in atmospheric CO2 over glacial-interglacial periods are intensely debated. Suggestions as to the importance of P evolved from an earlier proposal that P actively participated in changing productivity rates and therefore climate change, to most recent ones that changes in the glacial ocean inventory of phosphorus were important but not influential if compared to other macronutrients, such as nitrate. Using new data coming from a selection of ODP sites, we analyzed the distribution of oceanic P sedimentary phases and calculate reactive P burial fluxes, and we show how P burial fluxes changed over the last glacial-interglacial period at these sites. Concentrations of reactive P are generally lower during glacial times, while mass accumulation rates (MAR) of reactive P show higher variability. If we extrapolate for the analyzed sites, we may assume that in general glacial burial fluxes of reactive P are lower than those during interglacial periods by about 8%, because the lack of burial of reactive P on the glacial shelf reduced in size, was apparently not compensated by burial in other regions of the ocean. Using the calculated changes in P burial, we evaluate their possible impact on the phosphate inventory in the world oceans. Using a simple mathematical approach, we find that these changes alone could have increased the phosphate inventory of glacial ocean waters by 17–40% compared to interglacial stages. Variations in the distribution of sedimentary P phases at the investigated sites seem to indicate that at the onset of interglacial stages, shallower sites experienced an increase in reactive P concentrations, which seems to point to P-richer waters at glacial terminations. All these findings would support the Shelf-Nutrient Hypothesis, which assumes that during glacial low stands nutrients are transferred from shallow sites to deep sea with possible feedback on the carbon cycle.

High resolution CO2 record of the great Plio-Pleistocene glaciations using boron isotopes

2020 ◽  
Author(s):  
Rachel Brown ◽  
Thomas Chalk ◽  
Paul Wilson ◽  
Eelco Rohling ◽  
Gavin Foster
Keyword(s):  
High Resolution ◽  
Northern Hemisphere ◽  
Large Scale ◽  
Boron Isotope ◽  
Ocean Drilling Program ◽  
Proxy Record ◽  
Ocean Drilling ◽  
Integrated Ocean Drilling Program ◽  
Great Transition ◽  
Adequate Test

<p>The intensification of Northern Hemisphere glaciation (iNHG) at 3.4-2.5 million years ago (Ma) represents the last great transition in Cenozoic climate state with the development of large scale ice sheets in the Northern Hemisphere that waxed and waned with changes in insolation. Declining atmospheric CO<sub>2</sub> levels are widely suggested to have been the main cause of iNHG but the CO<sub>2</sub> proxy record is too poorly resolved to provide an adequate test of this hypothesis. The boron isotope-pH proxy, in particular, has shown promise when it comes to accurately estimating past CO<sub>2</sub> concentrations and is very good at reconstructing relative changes in CO<sub>2</sub> on orbital timescales. Here we present a new orbitally resolved record of atmospheric CO<sub>2 </sub>(1 sample per 3 kyr) change from Integrated Ocean Drilling Program Site 999 (12.74˚N, -78.74 ˚E) spanning ~2.6–2.4 Ma based on the boron isotope (δ<sup>11</sup>B) composition of planktic foraminiferal calcite, <em>Globingerinoides ruber</em> (senso stricto, white).  We find that δ<sup>11</sup>B values of <em>G. ruber</em> show clear glacial-interglacial cycles with a magnitude that is similar to those of the Mid-Pleistocene at the same site and elsewhere.  This new high-resolution view of CO<sub>2</sub> during the first large glacial events of the Pleistocene confirms the importance of CO<sub>2</sub> in amplifying orbital forcing of climate and offers new insights into the mechanistic drivers of natural CO<sub>2</sub> change. </p>

scholarly journals Twelve thousand years of dust: the Holocene global dust cycle constrained by natural archives

2014 ◽  
Vol 10 (6) ◽  
pp. 4277-4363 ◽  
Author(s):  
S. Albani ◽  
N. M. Mahowald ◽  
G. Winckler ◽  
R. F. Anderson ◽  
L. I. Bradtmiller ◽  
...  
Keyword(s):  
North Atlantic ◽  
Accumulation Rates ◽  
Dust Deposition ◽  
The Holocene ◽  
The North ◽  
Dust Mass ◽  
The North Atlantic ◽  
Mass Accumulation Rates ◽  
Mass Accumulation ◽  
Natural Archives

Abstract. Mineral dust plays an important role in the climate system by interacting with radiation, clouds, and biogeochemical cycles. In addition, natural archives show that the dust cycle experienced variability in the past in response to global and local climate change. The compilation of the DIRTMAP paleodust datasets in the last two decades provided a target for paleoclimate models that include the dust cycle, following a time slice approach. We propose an innovative framework to organize a paleodust dataset that moves on from the positive experience of DIRTMAP and takes into account new scientific challenges, by providing a concise and accessible dataset of temporally resolved records of dust mass accumulation rates and particle grain-size distributions. We consider data from ice cores, marine sediments, loess/paleosol sequences, lake sediments, and peat bogs for this compilation, with a temporal focus on the Holocene period. This global compilation allows investigation of the potential, uncertainties and confidence level of dust mass accumulation rates reconstructions, and highlights the importance of dust particle size information for accurate and quantitative reconstructions of the dust cycle. After applying criteria that help to establish that the data considered represent changes in dust deposition, 43 paleodust records have been identified, with the highest density of dust deposition data occurring in the North Atlantic region. Although the temporal evolution of dust in the North Atlantic appears consistent across several cores and suggest that minimum dust fluxes are likely observed during the Early to mid-Holocene period (6000–8000 years ago), the magnitude of dust fluxes in these observations is not fully consistent, suggesting that more work needs to be done to synthesize datasets for the Holocene. Based on the data compilation, we used the Community Earth System Model to estimate the mass balance and variability of the global dust cycle during the Holocene, with dust load ranging from 17.1 to 20.5 Tg between 2000 and 10 000 years ago, and a minimum in the Early to Mid-Holocene (6000–8000 years ago).

Sign in / Sign up

Export Citation Format

Share Document