IODP Survey of the "Shackleton sites" on the Southwest Iberian Margin

Lead Research Organisation: University of Cambridge
Department Name: Earth Sciences

Abstract

Advances in our understanding of the Earth's climate system will rely on our ability to link high-resolution sedimentary archives from the oceans, ice-cores and terrestrial sequences, and to interpret these records in the context of novel Earth system modeling approaches. Few places exist in the world where sufficiently detailed and unambiguous marine-ice-terrestrial linkages are possible. One challenge for IODP, and the broader drilling community in general, is to identify and recover marine, ice and terrestrial sequences from appropriate locations and with adequate temporal resolution to study processes of the integrated climate system.

One such region is the southwest Iberian Margin where it has been demonstrated that the surface oxygen isotopic record could be correlated precisely to temperature variations (i.e., d18O) in Greenland ice cores. By comparison, the benthic d18O signal in the same core resembled the temperature record from Antarctica. Moreover, the narrow continental shelf and proximity of the Tagus River results in the rapid delivery of terrestrial material to the deep-sea environment off Portugal, thereby providing a record of atmospheric changes and permitting correlation of marine and ice core records to European terrestrial sequences. This is the only place in the ocean where such marine-ice-terrestrial correlations have been demonstrated unambiguously. It is therefore highly desirable to extend the Iberian Margin record to encompass the full range of Plio-Pleistocene glacial-interglacial cycles by drilling with the JOIDES Resolution (JR).

Towards this end, Proposal 771-Full was submitted to IODP by an international group of 16 proponents led by the UK. The proposal was well received and reviewed by the Science Steering and Evaluation Panel (SSEP), but the IODP Site Survey Panel (SSP) identified major inadequacies in the quality of the seismic data:

"The panel raised several concerns on the suitability of the submitted data with regard to its appropriateness, both to image the target properly and with regard to the site location. The panel also discussed the need for 2 high-resolution lines and considered that places where Mass Transport Deposits (MTDs) or closely spaced faults were present deserved these 2 high-resolution lines."

This proposal requests 25 days of ship time to collect the necessary seismic and sediment data needed to meet the SSP requirements and recommendations. Several "stand-alone" scientific objectives are also proposed related to the modern hydrography and sedimentary processes on the southwest Iberian Margin, and calibration of palaeoceanographic proxies used for reconstructing past changes in deep-water circulation. This value-added science will make effective use of ship time and contribute key information needed to interpret the downcore records to be obtained by IODP.

Planned Impact

The primarily beneficiary will be members of the academic community who are engaged in IODP research, specifically millennial-scale climate variability in records from the Iberian Margin. The success of IODP is contingent upon grassroots efforts by the scientific community to propose the best science and identify the best places to drill on the ocean floor. As such, site survey is one of the most important activities for IODP and directly impacts the ultimate success of the program. The research proposed herein is directly relevant to the primary scientific objectives of the IODP Initial Science Plan. As such, the UK will benefit both through enhanced participation in the IODP and the results of the site survey will be important for the future success of the program.


More importantly for knowledge exchange will be links to the community through the Sedgwick Museum at the University of Cambridge, which attracts in excess of 84,000 visitors per year, including over 100 school group visits. We will establish a general display on how ocean drilling contributes to the study of past climate change. We will take advantage of the media and education resources available through IODP, including web content, media kits, an audiovisual library, fun and games activities for children, core replicas, press releases, brochures and other public relations materials. We will also engage school children with hands-on learning activities.

We will disseminate the results of our research to the wide range of beneficiaries through public and academic talks, a museum exhibit, workshops and symposia, and conference papers. Key scientific results deemed important enough to be of widespread media interest will be disseminated via the University of Cambridge's Office of External Affairs and Communications.

Publications

10 25 50
 
Description Cruise JC089 of the RSS James Cook set sail from Vigo, Spain, on 04 August 2013. The objectives were to collect geophysical data, water column samples, and sediment cores to support a proposal under consideration by the Integrated Ocean Drilling
Program (IODP 771-Full) to drill a series of sites on the SW Iberian Margin. The primary survey area was the Promonotorio dos Prinicipes de Avis (PPA), a topographic feature elevated above the Tagus Abyssal Plain.
A total of 755 line kilometres of seismic reflection profiles were acquired using a 3-km streamer and a small airgun source consisting of a generator-injector (GI) gun. Data quality was generally good with penetration of 3-4 seconds two-way travel time with excellent resolution. The resulting set of crossing lines provides the survey data needed to support the IODP proposal 771-Full. An important by-product of this survey is seismic imaging of the water column (i.e., seismic oceanography), which
was calibrated by a combination of disposable hydrographic probes and CTD casts. Multibeam bathymetry and 3.5 kHz echosounder data were collected continuously during the seismic survey.
In total, 13 CTD casts were made using a trace metal free system to characterize the physical and chemical properties of water masses on the Iberian Margin. The data are useful for interpreting the water-column seismic profiles and for groundtruthing palaeoceanographic proxies preserved in surface sediment. Water was collected at 13 stations using 10 liter Niskin bottles, totaling 246 bottles from which subsamples
were taken for isotopic and elemental analysis. Large volume in-situ filtration was carried out at 6 stations using Challenger Oceanic Stand Alone Pumps (SAPs) to capture both suspended and sinking particles in the water column. Radiocarbon and
geochemical analysis of the filtered samples will be used to determine the age, source, and transport of particles on the Iberian Margin.
Sediment cores were acquired along a bathymetric transect to meet IODP site survey requirements and to study sedimentary processes (e.g., sediment provenance and focussing), bioturbation, and calibrate geochemical and sedimentological proxies on the Iberian Margin. We recovered 10 piston cores, 12 box cores, 10 kasten cores, 4 gravity cores, 13 megacores, and 1 grab sample. The long cores span the last deglaciation and range in water depths from 600 to 4670 m, constituting as yet one of the most complete vertical transects of sediment cores from a continental margin. We will use the cores to reconstruct bathymetric transects of geochemical properties (e.g.,
oxygen isotopes, Mg/Ca, benthic d13C, radiocarbon) and infer past changes in water mass distributions from the last glacial period through the Holocene. All cores have been split and analyzed for elemental variations using a core scanning XRF. Radiocarbon chronologies for the cores are under development.
Oxygen, pH, and redox gradients in sediment pore waters were determined using micro-electrodes inserted into Megacore tubes. Interstitial waters were sampled directly from the Megacores at 1-cm intervals using Rhizon soil moisture samplers. A total of 900 pore water samples were collected and alkalinity measurements were made onboard for each sample.
Exploitation Route The data collected has been used to support a proposal to the International Ocean Discovery Program (IODP) to drill the Iberian Margin. This proposal has received favourable reviews and sits with the IODP Operational Task Force for scheduling once the ship (JOIDES Resolution) returns to the North Atlantic (anticipated in 2020).
Sectors Environment

URL https://www.bodc.ac.uk/data/information_and_inventories/cruise_inventory/report/13392/
 
Description The data collected on Research Cruise JC089 has been used to support an IODP drilling proposal (771-Full2). The revised proposal was submitted to IODP on October 1, 2014 and the site survey data was deposited in the site survey data bank on November 1, 2014. The proposal was favourably reviewed and now sits with the IODP Operational Task Force awaiting scheduling when the ship (JOIDES Resolution) returns to the North Atlantic (anticipated in 2020).
First Year Of Impact 2014
Sector Environment
 
Title Combined oxgyen and carbon isotope data for all benthic foraminifera in piston core MD01-2444 and IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951395
 
Title Combined oxgyen and carbon isotope data for the planktonic foraminifera Globigerina bulloides of sediment core MD01-2444 and IODPP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951397
 
Title Combined oxgyen and carbon isotope data of Cibiicidoides in piston core MD01-2444 and IODPP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951396
 
Title Hybrid age model from sediment core MD01-2444 and IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951393
 
Title Hybrid age model from sediment core MD01-2444 and IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.957786
 
Title Oxgyen and carbon isotope data for benthic foraminifera at IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951382
 
Title Oxgyen and carbon isotope data for the planktonic foraminifera Globigerina bulloides at IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951386
 
Title Radiocarbon ages of both, the leachate and the leached sample, of monospecific samples of Globigerina bulloides and Globigerinoides ruber from core SHAK06-5K, and age offsets between them 
Description Radiocarbon ages and associated 1-s confidence level (68.2% probability), and corresponding age discrepancies. * Stands for untreated samples. Numbers marked with # indicate age offsets that can be explained within the 1-s confidence level of the associated dates. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.898618
 
Title Radiocarbon ages of monospecific samples of Globigerina bulloides from sediment core SHAK06-5K, prepared with two different methods 
Description Influence of the sample preparation method on radiocarbon ages. 14C ages and associated 1-s confidence level (68.2% probability), and corresponding age discrepancies. Age offsets that can be explained within the 1-s confidence level of the associated dates are indicated with #. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.898608
 
Title Radiocarbon and calendar ages of monospecific samples of the planktonic foraminifera Globigerina bulloides from sediment core SHAK06-5K 
Description Age model for core SHAK06-5K based on monospecific samples of the planktonic foraminifera Globigerina bulloides. Convention radiocarbon ages and associated 1s uncertainties have been rounded according to convention 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.898607
 
Title Stable isotopes of Globigerina bulloides from core SHAK06-5K 
Description Oxygen and Carbon isotope data from Globigerina bulloides from sediment core SHAK06-5K. Between 6 and 12 specimens of each species were measured with a Gas Bench II connected to a Delta V Plus isotope ratio mass spectrometer at the Stable Isotope Laboratory of Climate Geology, ETH Zurich. Calibration to the Vienna Pee Dee Belemnite (VPDB) scale was accomplished using two in-house standards previously calibrated against the NBS-18 and NBS-19 international standards. The associated long-term standard deviation is <0.07‰. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.904435
 
Title Stable isotopes of Globigerinoides ruber from core SHAK06-5K 
Description Oxygen and Carbon isotope data from Globigerinoides ruber from sediment core SHAK06-5K. Between 6 and 12 specimens of G. ruber were measured with a Gas Bench II connected to a Delta V Plus isotope ratio mass spectrometer at the Stable Isotope Laboratory of Climate Geology, ETH Zurich. Calibration to the Vienna Pee Dee Belemnite (VPDB) scale was accomplished using two in-house standards previously calibrated against the NBS-18 and NBS-19 international standards. The associated long-term standard deviation is <0.07‰. This isotopic record was concluded to be affected by the coupled effect of bioturbation with changes in the abundance of G. ruber. We refer potential users to the published article. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.904433
 
Title Various age models from sediment core MD01-2444 and IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951387
 
Title Various age models from sediment core MD01-2444 and IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.957587
 
Title XRF Ca/Ti and Zr/Sr ratios for sediment core MD01-2444 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951398
 
Title XRF Ca/Ti and Zr/Sr ratios for the spliced stratigraphic section at IODP Site 339-U1385 
Description  
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://doi.pangaea.de/10.1594/PANGAEA.951383
 
Description Educational Video -- Cruise JC089 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A movie and article was presented demonstrating research life aboard Cruise JC089 aboard the NERC vessel James Cooke.
The reaserch was a feature of the University of Cambridge's magazine, Research Horizons, volume 24, p. 34-35.
Year(s) Of Engagement Activity 2014
URL http://www.cam.ac.uk/research/features/extreme-sleepover-14-all-aboard-the-floating-science-factory