Investigating the trace elements contained in the coccoliths, i.e., the carbonate exoskeleton, of... more Investigating the trace elements contained in the coccoliths, i.e., the carbonate exoskeleton, of unicellular marine phytoplankton called coccolithophores, is fundamental for calibrating environmental climate proxies, which are key tools for studying past and future climate changes. To date, lab-cultivated coccolithophores have been mainly used for measuring the elements retained within the coccoliths, whereas geochemical studies in fossil records have been limited by the difficulty in isolating monospecific samples from sediments containing highly diversified fossil assemblages. Since a comparison of the geochemical data collected from both fossil and living species is fundamental for calibrating the environmental proxies, an improvement of coccolith-picking methodology should be envisaged. Here, we present a significant advancement in the isolation of fossil species-specific coccolith achieved using a hydraulic micromanipulation system together with wet samples, never applied befo...
The biogeochemical and physical processes occurring in the oceans are pivotal in controlling the ... more The biogeochemical and physical processes occurring in the oceans are pivotal in controlling the atmospheric carbon dioxide (CO 2atm) concentration. In particular, the biological pump uptakes CO 2atm through photosynthesis, whereas the carbonate pump produces CO 2 during CaCO 3
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Bio- and magnetostratigraphic age data and nannofossil assemblage analysis from ODP Site 1165 evi... more Bio- and magnetostratigraphic age data and nannofossil assemblage analysis from ODP Site 1165 evidence an anomalous warming event of the surface waters in and around Prydz Bay during the Early Pleistocene, approximately 1 Ma. This results from an increase in the abundance of nannofossils at Site 1165, that occurred at 1 Ma. Detailed high-resolution sampling permits a new bio-magnetostratigraphic interpretation for ODP Site 1165. A decrease in delta18O values at Sites 1165 and 1167 also occurs at this time, supporting the presence of warming conditions in the Prydz Bay area. A return to colder surface waters, indicated by the absence or rare occurrence of nannofossils in the upper cores from Site 1165, suggests that more stable glacial conditions existed in the Prydz Bay basin, for the last 900 ka. The biogenic carbonate sequence identified at Site 1167 is similar to the carbonate shales recovered from the Cape Roberts Project 1. Both have been dated at about 1 Ma, supporting the idea that a significant surface waters warming occurred during the Pleistocene. These data and the presence of calcareous nannofossils from locations around the Antarctic continent also suggest that the warming event was not limited to the analysed basin, but it extended around the East Antarctic continent. These new evidence call for a re-evaluation of the notion that the East Antarctic Ice-Sheet has experienced stable conditions similar to today since the late Neogene.
International Ocean Discovery Program Preliminary Report, 2018
seismic reflection profiles, and can be correlated between the two sites using both seismic refle... more seismic reflection profiles, and can be correlated between the two sites using both seismic reflectors and biostratigraphy. Together with results from other holes previously drilled in the SCS, these samples will help to constrain changes in paleoceanographic conditions during the Miocene in this part of the SCS basin.
The table displays the relative abundances (%) of all the calcareous nannofossil species identifi... more The table displays the relative abundances (%) of all the calcareous nannofossil species identified on samples collected from ODP Site 1209B (Shatsky Rise, NW Pacific Ocean) in a time interval covering the Middle Pleistocene Transition, from 0.45 to 1.45 Myr.
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
We investigated which method among smearing, settling, filtration, and random settling is the mos... more We investigated which method among smearing, settling, filtration, and random settling is the most accurate for determining the relative abundance of Florisphaera profunda. This species is included in paleoproductivity indices because it is one of the most important deep-water dwellers. Therefore, an accurate assessment of its relative abundance is key to monitoring variations in thermocline and nutricline depths. The low birefringence and flat polygonal shape of F. profunda may lead to inaccurate estimates of its relative abundance as it is poorly visible under light microscopy (LM), and different sample preparation may affect the number of specimens on each slide. We studied eight samples from the Ocean Drilling Program (ODP) Site 1209B (Shatsky Rise, NW Pacific)
... the section. The species richness of sphenoliths is particularly high, and our data confirm t... more ... the section. The species richness of sphenoliths is particularly high, and our data confirm the occurrence of new sphenoliths during the middle Eocene as shown recently by Bown and Dunkley Jones (2006). In particular we ...
The research aims to reconstruct, through a multidisciplinary approach based on micropaleontologi... more The research aims to reconstruct, through a multidisciplinary approach based on micropaleontological and geochemical analyses, the main paleoceanographic and paleoclimate changes that have influenced the surface- and deep-water circulation in the South West Pacific Ocean (Chatham Rise, eastern New Zealand) during the last 1Myr. The oceans are the largest ecosystem on Earth and best record global changes in climate and atmospheric composition. Changes in the mean state of regional and global surface- and deep-water circulation regimes both contribute to and are diagnostic of different states in the evolution of Pleistocene. Past surface- and deep-water ocean circulation patterns may be mostly reconstructed using measurements of biological and chemical properties. However, the interpretation of data is complex or ambiguous in several cases and a multi-proxy approach to improve the comprehension of past changes has become imperative. Given the importance of calcareous plankton (calcare...
Many processes influence the ocean-atmosphere CO2 exchange, including physical, biological and ca... more Many processes influence the ocean-atmosphere CO2 exchange, including physical, biological and carbonate pumps. Coccolithophores are able to export carbonate to the deep sea and contribute to the biological pump through photosynthesis. They are the major pelagic carbonate producers in the NW Pacific over the last 450 ka (Bordiga et al., in press) possibly playing a significant role in regulating the ocean CO2 chemistry on timescales >1-100 ka. We present micropaleontological and geochemical analyses from the Pleistocene succession of ODP core 198-1209B (Shatsky Rise, NW Pacific) and evaluate calcareous nannoplankton contribution to the organic and inorganic carbon pumps. Calcareous nannofossil assemblages were analyzed in 59 samples to determine total coccolith-carbonate accumulation rates (CAR), nannofossil preservation (NDI) and paleoproductivity indices (N). Stable isotopic composition (δ18O and δ13C) and Sr/Ca of the 2-20 µm carbonate fraction (coccolith-derived component), a...
This work investigates the Pleistocene sediments from ODP Site 1209B, located on the Shatsky Rise... more This work investigates the Pleistocene sediments from ODP Site 1209B, located on the Shatsky Rise (NW Pacific). Calcareous nannofossil assemblages, a nannofossil-derived paleoproductivity index (N ratio) and a Warm Water Taxa (WWT) proxy are employed to investigate the paleoceanographic changes in the NW Pacific mid-latitudes over the last 450 ka, Marine Isotope Stages (MIS) 1-12. Multivariate statistical analyses on our quantitative micropaleontological data clarify the relationships between coccolith distribution and paleoenvironmental variables. We analyzed the calcareous nannofossil content of 59 samples and all data are processed using the software PAST (PAleontological STatistics, Hammer et al., 2001) to perform Principal Component Analysis (PCA) and Cluster Analysis. At Site 1209B, calcareous nannofossils are abundant and well diversified. The PCA retains two principal components accounting for 66.8% and 11.8% of the variance, respectively. Principal component 1 (PC1) is nega...
Investigating the trace elements contained in the coccoliths, i.e., the carbonate exoskeleton, of... more Investigating the trace elements contained in the coccoliths, i.e., the carbonate exoskeleton, of unicellular marine phytoplankton called coccolithophores, is fundamental for calibrating environmental climate proxies, which are key tools for studying past and future climate changes. To date, lab-cultivated coccolithophores have been mainly used for measuring the elements retained within the coccoliths, whereas geochemical studies in fossil records have been limited by the difficulty in isolating monospecific samples from sediments containing highly diversified fossil assemblages. Since a comparison of the geochemical data collected from both fossil and living species is fundamental for calibrating the environmental proxies, an improvement of coccolith-picking methodology should be envisaged. Here, we present a significant advancement in the isolation of fossil species-specific coccolith achieved using a hydraulic micromanipulation system together with wet samples, never applied befo...
The biogeochemical and physical processes occurring in the oceans are pivotal in controlling the ... more The biogeochemical and physical processes occurring in the oceans are pivotal in controlling the atmospheric carbon dioxide (CO 2atm) concentration. In particular, the biological pump uptakes CO 2atm through photosynthesis, whereas the carbonate pump produces CO 2 during CaCO 3
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Bio- and magnetostratigraphic age data and nannofossil assemblage analysis from ODP Site 1165 evi... more Bio- and magnetostratigraphic age data and nannofossil assemblage analysis from ODP Site 1165 evidence an anomalous warming event of the surface waters in and around Prydz Bay during the Early Pleistocene, approximately 1 Ma. This results from an increase in the abundance of nannofossils at Site 1165, that occurred at 1 Ma. Detailed high-resolution sampling permits a new bio-magnetostratigraphic interpretation for ODP Site 1165. A decrease in delta18O values at Sites 1165 and 1167 also occurs at this time, supporting the presence of warming conditions in the Prydz Bay area. A return to colder surface waters, indicated by the absence or rare occurrence of nannofossils in the upper cores from Site 1165, suggests that more stable glacial conditions existed in the Prydz Bay basin, for the last 900 ka. The biogenic carbonate sequence identified at Site 1167 is similar to the carbonate shales recovered from the Cape Roberts Project 1. Both have been dated at about 1 Ma, supporting the idea that a significant surface waters warming occurred during the Pleistocene. These data and the presence of calcareous nannofossils from locations around the Antarctic continent also suggest that the warming event was not limited to the analysed basin, but it extended around the East Antarctic continent. These new evidence call for a re-evaluation of the notion that the East Antarctic Ice-Sheet has experienced stable conditions similar to today since the late Neogene.
International Ocean Discovery Program Preliminary Report, 2018
seismic reflection profiles, and can be correlated between the two sites using both seismic refle... more seismic reflection profiles, and can be correlated between the two sites using both seismic reflectors and biostratigraphy. Together with results from other holes previously drilled in the SCS, these samples will help to constrain changes in paleoceanographic conditions during the Miocene in this part of the SCS basin.
The table displays the relative abundances (%) of all the calcareous nannofossil species identifi... more The table displays the relative abundances (%) of all the calcareous nannofossil species identified on samples collected from ODP Site 1209B (Shatsky Rise, NW Pacific Ocean) in a time interval covering the Middle Pleistocene Transition, from 0.45 to 1.45 Myr.
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
We investigated which method among smearing, settling, filtration, and random settling is the mos... more We investigated which method among smearing, settling, filtration, and random settling is the most accurate for determining the relative abundance of Florisphaera profunda. This species is included in paleoproductivity indices because it is one of the most important deep-water dwellers. Therefore, an accurate assessment of its relative abundance is key to monitoring variations in thermocline and nutricline depths. The low birefringence and flat polygonal shape of F. profunda may lead to inaccurate estimates of its relative abundance as it is poorly visible under light microscopy (LM), and different sample preparation may affect the number of specimens on each slide. We studied eight samples from the Ocean Drilling Program (ODP) Site 1209B (Shatsky Rise, NW Pacific)
... the section. The species richness of sphenoliths is particularly high, and our data confirm t... more ... the section. The species richness of sphenoliths is particularly high, and our data confirm the occurrence of new sphenoliths during the middle Eocene as shown recently by Bown and Dunkley Jones (2006). In particular we ...
The research aims to reconstruct, through a multidisciplinary approach based on micropaleontologi... more The research aims to reconstruct, through a multidisciplinary approach based on micropaleontological and geochemical analyses, the main paleoceanographic and paleoclimate changes that have influenced the surface- and deep-water circulation in the South West Pacific Ocean (Chatham Rise, eastern New Zealand) during the last 1Myr. The oceans are the largest ecosystem on Earth and best record global changes in climate and atmospheric composition. Changes in the mean state of regional and global surface- and deep-water circulation regimes both contribute to and are diagnostic of different states in the evolution of Pleistocene. Past surface- and deep-water ocean circulation patterns may be mostly reconstructed using measurements of biological and chemical properties. However, the interpretation of data is complex or ambiguous in several cases and a multi-proxy approach to improve the comprehension of past changes has become imperative. Given the importance of calcareous plankton (calcare...
Many processes influence the ocean-atmosphere CO2 exchange, including physical, biological and ca... more Many processes influence the ocean-atmosphere CO2 exchange, including physical, biological and carbonate pumps. Coccolithophores are able to export carbonate to the deep sea and contribute to the biological pump through photosynthesis. They are the major pelagic carbonate producers in the NW Pacific over the last 450 ka (Bordiga et al., in press) possibly playing a significant role in regulating the ocean CO2 chemistry on timescales >1-100 ka. We present micropaleontological and geochemical analyses from the Pleistocene succession of ODP core 198-1209B (Shatsky Rise, NW Pacific) and evaluate calcareous nannoplankton contribution to the organic and inorganic carbon pumps. Calcareous nannofossil assemblages were analyzed in 59 samples to determine total coccolith-carbonate accumulation rates (CAR), nannofossil preservation (NDI) and paleoproductivity indices (N). Stable isotopic composition (δ18O and δ13C) and Sr/Ca of the 2-20 µm carbonate fraction (coccolith-derived component), a...
This work investigates the Pleistocene sediments from ODP Site 1209B, located on the Shatsky Rise... more This work investigates the Pleistocene sediments from ODP Site 1209B, located on the Shatsky Rise (NW Pacific). Calcareous nannofossil assemblages, a nannofossil-derived paleoproductivity index (N ratio) and a Warm Water Taxa (WWT) proxy are employed to investigate the paleoceanographic changes in the NW Pacific mid-latitudes over the last 450 ka, Marine Isotope Stages (MIS) 1-12. Multivariate statistical analyses on our quantitative micropaleontological data clarify the relationships between coccolith distribution and paleoenvironmental variables. We analyzed the calcareous nannofossil content of 59 samples and all data are processed using the software PAST (PAleontological STatistics, Hammer et al., 2001) to perform Principal Component Analysis (PCA) and Cluster Analysis. At Site 1209B, calcareous nannofossils are abundant and well diversified. The PCA retains two principal components accounting for 66.8% and 11.8% of the variance, respectively. Principal component 1 (PC1) is nega...
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