Site U1304 Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
The objective at Integrated Ocean Drilling Program Site U1304 was to obtain a high-resolution (high sedimentation rate) Pliocene-Quaternary environmental record from a location within the central ...Atlantic ice-rafted debris (IRD) belt, at a water depth sufficient to sample North Atlantic Deep Water (NADW). A partially enclosed basin at the southern limit of the Gardar Drift just to the north of the Charlie Gibbs Fracture Zone provided a suitable location with water depth of 3024 m. This basin lies to the east of the Reykjanes Ridge on oceanic crust associated with magnetic Anomaly 5 ( similar to 10 Ma). The site is located 217 km (117 nmi) west-northwest of Deep Sea Drilling Project Site 611, drilled in 1983 on the southern rim of the Gardar Drift. The mean sedimentation rate (in the Brunhes Chron) at Site 611 was found to be 2.7 cm/k.y. The sedimentation rates at Site U1304 are greater by a factor of about six, thereby achieving the objective of recovering a high-sedimentation-rate record in deep water at the southern limit of the Gardar Drift.
Expedition 303 summary Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
Expedition 303 was designed to sample and study strategic sites that record components of North Atlantic Pliocene-Quaternary climate, including the composition and structure of surface or bottom ...waters and detrital-layer stratigraphy indicative of ice sheet instability. The sites are distributed from the mouth of the Labrador Sea (Eirik Drift and Orphan Knoll) to the central Atlantic in the region of the Charlie Gibbs Fracture Zone. The sites have important climate or paleoceanographic records, adequate sedimentation rates in the 5-20 cm/k.y. range for high-resolution studies, and the potential for stratigraphies based on relative geomagnetic paleointensity and oxygen isotope data. The sites contain distinct records of millennial-scale environmental variability (in terms of ice sheet-ocean interactions, deep circulation changes, or sea-surface conditions). They provide the requirements for developing millennial-scale stratigraphies (through geomagnetic paleointensity, oxygen isotopes, I microfossils, and regional environmental patterns). They also document the details of geomagnetic field behavior over the last few million years.
Site U1302-U1308 methods Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
At all Integrated Ocean Drilling Program (IODP) Expedition 303 sites, Global Positioning System (GPS) coordinates from precruise site surveys were used to position the vessel on site. The only ...seismic system used during the cruise was the 3.5 kHz profiler, which was monitored on the approach to each site to compare the seismic characteristics of the sediments with those from the precruise survey. Once the vessel was positioned at a site, the thrusters were lowered and a reference beacon was deployed. Although the automated stationkeeping system of the vessel usually uses GPS data, the beacon provides a backup reference in case of problems with the transmission of satellite data. The final site position was the mean position calculated from the GPS data collected over the time the site was occupied.
Site U1312-U1315 methods Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
At all Expedition 306 sites, Global Positioning System (GPS) coordinates from precruise site surveys were used to position the vessel on site. The only seismic system used during the cruise was the ...3.5 kHz profiler, which was monitored on the approach to each site to compare the seismic characteristics of the sediments with those from the precruise survey. Once the vessel was positioned at a site, the thrusters were lowered and a reference beacon was deployed. Although the automated stationkeeping system of the vessel usually uses GPS data, the beacon provides a backup reference in case of problems with the transmission of satellite data. The final site position was the mean position calculated from the GPS data collected over the time that the site was occupied.
Site U1314 Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
Integrated Ocean Drilling Program Site U1314 is located on the southern Gardar Drift in a water depth of 2820 m. Seismic data for positioning of Site U1314, including multichannel seismic profiling, ...3.5 kHz high-resolution profiling, and a SeaBeam survey, were collected during the Knorr KN166-14 cruise (principal investigator: Greg Mountain) in summer 2002. The high-quality seismic profiles indicate that Site U1314 is optimally positioned in a thick (>700 ms two-way traveltime), well-stratified sediment pile.
Site U1307 Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
Integrated Ocean Drilling Program Site U1307 is located 53 km (28 nmi) northwest of Site U1306 (Fig. F1 in the "Site 1306" chapter) in 2575 m water depth, 300 m deeper than the water depth at Site ...U1306. The objective at Site U1307 was to recover the older part of the section on the Eirik Drift below the Quaternary sections recovered at Sites U1305 and U1306. Along seismic Line 25 of the multichannel seismic (MCS) network obtained over the Eirik Drift during Knorr cruise KN166-14, the Pliocene section is accessible at penetration depths less than similar to 300 m and is therefore recoverable with the advanced piston corer (APC). The MCS profile for Line 25 indicates a series of well-developed mudwaves with axes oriented approximately northwest-southeast. The Quaternary sediment drape thins from northeast to southwest along this seismic line, bringing the Pliocene section closer to the sediment/water interface.
Expedition 306 summary Anon
Proceedings of the Integrated Ocean Drilling Program,
2005, Volume:
303 & 306
Book Chapter
Open access
The overall aim of the North Atlantic paleoceanography study of Integrated Ocean Drilling Program Expedition 306 is to place late Neogene-Quaternary climate proxies in the North Atlantic into a ...chronology based on a combination of geomagnetic paleointensity, stable isotope, and detrital layer stratigraphies, and in so doing generate integrated North Atlantic millennial-scale stratigraphies for the last few million years. To reach this aim, complete sedimentary sections were drilled by multiple advanced piston coring directly south of the central Atlantic "ice-rafted debris belt" and on the southern Gardar Drift. In addition to the North Atlantic paleoceanography study, a borehole observatory was successfully installed in a new similar to 180 m deep hole close to Ocean Drilling Program Site 642, consisting of a circulation obviation retrofit kit to seal the borehole from the overlying ocean, a thermistor string, and a data logger to document and monitor bottom water temperature variations through time.
Many applications of the Vostok ice core depend critically on the ability to make stratigraphic ties tomarine records in the adjacent Southern Ocean. Here we present oxygen isotopic records from ...highaccumulation rate sites in the South Atlantic sector of the Southern Ocean, collected for the purpose ofcomplementing the recently extended ∂D record from the Vostok ice core. The combination of severalplanktonic foraminiferal ∂18O records from northern subantarctic piston cores demonstrates that all of themillennial-scale oscillations expressed in the Vostok ice core over the last 60 ky are also present in marinerecords. The observations also support the assumption that the millennial-scale oscillations common toboth marine and ice archives are synchronous, thus providing a rationale for extending the marine-ice corecomparison through the last 400,000 years, making use of a marine drilled core (ODP Site 1089). Byaligning the phase of these common abrupt events, we anchor the Vostok chronology to an orbitally tunedmarine sediment chronology—a refinement that allows examination of a variety of paleoclimatologicalissues such as the relationship between deep ocean variability and Antarctic polar climate. For example,this exercise suggests that, over at least the 4 major deglaciation events, the primary (orbital scale) changesin the chemistry and, most likely, the temperature of the deep Southern ocean were synchronous withchanges in atmospheric pCO2 and polar air temperatures. We also find that the deuterium excess in the icecore resembles marine (foraminiferal) ∂13C records and that the deuterium excess is synchronous with an‘‘anomalous’’ foraminiferal ∂18O signal (the residual between normalized versions of Vostok ∂D andforaminiferal ∂18O). These observations demand a tight link between the Vostok isotopic record and the airseainteraction of the subantarctic zone.
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