This event will be taking place on Tuesday 09 November - Wednesday 10 November 2021.
Tuesday 9 November
13:05 – 13:35
Invited: Archaeological science and globalisation: scientific explorations of metallurgical crucibles from southern Africa
Invited: Archaeological science and globalisation: scientific explorations of metallurgical crucibles from southern Africa
Session One
Ancient southern Africa, metallurgy began with the processing and use of iron and copper early in the first millennium CE. Current evidence suggests that gold, tin and the alloys bronze and brass only appeared after the incorporation of the region into the Indian Ocean exchange system. Before then copper was melted in broken pottery, repurposed as receptacles in metallurgy. The appearance of gold, tin and bronze was accompanied by a use of custom-made crucibles. Archaeological work unearthed an assemblage of reused pottery and crucibles used in gold, copper, bronze and brass working. This provided an opportunity to study their structural and chemical characteristics using microscopic and geochemical techniques. The results showed that crucibles, reused pottery and domestic pottery were made of local clays with genetic relationships to local geologies. Consequently, the conclusion to this paper is that if the idea to make crucibles was from the Indian Ocean, then local people had agency and domesticated ideas from elsewhere in innovative ways. The continued use of pottery indicates cross craft overlaps in container use in technical and everyday activities. This makes materials analysis a profitable lens for engaging with local responses to incoming ideas in contexts of early forms of globalisation.Speakers
Shadreck Chirikure
13:35 – 13:50
Submitted: Better Together: Microanalysis of Archaeological Indigenous Ceramics using Petrography and Micro Computed Tomography
13:50 – 14:05
Submitted: Polychromatic polarization: new spectacles for the good old petrographic microscope
14:05 – 14:10
Techno Bite: Cultural Heritage Under the Microscope: getting to the fine detail with advance elemental analysis (Bruker)
14:10 – 14:25
Submitted: Macroscopic and microscopic analysis of cut marks and trampling on human remains from the Covesea Caves, Scotland, dating to the Late Bronze Age and Roman Iron Age
14:25 – 14:28
Flash Talk: Intraplate Volcanism in Our Solar System; Using Scanning Electron Microscopy to Search for Terrestrial Analogues for Mars
14:28 – 14:31
Flash Talk: Beyond macroscopy: correlative tomography to investigate dental health in an Inca population from Farfán, Peru
14:31 – 14:34
Flash Talk: Microanalytical methodological approach to archaeological human bones: Between conservation and the understanding of the past
14:50 – 15:20
Invited: Chemical Analysis of Low Energy x-rays in Geological Materials using EPMA
15:20 – 15:35
Submitted: Meteorite Northwest Africa 5315: Determining the History of a Recrystallised HED Breccia through Scanning Electron Microscopy
15:35 – 15:50
Submitted: Correlative cathodoluminescence and EDS imaging of the benthic agglutinated foraminifer Liebusella goesi
15:50 – 15:55
Techno Bite: From Ancient Relics to Life on Mars: Enhancing your materials characterisation with temperature controlled microscopy (Linkam Scientific Instruments)
15:55 – 16:10
Submitted: Quantifying platinum group elements (PGEs): A novel scanning electron microscope and energy dispersive spectrometry (SEM/EDS) approach to analysing terrestrial and extra-terrestrial samples
16:10 – 16:13
Flash Talk: Comparative Examination of Scanning Electron Microscopy and Microanalysis results from the Early Bronze Age pottery from Helike (Greece) and experimental briquettes
Wednesday 10 November
The analysis of bulk fabric, misorientations, and subgrain structure reveal a complex picture in the Homestead and Williams xenoliths. We have used predictions for dislocation creep in simple shear deformation as a “baseline” to frame our observations. However, few xenoliths fall neatly within this framework. For example, although the Homestead xenoliths primarily show B-type fabric, the analysis of MOA show evidence for A-type subgrains, and the orientation of the MOA in the sample reference frame are mostly inconsistent with a simple shear kinematics. Homestead xenoliths also contain higher water contents, a diagnostic feature of many B-type fabric olivines. At Williams, the opposite picture emerges, with dominantly A-type bulk CPO and many MOA consistent with E-, or C-type subgrains. Williams xenoliths are also drier on average and show evidence of a rapid cycle of high-temperature annealing. We propose complex lithospheric dynamics played a role in the apparent discrepancies between bulk fabric and intragrain microstructures. Our results indicate that multiple geochemical and tectonic factors contributed to the multi-layered fabric observed in the Wyoming xenoliths.
13:05 – 13:35
Invited: Microanalysis for Tephrochronology
Invited: Microanalysis for Tephrochronology
Session Three
Large volcanic eruptions disperse volcanic ash thousands of kilometres from the vent. The deposits from these eruptions, termed tephra, form marker layers in sedimentary sequences and ice records. Identifying the tephra layers from particular eruptions allows the sequences that contain them to be correlated, providing a relative chronology. Furthermore, many of the eruptions are dated so identifying the tephra layer can often also provide absolute chronology.
These tephra layers are comprised of volcanic glass (typically >85%) and some crystals. The composition of the volcanic glass varies between volcanoes and different eruption deposits, and so the major, minor and trace element composition serves as fingerprint for a particular eruption (e.g., Lowe 2011). Chemically characterising these tephra layers allows us to correlate sites, which is particularly useful for synchronising and dating palaeoenvironmental and archaeological records (e.g., Lowe et al., 2012). Furthermore, the robust identification of the ash away from the volcanic source provides insight into the magnitude and dynamics of the eruption and helps us to build better records of past volcanism, which is critical for hazard assessments (e.g., Albert et al., 2019).
Accurate and precise glass compositions are required for tephrochronology, and these can be determined using an electron microprobe (EMP) and laser-alation inductively coupled plasma-mass spectrometry (LA-ICPMS). However, glass is easily damaged by an electron beam and to minimise compositional changes it must be analysed using low beam currents and a defocused beam (e.g., Autefage & Couderc, 1980). The major element EMP data are used to normalise the LA-ICPMS data and any problems with accuracy are then transferred into the trace element data. There are a lot of published data that are not accurate, which means that samples need to be reanalysed to confirm correlation. The tephrochronological community is now strongly recommending that reference materials, such as the MPI-DING glasses (Jochum et al., 2006), are analysed during all EMP and LA-ICPMS runs and these secondary standard analyses and are included with the data in publications (Kuehn et al., 2011). This allows for any discrepancies in accuracy to be identified. The issues with accuracy that have been highlighted by the tephrochronological community are likely to be pervasive in published geochemical datasets, which has consequences for large databases and big data initiatives.
References
- Albert, P.G., Smith, V.C., Suzuki, T., et al., 2019. Geochemical characterisation of the Late Quaternary widespread Japanese tephrostratigraphic markers and correlations to the Lake Suigetsu sedimentary archive (SG06 core). Quaternary Geochronology 1–75. https://doi.org/10.1016/j.quageo.2019.01.005
- Autefage, F., & Couderc, J. J., 1980. Étude du mécanisme de la migration du sodium et du potassium au cours de leur analyse à la microsonde électronique. Bulletin de Minéralogie, 103, 623-629.
- Jochum, K.P., Stoll, B., Herwig, K., et al., 2006. MPI-DING reference glasses for in situ microanalysis: New reference values for element concentrations and isotope ratios. Geochemistry, Geophysics, Geosystems 7. https://doi.org/10.1029/2005gc001060
- Kuehn, S.C., Froese, D.G., Shane, P.A.R., Participants1, I.I., 2011. The INTAV intercomparison of electron-beam microanalysis of glass by tephrochronology laboratories: Results and recommendations. Quaternary International 246, 19–47. https://doi.org/10.1016/j.quaint.2011.08.022
- Lowe, D.J., 2011. Tephrochronology and its application: A review. Quaternary Geochronology 6, 107–153. https://doi.org/10.1016/j.quageo.2010.08.003
- Lowe, J., Barton, N., Blockley, S., et al., 2012. Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards. Proceedings of the National Academy of Sciences 109, 13532–13537. https://doi.org/10.1073/pnas.1204579109
Speakers
Victoria C. Smith
13:35 – 13:50
Submitted: Can we distinguish between ancient black glazed pottery and its contemporary replica? TEM Phase Mapping Microscopy studies towards authentication
13:50 – 14:05
Submitted Talk: When is a biomineral not a biomineral? Multi-scale complexity of iron oxide crystallisation in the Gunflint Chert
14:10 – 14:25
Submitted: Nanometre functional chemistry of organic meteorites using STEM-EELS
14:25 – 14:28
Flash Talk: Geologist v Machine: Why a geologist is still important, even in ‘automated’ data collection
14:28 – 14:31
Flash Talk: High Spatial Resolution Mineralogical Quantification by Unsupervised Machine Learning of Energy Dispersive X-ray Spectrometry (EDS)
14:50 – 15:20
Invited: Maximizing data extraction from large are EBSD maps of geological thin sections: recent examples using mantle xenoliths
Invited: Maximizing data extraction from large are EBSD maps of geological thin sections: recent examples using mantle xenoliths
Session Four
Xenoliths play a crucial role in interpretation of mantle deformation and geochemistry. Here, we integrate a suite of interrelated datasets extracted from large area EBSD mapping of entire geological thin sections of peridotite (olivine-rich) xenoliths from the Williams and Homestead kimberlites from the Wyoming Craton, Montana, USA to constrain bulk fabric and intragranular deformation mechanisms (misorientation analysis, “MOA”) in olivine. We compare these results to experimental values of the effect of trace amounts (ppm) of water on olivine slip systems. We also place our results in the context of the classic mantle deformation cycle, originally proposed by Mercier and Nicolas (1975).The analysis of bulk fabric, misorientations, and subgrain structure reveal a complex picture in the Homestead and Williams xenoliths. We have used predictions for dislocation creep in simple shear deformation as a “baseline” to frame our observations. However, few xenoliths fall neatly within this framework. For example, although the Homestead xenoliths primarily show B-type fabric, the analysis of MOA show evidence for A-type subgrains, and the orientation of the MOA in the sample reference frame are mostly inconsistent with a simple shear kinematics. Homestead xenoliths also contain higher water contents, a diagnostic feature of many B-type fabric olivines. At Williams, the opposite picture emerges, with dominantly A-type bulk CPO and many MOA consistent with E-, or C-type subgrains. Williams xenoliths are also drier on average and show evidence of a rapid cycle of high-temperature annealing. We propose complex lithospheric dynamics played a role in the apparent discrepancies between bulk fabric and intragrain microstructures. Our results indicate that multiple geochemical and tectonic factors contributed to the multi-layered fabric observed in the Wyoming xenoliths.
Speakers
Emily Chin
15:20 – 15:35
Submitted: 3D non-destructive Crystallographic Imaging of Peridotite with Lab-based X-ray Diffraction Contrast Tomography
15:35 – 15:50
Submitted: Determining the P-T history of metamorphic rocks using combined EBSD and EDS
15:50 – 15:55
Techno Bite: Enhanced understanding of geological and archaeological materials using combined x-ray and optical spectroscopies (Gatan EDAX)
15:55 – 16:10
Submitted: Automated identification and evaluation of minerals by SEM-EDS: maps mineralogy – the simple tool for complex rocks
16:10 – 16:13
Flash Talk: Magnetic recording of Earth’s history: A 3D nanoscale characterisation of Glen Mountain GC4-3-13
16:13 – 16:16
Flash Talk: Geochemical composition of archaeological soils as an environmental archive of changes between Celtic and medieval occupation; case study from hillfort Chotěbuz
