Coccolithophore and benthic foraminifera distribution patterns in the Gulf of Cadiz and Western Iberian Margin during Integrated Ocean Drilling Program (IODP) Expedition 339

2017 ◽  
Vol 170 ◽  
pp. 50-67 ◽  
Author(s):  
B. Balestra ◽  
P. Grunert ◽  
B. Ausin ◽  
D. Hodell ◽  
J-A. Flores ◽  
...  
Keyword(s):  
Benthic Foraminifera ◽  
Distribution Patterns ◽  
Gulf Of Cadiz ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Integrated Ocean Drilling Program ◽  
Gulf Of Cádiz ◽  
Iberian Margin

Global and regional geomagnetic variabilities recorded in late Quaternary sediments from the west Iberian Margin

2020 ◽  
Author(s):  
Chuang Xuan ◽  
Matthew Nichols ◽  
Joseph Stoner ◽  
Carl Richter ◽  
Gary Acton
Keyword(s):  
Time Scales ◽  
Late Quaternary ◽  
Ice Cores ◽  
Ocean Drilling Program ◽  
The West ◽  
Ocean Drilling ◽  
Integrated Ocean Drilling Program ◽  
Before And After ◽  
Lock In ◽  
Iberian Margin

<p>High-resolution palaeomagnetic records preserved in sediments (especially those that are well dated) provide valuable continuous information on past changes in Earth’s magnetic field. These data are essential for us to develop better understanding on the dynamics and causes of geomagnetic changes at various time scales. In this study, we conducted palaeomagnetic analyses on continuous u-channel samples collected from well-dated late Quaternary sediment sequences cored in the west Iberian Margin during Integrated Ocean Drilling Program (IODP) Expedition 339. Natural remanent magnetisations (NRM) as well as a suite of laboratory-induced magnetisations of the samples were measured at 1-cm interval resolution on a superconducting rock magnetometer before and after stepwise alternating field (AF) demagnetisation. NRM demagnetization data of the samples reveal a very stable and well-defined primary magnetisation component. Chronology of the studied cores is well constrained and tied to the polar ice cores as well as the absolutely dated Asian speleothem records. Average sedimentation rates of the studied cores range between ~10 cm/kyr to over 70 cm/kyr. Relative palaeointensity (RPI) records reconstructed from these sediments, when placed on the acquired age models, correlate well with other global and regional RPI records on time scales of ~10 kyr or longer. RPI features recorded at higher sedimentation rate sites appear slightly younger (a few hundreds to a couple of thousand years), possibly due to effects of the sediment magnetisation lock-in process. These Iberian Margin RPI records also show common millennial to multi-millennial scale variabilities, especially after deconvolution and correction of the lock-in induced age offset.</p>

Biogeography of benthic foraminifera in contourite drift systems

2021 ◽  
Author(s):  
Anna Saupe ◽  
Johanna Schmidt ◽  
Jassin Petersen ◽  
André Bahr ◽  
Patrick Grunert
Keyword(s):  
North Atlantic ◽  
High Latitude ◽  
Benthic Foraminifera ◽  
Distribution Patterns ◽  
Bottom Current ◽  
Data Sets ◽  
Data Set ◽  
Suspension Feeders ◽  
Gulf Of Cádiz ◽  
Iberian Margin

<div> <p><span>Benthic foraminifera colonize a wide range of marine environments, including contourite drift systems (CDS). CDS are characterized by sustained bottom currents and cover large areas on the seafloor, e.g., in the North Atlantic. Due to their high sedimentation rates, they represent fundamental archives for paleoclimatology and paleoceanography. Some studies already highlight the influence of high current velocities on assemblages of epibenthic foraminifera and suggest their applicability as a reliable proxy for bottom current reconstructions (Schönfeld, 2002; Jorissen et al., 2007 and references therein). Certain epibenthic foraminiferal species live as highly adapted opportunistic suspension feeders using elevated substrates as a unique ecological niche. Through their elevated microhabitat, they optimize the uptake of suspended food particles gaining an advantage over other epibenthic organisms. However, their application as a bottom current proxy has so far been limited to the Iberian Margin and has been barely tested outside the Gulf of Cadiz (e.g., Diz et al., 2004).</span></p> </div><div> <p><span>The present study aims to document biogeographic distribution patterns of benthic foraminifera in extended CDS from different latitudes. Two data sets from the high-latitude North Atlantic (50-62°N) are presented here. The surface samples of the first data set originate from the Björn and Gardar drifts between the Reykjanes Ridge and the Rockall Plateau south of Iceland. Deposition is primarily controlled by the Iceland Scotland Overflow Water. The second data set is located further west within the Eirik Drift on the southern slope of the Greenland margin. The main controlling water mass is the Deep Western Boundary Current.</span></p> </div><div> <p><span>Initial results show that epibenthic species dominate over infaunal taxa. The data set is mainly determined by the tubular agglutinated species <em>Rhabdammina abyssorum</em>, <em>Saccorhiza ramosa</em>, and <em>Rhizammina algaeformis</em>, as well as hyaline forms such as <em>Hoeglundina elegans</em>, <em>Cibicidoides wuellerstorfi</em>, and <em>Cibicides refulgens</em>. </span><span>Thus, several different suspension-feeding taxa dominate the data set. Three assemblages of benthic foraminifera are distinguished: agglutinated suspension feeders dominating in more clayey environments, hyaline suspension feeders dominating in sandier environments with increased current velocities, and infaunal detritus feeders dominating below 2000 m water depth.</span></p> </div><div> <p><span>The presented data sets are currently complemented by samples from the Campos drift on the Brazilian margin (10°-22°S). Together, the low, mid and high latitude data sets will improve our understanding of biogeographic distribution patterns of benthic foraminifera in CDS. The expected results will be fundamental to ensure the applicability of foraminifera-based proxy methods for bottom current reconstruction.</span></p> </div><div> <p><strong><span>References</span></strong></p> </div><div> <p><span>Diz, P., Guillermo, F., Costas, S., Souto, C., Alejo, I., 2004. Distribution of benthic foraminifera in coarse sediments, Ria de Vigo, NW Iberian Margin. </span>J. Foraminifer. Res. 34, 258–275. https://doi.org/10.2113/34.4.258</p> </div><div> <p>Jorissen, F.J., Fontanier, C., Thomas, E., 2007. <span>Paleoceanographical proxies based on deep-sea benthic foraminiferal assemblage characteristics, in: Hillaire-Marcel, C., de Vernal, A. (Eds.), Proxies in Late Cenozoic Paleoceanography: Pt. 2: Biological Tracers and Biomarkers. pp. 263–325. https://doi.org/10.1016/S1572-5480(07)01012-3</span></p> </div><div><span>Schönfeld, J., 2002. Recent benthic foraminiferal assemblages in deep high-energy environments from the Gulf of Cadiz (Spain). </span></div><p>Mar. Micropaleontol. 44, 141–162. https://doi.org/10.1016/S0377-8398(01)00039-1</p>

scholarly journals IODP Expedition 318: From Greenhouse to Icehouse at the Wilkes Land Antarctic Margin

2011 ◽  
Vol 12 ◽  
pp. 15-23 ◽  
Author(s):  
C. Escutia ◽  
H. Brinkhuis ◽  
A. Klaus ◽  
Keyword(s):  
Middle Eocene ◽  
Second Phase ◽  
Last Deglaciation ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Integrated Ocean Drilling Program ◽  
Tectonic History ◽  
Wilkes Land ◽  
History Of

Integrated Ocean Drilling Program (IODP) Expedition 318, Wilkes Land Glacial History, drilled a transect of sites across the Wilkes Land margin of Antarctica to provide a long-term record of the sedimentary archives of Cenozoic Antarctic glaciation and its intimate relationships with global climatic and oceanographic change. The Wilkes Land drilling program was undertaken to constrain the age, nature, and paleoenvironment of the previously only seismically inferred glacial sequences. The expedition (January–March 2010) recovered ~2000 meters of high-quality middle Eocene–Holocene sediments from water depths between 400 m and 4000 m at four sites on the Wilkes Land rise (U1355, U1356, U1359, and U1361) and three sites on the Wilkes Land shelf (U1357, U1358, and U1360). <br><br> These records span ~53 million years of Antarctic history, and the various seismic units (WL-S4–WL-S9) have been successfully dated. The cores reveal the history of the Wilkes Land Antarctic margin from an ice-free “greenhouse” Antarctica, to the first cooling, to the onset and erosional consequences of the first glaciation and the subsequent dynamics of the waxing and waning ice sheets, all the way to thick, unprecedented "tree ring style" records with seasonal resolution of the last deglaciation that began ~10,000 y ago. The cores also reveal details of the tectonic history of the Australo-Antarctic Gulf from 53 Ma, portraying the onset of the second phase of rifting between Australia and Antarctica, to ever-subsiding margins and deepening, to the present continental and ever-widening ocean/continent configuration. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.12.02.2011" target="_blank">10.2204/iodp.sd.12.02.2011</a>

scholarly journals IODP Expedition 335: Deep Sampling in ODP Hole 1256D

2012 ◽  
Vol 13 ◽  
pp. 28-34 ◽  
Author(s):  
D. A. H. Teagle ◽  
B. Ildefonse ◽  
P. Blum ◽  
Keyword(s):  
Theoretical Models ◽  
Spreading Rate ◽  
Ocean Crust ◽  
Ocean Drilling Program ◽  
Drill Cuttings ◽  
Ocean Drilling ◽  
Ocean Ridges ◽  
Integrated Ocean Drilling Program ◽  
Geological Conditions ◽  
Ocean Lithosphere

Observations of the gabbroic layers of untectonized ocean crust are essential to test theoretical models of the accretion of new crust at mid-ocean ridges. Integrated Ocean Drilling Program (IODP) Expedition 335 ("Superfast Spreading Rate Crust 4") returned to Ocean Drilling Program (ODP) Hole 1256D with the intention of deepening this reference penetration of intact ocean crust a significant distance (~350 m) into cumulate gabbros. Three earlier cruises to Hole 1256D (ODP 206, IODP 309/312) have drilled through the sediments, lavas, and dikes and 100 m into a complex dike-gabbro transition zone. <br><br> Operations on IODP Expedition 335 proved challenging throughout, with almost three weeks spent re-opening and securing unstable sections of the hole. When coring commenced, the comprehensive destruction of the coring bit required further remedial operations to remove junk and huge volumes of accumulated drill cuttings. Hole-cleaning operations using junk baskets were successful, and they recovered large irregular samples that document a hitherto unseen sequence of evolving geological conditions and the intimate coupling between temporally and spatially intercalated intrusive, hydrothermal, contact-metamorphic, partial melting, and retrogressive processes. <br><br> Hole 1256D is now clean of junk, and it has been thoroughly cleared of the drill cuttings that hampered operations during this and previous expeditions. At the end of Expedition 335, we briefly resumed coring before undertaking cementing operations to secure problematic intervals. To ensure the greatest scientific return from the huge efforts to stabilize this primary ocean lithosphere reference site, it would be prudent to resume the deepening of Hole 1256D in the nearest possible future while it is open to full depth. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.13.04.2011" target="_blank">10.2204/iodp.sd.13.04.2011</a>

scholarly journals How deep does sand deposits in the Alentejo basin (Gulf of Cadiz) reach? Evaluating slope stability from bottom-current activities through time

2020 ◽  
Author(s):  
Davide Mencaroni ◽  
Roger Urgeles ◽  
Jonathan Ford ◽  
Jaume Llopart ◽  
Cristina Sànchez Serra ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Sediment Supply ◽  
Excess Pore Pressure ◽  
Bottom Current ◽  
Gulf Of Cadiz ◽  
Strait Of Gibraltar ◽  
Gulf Of Cádiz ◽  
The Stability ◽  
Iberian Margin ◽  
Excess Pore

&lt;p&gt;Contourite deposits are generated by the interplay between deepwater bottom-currents, sediment supply and seafloor topography. The Gulf of Cadiz, in the Southwest Iberian margin, is a famous example of extensive contourite deposition driven by the Mediterranean Outflow Water (MOW), which exits the Strait of Gibraltar, flows northward following the coastline and distributes the sediments coming from the Guadalquivir and Guadiana rivers. The MOW and related contourite deposits affect the stability of the SW Iberian margin in several ways: on one hand it increases the sedimentation rate, favoring the development of excess pore pressure, while on the other hand, by depositing sand it allows pore water pressure to dissipate, potentially increasing the stability of the slope.&lt;/p&gt;&lt;p&gt;In the Gulf of Cadiz, grain size distribution of contourite deposits is influenced by the seafloor morphology, which splits the MOW in different branches, and by the alternation of glacial and interglacial periods that affected the MOW hydrodynamic regimes. Fine clay packages alternates with clean sand formations according to the capacity of transport of the bottom-current in a specific area. Generally speaking, coarser deposits are found in the areas of higher MOW flow energy, such as in the shallower part of the slope or in the area closer to the Strait of Gibraltar, while at higher water depths the sedimentation shifts to progressively finer grain sizes as the MOW gets weaker. Previous works show that at present-day the MOW flows at a maximum depth of 1400 m, while during glacial periods the bottom-current could have reached higher depths.&lt;/p&gt;&lt;p&gt;In this study we derived the different maximum depths at which the MOW flowed by analyzing the distribution of sands at different depths along the Alentejo basin slope, in the Northern sector of the Gulf of Cadiz.&lt;/p&gt;&lt;p&gt;Here we show how changes in sand distribution along slope, within the stratigraphic units deposited between the Neogene and the present day, are driven by glacial &amp;#8211; interglacial period alternation that influenced the hydrodynamic regime of the MOW.&lt;/p&gt;&lt;p&gt;By deriving the depositional history of sand in the Alentejo basin, we are able to correlate directly the influence that climatic cycles had on the MOW activity. Furthermore, by interpreting new multi-channel seismic profiles we have been able to derive a detailed facies characterization of the uppermost part of the Gulf of Cadiz.&lt;/p&gt;&lt;p&gt;An accurate definition of sand distribution along slope plays an important role in evaluating the stability of the slope itself, e.g. to understand if the sediments may be subjected to excess pore pressure generation. As sand distribution is a direct function of the bottom-current transport capacity, the ultimate goal of this study is to understand how climate variations can affect the stability of submarine slope by depositing contourite-related sand.&lt;/p&gt;

Abyssal benthic foraminifera in the eastern equatorial Pacific (IODP EXP 320) during the middle Eocene

2013 ◽  
Vol 87 (6) ◽  
pp. 1160-1185 ◽  
Author(s):  
Hiroyuki Takata ◽  
Ritsuo Nomura ◽  
Akira Tsujimoto ◽  
Boo-Keun Khim ◽  
Ik Kyo Chung
Keyword(s):  
Water Depth ◽  
Benthic Foraminifera ◽  
Middle Eocene ◽  
Accumulation Rate ◽  
Equatorial Pacific ◽  
Equatorial Pacific Ocean ◽  
Ocean Drilling Program ◽  
Integrated Ocean Drilling Program ◽  
Eastern Equatorial Pacific ◽  
Study Interval

We report on the faunal transition of benthic foraminifera during the middle Eocene at Site U1333 (4862 m water depth, 3,560–3,720 m paleo-water depth) of Integrated Ocean Drilling Program Expedition 320 in the eastern equatorial Pacific Ocean. During the period ∼41.5–40.7 Ma, which includes carbonate accumulation event 3 (CAE-3), the benthic foraminiferal accumulation rate (BFAR) increased gradually and then it declined rapidly. In contrast, BFAR was considerably lower during ∼40.7–39.4 Ma, corresponding to the middle Eocene climatic optimum (MECO), and then it increased during ∼39.3–38.4 Ma, including CAE-4. Diversity (E [S200]) was slightly lower in the upper part of the study interval than in the lower part. The most common benthic foraminifera were Nuttallides truempyi, Oridorsalis umbonatus, and Gyroidinoides spp. in association with Globocassidulina globosa and Cibicidoides grimsdalei during the period studied. Quadrimorphina profunda occurred abundantly with N. truempyi, O. umbonatus, and G. globosa during ∼39.4–38.4 Ma, including CAE-4, although this species was also relatively common in the lower part of the study interval. Virgulinopsis navarroanus and Fursenkoina sp. A, morphologically infaunal taxa, were common during ∼38.8–38.4 Ma, corresponding to the late stage of CAE-4. Based on Q-mode cluster analysis, four sample clusters were recognized and their stratigraphic distributions were generally discriminated in the lower and upper parts of the study interval. Thus, there was only a small faunal transition in the abyssal eastern equatorial Pacific during the middle to late-middle Eocene. The faunal transition recognized in this study may be related to recovery processes following intense carbonate corrosiveness in the eastern equatorial Pacific during MECO.

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

&lt;p&gt;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&lt;sub&gt;2&lt;/sub&gt; levels are widely suggested to have been the main cause of iNHG but the CO&lt;sub&gt;2&lt;/sub&gt; 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&lt;sub&gt;2&lt;/sub&gt; concentrations and is very good at reconstructing relative changes in CO&lt;sub&gt;2&lt;/sub&gt; on orbital timescales. Here we present a new orbitally resolved record of atmospheric CO&lt;sub&gt;2 &lt;/sub&gt;(1 sample per 3 kyr) change from Integrated Ocean Drilling Program Site 999 (12.74&amp;#730;N, -78.74 &amp;#730;E) spanning ~2.6&amp;#8211;2.4&amp;#160;Ma based on the boron isotope (&amp;#948;&lt;sup&gt;11&lt;/sup&gt;B) composition of planktic foraminiferal calcite, &lt;em&gt;Globingerinoides ruber&lt;/em&gt; (senso stricto, white). &amp;#160;We find that &amp;#948;&lt;sup&gt;11&lt;/sup&gt;B values of &lt;em&gt;G. ruber&lt;/em&gt; show clear glacial-interglacial cycles with a magnitude that is similar to those of the Mid-Pleistocene at the same site and elsewhere.&amp;#160; This new high-resolution view of CO&lt;sub&gt;2&lt;/sub&gt; during the first large glacial events of the Pleistocene confirms the importance of CO&lt;sub&gt;2&lt;/sub&gt; in amplifying orbital forcing of climate and offers new insights into the mechanistic drivers of natural CO&lt;sub&gt;2&lt;/sub&gt; change.&amp;#160;&lt;/p&gt;

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