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EARTH SCIENCE > Solid Earth > Geochemistry > Isotopes

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  • These spreadsheets contain the EME-AFC fractional crystallisation and assimilation model discussed in Burton-Johnson et al. (2019). EME-AFC is based on the model of Grove and Donnelly-Nolan (1986) but developed to model expected variation of all major and minor elements of each fractionating phase whilst simultaneously modelling the trace elements and isotopic compositions of the fractionating assemblage, evolving melt and bulk cumulate composition. These spreadsheets are supplementary to the following manuscript. For further details refer to the manuscript and its supplementary material: Burton-Johnson, A., Macpherson, C. G., Ottley, C. J., Nowell, G. M. & Boyce, A. J. (2019). Generation of the Mt Kinabalu granite by crustal contamination of intraplate magma modelled by Equilibrated Major Element Assimilation with Fractional Crystallisation (EME-AFC). Journal of Petrology. Two files are included: a blank template for completion by the user and, for illustrative purposes, a completed spreadsheet containing the data used to model the evolution of Mt Kinabalu, Borneo.

  • Datasets related to istopic dating of mylonites and detrital grains from central Alexander Island. Argon-argon dating of mylonites and detrital grains, as well as uranium-lead dating of detrital zircons has been completed. Rock samples were collected from the northern LeMay Range, southern Douglas Range and the Lully Foothills.

  • This dataset comprises 52 cosmogenic 10Be surface exposure ages and associated analytical data from quartz-bearing rocks from Mount Murphy and surrounding nunataks in Marie Byrd Land, Antarctica. The samples - glacial erratics and bedrock - were collected between 2006 and 2016 by Joanne Johnson, Stephen Roberts and James Smith (British Antarctic Survey), in order to determine timing and duration of ice sheet thinning in the Amundsen Sea sector of the West Antarctic Ice Sheet, specifically thinning of Pope Glacier. The data are published and interpreted in the following paper: Johnson, J.S., Roberts, S.J., Rood, D.H., Pollard, D., Schaefer, J.M., Whitehouse, P.L., Ireland, L.C., Lamp, J.L., in review. Deglaciation of Pope Glacier implies widespread early Holocene ice sheet thinning in the Amundsen Sea sector of Antarctica. Earth & Planetary Science Letters. doi: xxxxx This data forms part of the ANiSEED project (''Amundsen Sea Embayment Exposure Dating''), funded by the Natural Environment Research Council (grants NE/K012088/1 and NE/K011278/1).

  • Geological station and sample registers related to rock samples collected from eastern Ellsworth Land during the 2002-2003 field season. In addition, processed data related to zircon mineral analysis using a technique that combines measurement of the U-Pb and Lu-Hf isotope systems. Minerals found in sediments that are resistant to earth surface processes, such as weathering and erosion, can yield information including the age and geological evolution of the sediment source region. Such a fingerprint is often unique and can be put in geographical context allowing an evaluation as to whether rock units today found adjacent to each other were originally deposited close to each other or not. Ultimately through rigorous zircon provenance analysis a new model for the crustal makeup of the Antarctic Peninsula can be tested.

  • A new technique that coupled SHRIMP (Sensitive High Resolution Ion Microprobe) U-Pb analyses with Laser ablation ICP isotope analyses for detrital zircons enabled the provenance of sediments from the English Coast region to be better assessed than had been previously possible. Such analyses, combined with Sm-Nd, Sr and Pb analyses for the sediments and plutonic rocks that cut the sediments, enabled a better assessment of the affinity of the English Coast rocks.

  • Geological analyses were conducted on rock samples collected in Dronning-Maud Land during the 2007-2008 field season. Analyses included grain-size determination, dating, whole rock and inclusion mineralogy, and geochemical analyses. All of the samples taken were of rocks that were found cropping out as nunataks. The investigation took place entirely within the the Dronning-Maud Land area of East Antarctica (Norwegian Sector).

  • Geochemical analysis of rock samples acquired by dredging activities in the Scotia Sea between Feb and Mar 2004 aboard James Clark Ross (cruise no JR77). The initial aim of this project was to carry out a higher resolution geochemical study of mantle flow using existing samples. This confirmed flow from the Bouvet domain into the East Scotia Sea and placed constraints on flow pathways. The second stage was to sample further within the West Scotia Sea and to use elemental and isotope (Sr, Nd, Pb, Hf) analyses to fingerprint mantle provenance. The results were used to locate and investigate the nature of the Pacific-South Atlantic mantle domain boundary and thus to contribute to the understanding and quantification of global upper mantle fluxes.

  • Dredging for rock samples was conducted in the West Scotia Sea during James Clark Ross cruise no JR77 between Feb and Mar 2004. The aim was to acquire rock samples to constrain the history of the mantle beneath the Scotia Sea, from which the oceanic crust was derived by melting. Twenty days of rock dredging were conducted at fourteen sites in five main areas. Thirteen dredges were successful in recovering oceanic rocks of mixed sizes, up to and including very large boulders and dredge paths of up to 1 km were followed. The cruise also (remarkably) recovered fresh mantle peridotite nodules from the West Scotia Ridge, the first of its type - to our knowledge - from the world''s ocean ridge system.

  • Dredge sampling was carried out aboard the James Clark Ross (cruise no JR77 ) during Feb and Mar 2004. The dredge target area was along the eastern segments of the West Scotia Ridge, an ocean spreading centre which stopped spreading about 10 million years ago. The spreading centre has high topographic relief and contains an axial rift, which has flanks that are suitable for dredging. The plan was to map the spreading centre using the swath bathymetry system, and then to use this map to locate the best dredging sites. Thirteen dredges were successful in recovering oceanic rocks of mixed sizes, up to and including very large boulders and dredge paths of up to 1 km were followed.

  • The dataset consists of Ar-Ar isotope dating, field data, and selected geochemical analysis of igneous dykes and sills collected from Dronning Maud Land during the 2000-2001 field season. The aim was to measure ages of volcanism during flood basalt events in Dronning Maud Land associated with the breakup of Gondwana.The style and volume of magmatism varies between margins from large volume flood basalts such as the Parana or Deccan provinces to less volumetric margins such as the southern part of the South Atlantic. This case (Collaborative Awards in Science and Engineering) studentship was intended to provide support to study the evolution of the break-up of Africa and East Antarctica which occurred in the early Jurassic. An extended period of magmatism has been suggested for this margin associated with complex extensional tectonics. A combined geochronological / geochemical approach was used to understand the evolution of the crust and sub-continental lithospheric mantle during the break-up of one central portion of the Gondwana super continent.