Ocean Drilling Program; scientific prospectus; Northwest Atlantic sediment drifts

Online Access: Get full text
http://www-odp.tamu.edu/publications/prosp/172_prs/172table.html
Author(s): Keigwin, Lloyd D.; Rio, Domenico; Acton, Gary D.
Author Affiliation(s): Primary:
Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Other:
Universita di Padova, Italy
Ocean Drilling Program, United States
Source: Scientific Prospectus, Vol.172, 67p. Publisher: Ocean Drilling Program, Texas A&M University, College Station, TX, United States. ISSN: 1058-1448
Note: In English. The reports in this series become obsolete after a cruise sails and will not be distributed. 44 refs.Scientific Prospectus No. 72
Summary: The Blake-Bahama Outer Ridge (BBOR) and Carolina Slope (CS) form the western boundary for deep- and surface-water circulation in the North Atlantic. Between the northward-flowing surface waters of the Gulf Stream and the net southerly flow of intermediate and deep waters, most of the climatically important exchanges of heat, salt, and water with other ocean basins occur in the westernmost North Atlantic. Ocean Drilling Program Leg 172 is designed to monitor changes in these water masses and their fluxes through the late Pliocene and Quaternary. Virtually all water transported by the Gulf Stream to sites of convection in the northern North Atlantic comes from the western subtropical North Atlantic. The Carolina Slope (∼1-2 km depth) underlies the axis of the Gulf Stream, as well as the shallowest component of Labrador Sea water. At depths greater than ∼2 to ∼4 km, the Blake Outer Ridge monitors changes in North Atlantic Deep Water (NADW), and the Bahama Outer Ridge (∼4 to 5 km depth) extends coverage from the deepest components of NADW to Antarctic Bottom Water (AABW). On geological time scales it is known that during cold epochs the North Atlantic switches from today's circulation mode of deep nutrient-depleted water mass production (i.e., NADW) to production of a less dense nutrient-depleted water mass at intermediate depths. A shallow component of Labrador Sea water was identified recently, which interacts with the Gulf Stream and probably controls the distribution of sediment on the Carolina Slope. This water mass may be the modern equivalent of glacial NADW. According to the "Great Ocean Conveyor" paradigm, knowledge of the history of these surface, intermediate, and deep-water masses is essential to understanding the world ocean's role in climate change. Drilling on Leg 172 will provide paleoenvironmental records for late Neogene hemipelagic sediments that are deposited at accelerated rates on western North Atlantic sediment drifts on the BBOR and CS. These two areas may represent the only sediment drift locations in the world's oceans where it is possible to conduct high-resolution paleoclimate studies through a 3500-m range of water depths. Data obtained from the gyre-center, which will be sampled at the Bermuda Rise (BR) site at a depth of ∼4.5 km, will be compared with data from sites located at deep, high-deposition-rate locations on the BBOR and CS to document late Neogene oceanographic changes in the western North Atlantic for millennial, as well as Milankovitch times scales over the entire deep and intermediate water column. In addition to geochemical and micropaleontological studies of climate change, the hemipelagic composition and high deposition rates of BBOR, CS, and BR sites will enable high resolution studies of magnetic reversals and excursions and studies of current-controlled sedimentation.
Year of Publication: 1996
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Bermuda Rise; Biostratigraphy; Blake-Bahama Outer Ridge; Cenozoic; Cores; Leg 172; Lithostratigraphy; Marine sediments; Milankovitch theory; Neogene; North Atlantic; North Atlantic Deep Water; Northwest Atlantic; Ocean Drilling Program; Ocean floors; Paleo-oceanography; Paleoclimatology; Pliocene; Quaternary; Sediments; Tertiary
Coordinates: N280000 N340000 W0570000 W0770000
Record ID: 2007086543
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.
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072 7 |a 12  |2 georeft 
100 1 |a Keigwin, Lloyd D.  |u Woods Hole Oceanographic Institution, Woods Hole, MA 
245 1 0 |a Ocean Drilling Program; scientific prospectus; Northwest Atlantic sediment drifts 
260 |a College Station, TX :   |b Ocean Drilling Program, Texas A&M University,   |c 1996 
300 |a 67 p.  |b illus., incl. 2 tables, sketch maps 
440 0 |a Scientific Prospectus  |x 1058-1448 ;  |v Vol. 172 
500 |a In English. The reports in this series become obsolete after a cruise sails and will not be distributed. 44 refs.Scientific Prospectus No. 72 
500 |a Research program: ODP Ocean Drilling Program 
500 |a Affiliation: Woods Hole Oceanographic Institution; Woods Hole, MA; USA; United States 
500 |a Affiliation: Universita di Padova; ; ITA; Italy 
500 |a Affiliation: Ocean Drilling Program; ; USA; United States 
500 |a Source note: Scientific Prospectus, Vol.172, 67p. Publisher: Ocean Drilling Program, Texas A&M University, College Station, TX, United States. ISSN: 1058-1448 
500 |a Publication type: monograph 
504 |b 44 refs. 
510 3 |a GeoRef, Copyright 2019 American Geosciences Institute. 
520 |a The Blake-Bahama Outer Ridge (BBOR) and Carolina Slope (CS) form the western boundary for deep- and surface-water circulation in the North Atlantic. Between the northward-flowing surface waters of the Gulf Stream and the net southerly flow of intermediate and deep waters, most of the climatically important exchanges of heat, salt, and water with other ocean basins occur in the westernmost North Atlantic. Ocean Drilling Program Leg 172 is designed to monitor changes in these water masses and their fluxes through the late Pliocene and Quaternary. Virtually all water transported by the Gulf Stream to sites of convection in the northern North Atlantic comes from the western subtropical North Atlantic. The Carolina Slope (∼1-2 km depth) underlies the axis of the Gulf Stream, as well as the shallowest component of Labrador Sea water. At depths greater than ∼2 to ∼4 km, the Blake Outer Ridge monitors changes in North Atlantic Deep Water (NADW), and the Bahama Outer Ridge (∼4 to 5 km depth) extends coverage from the deepest components of NADW to Antarctic Bottom Water (AABW). On geological time scales it is known that during cold epochs the North Atlantic switches from today's circulation mode of deep nutrient-depleted water mass production (i.e., NADW) to production of a less dense nutrient-depleted water mass at intermediate depths. A shallow component of Labrador Sea water was identified recently, which interacts with the Gulf Stream and probably controls the distribution of sediment on the Carolina Slope. This water mass may be the modern equivalent of glacial NADW. According to the "Great Ocean Conveyor" paradigm, knowledge of the history of these surface, intermediate, and deep-water masses is essential to understanding the world ocean's role in climate change. Drilling on Leg 172 will provide paleoenvironmental records for late Neogene hemipelagic sediments that are deposited at accelerated rates on western North Atlantic sediment drifts on the BBOR and CS. These two areas may represent the only sediment drift locations in the world's oceans where it is possible to conduct high-resolution paleoclimate studies through a 3500-m range of water depths. Data obtained from the gyre-center, which will be sampled at the Bermuda Rise (BR) site at a depth of ∼4.5 km, will be compared with data from sites located at deep, high-deposition-rate locations on the BBOR and CS to document late Neogene oceanographic changes in the western North Atlantic for millennial, as well as Milankovitch times scales over the entire deep and intermediate water column. In addition to geochemical and micropaleontological studies of climate change, the hemipelagic composition and high deposition rates of BBOR, CS, and BR sites will enable high resolution studies of magnetic reversals and excursions and studies of current-controlled sedimentation. 
650 7 |a Biostratigraphy  |2 georeft 
650 7 |a Cenozoic  |2 georeft 
650 7 |a Cores  |2 georeft 
650 7 |a Lithostratigraphy  |2 georeft 
650 7 |a Marine sediments  |2 georeft 
650 7 |a Milankovitch theory  |2 georeft 
650 7 |a Neogene  |2 georeft 
650 7 |a North Atlantic Deep Water  |2 georeft 
650 7 |a Ocean Drilling Program  |2 georeft 
650 7 |a Ocean floors  |2 georeft 
650 7 |a Paleo-oceanography  |2 georeft 
650 7 |a Paleoclimatology  |2 georeft 
650 7 |a Pliocene  |2 georeft 
650 7 |a Quaternary  |2 georeft 
650 7 |a Sediments  |2 georeft 
650 7 |a Tertiary  |2 georeft 
651 7 |a Atlantic Ocean  |2 georeft 
651 7 |a Bermuda Rise  |2 georeft 
651 7 |a Blake-Bahama Outer Ridge  |2 georeft 
651 7 |a Leg 172  |2 georeft 
651 7 |a North Atlantic  |2 georeft 
651 7 |a Northwest Atlantic  |2 georeft 
700 1 |a Rio, Domenico,  |u Universita di Padova 
700 1 |a Acton, Gary D.,  |u Ocean Drilling Program 
856 4 |u http://www-odp.tamu.edu/publications/prosp/172_prs/172table.html  |2 http