Tasman Front shifts and associated paleoceanographic changes during the last 250,000 years: foraminiferal evidence from the Lord Howe Rise

Kawagata, Shungo

doi:10.1016/s0377-8398(00)00058-x

Cited by 34 publications

(29 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A two-and-a-halfyear analysis of the TF position (Mulhearn, 1987) has shown that it migrates between 30 and 38 ‡S, but lies between 31 and 32.5 ‡S for over half of the year. The TF may have migrated several degrees north during Pleistocene glacial intervals (Mart| ¤-nez, 1994;Kawagata, 2001). However, its average latitudinal position in the late Neogene was probably similar to that at present because the front is strongly in£uenced by the bathymetry of the Central Tasman Basin (Heath, 1985;Uddstrom and Oien, 1999) and this has been relatively stable for at least the past 15 million years (Myr) (Hayes and Ringis, 1973;Gaina et al, 1998).…”

Section: Oceanographic Settingmentioning

confidence: 97%

Coupled productivity and carbon isotope records in the southwest Pacific Ocean during the late Miocene–early Pliocene biogenic bloom

Grant

Dickens

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

View full text Add to dashboard Cite

Biogenic components of sediment accumulated at high rates beneath frontal zones of the Indian and Pacific oceans during the late Miocene and early Pliocene. The N 13 C of bulk and foraminiferal carbonate also decreased during this time interval. Although the two observations may be causally linked, and signify a major perturbation in global biogeochemical cycling, no site beneath a frontal zone has independent records of export production and N 13 C on multiple carbonate phases across the critical interval of interest. Deep Sea Drilling Project (DSDP) site 590 lies beneath the Tasman Front (TF), an eddy-generating jetstream in the southwest Pacific Ocean. To complement previous N 13 C records of planktic and benthic foraminifera at this location, late Neogene records of CaCO 3 mass accumulation rate (MAR), Ca/Ti, Ba/Ti, Al/Ti, and of bulk carbonate and foraminiferal N 13 C were constructed at site 590. The N 13 C records include bulk sediment, bulk sediment fractions ( 6 63 Wm and 5^25 Wm), and the planktic foraminifera Globigerina bulloides, Globigerinoides sacculifer (with and without sac), and Orbulina universa. Using current time scales, CaCO 3 MARs, Ca/Ti, Al/Ti and Ba/Ti ratios are two to three times higher in upper Miocene and lower Pliocene sediment relative to overlying and underlying units. A significant decrease also occurs in all N 13 C records. All evidence indicates that enhanced export production^the 'biogenic bloom'^extended to the southwest Pacific Ocean between ca. 9 and 3.8 Ma, and this phenomenon is coupled with changes in N 13 C^the 'Chron C3AR carbon shift'. However, CaCO 3 MARs peak ca. 5 Ma whereas elemental ratios are highest ca. 6.5 Ma; foraminiferal N 13 C starts to decrease ca. 8 Ma whereas bulk carbonate N 13 C begins to drop ca. 5.6 Ma. Temporal discrepancies between the records can be explained by changes in the upwelling regime at the TF, perhaps signifying a link between changes in ocean^atmosphere circulation change and widespread primary productivity. ß

show abstract

Section: Oceanographic Settingmentioning

confidence: 97%

Coupled productivity and carbon isotope records in the southwest Pacific Ocean during the late Miocene–early Pliocene biogenic bloom

Grant

Dickens

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

View full text Add to dashboard Cite

show abstract

“…Note that, although the EAC is weaker than the AC, it is the Pacific analog of the AC. According to Martinez (1994), Kawagata (2001), Martinez et al (2002), andBostock et al (2006), there was a large northward shift of the Tasman Front (a branch of the EAC) from its present latitude of 33 • S to about 25 • S during the last glacial. Tilburg et al (2001) the latitude of the EAC separation, implying that the EAC does not separate completely from the coast.…”

Section: The Glacial-interglacial Hypothesismentioning

confidence: 99%

Agulhas ring injection into the South Atlantic during glacials and interglacials

Zharkov

Nof

2008

Ocean Sci.

View full text Add to dashboard Cite

Abstract. Recent proxies suggest that, at the end of the last glacial, there was a significant increase in the injection of Agulhas rings into the South Atlantic (SA). This brought about a dramatic increase in the salt-influx (from the Indian Ocean) into the SA helping re-start the then-collapsed meridional overturning cell (MOC), leading to the termination of the Younger Dryas (YD). Here, we propose a mechanism through which large variations in ring production take place.Using nonlinear analytical solutions for eddy shedding, we show that there are restricted possibilities for ring detachment when the coast is oriented in the north-south direction. We define a critical coastline angle below which there is rings shedding and above which there is almost no shedding. In the case of the Agulhas region, the particular shape of the African continent implies that rings can be produced only when the retroflection occurs beyond a specific latitude where the angle is critical. During glaciation, the wind stress curl (WSC) vanished at a latitude lower than that of the critical angle, which prohibited the retroflection from producing rings. When the latitude at which the WSC vanishes migrated poleward towards its present day position, the corresponding coastline angle decreased below the critical angle and allowed for a vigorous production of rings.Simple process-oriented numerical simulations (using the Bleck and Boudra model) are in satisfactory agreement with our results and enable us to affirm that, during the glacials, the behavior of the Agulhas Current (AC) was similar to that of the modern East Australian Current (EAC), for which the coastline slant is supercritical.

show abstract

“…Morley, 1989;Howard and Prell, 1992;Passlow et al, 1997;Nees et al, 1999;Kawagata, 2001). In contrast, New Zealand (Fig.…”

Section: Introductionmentioning

confidence: 96%

The effect of submerged plateaux on Pleistocene gyral circulation and sea-surface temperatures in the Southwest Pacific

Hayward

Scott

Crundwell

et al. 2008

Global and Planetary Change

View full text Add to dashboard Cite

Tasman Front shifts and associated paleoceanographic changes during the last 250,000 years: foraminiferal evidence from the Lord Howe Rise

Cited by 34 publications

References 46 publications

Coupled productivity and carbon isotope records in the southwest Pacific Ocean during the late Miocene–early Pliocene biogenic bloom

Coupled productivity and carbon isotope records in the southwest Pacific Ocean during the late Miocene–early Pliocene biogenic bloom

Agulhas ring injection into the South Atlantic during glacials and interglacials

The effect of submerged plateaux on Pleistocene gyral circulation and sea-surface temperatures in the Southwest Pacific

Contact Info

Product

Resources

About