Geologic hazards of the Ocoña river valley,Peru and the influence of small-scale mining     

Santi  P.  Manning  J.  Zhou  W.  Meza  P.  Colque  P. 《Natural Hazards》2021,108(3):2679-2700

Natural Hazards - The Ocoña River Valley, in the Arequipa Department in southern Peru, extends over 150 km from the Pacific coast to its headwaters in the Andes Mountains. While...  相似文献   

The 2011 International Conference on Cohesive Sediment Transport (INTERCOH 2011)     

Qing He  Johan C. Winterwerp  Andrew James Manning 《Ocean Dynamics》2015,65(7):1047-1049

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Experimental determination of liquidus H<Subscript>2</Subscript>O contents of haplogranite at deep-crustal conditions     

A.?R.?MakhlufEmail author  R.?C.?Newton  C.?E.?Manning 《Contributions to Mineralogy and Petrology》2017,172(9):77

The liquidus water content of a haplogranite melt at high pressure (P) and temperature (T) is important, because it is a key parameter for constraining the volume of granite that could be produced by melting of the deep crust. Previous estimates based on melting experiments at low P (≤0.5 GPa) show substantial scatter when extrapolated to deep crustal P and T (700–1000 °C, 0.6–1.5 GPa). To improve the high-P constraints on H₂O concentration at the granite liquidus, we performed experiments in a piston–cylinder apparatus at 1.0 GPa using a range of haplogranite compositions in the albite (Ab: NaAlSi₃O₈)—orthoclase (Or: KAlSi₃O₈)—quartz (Qz: SiO₂)—H₂O system. We used equal weight fractions of the feldspar components and varied the Qz between 20 and 30 wt%. In each experiment, synthetic granitic composition glass + H₂O was homogenized well above the liquidus T, and T was lowered by increments until quartz and alkali feldspar crystalized from the liquid. To establish reversed equilibrium, we crystallized the homogenized melt at the lower T and then raised T until we found that the crystalline phases were completely resorbed into the liquid. The reversed liquidus minimum temperatures at 3.0, 4.1, 5.8, 8.0, and 12.0 wt% H₂O are 935–985, 875–900, 775–800, 725–775, and 650–675 °C, respectively. Quenched charges were analyzed by petrographic microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), and electron microprobe analysis (EMPA). The equation for the reversed haplogranite liquidus minimum curve for Ab_36.25Or_36.25Qz_27.5 (wt% basis) at 1.0 GPa is \(T = - 0.0995 w_{{{\text{H}}_{ 2} {\text{O}}}}^{ 3} + 5.0242w_{{{\text{H}}_{ 2} {\text{O}}}}^{ 2} - 88.183 w_{{{\text{H}}_{ 2} {\text{O}}}} + 1171.0\) for \(0 \le w_{{{\text{H}}_{ 2} {\text{O}}}} \le 17\) wt% and \(T\) is in °C. We present a revised \(P - T\) diagram of liquidus minimum H₂O isopleths which integrates data from previous determinations of vapor-saturated melting and the lower pressure vapor-undersaturated melting studies conducted by other workers on the haplogranite system. For lower H₂O (<5.8 wt%) and higher temperature, our results plot on the high end of the extrapolated water contents at liquidus minima when compared to the previous estimates. As a consequence, amounts of metaluminous granites that can be produced from lower crustal biotite–amphibole gneisses by dehydration melting are more restricted than previously thought.  相似文献   

Thick and thin models of the evolution of carbon dioxide on Mars     

Curtis V. Manning  Christopher P. McKay 《Icarus》2006,180(1):38-59

We present results from a new simulation code that accounts for the evolution of the reservoirs of carbon dioxide on Mars, from its early years to the present. We establish a baseline model parameter set that produces results compatible with the present (i.e., Patm?6.5 mbar with permanent CO₂ ice cap) for a wide range of initial inventories. We find that the initial inventory of CO₂ broadly determines the evolutionary course of the reservoirs of CO₂. The reservoirs include the atmosphere, ice cap, adsorbed CO₂ in the regolith, and carbonate rocks. We track the evolution of the free inventory: the atmosphere, ice cap and regolith. Simulations begin at 4.53 Gyr before present with a rapid loss of free inventory to space in the early Noachian. Models that assume a relatively small initial inventory (?5 bar) have pronounced minima in the free inventory of CO₂ toward the end of the Noachian. Under baseline parameters, initial inventories below ∼4.5 bar result in a catastrophic loss of the free inventory to space. The current free inventory would be then determined by the balance between outgassing, sputtering losses and chemical weathering following the end of the late bombardment. We call these “thin” models. They generically predict small current free inventories in line with expectations of a small present CO₂ ice cap. For “thick” models, with initial inventories ?5 bar, a surplus of 300-700 mbar of free CO₂ remains during the late-Noachian. The histories of free inventory in time for thick models tend to converge within the last 3.5 Gyr toward a present with an ice cap plus atmospheric inventory of about 100 mbar. For thick models, the convergence is largely due to the effects of chemical weathering, which draws down higher free inventories more rapidly than the low. Thus, thick models have ?450 mbar carbonate reservoirs, while thin models have ?200 mbar. Though both thick and thin scenarios can reproduce the current atmospheric pressure, the thick models imply a relatively large current CO₂ ice cap and thin models, little or none. While the sublimation of a massive cap at a high obliquity would create a climate swing of greenhouse warming for thick models, under the thin model, mean temperatures and pressures would be essentially unaffected by increases in obliquity.  相似文献   

The Nippon/Norway Svalbard Meteor Radar: First results of small-scale structure observations     

BO Husφy 《极地研究(英文版)》2002,13(1)

1　ＩｎｔｒｏｄｕｃｔｉｏｎＡｔｌａｔｉｔｕｄｅｓａｒｏｕｎｄ 80°Ｎａｎｄｉｎｔｈｅｍｅｓｏｓｐｈｅｒｅ /ｌｏｗｅｒｔｈｅｒｍｏｓｐｈｅｒｅ (ＭＬＴ) ,ｔｈｅｒｅｈａｖｅｂｅｅｎｆｅｗｍｅａｓｕｒｅｍｅｎｔｓｏｆｎｅｕｔｒａｌｄｙｎａｍｉｃｓ.ＡｒｅｑｕｉｒｅｍｅｎｔｗａｓｓｅｅｎｆｏｒｌｏｎｇｔｅｒｍｃｏｎｔｉｎｕａｌｍｏｎｉｔｏｒｉｎｇａｎｄａＶＨＦｍｅｔｅｏｒｒａｄａｒｗａｓｉｄｅｎｔｉｆｉｅｄａｓｂｅｉｎｇａｍｏｓｔｓｕｉｔａｂｌｅｉｎｓｔｒｕｍｅｎｔ.ＲａｄａｒｓｌｉｋｅｔｈｅＥＩＳＣＡ…  相似文献   

The Mars oxidant experiment (MOx) for Mars '96     

McKay CP  Grunthaner FJ  Lane AL  Herring M  Bartman RK  Ksendzov A  Manning CM  Lamb JL  Williams RM  Ricco AJ  Butler MA  Murray BC  Quinn RC  Zent AP  Klein HP  Levin GV 《Planetary and Space Science》1998,46(6-7):769-777

The MOx instrument was developed to characterize the reactive nature of the martian soil. The objectives of MOx were: (1) to measure the rate of degradation of organics in the martian environment; (2) to determine if the reactions seen by the Viking biology experiments were caused by a soil oxidant and measure the reactivity of the soil and atmosphere: (3) to monitor the degradation, when exposed to the martian environment, of materials of potential use in future missions; and, finally, (4) to develop technologies and approaches that can be part of future soil analysis instrumentation. The basic approach taken in the MOx instrument was to place a variety of materials composed as thin films in contact with the soil and monitor the physical and chemical changes that result. The optical reflectance of the thin films was the primary sensing-mode. Thin films of organic materials, metals, and semiconductors were prepared. Laboratory simulations demonstrated the response of thin films to active oxidants.  相似文献   

Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics     

CV Ramana  U Becker  V Shutthanandan  CM Julien 《Geochemical transactions》2008,9(1):8

Molybdenum disulfide (MoS₂), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS₂ is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia.  相似文献   

Considerations for conducting incubations to study the mechanisms of As release in reducing groundwater aquifers     

Kathleen A. Radloff  Anya R. Manning  Brian Mailloux  Yan Zheng  M. Moshiur Rahman  M. Rezaul Huq  Kazi M. Ahmed  Alexander van Geen 《Applied Geochemistry》2008

Microbial Fe reduction is widely believed to be the primary mechanism of As release from aquifer sands in Bangladesh, but alternative explanations have been proposed. Long-term incubation studies using natural aquifer material are one way to address such divergent views. This study addresses two issues related to this approach: (1) the need for suitable abiotic controls and (2) the spatial variability of the composition of aquifer sands. Four sterilization techniques were examined using orange-colored Pleistocene sediment from Bangladesh and artificial groundwater over 8 months. Acetate (10 mM) was added to sacrificial vials before sterilization using either (1) 25 kGy of gamma irradiation, (2) three 1-h autoclave cycles, (3) a single addition of an antibiotic mixture at 1× or (4) 10× the typical dose, and (5) a 10 mM addition of azide. The effectiveness of sterilization was evaluated using two indicators of microbial Fe reduction, changes in diffuse spectral reflectance and leachable Fe(II)/Fe ratios, as well as changes in P-extractable As concentrations in the solid phase. A low dose of antibiotics was ineffective after 70 days, whereas autoclaving significantly altered groundwater composition. Gamma irradiation, a high dose of antibiotics, and azide were effective for the duration of the experiment.  相似文献   

Changes in mitochondrial gene and protein expression in grass shrimp, Palaemonetes pugio, exposed to chronic hypoxia     

Brouwer M  Brown-Peterson NJ  Hoexum-Brouwer T  Manning S  Denslow N 《Marine environmental research》2008,66(1):143-145

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Integrating field and laboratory approaches for ripple development in mixed sand–clay–EPS     

Jaco H. Baas  Megan L. Baker  Jonathan Malarkey  Sarah J. Bass  Andrew J. Manning  Julie A. Hope  Jeffrey Peakall  Ian D. Lichtman  Leiping Ye  Alan G. Davies  Daniel R. Parsons  David M. Paterson  Peter D. Thorne 《Sedimentology》2019,66(7):2749-2768

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