Data/hora: 27/07/2024 03:01:57

Provedor de dados: 	5	
País: 	France	
Título: 	West Pacific climate and circulation over the last 160 kyr: A palaeontological and geochemical multiproxy reconstruction within the inflow path of the Indonesian Throughflow

Klima und Zirkulation des West Pazifik während der letzten 160 000 Jahre: Eine paläontologische und geochemische Multiproxy-Rekonstruktion im Einstrombereich des Indonesischen Durchstroms	
Autores: 	Bolliet, Timothé Geoffroy.	
Data: 	2010-07-19	
Ano: 	2010	
Palavras-chave: 	West Pacific; Paleoclimate; Circulation; Indonesian Throughflow.	
Resumo: 	Understanding the Earth´s present day climate and predicting its future evolution require investigation of high resolution sedimentary archives providing critical information of past oceanic and atmospheric variability. This study is based on two continuous marine sedimentary successions (Cores MD06-3067 and MD06-3075), recovered close to Mindanao Island (Philippines). The Indo-Pacific region represents a major source of heat and moisture, which are redistributed to the high latitudes by atmospheric and oceanic circulations; thus this region is a major actor in regulating global climate. The two cores investigated in this work are located within the inflow path of the Indonesian Throughflow. This ocean current provides a critical link within the thermohaline circulation by transferring relatively cold and fresh upper water from the equatorial western Pacific to the Indian Ocean through the complex seaways of the Indonesian archipelago, in turn affecting atmospheric and oceanic circulation within the entire Pacific and Indian Oceans. Our data indicate that Core MD06-3067 (1575 m water depth) provides an essential archive of atmospheric and surface to mid-depth oceanic circulation for the western equatorial Pacific over the last 160 kyr. Paleotemperature reconstruction performed on surface and deep-dwelling species of foraminifera from this core indicates largeamplitude variations in sea surface and thermocline temperatures and major fluctuations of the upper ocean thermal contrast occurring on glacial-interglacial and suborbital timescales. These variations in upper-ocean thermal contrast are interpreted as reflecting changes in the activity of a major regional upwelling system (Mindanao Dome). Enhanced activity of the Mindanao Dome during the last glacial maximum and MIS 4 compared to MIS 6 is revealed by anomalously cold surface waters and increased productivity, indicated by coccolith and benthic foraminiferal assemblages. In contrast, high sea surface temperature resulting from episodic decreases in the activity of the dome coincide with Antarctic warm events A1-4. These fluctuations in upwelling activity appear related to latitudinal migrations of the Intertropical Convergence Zone, inducing fundamental changes in monsoonal wind regimes and oceanic circulation patterns. Oxygen and carbon stable isotopes analysis performed on benthic foraminifera from Core MD06-3067 in the open west Pacific Ocean indicate long-term influence of mid2 depth water originating from the Southern Ocean, interrupted during terminations I and II by abrupt incursions of 13C-depleted water masses coming from the North Pacific. These sudden shifts in the intermediate and deep water circulations close to Mindanao island indicate major re-organization of the latitudinal extent of the middepth water masses in the whole Pacific basin, related to glacial/interglacial climatic transitions. Comparison with stable isotope records from the deeper Core MD06-3075 (1878 m), located in the more marginal Davao Gulf, indicates a highly contrasted evolution of the mid-depth circulation at these two sites over the last termination. Lower benthic δ13C values in Core MD06-3075, particularly during MIS2, reflect poorer ventilation and/or differences in carbon export flux at this more proximal location within the Davao Gulf. There is no evident incursion of North Pacific intermediate or deep water during deglaciation, possibly due to the relative isolation of the Davao Gulf from the open Pacific Ocean and/or to different sourcing of deep and intermediate waters at this site.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	https://archimer.ifremer.fr/doc/00495/60658/64155.pdf

https://archimer.ifremer.fr/doc/00495/60658/	
Editor: 	Universitat Kiel	
Formato: 	application/pdf	
Fonte: 	info:eu-repo/semantics/openAccess

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