Temporal and spatial patterns of monsoonal upwelling along Arabia: A modem analogue for the interpretation of Quaternary SST anomalies

Several lines of evidence suggest that monsoonal circulation and its associated upwelling in the Arabian Sea have experienced significant fluctuations during the past 105 years. To construct an analogue model to interpret such changes, we have used the monthly average sea-surface temperature (SST) data from Hastenrath and Lamb (1979) to define the temporal and spatial pattern of upwelling along Arabia...

Site 502: Colombia Basin, Western Caribbean

Our specific objective at Site 502 was to recover an undisturbed, complete section that could be used as a Neogene and Quaternary reference section. A complete record such as this would allow intercorrelations between (1) paleomagnetic stratigraphy, (2) calcareous biostratigraphy, (3) cyclic accumulation of sediment, (4) paleoceanographic changes, (5) oxygen and carbon isotope stratigraphies, (6) the chronology of Central American volcanism, (7) the timing and effects of the emergence of the Isthmus of Panama, and (8) the timing and effects of the initiation of Northern Hemisphere glaciation

Site 503: Eastern Equatorial Pacific

Our primary objective at Site 503 (Fig. 1) was to re- cover a complete, undisturbed Neogene and Quaternary section in the eastern equatorial Pacific. Site 503 is located near Site 83 in an area that contains an almost continuous pelagic record of the past 10 m.y. (Hays et al., 1972). Unfortunately, Site 83 was only spot-cored, and the recovered sediment is so badly disturbed by rotary drilling that most of the detailed record is lost. The section has an average sedimentation rate of 2.0 to 2.5 cm/k.y. with good-to-moderate preservation of all the major microfossil groups. We returned to Site 83 to core the same section, using the Hydraulic Piston Corer (HPC) to obtain an undisturbed, continuous section for high-resolution stratigraphic studies

The orbital theory of Pleistocene climate: support from a revised chronology of the marine d18O record

https://www.researchgate.net/publication/230891291_The_Orbital_Theory_of_Pleistocene_Climate_Support_frim_a_Revised_Chronology_of_the_Marine_d18O_Recor

Interocean Exchange of Thermocline Water

Formation of North Atlantic Deep Water (NADW) represents a transfer of upper layer water to abyssal depths at a rate of 15 to 20 × 106 m3/s. NADW spreads throughout the Atlantic Ocean and is exported to the Indian and Pacific Oceans by the Antarctic Circumpolar Current and deep western boundary currents. Naturally, there must be a compensating flow of upper layer water toward the northern North Atlantic to feed NADW production. It is proposed that this return flow is accomplished primarily within the ocean's warm water thermocline layer. In this way the main thermoclines of the ocean are linked as they participate in a thermohaline-driven global scale circulation cell associated with NADW formation. The path of the return flow of warm water is as follows: Pacific to Indian flow within the Indonesian Seas, advection across the Indian Ocean in the 10°–15°S latitude belt, southward transfer in the Mozambique Channel, entry into the South Atlantic by a branch of the Agulhas Current that does not complete the retroflection pattern, northward advection within the subtropical gyre of the South Atlantic (which on balance with the southward flux of colder North Atlantic Deep Water supports the northward oceanic heat flux characteristic of the South Atlantic), and cross-equatorial flow into the western North Atlantic. The magnitude of the return flow increases along its path as more NADW is incorporated into the upper layer of the ocean. Additionally, the water mass characteristics of the return flow are gradually altered by regional ocean-atmosphere interaction and mixing processes. Within the Indonesian seas there is evidence of strong vertical mixing across the thermocline. The cold water route, Pacific to Atlantic transport of Subantarctic water within the Drake Passage, is of secondary importance, amounting to perhaps 25% of the warm water route transport. The continuity or vigor of the warm water route is vulnerable to change not only as the thermohaline forcing in the northern North Atlantic varies but also as the larger-scale wind-driven circulation factors vary. The interocean links within the Indonesian seas and at the Agulhas retroflection may be particularly responsive to such variability. Changes in the warm water route continuity may in turn influence formation characteristics of NADW

(Table 1) Globigerinoides sacculifer oxygen and carbon isotopes at DSDP Site 68-502

The oxygen and carbon isotopic record of G. sacculifer in DSDP Holes 502 and 502B shows that the Quaternary interval is almost complete. A slight hiatus exists in the upper Matuyama chron. The d18O data show two modes of isotopic variation: depleted values and low variability in the early Quaternary (910-1660 k.y.) and enriched composition and high variability in the late Quaternary (0-730 k.y.). These data document the change in mean composition between the early and late Quaternary, which occurs about 900 k.y. ago. These two modes of d18O variation reflect the changing ice budget on the continents and imply different envelopes of sea level variation during the early and late Quaternary. The occurrence of these two modes implies that boundary conditions during the early Quaternary were significantly different from those of the late Quaternary