Relative Paleointensity Record of Integrated Ocean Drilling Program Site U1396 in the Caribbean Sea: Geomagnetic and Chronostratigraphic Observations in the Pliocene

Author(s):  
R.G Hatfield ◽  
J.S Stoner ◽  
A.J Fraass
2011 ◽  
Vol 12 ◽  
pp. 15-23 ◽  
Author(s):  
C. Escutia ◽  
H. Brinkhuis ◽  
A. Klaus ◽  

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>


2012 ◽  
Vol 13 ◽  
pp. 28-34 ◽  
Author(s):  
D. A. H. Teagle ◽  
B. Ildefonse ◽  
P. Blum ◽  

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>


2020 ◽  
Author(s):  
Rachel Brown ◽  
Thomas Chalk ◽  
Paul Wilson ◽  
Eelco Rohling ◽  
Gavin Foster

&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;


Geosphere ◽  
2013 ◽  
Vol 9 (4) ◽  
pp. 1009-1024 ◽  
Author(s):  
Johanna Lofi ◽  
Jennifer Inwood ◽  
Jean-Noël Proust ◽  
Donald H. Monteverde ◽  
Didier Loggia ◽  
...  

2008 ◽  
Vol 23 (1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Thomas M. Cronin ◽  
Shannon A. Smith ◽  
Frédérique Eynaud ◽  
Matthew O'Regan ◽  
John King

2014 ◽  
Vol 80 (19) ◽  
pp. 6126-6135 ◽  
Author(s):  
Katsunori Yanagawa ◽  
Anja Breuker ◽  
Axel Schippers ◽  
Manabu Nishizawa ◽  
Akira Ijiri ◽  
...  

ABSTRACTThe impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of theChloroflexiand deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group IThaumarchaeotadominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments.


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