The South Asian Monson (SAM) is one of the most intense climatic elements yet its initiation and ... more The South Asian Monson (SAM) is one of the most intense climatic elements yet its initiation and variations are not well established. Dating the deposits of SAM wind-driven currents in IODP cores from the Maldives yields an age of 12. 9 Ma indicating an abrupt SAM onset, over a short period of 300 kyrs. This coincided with the Indian Ocean Oxygen Minimum Zone expansion as revealed by geochemical tracers and the onset of upwelling reflected by the sediment's content of particulate organic matter. A weaker 'proto-monsoon' existed between 12.9 and 25 Ma, as mirrored by the sedimentary signature of dust influx. Abrupt SAM initiation favors a strong influence of climate in addition to the tectonic control, and we propose that the post Miocene Climate Optimum cooling, together with increased continentalization and establishment of the bipolar ocean circulation, i.e. the beginning of the modern world, shifted the monsoon over a threshold towards the modern system.
The seafloor is broadly divided into two regions (Emerson et al., 1985): one where sedimentary mi... more The seafloor is broadly divided into two regions (Emerson et al., 1985): one where sedimentary microbial respiration is high and oxygen (O2) penetrates only millimeters to centimeters into the sediment (Revsbech et al., 1980), and another where sedimentary respiration is low and O2 penetrates much deeper (Murray& Grundmanis, 1980; D’Hondt et al., 2011; Røy et al, 2012; Orcutt et al., 2013). Active anaerobic microbial communities persist for hundreds of meters or more in subseafloor sediment of the high-respiration region. In the low-respiration region, the existence of microbial communities is previously unknown throughout most of the sedimentary sequence (Morita & Zobell, 1955; D’Hondt et al., 2009; Røy et al., 2012). Here we show that microbial cells and aerobic respiration persist through the entire sediment sequence (to depths of at least 75 m below seafloor) throughout the vast expanse of the oligotrophic South Pacific Gyre. This sediment and underlying basalt may be continuous...
International Ocean Discovery Program (IODP) Expedition 359 is designed to address sea level, cur... more International Ocean Discovery Program (IODP) Expedition 359 is designed to address sea level, currents, and monsoon evolution in the Indian Ocean. Seven proposed drill sites are located in the Maldives and one site is located in the Kerala-Konkan Basin on the western Indian continental margin. The Maldives carbonate edifice bears a unique and mostly unread Indian Ocean archive of the evolving Cenozoic icehouse world. It has great potential to serve as a key area for better understanding the effects of this global evolution in the Indo-Pacific realm. Based mainly on seismic stratigraphic data, a model for the evolution of this carbonate bank has been developed, showing how changing sea level and ocean current patterns shaped the bank geometries. A dramatic shift in development of the carbonate edifice from a sea level–controlled to a predominantly current-controlled system is thought to be directly linked to the evolving Indian monsoon. Fluctuations in relative sea level control the ...
ABSTRACT The semi enclosed marginal sea bordered by the Eurasian continent, the Korean peninsula ... more ABSTRACT The semi enclosed marginal sea bordered by the Eurasian continent, the Korean peninsula and the Japanese Islands has an average depth of 1350 m and is connected with other marginal seas in the region by shallow and narrow straits. At present, the Tsushima Warm Current (TWC), a branch of the Kuroshio Current, is the only warm current flowing into the marginal sea west of Japan. The TWC carries both subtropical water originating from the North Pacific and fresher runoff water derived from East China Sea continental shelf. The northerly flow of the TWC through the shallow Tsushima Straits is ultimately controlled by relative sea level variations over time. IODP Expedition 346 Sites U1427 and U1428/29 are ideally located to record changes in (i) the intensity of the influx of the TWC, and (ii) the intermediate ventilation of the marginal sea over the last million years. The Japan Sea Intermediate Water (JSIW) corresponds to a vertical salinity minimum, found below the TWC, between 200 and 400-500 m water depth. The JSIW shows a relatively high oxygen concentration, related to the deep water convection in winter and linked to fresh water supply during winter monsoon intervals. Based on recent observations, it is thought during glacial and interglacial conditions, and millennial scale climate cycles the intensity of deep and intermediate water currents varied but the mechanisms of such variations are not fully known. Microfossil faunal proxies can be used for tracking bottom environmental conditions related to variability of the bottom water circulation intensity. Here, we present preliminary results obtained using ostracods (benthic microcrustaceans) that are abundant in the sedimentary sequences recovered at Sites U1427 and U1428/29, and are known to react sensitively to changes in water masses physicochemical parameters. In particular, the variability of the genus Krithe through time is correlated with the sortable silt (carbonate-free, 10–63 μm sediment size distribution) to infer current speed and bottom water ventilation.
The IODP Expedition 323 was the first expedition that successfully recovered continuous sediment ... more The IODP Expedition 323 was the first expedition that successfully recovered continuous sediment record back to 5.0 Ma in the Bering Sea. Among the seven sites drilled during this expedition, Site U1343 is situated at the Beringian slope that is proximal to the current seasonal ice-margin. According to the shipboard biostratigraphy, this site covers complete records during the last 2.1 Myrs. In addition to the long time-range recovery at this site, relatively good preservation of foraminifer shells suggest that Site U1343 is suitable for characterizing the general paleoceanographic trend during the Pleistocene using by planktic and benthic oxygen and carbon isotopic records at the Gateway to the Arctic in the Bering Sea. In order to ascertain comprehensive understanding of composite oxygen and carbon isotope records, multi-species analysis of oxygen and carbon isotope has been conducted for benthic (total of five species: Elphidium batialis, Uvigerina spp. Cibicidoides sp., Noninella labradorica, and Globobulimina pacifica) and planktic foraminfers (total of two species: Neogloboquadrina pachyderma sinistral and dextral form, and Globigerina bulloides). Their good correlations in the oxygen isotope (for benthics: r to E. batialis = 0.732 to 0.825; for planktics: r to G. bulloides = 0.956) suggest that their records can be calibrated one composite record throughout the site. The approximately 1.0 ‰ VPDB gradual increase in the composite benthic oxygen isotope records from the site bottom to the site top suggest gradual cooling trend during the last 2.1 Myrs. Notable drops in carbon isotopic values (approximately -10 ‰ VPDB) were recognized above 200m CCSF-A for both benthic and planktic foraminifers. The significant drops in the carbon isotope records are considered to be due to post depositional alteration or contamination in the shallow surface-methane transition zone (SMTZ). The formation of authigenic carbonate in the SMTZ can contaminate other biogenic carbonate such as foraminifer shells.
Microbially-mediated diagenetic processes driven by carbon mineralization were studied in the sub... more Microbially-mediated diagenetic processes driven by carbon mineralization were studied in the subseafloor sediment of the northeastern Bering Sea Slope down to a depth of 745 mbsf. The three study sites, drilled during Integrated Ocean Drilling Program (IODP) Expedition 323, are situated in the high primary productivity ``Green Belt'' region characterized by high sedimentation rates. The sequence of microbially-mediated processes in
Paleoclimate and paleoceanographic studies present opportunities to study the dynamics of the cli... more Paleoclimate and paleoceanographic studies present opportunities to study the dynamics of the climate system by examining how it responds to external forcing (e.g., greenhouse gas and solar radiation changes) and how its interacting components generate climate oscillations and abrupt changes. Of note is the amplified recent warming of the high latitudes in the Northern Hemisphere, which is presumably related to sea ice albedo feedback and teleconnections to other regions; both the behavior of sea ice–climate interactions and the role of large-scale atmospheric and oceanic circulation in climate change can be studied with geologic records of past climate change in the Bering Sea. Over the last 5 m.y., global climate has evolved from being warm with only small Northern Hemisphere glaciers to being cold with major Northern Hemisphere glaciations every 100–40 k.y. The ultimate reasons for this major transition are unknown. In addition, climate cycles on orbital and millennial timescales...
Continuous paleoceanographic records of the evolution of climate since Northern Hemisphere Glacia... more Continuous paleoceanographic records of the evolution of climate since Northern Hemisphere Glaciation (NHG) in the Bering Sea provide new insight into understanding how the north Pacific plays a role in glacial - interglacial climate cycles since 2.7Ma. IODP Site U1343 (54 ° 33.4'N, 176 ° 49.0' E, water depth 1950m) is situated at the Beringian Slope,proximal to the current seasonal sea ice margin, and is therefore a suitable location to study post NHG paleoceanographic changes. To augment the ship-board data from this site, we present orbital-scale oxygen and carbon isotope records, of both planktic and benthic foraminifers, spanning the last 2.3 Myrs. In order to construct a precise age model, a composite benthic oxygen isotope record was established using inter-species calibration of total of five benthic species (Elphidium batialis, Uvigerina spp. Cibicidoides sp., Noninella labradorica, and Globobulimina pacifica). The oxygen isotope stratigraphy converges with the ship...
ABSTRACT Integrated Ocean Drilling Program (IODP) Expedition 346 (29 July - 28 September, 2013) o... more ABSTRACT Integrated Ocean Drilling Program (IODP) Expedition 346 (29 July - 28 September, 2013) occupied a series of sites covering a depth and latitudinal range in the Japan Sea/East Sea, as well as one site in the northern East China Sea. The overall goal of the expedition was to test the hypothesis that Pliocene-Pleistocene uplift of the Himalaya and Tibetan Plateau, and the consequent emergence of the two discrete modes of Westerly Jet circulation, caused the amplification of millennial-scale variability of the East Asian summer monsoon (EASM) and East Asian winter monsoon (EAWM) and provided teleconnection mechanism(s) for Dansgaard-Oeschger cycles. The expedition's main focus is to investigate the timing of onset of orbital- and millennial-scale variability of the EASM and EAWM and their relation with variability of Westerly Jet circulation, reconstruct orbital- and millennial-scale changes in surface and deepwater circulations and surface productivity in the Japan Sea/East Sea during at least the last 5 m.y. Another expedition goal is to reconstruct the history of the Yangtze River discharge as it reflects variation and evolution in EASM and exerts an impact on the paleoceanography of the Japan Sea/East Sea. Through these studies, we hope to examine the interrelationship among the EASM, EAWM, nature and intensity of the influx through the Tsushima Strait, the intensity of winter cooling, surface productivity, ventilation, and bottom water oxygenation in the Japan Sea/East Sea and their changes during the last 5 m.y. The latitudinal transect of the Japan Sea will help monitor the behaviors of the Westerly Jet, EAWM, and the Tsushima Warm Current. The southern part of the transect is being used to reconstruct the behavior of the Subpolar Front and examine its relationship with the Westerly Jet and sea level changes, whereas the northern part of the transect is being used to identify ice-rafted debris events and reconstruct temporal variation in its southern limit. By drilling a depth transect, we aimed to reconstruct the ventilation history of the Japan Sea/East Sea and examine the relation between ventilation and the nature of the influx through the Tsushima Strait and/or the intensity of winter cooling. Drilling in the northern part of the East China Sea is helping constrain the Yangtze River discharge history that should reflect variations in EASM intensity. Preliminary data from the expedition will be presented, in the context of new results from the first ODP/IODP cruise to return to the Japan Sea/East Sea since 1989.
IODP Expedition 346 (Asian Monsoon) tested the hypothesis that Plio-Pleistocene uplift of the Him... more IODP Expedition 346 (Asian Monsoon) tested the hypothesis that Plio-Pleistocene uplift of the Himalaya and Tibetan Plateau, and/or emergence and growth of the northern hemisphere ice sheets and establishment of the two discrete modes of Westerly Jet circulation, is the cause of the millennial-scale variability of the East Asian summer monsoon (EASM) and amplification of Dansgaard-Oeschger cycles. We also examined whether the nature and strength of flow through the Tsushima Strait (which is strongly affected by EASM precipitation, sea level changes, and EAWM cooling) influenced surface and deepwater conditions of the Japan, Yamato, and Ulleung Basins. During only six weeks of drilling, Expedition 346 recovered 6135.3 m of core, which established an IODP record for the amount of recovered material. Because of recent advances in drilling technology and newly developed analytical tools, we were able to examine records that were impossible to acquire even a few years ago. The newly engine...
IODP Expedition 339 recently drilled 5 sites in the Gulf of Cádiz and 2 west off Portugal, and re... more IODP Expedition 339 recently drilled 5 sites in the Gulf of Cádiz and 2 west off Portugal, and recovered 5.5 km of core. The Gulf of Cádiz was targeted for drilling 1) to investigate the Mediterranean Outflow Water (MOW) and its influence on global circulation and climate, and 2) to understand the effects of tectonic activity and eustatic changes on evolution of the Gibraltar Gateway and margin sedimentation. During the expedition samples from surface-waters and the seafloor were collected to evaluate recent communities of foraminifers, ostracods and calcareous nannoplankton. The results will serve as an important reference for future paleoceanographic work based on the actualistic approach in the Upper Miocene-Pleistocene deposits drilled during IODP Expedition 339. Over 400 foraminiferal taxa have been identified in size fractions >125µm at six sites of IODP Expedition 339. The preliminary results show that living specimens are rare (1-5% of the assemblages), which is most like...
During IODP expedition 323 in the Bering Sea (July 5- September 4, 2009) a series of drilling (do... more During IODP expedition 323 in the Bering Sea (July 5- September 4, 2009) a series of drilling (down to 750 meters below sea floor) was realized at 7 sites localized on the Umnak plateau (U1339), on the Bowers Ridge (U1340, U1341, U1342) and on the Beringian margin (U1343, U1344, U1345) ; the oldest sediments dated at 5 Myrs were recovered
The South Asian Monson (SAM) is one of the most intense climatic elements yet its initiation and ... more The South Asian Monson (SAM) is one of the most intense climatic elements yet its initiation and variations are not well established. Dating the deposits of SAM wind-driven currents in IODP cores from the Maldives yields an age of 12. 9 Ma indicating an abrupt SAM onset, over a short period of 300 kyrs. This coincided with the Indian Ocean Oxygen Minimum Zone expansion as revealed by geochemical tracers and the onset of upwelling reflected by the sediment's content of particulate organic matter. A weaker 'proto-monsoon' existed between 12.9 and 25 Ma, as mirrored by the sedimentary signature of dust influx. Abrupt SAM initiation favors a strong influence of climate in addition to the tectonic control, and we propose that the post Miocene Climate Optimum cooling, together with increased continentalization and establishment of the bipolar ocean circulation, i.e. the beginning of the modern world, shifted the monsoon over a threshold towards the modern system.
The seafloor is broadly divided into two regions (Emerson et al., 1985): one where sedimentary mi... more The seafloor is broadly divided into two regions (Emerson et al., 1985): one where sedimentary microbial respiration is high and oxygen (O2) penetrates only millimeters to centimeters into the sediment (Revsbech et al., 1980), and another where sedimentary respiration is low and O2 penetrates much deeper (Murray& Grundmanis, 1980; D’Hondt et al., 2011; Røy et al, 2012; Orcutt et al., 2013). Active anaerobic microbial communities persist for hundreds of meters or more in subseafloor sediment of the high-respiration region. In the low-respiration region, the existence of microbial communities is previously unknown throughout most of the sedimentary sequence (Morita & Zobell, 1955; D’Hondt et al., 2009; Røy et al., 2012). Here we show that microbial cells and aerobic respiration persist through the entire sediment sequence (to depths of at least 75 m below seafloor) throughout the vast expanse of the oligotrophic South Pacific Gyre. This sediment and underlying basalt may be continuous...
International Ocean Discovery Program (IODP) Expedition 359 is designed to address sea level, cur... more International Ocean Discovery Program (IODP) Expedition 359 is designed to address sea level, currents, and monsoon evolution in the Indian Ocean. Seven proposed drill sites are located in the Maldives and one site is located in the Kerala-Konkan Basin on the western Indian continental margin. The Maldives carbonate edifice bears a unique and mostly unread Indian Ocean archive of the evolving Cenozoic icehouse world. It has great potential to serve as a key area for better understanding the effects of this global evolution in the Indo-Pacific realm. Based mainly on seismic stratigraphic data, a model for the evolution of this carbonate bank has been developed, showing how changing sea level and ocean current patterns shaped the bank geometries. A dramatic shift in development of the carbonate edifice from a sea level–controlled to a predominantly current-controlled system is thought to be directly linked to the evolving Indian monsoon. Fluctuations in relative sea level control the ...
ABSTRACT The semi enclosed marginal sea bordered by the Eurasian continent, the Korean peninsula ... more ABSTRACT The semi enclosed marginal sea bordered by the Eurasian continent, the Korean peninsula and the Japanese Islands has an average depth of 1350 m and is connected with other marginal seas in the region by shallow and narrow straits. At present, the Tsushima Warm Current (TWC), a branch of the Kuroshio Current, is the only warm current flowing into the marginal sea west of Japan. The TWC carries both subtropical water originating from the North Pacific and fresher runoff water derived from East China Sea continental shelf. The northerly flow of the TWC through the shallow Tsushima Straits is ultimately controlled by relative sea level variations over time. IODP Expedition 346 Sites U1427 and U1428/29 are ideally located to record changes in (i) the intensity of the influx of the TWC, and (ii) the intermediate ventilation of the marginal sea over the last million years. The Japan Sea Intermediate Water (JSIW) corresponds to a vertical salinity minimum, found below the TWC, between 200 and 400-500 m water depth. The JSIW shows a relatively high oxygen concentration, related to the deep water convection in winter and linked to fresh water supply during winter monsoon intervals. Based on recent observations, it is thought during glacial and interglacial conditions, and millennial scale climate cycles the intensity of deep and intermediate water currents varied but the mechanisms of such variations are not fully known. Microfossil faunal proxies can be used for tracking bottom environmental conditions related to variability of the bottom water circulation intensity. Here, we present preliminary results obtained using ostracods (benthic microcrustaceans) that are abundant in the sedimentary sequences recovered at Sites U1427 and U1428/29, and are known to react sensitively to changes in water masses physicochemical parameters. In particular, the variability of the genus Krithe through time is correlated with the sortable silt (carbonate-free, 10–63 μm sediment size distribution) to infer current speed and bottom water ventilation.
The IODP Expedition 323 was the first expedition that successfully recovered continuous sediment ... more The IODP Expedition 323 was the first expedition that successfully recovered continuous sediment record back to 5.0 Ma in the Bering Sea. Among the seven sites drilled during this expedition, Site U1343 is situated at the Beringian slope that is proximal to the current seasonal ice-margin. According to the shipboard biostratigraphy, this site covers complete records during the last 2.1 Myrs. In addition to the long time-range recovery at this site, relatively good preservation of foraminifer shells suggest that Site U1343 is suitable for characterizing the general paleoceanographic trend during the Pleistocene using by planktic and benthic oxygen and carbon isotopic records at the Gateway to the Arctic in the Bering Sea. In order to ascertain comprehensive understanding of composite oxygen and carbon isotope records, multi-species analysis of oxygen and carbon isotope has been conducted for benthic (total of five species: Elphidium batialis, Uvigerina spp. Cibicidoides sp., Noninella labradorica, and Globobulimina pacifica) and planktic foraminfers (total of two species: Neogloboquadrina pachyderma sinistral and dextral form, and Globigerina bulloides). Their good correlations in the oxygen isotope (for benthics: r to E. batialis = 0.732 to 0.825; for planktics: r to G. bulloides = 0.956) suggest that their records can be calibrated one composite record throughout the site. The approximately 1.0 ‰ VPDB gradual increase in the composite benthic oxygen isotope records from the site bottom to the site top suggest gradual cooling trend during the last 2.1 Myrs. Notable drops in carbon isotopic values (approximately -10 ‰ VPDB) were recognized above 200m CCSF-A for both benthic and planktic foraminifers. The significant drops in the carbon isotope records are considered to be due to post depositional alteration or contamination in the shallow surface-methane transition zone (SMTZ). The formation of authigenic carbonate in the SMTZ can contaminate other biogenic carbonate such as foraminifer shells.
Microbially-mediated diagenetic processes driven by carbon mineralization were studied in the sub... more Microbially-mediated diagenetic processes driven by carbon mineralization were studied in the subseafloor sediment of the northeastern Bering Sea Slope down to a depth of 745 mbsf. The three study sites, drilled during Integrated Ocean Drilling Program (IODP) Expedition 323, are situated in the high primary productivity ``Green Belt'' region characterized by high sedimentation rates. The sequence of microbially-mediated processes in
Paleoclimate and paleoceanographic studies present opportunities to study the dynamics of the cli... more Paleoclimate and paleoceanographic studies present opportunities to study the dynamics of the climate system by examining how it responds to external forcing (e.g., greenhouse gas and solar radiation changes) and how its interacting components generate climate oscillations and abrupt changes. Of note is the amplified recent warming of the high latitudes in the Northern Hemisphere, which is presumably related to sea ice albedo feedback and teleconnections to other regions; both the behavior of sea ice–climate interactions and the role of large-scale atmospheric and oceanic circulation in climate change can be studied with geologic records of past climate change in the Bering Sea. Over the last 5 m.y., global climate has evolved from being warm with only small Northern Hemisphere glaciers to being cold with major Northern Hemisphere glaciations every 100–40 k.y. The ultimate reasons for this major transition are unknown. In addition, climate cycles on orbital and millennial timescales...
Continuous paleoceanographic records of the evolution of climate since Northern Hemisphere Glacia... more Continuous paleoceanographic records of the evolution of climate since Northern Hemisphere Glaciation (NHG) in the Bering Sea provide new insight into understanding how the north Pacific plays a role in glacial - interglacial climate cycles since 2.7Ma. IODP Site U1343 (54 ° 33.4'N, 176 ° 49.0' E, water depth 1950m) is situated at the Beringian Slope,proximal to the current seasonal sea ice margin, and is therefore a suitable location to study post NHG paleoceanographic changes. To augment the ship-board data from this site, we present orbital-scale oxygen and carbon isotope records, of both planktic and benthic foraminifers, spanning the last 2.3 Myrs. In order to construct a precise age model, a composite benthic oxygen isotope record was established using inter-species calibration of total of five benthic species (Elphidium batialis, Uvigerina spp. Cibicidoides sp., Noninella labradorica, and Globobulimina pacifica). The oxygen isotope stratigraphy converges with the ship...
ABSTRACT Integrated Ocean Drilling Program (IODP) Expedition 346 (29 July - 28 September, 2013) o... more ABSTRACT Integrated Ocean Drilling Program (IODP) Expedition 346 (29 July - 28 September, 2013) occupied a series of sites covering a depth and latitudinal range in the Japan Sea/East Sea, as well as one site in the northern East China Sea. The overall goal of the expedition was to test the hypothesis that Pliocene-Pleistocene uplift of the Himalaya and Tibetan Plateau, and the consequent emergence of the two discrete modes of Westerly Jet circulation, caused the amplification of millennial-scale variability of the East Asian summer monsoon (EASM) and East Asian winter monsoon (EAWM) and provided teleconnection mechanism(s) for Dansgaard-Oeschger cycles. The expedition's main focus is to investigate the timing of onset of orbital- and millennial-scale variability of the EASM and EAWM and their relation with variability of Westerly Jet circulation, reconstruct orbital- and millennial-scale changes in surface and deepwater circulations and surface productivity in the Japan Sea/East Sea during at least the last 5 m.y. Another expedition goal is to reconstruct the history of the Yangtze River discharge as it reflects variation and evolution in EASM and exerts an impact on the paleoceanography of the Japan Sea/East Sea. Through these studies, we hope to examine the interrelationship among the EASM, EAWM, nature and intensity of the influx through the Tsushima Strait, the intensity of winter cooling, surface productivity, ventilation, and bottom water oxygenation in the Japan Sea/East Sea and their changes during the last 5 m.y. The latitudinal transect of the Japan Sea will help monitor the behaviors of the Westerly Jet, EAWM, and the Tsushima Warm Current. The southern part of the transect is being used to reconstruct the behavior of the Subpolar Front and examine its relationship with the Westerly Jet and sea level changes, whereas the northern part of the transect is being used to identify ice-rafted debris events and reconstruct temporal variation in its southern limit. By drilling a depth transect, we aimed to reconstruct the ventilation history of the Japan Sea/East Sea and examine the relation between ventilation and the nature of the influx through the Tsushima Strait and/or the intensity of winter cooling. Drilling in the northern part of the East China Sea is helping constrain the Yangtze River discharge history that should reflect variations in EASM intensity. Preliminary data from the expedition will be presented, in the context of new results from the first ODP/IODP cruise to return to the Japan Sea/East Sea since 1989.
IODP Expedition 346 (Asian Monsoon) tested the hypothesis that Plio-Pleistocene uplift of the Him... more IODP Expedition 346 (Asian Monsoon) tested the hypothesis that Plio-Pleistocene uplift of the Himalaya and Tibetan Plateau, and/or emergence and growth of the northern hemisphere ice sheets and establishment of the two discrete modes of Westerly Jet circulation, is the cause of the millennial-scale variability of the East Asian summer monsoon (EASM) and amplification of Dansgaard-Oeschger cycles. We also examined whether the nature and strength of flow through the Tsushima Strait (which is strongly affected by EASM precipitation, sea level changes, and EAWM cooling) influenced surface and deepwater conditions of the Japan, Yamato, and Ulleung Basins. During only six weeks of drilling, Expedition 346 recovered 6135.3 m of core, which established an IODP record for the amount of recovered material. Because of recent advances in drilling technology and newly developed analytical tools, we were able to examine records that were impossible to acquire even a few years ago. The newly engine...
IODP Expedition 339 recently drilled 5 sites in the Gulf of Cádiz and 2 west off Portugal, and re... more IODP Expedition 339 recently drilled 5 sites in the Gulf of Cádiz and 2 west off Portugal, and recovered 5.5 km of core. The Gulf of Cádiz was targeted for drilling 1) to investigate the Mediterranean Outflow Water (MOW) and its influence on global circulation and climate, and 2) to understand the effects of tectonic activity and eustatic changes on evolution of the Gibraltar Gateway and margin sedimentation. During the expedition samples from surface-waters and the seafloor were collected to evaluate recent communities of foraminifers, ostracods and calcareous nannoplankton. The results will serve as an important reference for future paleoceanographic work based on the actualistic approach in the Upper Miocene-Pleistocene deposits drilled during IODP Expedition 339. Over 400 foraminiferal taxa have been identified in size fractions >125µm at six sites of IODP Expedition 339. The preliminary results show that living specimens are rare (1-5% of the assemblages), which is most like...
During IODP expedition 323 in the Bering Sea (July 5- September 4, 2009) a series of drilling (do... more During IODP expedition 323 in the Bering Sea (July 5- September 4, 2009) a series of drilling (down to 750 meters below sea floor) was realized at 7 sites localized on the Umnak plateau (U1339), on the Bowers Ridge (U1340, U1341, U1342) and on the Beringian margin (U1343, U1344, U1345) ; the oldest sediments dated at 5 Myrs were recovered
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Papers by Carlos Zarikian