http://www.dspace.cam.ac.uk:80/handle/1810/195764 Sun, 19 May 2013 17:23:43 GMT 2013-05-19T17:23:43Z http://www.dspace.cam.ac.uk:80/retrieve/366789/new_logo es.gif http://www.dspace.cam.ac.uk:80/handle/1810/195764 http://www.dspace.cam.ac.uk:80/handle/1810/244506 Title: Fluid-rock interactions in a carbon storage site analogue, Green River, Utah Authors: Kampman, Niko Abstract: Reactions between CO2-charged brines and reservoir minerals might either enhance the long-term storage of CO2 in geological reservoirs or facilitate leakage by corroding cap rocks and fault seals. Modelling the progress of such reactions is frustrated by uncertainties in the absolute mineral surface reaction rates and the significance of other rate limiting steps in natural systems. This study uses the chemical evolution of groundwater from the Jurassic Navajo Sandstone, part of a leaking natural accumulation of CO2 at Green River, Utah, in the Colorado Plateau, USA, to place constraints on the rates and potential controlling mechanisms of the mineral-fluid reactions,under elevated CO2 pressures, in a natural system. The progress of individual reactions, inferred from changes in groundwater chemistry is modelled using mass balance techniques. The mineral reactions are close to stoichiometric with plagioclase and K-feldspar dissolution largely balanced by precipitation of clay minerals and carbonate. Mineral modes, in conjunction with published surface area measurements and flow rates estimated from hydraulic head measurements, are then used to quantify the kinetics of feldspar dissolution. Maximum estimated dissolution rates for plagioclase and K-feldspar are 2x10-14 and 4x10-16 mol·m-2·s-1, respectively. Fluid ion-activity products are close to equilibrium (e.g. DGr for plagioclase between -2 and -10 kJ/mol) and lie in the region in which mineral surface reaction rates show a strong dependence on DGr. Local variation in DGr is attributed to the injection and disassociation of CO2 which initially depresses silicate mineral saturation in the fluid, promoting feldspar dissolution. With progressive flow through the aquifer, feldspar hydrolysis reactions consume H+ and liberate solutes to solution which increase mineral saturation in the fluid and rates slow as a consequence. The measured plagioclase dissolution rates at low DGr would be compatible with far-from-quilibrium rates of ~1x10-13 mol·m-2·s-1 as observed in some experimental studies. This suggests that the discrepancy between field and laboratory reaction rates may in part be explained by the differences in the thermodynamic state of natural and experimental fluids, with field-scale reactions occurring close to equilibrium whereas most laboratory experiments are run far-from-equilibrium. Surface carbonate deposits and cementation within the footwall of the local fault systems record multiple injections of CO2 into the Navajo Aquifer and leakage of CO2 from the site over ca. 400,000 years. The d18O, d13C and 87Sr/86Sr of these deposits record rapid rates of CO2 leakage (up to ~1000 tonnes/a) following injection of CO2, but rates differ by an order of magnitude between each fault, due to differences in the fault architecture. Elevated pCO2 enhances rates of feldspar dissolution in the host aquifer and carbonate precipitation in fracture conduits. Silicate mineral dissolution rates decline and carbonate precipitation rates increase as pH and the CO2 charge dissipate. The Sr/Ca of calcite cements record average precipitation rates of ~2x10-6 mol/m2/s, comparable to laboratory derived calcite precipitation rates in fluids with elevated Mn/Ca and Fe/Ca, at cc of ~1 to 3. This suggests that far-from-equilibrium carbonate precipitation, which blocks fracture conduits and causes the leaking system to self-seal, driven by CO2 degassing in the shallow subsurface, can be accurately modeled with laboratory derived rates. Sandstones altered in CO2 leakage conduits exhibit extensive dissolution of hematite grain coatings and are chemically bleached as a result. Measurements of Eh-pH conditions in the modern fluid, and modeling of paleo-Eh-pH conditions using calcite Fe and Mn concentrations, suggests that the CO2-charged groundwaters are reducing, due to their low dissolved O2 content and that pH suppression due to high pCO2 is capable of dissolving and transporting large concentrations of metals. Exhumed paleo-CO2 reservoirs along the crest of the Green River anticline have been identified using volatile hosting fluid inclusions. Paleo-CO2-charged fluids mobilized hydrocarbons and CH4 from deeper formations, enhancing the reductive dissolution of hematite, which produced spectacular km-scale bleached patterns in these sediment. Description: Pagination differs from hardbound copy deposited in Cambridge University Library. Mon, 11 Jul 2011 23:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/244506 2011-07-11T23:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/243629 Title: The evolution of the Baie Verte Lineament, Burlington Peninsula, Newfoundland Authors: Kidd, William Abstract: An area measuring about 5 km by 30 km, of the relatively well-exposed central part of the Baie Verte Lineament, has been mapped in detail. Two major rock divisions are recognised by their differing structural and metamorphic histories. A terrain of psammitic, semipelitic and mafic schists borders the western side of the Lineament. These rocks (part of the Fleur de Lys Supergroup) are in upper greenschist to epidote-amphibolite metamorphic facies, and are affected by a polyphase deformation sequence. They are intruded by post-kinematic granite and tonalite. A large, generally unfoliated, granodiorite (Burlington Granodiorite) borders the eastern side of the Lineament. Outside the map area, it is seen to be either a pre- or early syn-kinematic intrusion into Fleur de Lys schists. The Baie Verte Lineament consists, in the mapped area, of two adjacent narrow-parallel belts; to the west the Baie Verte Group of uncertain (?Arenigian) age, and to the east the early Devonian Mic Mac Lake Group. Large lensoid "alpine-type" (ophiolitic) ultramafic bodies are situated along the tectonic contact between the Fleur de Lys schists and the Baie Verte Group. A narrow discontinuous strip containing bodies of ophiolitic gabbro with parallel diabase dykes is found at the western side of the Baie Verte Group adjoining the tectonic contact. The internal structures and textures of the ophiolitic rocks are described. The Baie Verte Group consists mainly of mafic pillow lava and mafic volcaniclastic sediments, subvertical to moderately west-dipping, and facing east, for which a stratigraphy is defined. At or near the base, a conglomerate, resting on ophiolite gabbro megabreccia, contains clasts mainly referable to the mafic parts of an ophiolite complex, with some clasts identical to the Burlington Granodiorite, and rare clasts referable to previously deformed silicic volcanics and related sediments of the Fleur de Lys Supergroup found to the east of the map area. Redeposited carbonate rocks are very occasionally found near this horizon. The Mic Mac Lake Group rests with spectacular unconformity, including a significant amount of palaeotopographic relief, on the Burlington Granodiorite. It also contains a similar erosion surface within the subaerial sequence of silicic volcanics, mafic and trachyte lava flows, and mostly conglomeratic sediments. A stratigraphy is defined for the Mic Mac Lake Group. The sequence dips west at moderate angles and, with the significant exception of a narrow strip at the western side, faces west. The Baie Verte and Mic Mac Lake Groups share a single steep cleavage and low greenschist facies metamorphic grade. An autochthonous contact between Baie Verte Group and east-facing Mic Mac Lake Group in the southern part of the area indicates that the Mic Mac Lake Group is in a highly-disrupted syncline, and is unconformable on the Baie Verte Group. To the north an attenuated Mic Mac Lake Group is overthrust by the Baie Verte Group, and must eventually be cut out to the north of the map area where the Baie Verte Group directly overthrusts Burlington Granodiorite. It is shown that the deformation of the Baie Verte and Mic Mac Lake Groups, and the tectonic emplacement of the ophiolitic ultramafic bodies into their present position, was wholly later than all the regional polyphase deformation and metamorphism of the Fleur de Lys Supergroup, and that this later deformation is almost wholly localised in the belt of less complexely deformed rock. Joint mapping with J.M. Bird and J.F. Dewey at the northeast end of the Baie Verte Lineament demonstrated the presence of all members of a full ophiolite suite, overlain by mafic volcaniclastic sediments and a thick pile of pillow lava. The internal igneous-relationships of the ophiolite complex are described. These rocks are disposed in three thrust sheets (two being inverted), which are overthrust eastward above previously deformed and metamorphosed Fleur de Lys schists. One model has been proposed that coherently interprets the Palaeozoic evolution of the central and western Newfoundland Appalachians in terms of present-day continental margin / island arc sedimentation, magmatism, and tectonics. The results of this mapping are interpreted within the framework of this model. The Fleur de Lys schists and Burlington Granodiorite represent rifted continental margin sediments, and a volcanic arc built on and intruding them prior to polyphase deformation and metamorphism. The Baie Verte Group is interpreted as the remains of the oceanic crust and mantle floor and mafic volcanic fill of one of several small marginal (inter-arc) basins that developed in the northwestern Newfoundland area in lower Ordovician times. It is interpreted to be in the place where the basin formed relative to the eastern and western Fleur de Lys blocks that border it. The Mic Mac Lake Group is a proximal section to an early Devonian calc-alkaline cordilleran caldera complex which may have been related either to subduction or to continental collision processes. It was laid down over an eroded surface of Burlington Granodiorite and over little to undeformed mafic rocks filling the Baie Verte marginal basin. Both were then deformed during the Acadian continental collision orogeny by contraction of the Baie Verte basin, with medium to high angle eastward overthrusting. Description: Notes for the reader. Thin sections and corresponding rock samples used for this study are deposited in the Harker collection of the Department of Mineralogy and Petrology, University of Cambridge. (Catalogue no. 33, p. 251-253, 255- 283; serial numbers 110403-110456, and 110476-110990). The magnification quoted in captions to photomicrographs is the true scale of the print to the thin section. The prints are about 85 X 57 mm., and their longest side therefore represents about 8.5, 3.4, 2.1 and 0.85 mm. for magnifications of X 10, X 25, X 40 and X 100 respectively. The camera lens cap seen in photographs of outcrop surfaces is 45 mm across. Tue, 29 Oct 1974 00:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/243629 1974-10-29T00:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/243432 Title: Iceland 1965 Two Land Rovers Authors: Bennet, J Description: two Land Rovers, parked in the Icelandic countryside. Fri, 01 Jan 1965 00:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/243432 1965-01-01T00:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/237561 Title: Bats that walk: a new evolutionary hypothesis for the terrestrial behaviour of New Zealand's endemic mystacinids Authors: Hand, Suzanne J; Weisbecker, Vera; Beck, Robin M D; Archer, Michael; Godthelp, Henk; Tennyson, Alan J D; Worthy, Trevor H Abstract: Abstract Background New Zealand's lesser short-tailed bat Mystacina tuberculata is one of only two of c.1100 extant bat species to use a true walking gait when manoeuvring on the ground (the other being the American common vampire bat Desmodus rotundus). Mystacina tuberculata is also the last surviving member of Mystacinidae, the only mammalian family endemic to New Zealand (NZ) and a member of the Gondwanan bat superfamily Noctilionoidea. The capacity for true quadrupedal terrestrial locomotion in Mystacina is a secondarily derived condition, reflected in numerous skeletal and muscular specializations absent in other extant bats. The lack of ground-based predatory native NZ mammals has been assumed to have facilitated the evolution of terrestrial locomotion and the unique burrowing behaviour of Mystacina, just as flightlessness has arisen independently many times in island birds. New postcranial remains of an early Miocene mystacinid from continental Australia, Icarops aenae, offer an opportunity to test this hypothesis. Results Several distinctive derived features of the distal humerus are shared by the extant Mystacina tuberculata and the early Miocene Australian mystacinid Icarops aenae. Study of the myology of M. tuberculata indicates that these features are functionally correlated with terrestrial locomotion in this bat. Their presence in I. aenae suggests that this extinct mystacinid was also adapted for terrestrial locomotion, despite the existence of numerous ground-based mammalian predators in Australia during the early Miocene. Thus, it appears that mystacinids were already terrestrially-adapted prior to their isolation in NZ. In combination with recent molecular divergence dates, the new postcranial material of I. aenae constrains the timing of the evolution of terrestrial locomotion in mystacinids to between 51 and 26 million years ago (Ma). Conclusion Contrary to existing hypotheses, our data suggest that bats are not overwhelmingly absent from the ground because of competition from, or predation by, other mammals. Rather, selective advantage appears to be the primary evolutionary driving force behind habitual terrestriality in the rare bats that walk. Unlike for birds, there is currently no evidence that any bat has evolved a reduced capacity for flight as a result of isolation on islands. Description: RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are. Sun, 19 Jul 2009 23:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/237561 2009-07-19T23:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/236783 Title: Network equilibration and first-principles liquid water Authors: Artacho, Emilio; Fernandez-Serra, M V Abstract: Motivated by the very low diffusivity recently found in ab initio simulations of liquid water, we have studied its dependence with temperature, system size, and duration of the simulations. We use ab initio molecular dynamics (AIMD), following the Born–Oppenheimer forces obtained from density-functional theory (DFT). The linear-scaling capability of our method allows the consideration of larger system sizes (up to 128 molecules in this study), even if the main emphasis of this work is in the time scale. We obtain diffusivities that are substantially lower than the experimental values, in agreement with recent findings using similar methods. A fairly good agreement with D(T) experiments is obtained if the simulation temperature is scaled down by 20%. It is still an open question whether the deviation is due to the limited accuracy of present density functionals or to quantum fluctuations, but neither technical approximations (basis set, localization for linear scaling) nor the system size (down to 32 molecules) deteriorate the DFT description in an appreciable way. We find that the need for long equilibration times is consequence of the slow process of rearranging the H-bond network (at least 20 ps at AIMDs room temperature). The diffusivity is observed to be very directly linked to network imperfection. This link does not appear an artifact of the simulations, but a genuine property of liquid water. Wed, 08 Dec 2004 00:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/236783 2004-12-08T00:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/226116 Title: Dynamic Properties of Materials: Phonons from Neutron Scattering Authors: Cope, Elizabeth Ruth Abstract: A detailed understanding of fundamental material properties can be obtained through the study of atomic vibrations, performed experimentally with neutron scattering techniques and coupled with the two powerful new computational methodologies I have developed. The first approach involves phonon-based simulations of the pair distribution function -- a histogram of localised atomic positions generated experimentally from total scattering data. This is used to reveal ordering behaviour, to validate interatomic models and localised structure, and to give insights into how far dynamic behaviour can be studied using total scattering techniques. Most importantly, the long-standing controversy over dynamic disorder in $\beta$-cristobalite is resolved using this technique. Inelastic neutron spectroscopy (INS) allows \emph{direct} study of vibrational modes through their interaction with the neutron beam, and is the experimental basis for the second strand of the new methodology. I have developed new simulation and refinement tools based on the next generation of spectrometers currently being commissioned at the ISIS pulsed neutron source. This allows a detailed powder spectroscopy study of cristobalite and vitreous silica demonstrating that the Bose peak and so-called `fast sound' features can be derived from standard lattice dynamics in both the crystal and the amorphous counterpart, and allowing discussion of their origins. Given the controversy in the literature, this is a key result. The new methodology also encompasses refinement of interatomic models against powder INS data, with aluminium providing a successful test-case. A more complex example is seen in calcite, with experimental data collected during the commissioning of the new MERLIN spectrometer. Simulated one-phonon coherent INS spectra for the single crystal and powder (the latter including approximations to multi-phonon and multiple scatter) are fully convolved with experimental resolution functions. These are used in the analysis of the experimental data, yielding previously unpublished dispersion curves and soft mode information, as well as allowing the effectiveness of powder refinement of more complex materials to be assessed. Finally, I present further applications with technologically important materials -- relaxor ferroelectrics and high temperature pnictide superconductors. The conclusions draw together the different strands of the work, discussing the importance of these new advances together with future developments and scientific applications. Description: Related article - "FORTRAN routines for the new SQW and PDF modules of GULP and TOBYFIT" at http://www.dspace.cam.ac.uk/handle/1810/225173 in the Data sets - Mineral Science Collection Fri, 01 Jan 2010 00:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/226116 2010-01-01T00:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/225173 Title: FORTRAN routines for the new SQW and PDF modules of GULP and TOBYFIT Authors: Cope, Elizabeth Ruth Abstract: A detailed understanding of fundamental material properties can be obtained through the study of atomic vibrations, performed experimentally with neutron scattering techniques and coupled with the two powerful new computational methodologies I have developed. The first approach involves phonon-based simulations of the pair distribution function -- a histogram of localised atomic positions generated experimentally from total scattering data. Inelastic neutron spectroscopy (INS) allows \emph{direct} study of vibrational modes through their interaction with the neutron beam, and is the experimental basis for the second strand of the new methodology. I have developed new simulation and refinement tools based on the next generation of spectrometers currently being commissioned at the ISIS pulsed neutron source. The new methodology also encompasses refinement of interatomic models against powder INS data, and simulated one-phonon coherent INS spectra for the single crystal and powder (the later including approximations to multi-phonon and multiple scatter) fully convolved with experimental resolution functions. The new modules are written in FORTRAN, and represent additions to the current version of GULP (v.3.4) and of TOBYFIT (v.2). Minor modifications (discussed in my thesis) are also necessary to make these two pre-exisiting codes interact properly. Description: This contains the source code for new modules for GULP and TOBYFIT, and is to be used in conjunction with these pre-exisiting codes. Wed, 19 May 2010 23:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/225173 2010-05-19T23:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/218854 Title: Aspects of structural and electronic disorder in network materials: approaches to simulation Authors: Walkingshaw, Andrew D Abstract: Disorder in solids is one of the critical problems facing exponents of simulation-based studies in the mineral sciences. This thesis presents some novel techniques which can be used to probe the structure and dynamics of such systems under simulation. Two techniques are focussed upon. Firstly, the use of simulated charge as a probe to investigate the bonding and electrochromic properties of materials (particularly tungsten trioxide); secondly, derivation of a novel algorithm (Constrained Linear Maximization) for prediction of transition states by simulation, and its application to diffusion simulations in both crystalline network silicates and silica glass. Tue, 06 Mar 2007 00:00:00 GMT http://www.dspace.cam.ac.uk:80/handle/1810/218854 2007-03-06T00:00:00Z http://www.dspace.cam.ac.uk:80/handle/1810/198579 Title: Field Trip Picture Lake District 02 Authors: Jones, Hugh L K Abstract: Lake District. Mr.Nicholls (taller) and Prof. King Mon, 20 Oct 2008 08:20:32 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198579 2008-10-20T08:20:32Z http://www.dspace.cam.ac.uk:80/handle/1810/198578 Title: Field Trip Picture Lake District 01 Authors: Jones, Hugh L K Abstract: Lake District (Jenkins Crag) Derek Gobbett (with beard), Mike Fuller and Prof.King behind. Mon, 20 Oct 2008 08:09:34 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198578 2008-10-20T08:09:34Z http://www.dspace.cam.ac.uk:80/handle/1810/198577 Title: Barrington chalk pit Authors: Jones, Hugh L K Abstract: Barrington chalk pit (?). Form tutor is at the top. Dr.Hay facing the students. Mon, 20 Oct 2008 08:07:22 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198577 2008-10-20T08:07:22Z http://www.dspace.cam.ac.uk:80/handle/1810/198367 Title: Sedgwick Museum in the snow Authors: Jones, Hugh L K Abstract: Sedgewick in the snow. Mr Harland (on the right) and A. N. Other Thu, 25 Sep 2008 07:52:38 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198367 2008-09-25T07:52:38Z http://www.dspace.cam.ac.uk:80/handle/1810/198362 Title: Photograph of Illustration from 'Thoughts on a Pebble or an Introduction to Geology' by Gideon Mantell Authors: Simons, Dudley Description: Photograph taken by the Earth Sciences Departmental Photographer, D. Simons, of colour illustration from Gideon Mantell's book: "Thoughts on a Pebble, or, A First Lesson in Geology". Mon, 15 Sep 2008 14:54:01 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198362 2008-09-15T14:54:01Z http://www.dspace.cam.ac.uk:80/handle/1810/198361 Title: Pembrokeshire in the rain. Twr-y-felin hotel? Authors: Jones, Hugh L K Description: 'X' signifies name unknown. From the right. X,X,X, Derek Gobbett,X,Roger Lushington, X, Alec Gethin,Marjorie Entwhistle, X ,Margaret Roddam (tiny), X,X,X,X,X Mon, 15 Sep 2008 14:32:39 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198361 2008-09-15T14:32:39Z http://www.dspace.cam.ac.uk:80/handle/1810/198357 Title: Field Trip Picture Pembrokeshire 02 Authors: Jones, Hugh L K Description: (possibly) Dr Black and Mr.Forbes Mon, 15 Sep 2008 14:17:03 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198357 2008-09-15T14:17:03Z http://www.dspace.cam.ac.uk:80/handle/1810/198355 Title: Field Trip Picture Pembrokeshire 01 Authors: Jones, Hugh L K Description: St.Davids or Fishguard. Derek Gobbett conspicuous in the centre (pale anorak) talking to Mike Fuller; and William Durran the tallest chap in the back row near the door. Dr.Hay just visible behind the chap on the left who appears to be 'conducting' things. Mon, 15 Sep 2008 14:11:07 GMT http://www.dspace.cam.ac.uk:80/handle/1810/198355 2008-09-15T14:11:07Z