• The Airless Project

      Allington-Jones, L; Trafford, A (Natural Sciences Collections Association, 2017-04-20)
      A project to combat pyrite oxidation at the NHM (London, UK) is currently in its second year. The project aims to undertake conservation treatments and store highest risk specimens in low oxygen microenvironments. An emergent benefit of the conservation-driven project has been the digitisation of specimens on the collection management system KE Emu, through the use of barcodes and web-based applications.
    • Alkali-rich replacement zones in evolved NYF pegmatites: metasomatic fluids or immiscible melts?

      Muller, A; Spratt, J; Thomas, R; Williamson, BJ; Seltmann, Reimar (International Mineralogical Association, 2018-08-13)
      IMA2018 Abstract submission Pegmatite mineralogy, geochemistry, classification and origins IMA2018-1337 Alkali-rich replacement zones in evolved NYF pegmatites: metasomatic fluids or immiscible melts? Axel Muller* 1, John Spratt2, Rainer Thomas3, Ben J. Williamson4, Reimar Seltmann2 1Natural History Museum, University of Oslo, Oslo, Norway, 2Department of Earth Sciences, Natural History Museum, London, United Kingdom, 3Chemistry and Physics of Earth Materials, German Research Centre for Geoscience GFZ, Potsdam, Germany, 4Camborne School of Mines, University of Exeter, Penryn, United Kingdom What is your preferred presentation method?: Oral or poster presentation : Replacement zones (RZ), which are a common feature of evolved granitic pegmatites, are irregular, commonly alkali-rich zones superimposing, cross-cutting and replacing the primary zonation in almost all consolidated pegmatite bodies. RZ are widely considered to result from late-stage metasomatism even though little is known about the melts and/or fluids involved in their formation. However, the observed textures and mineral paragenesis of RZ cannot be explained by metasomatism in a strict sense. In this study, the nature of the late stage silicate melt forming “cleavelandite” RZ is assessed from textural, mineralogical, chemical and melt inclusion studies of evolved, Proterozoic Niobium-Yttrium-Fluorine (NYF) rare metal pegmatites from Evje–Iveland, southern Norway. These were studied as they are mineralogically simple, compared with RZ in evolved Lithium-Caesium-Tantalum (LCT) pegmatites. Silicate melt inclusions in RZ-forming topaz and “cleavelandite” document high H2O contents of up to18 wt.% of the F-rich silicate melt from which the RZ crystallized. In addition, from mineral compositions (“cleavelandite”, “amazonite”, white mica, garnet, columbite group minerals, topaz, fluorite, and beryl), they must have also been strongly alkaline (Na-dominated) with enrichments in F (at least 4 wt.%), Cs, Rb, Ta, Nb, Mn, Ge, Bi, As, and in some cases also Li compared with host pegmatites. These elements are concentrated in a few RZ-forming minerals resulting in very distinctive mineral-trace element signatures. “Amazonite” is strongly enriched in Cs and Rb and often white mica and beryl in Li and Cs. To acquire these mineral compositions, the overall Li-Cs-Ta-poor Evje-Iveland original pegmatite melt must have undergone extreme internal chemical differentiation resulting in melt/melt immiscibility aiding rheology contrasts and resulting in RZ formation. The resulting RZ-forming H2O-F-rich silicate melt would have shown large differences in viscosity and density, and therefore physical flow/transport properties, to the host pegmatite melt resulting in discordant contacts. The mineralogy and melt inclusion data from the Evje-Iveland pegmatites document a gradient of crystallization temperatures within the investigated pegmatite bodies with highest temperatures at the pegmatite margin (during initial emplacement, ~680°C) and lowest temperatures within the RZ (<500°C). Considering the temperature and pressure conditions of the host rocks gneisses and amphibolites (~650°C, up to 5 kbar) at the time of pegmatite emplacement and the crystallization conditions of the RZ, the Evje- Iveland pegmatites and RZ likely formed over a period of 2.2 million years, assuming an exhumation rate of 1.5 mm per million years and a geothermal gradient of 45°C km-1. Such a long crystallization time contradicts the classical view that pegmatites represent strongly undercooled melts which crystallize relatively fast.
    • Blue Whale on the Move: Dismantling a 125 Year-Old Specimen

      Bernucci, A; Cornish, L; Lynn, C (museum fur naturkunde berlinBerlin, Germany, 2016)
      The Natural History Museum (London, UK) intends to suspend a 25 metre-long, blue whale (Balaenoptera musculus) from its central Hintze Hall. Alongside other specimens which are to be put on open display in this space the environment was looked at in terms of sustainable improvements. Works are being undertaken to improve the conditions by utilizing natural ventilation and re-using existing duct work. This specimen, acquired by the Museum in 1891, was suspended from the ceiling of the Mammal Hall, where it has been on display since 1934. Conservators worked with a specialist specimen handling company to carefully dismantle and remove each of the 220 bones from its original mount. The skull required a special frame and a precise calculation of movement to dismantle it and remove it. Many complex decisions were made during this process – as each bone removal did not dictate what the next would bring. During the dismantling phase, the conservation team have had to address the many requirements of curators, researchers, senior management and the media.
    • Bridging the Skills Gap in UK Species Identification: Lessons Learnt & Next Steps

      West, SVL; Tweddle, JC (National Biodiversity Network, 2017-11-17)
      As the Identification Trainers for the Future project draws to a close, we take this opportunity to reflect on what we have learnt from the project and where the Natural History Museum is heading next in terms of supporting UK natural history skills development.
    • Classification and characterisation of magmatic-hydrothermal tourmaline by combining field observations and microanalytical techniques

      Drivenes, K; Brownscombe, W; Larsen, RB; Seltmann, Reimar; Spratt, J; Sørensen, BE (IOP Publishing, 2020)
      Tourmaline from the St. Byron lobe of the Land’s End granite, SW England, was assessed by macroscopic, optical and quantitative microanalytical methods. In total, seven types of tourmaline were distinguished. The seven types reflect different crystallisation environments and stages in the magmatic-hydrothermal transition. Types 1-3 are interpreted to represent a gradual transition from tourmaline crystallising from a silicate melt to precipitation from magmatic aqueous fluids. Types 5-7 crystallised at subsolidus conditions from a different fluid generation than types 1-3. These fluids may be magmatic or mixed with other fluids (e.g., meteoric or formation waters). The Sn-mineralisation in the area is mostly related to the latter fluid generation, and the mineralising potential is reflected by the tourmaline composition.
    • Conservation challenges for a microscopic world: Documenting desmids

      Wilbraham, Joanna (British Phycological Society, 2020)
      Freshwaters are amongst the most threatened habitats in the world. Many waters in the UK have irreversibly changed or disappeared and those that remain are under immense pressure largely due to habitat loss, pollution, recreation, abstraction and the introduction of nonnative species. Climate change is also becoming a major concern for freshwater life. The conservation of biodiversity associated with freshwaters has for obvious reasons focused on the larger animal and plant species, however, microorganisms such as the algae play a fundamental role in these ecosystems and constitute rich assemblages which are also threatened. Desmids are a diverse group of freshwater microalgae which dominate the algal flora of nutrient poor, lentic waters and are particularly diverse in such oligotrophic habitats as moorland pools and shallow lakes. They are ecologically highly sensitive, acting as useful indicators of water quality. The conservation of microscopic organisms poses many difficulties due to taxonomic impediments and lack of knowledge of ecology and distribution. To gain a better understanding of desmid distribution patterns across the UK and Ireland this project has undertaken the digitisation of 50 years worth of biological recording data collated by desmid expert David Williamson. Reliable datasets of species occurrence are essential to biodiversity research and conservation so these data, in conjunction with published literature, will provide a basis for developing a more robust checklist of verified desmid taxa known to occur in the UK and Ireland and provide distribution information for these taxa. Furthermore, this will enable us to review the conservation status of the desmid flora and provide data of practical use in the designation and management of protected freshwater habitats.
    • Conservation in a Barcode Age: A cross-discipline re-storage project for pyritic specimens

      Allington-Jones, L; Trafford, A (International Council of Museums, 2017-01-01)
      The dichotomy of conservation and access has long been recognised within the museum profession. The recent push for digitisation has added a new dimension to this argument: digital records can both increase potential access, due to increased awareness of the existence of objects, and decrease potential handling, since a more thorough awareness of an object creates a more informed decision regarding whether access is actually necessary. The use of barcodes and the creation of digital resources have therefore been incorporated into a re-storage project at the Natural History Museum, London to reduce duplication of work (and handling) by staff and to combat the reduction in access caused by the enclosure of objects within microenvironments, which in turn helps preserve specimens for future access. This project demonstrates how conservation and digitisation can successfully synthesise through the use of barcodes, when working with a cross-discipline team.
    • Detecting foraminiferal photosymbionts in the fossil record: a combined micropalaeontological and geochemical approach

      Bhatia, R; Wade, B; Hilding-Kronforst, S; Spratt, J; Leng, M; Thornalley, D (2016-08-30)
    • Diversification dynamics in freshwater bivalves (Unionidae) from the East African Rift

      Ortiz-Sepulveda, C; Stelbrink, B; Poux, C; Monnet, C; Albrecht, C; Todd, JA; Michel, E; Van Bocxlaer, B; Anon (SIAL, 2018-07-29)
      Invertebrates are exceptionally diverse, but declining because of anthropogenic changes to their habitat, as exemplified by freshwater bivalves in Europe and North America. Much less information is available for African freshwater bivalves, especially for Unionidae, which comprise 9 genera and ~40 nominal species, many of which are endemic to African ancient lakes. The phylogenetic position of most of these genera and species remains uncertain, and their conservation status unassessed. Here, we present preliminary results of phylogenetic studies on the Unionidae of the East African Rift. We integrate a phylogenetic backbone based on four gene fragments with (1) sampling information to examine geographic patterns of diversity and with (2) geometric morphometrics of shell shape to examine the relation between morphological disparity and molecular diversity. African Unionidae apart from ‘Cafferia’ form a monophyletic clade, and the basal splits in this clade occur between the reciprocally monophyletic genera Pseudospatha and Grandidieria, both of which are currently endemic to Lake Tanganyika. Mweruella, Nyassunio and Prisodontopsis are also monophyletic in the preliminary analyses as is Nitia, although this latter taxon is nested within Coelatura, which highlights the need of systematic revisions. Biogeographic analyses indicate a statistically significant North-to-South colonization of the East African Rift by Coelatura sensu lato. Beyond deep phylogenetic splits among individual clades, limited molecular differentiation is observed within most clades, calling for population genetic studies. Ongoing morphometric analyses suggest strong morphological differentiation among several clades, but substantial disparity in shell shape is observed within many clades, which needs further examination.
    • Giant Sequoia: an extraordinary case study involving Carbopol® gel

      McKibbin, C; Allington-Jones, L; Verveniotou, E (Archetype Publishing LtdLondon, 2017-10-18)
      In 2016 a project was undertaken to stabilise and aestheticise the transverse section of giant sequoia on display at the Natural History Museum (NHM) in London, UK. This iconic specimen, which now dominates the top floor of the central hall, was 1300 years old when felled and has been part of the exhibitions for 122 years. Measuring over 4.5 metres in diameter, it posed many challenges during remedial conservation. The largest involved removal of the discoloured waxy substance and opacified shellac-based varnish that had been applied in the early 1980s. Solvent tests revealed that the coating was soluble in Industrial Methylated Spirits (IMS) and that the gel worked most effectively at a 1 hour application time. At longer durations the varnish itself gelled and the waxy component was re-deposited. The waxy substance was effectively removed by wiping with alternate white spirit and IMS swabs.
    • HYPERVELOCITY IMPACT IN LOW EARTH ORBIT: FINDING SUBTLE IMPACTOR SIGNATURES ON THE HUBBLE SPACE TELESCOPE

      Kearsley, AT; Colaux, JL; Wozniakiewicz, PJ; Gerlach, L; Anz-Meador, P; Liou, JC; Griffin, T; Reed, B; Opiela, J; Palitsin, VV; et al. (2018-04)
      HYPERVELOCITY IMPACT IN LOW EARTH ORBIT: FINDING SUBTLE IMPACTOR SIGNATURES ON THE HUBBLE SPACE TELESCOPE A T Kearsley 1,2,5, J L Colaux 3, D K Ross 4, P J Wozniakiewicz 2,5, L Gerlach 6, P Anz-Meador 4, J-C Liou 7, T Griffin 8, B Reed 8, J Opiela 4, V V Palitsin 3, G W Grime 3, R P Webb 3, C Jeynes 3, J Spratt 2, M J Cole 5, M C Price 5 and M J Burchell 5. 1 Dunholme, Raven Hall Road, Ravenscar, YO13 0NA, UK (kearsleys@runbox.com); 2 Natural History Museum (NHM), Cromwell Road, London, UK. 3 Ion Beam Centre, University of Surrey, Guildford, UK. 4 ESCG-Jacobs, NASA-JSC, Houston, TX, USA. 5 School of Physical Sciences, University of Kent, Canterbury, Kent, UK. 6 European Space Agency (ESA, retired), Noordwijk, The Netherlands. 7 NASA Johnson Space Center, Houston, TX, USA. 8 NASA Goddard Space Flight Center (GSFC), Greenbelt, Maryland, USA. ABSTRACT Introduction Return of large surface area components from the Hubble Space Telescope (HST) during shuttle orbiter service missions has allowed inspection of large numbers of hyper-velocity impact features from long exposure in low Earth orbit (LEO). Particular attention has been paid to the origin of the impacting particles, whether artificial Orbital Debris (OD) or natural Micrometeoroid (MM). Extensive studies have been made of solar cells (Graham et al., 2001; Kearsley et al 2005, Moussi et al., 2005) and recently, the painted metal surface of the Wide Field and Planetary Camera 2 WFPC2 radiator shield (Anz-Meador et al., 2013; Colaux et al., 2014; Kearsley et al., 2014a; Ross et al., 2014). Both of these materials from HST have layers of complex chemical composition, into which particle fragments and melt may infiltrate during impact. Experimental light gas gun (LGG) impacts (e.g. Price et al., 2014) have shown that impactor remains may be dispersed and dilute, often as a very thin and patchy coating within an irregular impact-generated pit. In previous studies, the low concentration of particle residue, the rugged topography of impact features, and especially the complex multi-element composition of the impacted surface were considered significant barriers to recognition of extraneous impactor-derived components. Analysis was both difficult and time consuming (e.g. Graham et al., 2001), and a substantial proportion of impactors (25-65%) could not be identified. Recent advances in energy dispersive X-ray microanalysis (EDX) now permit routine identification of impactor origins using scanning electron microscope (SEM); particle induced X-ray emission (PIXE) and micro-X-ray fluorescence (µ-XRF) instruments (Kearsley et al., 2012, 2014b). Here we demonstrate how these techniques have allowed impactor composition to be isolated, and the particle source determined for the great majority of WFPC2 samples studied. Methods To analyse impact melt on the zinc orthotitanate (ZOT) and aluminium alloy (Al-6061) of the WFPC2 radiator shield we used the Oxford Instruments INCA SEM-EDX spectrum pro-cessing software to separate peak and background X-ray counts for specified X-ray emission lines. From tables of likely OD and MM signature elements (e.g. Kearsley et al., 2005), and knowledge of the pristine WFPC paint and alloy compositions, we extracted data for the fol-lowing elements: Mg, Al, Si, S, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu and Zn. Two types of graphical plot were developed, to highlight extraneous element signatures in small impacts on the ZOT paint (Fig. 1), and larger craters into the Al-alloy (Fig. 2). The impactor origin was then clas-sified by reference to a suite of decision trees (Kearsley et al., 2012). A Bruker X-Flash 6050 EDX detector was also used to obtain signal from the interior of deeper craters. PIXE maps and spectra were acquired in the Ion Beam Centre, University of Surrey (Colaux et al., 2014). Results Figure 1. WFPC2 impact feature 339: a) SEM backscattered electron (BE) image; b) SEM depth model; c) SEM-EDX maps show high Mg concentration in the impact melt lining the impact feature d) plots of SEM-EDX X-ray counts for Mg and Fe show much higher levels in impact melt (red) than in clean ZOT paint (blue), and a similar level to impact residue from LGG impacts of olivine grains (open black squares). Excess Mg and Fe contents in frothy impact melt show impactor was a micrometeoroid. Figure 2). WFPC2 impact feature 462: a) SEM BE image; b) SEM depth profile; c and d) PIXE EDX maps show Fe and Ni across crater pit and surrounding metal, some iron-rich in-clusions in the Al alloy, but Ni only enriched in pit; e) PIXE EDX spectra show high Fe and Ni on crater floor, similar to micrometeoroid metal composition; f) plot of Mg/Al versus Cr/Fe X-ray counts in SEM-EDX spectra from the crater edge (red) show enrichment of Mg and Fe over alloy composition (black, grey, yellow and green), indicating a mafic silicate mi-crometeoroid component has also been added from the impacted micrometeoroid. Summary and conclusions Together, SEM-EDX and PIXE-EDX maps, spectra and X-ray count plots showed 166 MM residues and 2 OD residues in this survey of 188 impact features on WFPC2, ~ 90% of those examined, considerable enhancement of impactor recognition over an earlier study of HST impacts (~75% identified as MM or OD in origin, Kearsley et al., 2005). Acknowledgements ESA contract 40001105713/12/NL/GE awarded to NHM and the University of Surrey; Bruker for expertise in use of the X-Flash detector and loan of the M4 Tornado µ-XRF. References quoted Anz-Meador P. et al. (2013) Proc. 6th European Conf. Space Debris, ESA SP 723: s1b_anzme.pdf, CD-ROM. Colaux J. L. et al. (2014) LPSC 45 Abstract #1727. Graham, G.A. et al. (2001) Proc. 3rd European Conf. Space Debris, ESA SP 473:197–203. Kearsley A.T. et al., (2005) Adv. Space Res. 35:1254–1262. Kearsley A. T. et al. (2012) Technical Note 1 for ESA contract 40001105713/12/NL/GE. Kearsley A. T. et al. (2014a) LPSC 45 abstract #1722. Kearsley A.T. et al. (2014b) LPSC 45 abstract #1733. Moussi A. et al. (2005) Adv. Space Res. 35:1243–1253. Price M. C. et al. (2014) LPSC 45 abstract #1466. Ross D. K. et al. (2014) LPSC 45 abstract #1514.
    • Identification Trainers for the Future: Bridging the skills gap in natural history

      West, SVL (Linnean Society, 2017-09-07)
      The Identification Trainers for the Future project has been a 3-year project developing a new model of species identification training for the Museum, while also looking at sector-related career issues, particularly methods of recruitment from non-traditional entry routes into the UK biodiversity and museums sectors. Through funding from the HLF’s Skills for the Future programme and working in partnership with the NBNT and FSC, 15 trainees have worked through 12-month long work-based traineeships with us, developing their technical skills in species identification for cryptic UK taxa and developing experience in teaching and scientific communication. This talk will look at some of the lessons learnt from the project, as well as discussing some of the ways forward for the Museum now the project is starting to draw to a close.
    • Impact vaporization and Condensation: Laser Irradiation Experiments with Natural Planetary Materials

      Hamann, C; Hecht, L; Schäffer, S; Heunoske, D; Salge, T; Garbout, A; Osterholz, J; Greshake, A (The Woodlands, Texas, USA, 2018)
    • A Late Miocene methane-seep fauna from Kalimantan, Indonesia

      Kiel, S; Reich, S; Renema, W; Taylor, JD; Wesselingh, FP; Todd, JA; Anon (Instytut Paleobiologii PAN.Warsaw, 2016-06-13)
    • Lycopodiella inundata: insights into plant-fungal associations in early vascular plants

      Kowal, J; Duckett, J; Jacob, A; Rimington, W; Bidartondo, M; Field, K; Schornack, S; Pressel, S (2017-03-07)
      Recent studies have revealed that extant basal vascular plants associate with a wide range of Mucoromycotina and/or Glomeromycota fungi, paralleling the same in non-vascular liverworts and hornworts. This dispels the long-held paradigm that these early diverging lineages harbour Glomeromycota exclusively. Endophytes belonging to both fungal lineages have also been reported, for the first time, in a Devonian plant (Horneophyton ligneri). Together these discoveries point to much more diverse plant-fungus interactions in early vascular plants than previously assumed, however our understanding of these remains limited. In order to gain further insights into these key partnerships, especially those involving the early diverging Mucoromycotina, we are developing the lycophyte Lycopodiella inundata as an experimental system. L. inundata sporophytes have been shown to harbour solely Mucoromycotina fungi but equally fundamental, the identity of its gametophyte endophyte remains unknown. Using molecular and cytological approaches, we confirm that young L. inundata sporophytes are colonized exclusively by Mucoromycotina and show that the cytology of colonisation - consisting of both inter- and intracellular phases - closely resembles that in Haplomitriopsida liverwort-Mucoromycotina partnerships and the corm of H. ligneri. Our current isolation, resynthesis and molecular studies will provide further insights into both host and fungi specificity.
    • The marine mollusc collection at the Natural History Museum, London

      Salvador, A (2016-07-01)
      The Natural History Museum, London holds one of the largest and most important collections of molluscs in the world with an estimate 8 million specimens. The marine collection includes around 40,000 type lots for the phylum, mainly from the collections of Cuming, Sowerby, Smith, Gray, Adams, Melvill, Hinds, Carpenter, d’Orbigny, to name a few. As well as the scientific importance of the collections, a wealth of material originating with Sloane, Banks, Cook, Darwin, Lyell, Cracherode and Montagu gives an unparalleled historic dimension to our holdings. A dedicated library of over 6,000 bound volumes and 30,000 reprints on molluscs, dating from the 17th century, provides an incredibly accessible source of information to support collections, curation and research.
    • Mechanisms for the generation of HREE mineralization in carbonatites: Evidence from Huanglongpu, China.

      Smith, M; Cangelosi, D; Yardley, B; Wenlei Song, CX; Spratt, J (The Society for Geology Applied to Mineral Deposits, 2019-12-30)
      The Hunaglongpu carbonatites, Qinling Mountains, China, are exceptional as they form both an economic Mo resource, and are enriched in the HREE compared to typical carbonatites, giving a metal profile that may closely match projected future demand. The carbonatites at the level currently exposed appear to be transitional between magmatic and hydrothermal processes. The multistage dykes and veins are cored by quartz which hosts a fluid inclusion assemblage with a high proportion of sulphate daughter or trapped minerals, and later stage, cross-cutting veins are rich in barite-celestine. The REE mineral paragenesis evolves from monazite, through apatite and bastnäsite to Ca-REE fluorcabonates, with an increase in HREE enrichment at every stage. Radio-isotope ratios are typical of enriched mantle sources and sulphur stable isotopes are consistent with magmatic S sources. However, Mg stable isotopes are consistent with a component of recycled subducted marine carbonate in the source region, The HREE enrichment is a function of both unusual mantle source for the primary magmas and REE mobility and concentration during post-magmatic modification in a sulphate-rich hydrothermal system. Aqueous sulphate is a none specific ligand for the REE, and this coupled with crystal fraction lead to HREE enrichment during subsolidus alteration.
    • Mineralogical study of the Gonçalo Li-pegmatite deposit, Portugal

      Dolgopolova, Alla; Seltmann, Reimar; Stanley, Christopher; Armstrong, R; Noronha, F; Ramos, V; Guedes, A; Simons, B; Rollinson, G; Andersen, J; et al. (Norsk Geologisk Forening (NGF), 2017-08-01)
      Beside the Scandinavian countries and Serbia, Portugal is among the European countries with the most significant lithium resources. The Li-rich occurrences in Portugal are mainly associated with aplite-pegmatite dykes and sills intruded in granitic and metasedimentary rocks of the Central Iberian and Galicia – Trás-os-Montes geotectonic zones (Carvalho & Farinha, 2004). The Gonçalo Li-pegmatites in the Guarda district (currently only used as decorative stone) have significant economic importance. Among other deposits, Gonçalo is a reference site in the focus of the EU FAME project (www.fame-project.eu) that aims to unlock the development potential of the most promising European Sn-W-Li ore types. Results of optical microscopy, QEMSCAN©, Raman and electron-probe microanalysis of the Gonçalo Li-pegmatite deposit have been employed to determine the mineralogical variability of the pegmatites with the aim to determine the deportment of lithium and potential rare-metal by-products and to guide enhanced mineral processing technologies.
    • The mineralogy of the effusive silicate rocks from the Mosonik volcano, Northern Tanzania.

      Sedova, AM; Zaitsev, AN; Spratt, J (Vernadsky Institute of Geochemistry and Anlytical Chemistry of Russian Academy of Sciences (GEOKHI RAS), 2018-10-01)
      International Conference on Magmatism of the Earth and Related Strategic Metal Deposits 3-7 September, 2018 Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academу of Sciences, Moscow, Russia. The mineralogy of the effusive silicate rocks from the Mosonik volcano, Northern Tanzania Sedova А.М.1, Zaitsev A.N.1,2, J. Spratt2 1 Department of Mineralogy, St. Petersburg State University, Saint-Petersburg, Russia, e-mail: a.sedova@spbu.ru 2Department of Core Research Laboratories, Natural History Museum, London, UK The Mosonik volcano belongs to the Neogene-Resent volcanics of the Natron-Engaruka region of the East African Rift system. It is one of several stratovolcanoes located on the northeastern tip of the Gregory Rift Valley. Mosonik is attributed as having the earliest phase of eruptions in this province (Dawson, 2008) and is dated in the range 3.18-1.28 Ma (Isaac & Curtis, 1974; Dawson, 2008). In 1961, it was mapped by the Tanganyika Geological Survey (Guest et al., 1961), with published data (Paslick et al., 1996) on the composition of minerals from basanites, nephelinites and phonolites. According to the results of this study the compositions of melilite and nephelinite, Zaitsev et al. (2015) have indicated that the Mosonik volcano could be a potential source for the Upper Laetolil Footprint Tuff 7. According to our data the main effusive rocks of Mosonic are various nephelinites and phonolites, quite often they contain xenoliths of plutonic rocks: melteigites, foyaites, ijolites, and rocks of the enclosing stratum (andesites). Carbonatites mostly occur as boulders of various sizes within creek deposits. Among nephelinites there are nephelinites s.s., phonolitic nephelinites, calcite-phonolite nephelinites and melilite nephelinites. Microphenocrysts are represented by nepheline (45-60%), pyroxenes of diopside-hedenbergite solid solution, in some cases with aegirine edging (15-30%), apatite (3-10%) and titanite (3-10%). Calcite content reaches 10% within the calcite varieties of nephelinites; sanidine up to 10% in phonolitic nephelinites, which are strongly altered. Melilite nephelinites are also characterized by the following coposition: melilite (20%), perovskite (5%), sherlomite (3%). In rare cases within the nephelinites there are microphenocrysts of nepheline. Phonolites are represented by the following species: phonolites, sodalite phonolites and calcite phonolites. Phenocrysts are represented by nepheline (40-65%), pyroxenes of the diopside-hedenbergite series, rarely with aegirine edging (10-50%), sanidine (15-40%), Mg-Fe mica (0-5%), titanite (1-10%), and apatite (0-8%). In these rocks a large number of macrophenic crystals of nepheline, pyroxene, and often sanidine are observed. The work is supported by Russian Foundation of Basic Research (grant 18-05-00835) and St. Petersburg State University (Geomodel Resource Center) References Dawson J. B. The Gregory Rift Valley and Neogene-Recent Volcanoes of Northern Tanzania. London. 2008. 112 pp. Guest N. J., James, T. C Pickering R., and Dawson J. B. Angata salei. Geol. Surv. Tanganyika. Quarter degree sheet 39. 1961 Isaac, G. L. & Curtis, G. H. Age of the Acheulian industries from the Peninj Group, Tanzania // Nature. 1974. p.249. Paslick, C., Halliday, A. N., Lange, R. A., James, D. & Dawson, J. B. Indirect crustal contamination: evidence from isotopic and chemical disequilibria in minerals from alkali basalts and nephelinites from northern Tanzania // Contributions to Mineralogy and Petrology. Vol. 125. 1996. 277–292. Zaitsev A.N., Spratt J., Sharygin V.V., Wenzel T., Zaitseva O.A., Markl G. Mineralogy of the Laetolil Footprint Tuff: A comparison with possible volcanic sources from the Crater Highlands and Gregory Rift // Journal of African Earth Sciences. Vol. 111. 2015. pp. 214–221.
    • New model systems for early land plant evolution (w16-05) Vienna, Austria, 22 - 24 June 2016

      Kenrick, P (2016)
      Microbial communities have existed on land since at least the Neoarchean (2800 to 2500 million years), but fossil evidence indicates that the ancestors of land plants first appeared much later during the mid-Ordovician some 470 million years ago. These latter communities probably comprised varied and mixed associations of Archaea, Bacteria, arthropods, lichens, fungi, green algae and extinct land plants called ‘cryptophytes’. Little is known about the cryptophytes, but emerging evidence from fossil charcoal records minute sporophytes at the bryophyte level of complexity but with novel combinations of characteristics. Some are known to contain spores dispersed as tetrads and dyads suggesting that significant differences in sporogenesis operated in some early extinct lineages. The most intact and earliest well-preserved fossil ecosystem is the 407 million year old Rhynie Chert (Scotland). Here, plants were fossilised near to their sites of growth preserving soft tissues and organism associations. Such fossils provide unparalleled insights into the evolution of major organ systems in stem group vascular plants and lycophytes, including roots, shoots, leaves, vascular system and reproductive structures. They are helping us to understand how key plant organs evolved from precursor structures, to disentangle homology from homoplasy, to better reconstruct early life cycle evolution, and to learn about the co-evolution of plants and their fungal symbionts.