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821.
Skarns are developed over two temperature‐time intervals in calcite limestone adjacent to the southern extension of the Glenrock Granodiorite, a pluton of the Marulan Batholith, Southern Highlands, New South Wales. The initial volumetrically‐dominant prograde phase of skarn formation produced a suite comprising bimetasomatic skarn, including pyroxene endoskarn, potassic endoskarn and wollastonite‐bearing exoskarn, together with mineralogically‐zoned vein skarn, massive garnet‐pyroxene skarn and calcite‐vesuvianite skarn. Retrograde replacement is manifested by the development of hydrous silicate minerals, carbonate and cross‐cutting sulphide veinlets. A genetic model is proposed to account for the development of bimetasomatic skarn in the deposit. Exoskarn geochemistry indicates addition of many components relative to an essentially pure limestone precursor, including Si, Al, Fe, Zr, Zn, S, Mn and Cu, negligible transfer of K, Na and Rb and loss of CO2. Strontium and Ca loss from the parent limestone is indicated by mass balance calculations at constant volume. Garnet and pyroxene compositions in the massive garnet‐pyroxene skarn range from Gr30 to Gr66 and Hd61 to Hd87, respectively. Compositions from Gr67 to Gr95 are typical of the vein skarn garnets. Chemical zonation patterns in garnet, pyroxene and vesuvianite are generally characterized by rim Fe depletion relative to cores of grains. Prograde skarn probably formed at T = 500–580°C; P < 220 MPa. The massive garnet‐pyroxene skarn evolved under conditions of log fO2 = ‐18.9 to ‐22.9 (assuming a constant fCO2 of 20 MPa) within the fS2 stability field of pyrrhotite. Retrograde skarn formed at T < 400°C, possibly under conditions of XH2O < 0.01. Vesuvianite plus wollastonite assemblages, present in exoskarn, probably attest to very water‐rich conditions. The marble wall rocks, isolated from the source of skarn‐forming fluids, probably evolved under conditions of minimum Xco2 >0.2. Low temperature CO2 ‐rich fluid inclusions and prehnite (stable at Xco2 <0.01), present in the marble and skarn, respectively, suggest that substantial differences in Xco2: XH2O were maintained during cooling. Observed mineralogical and chemical zonation within the skarn reflects the complex interaction of T, P, fO2, Xco2 and other chemical variables such as aSiO2 and aAl2O3 throughout the skarn system. No single variable can account adequately for the mineralogical diversity observed in the skarn deposit. 相似文献
822.
研究区5号煤层位于三叠系瓦窑堡组第四段上部,煤层直接顶以泥岩、砂质泥岩为主,老顶以粉砂岩、泥岩和细粒砂岩为主,从岩性分布来看,总体呈现出向上变粗的沉积层序,对应的顶板类型为下软上硬型.进一步分析其岩石力学性质、测井曲线与岩体质量指标,参考岩层厚度、层理及裂隙等,综合分析确定该区5号煤层顶板属基本稳定型.该研究为煤矿的安全生产提供了技术支持. 相似文献
823.
824.
以古交镇城底煤矿生活污水处理厂二级出水为研究对象,采用F/BF净化工艺,进行了污水深度处理的生产性试验。研究表明,该工艺对二级处理后的生活污水具有稳定、高效的净化能力,出水水质基本达到地面水Ⅳ类标准,可用于工业冷却水和低压水暖锅炉补充水,具有显著的经济效益和环境效益。试验还对不同滤料进行了分析,认为作为工业废料的炉渣是一种廉价、高效的新型生物膜过滤材料。 相似文献
825.
In October 1998 a multiple peat slide occurred on the northern slopes of Cuilcagh Mountain, Co. Fermanagh, in response to a high‐magnitude rainfall event. Few peat slides have been recorded in Ireland, and a detailed field survey and investigation of the failure was undertaken within four weeks of the event. The morphological evidence indicated a distinct sequence of events which appeared to begin with the failure of a small segment of slope above a degraded transverse drainage ditch which was cut less than ten years previously. This segment of slope was no more than 42 m wide and 25 m long, with 0·7 m of peat overlying up to 0·5 m of a pale coloured clay, the latter containing small pipes and resting on the surface of a darker coloured loamy material. The failure surface was located at or near the base of the pale clay layer. Finite element software was used to model hydrological conditions within the upper segment of slope and to calculate factors of safety for different slope configurations including the presence or absence of a drain or a subsurface pipe. Using the peak shear strength of the pale clay, as determined in the laboratory, both the drain and subsurface pipes were required to obtain a factor of safety of 1·0 or less. Allowing for the uncertainties associated with the hydrological modelling of the pipes, it is suggested that the cutting of the drain and the hydrological impacts of its subsequent degradation are ultimately responsible for the failure. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
826.
楚雄盆地烃源岩有机地化特征及综合评价 总被引:5,自引:0,他引:5
对楚雄盆地各组段烃源岩的厚度分布特征、地化特征及成熟度特征分别进行静态研究,对各组段烃源岩的优劣及生烃潜力作出了综合评价,并预测了各区块的油气勘探前景。 相似文献
827.
828.
As a solid reservoir, a glacier can regulate regional water resources. The annual net mass balance directly reflects the
fluctuation of the glacier and climate variability. Based on 51 years of mass balance observation data, the mass balance of
Tianshan Mountains Urumqi Glacier No. 1 experienced a nine times positive balance fluctuation and nine times negative
balance fluctuation. There were 35 and 16 negative and positive balance years, respectively. From 1996/97 to 2008/09, 12
consecutive negative balance years were observed at Tianshan Mountains Urumqi Glacier No. 1. These results demonstrate
that the Urumqi Glacier No. 1 is experiencing a strong negative balance, and the strongest negative balance, -931
mm w.e. (mm water equivalent), during the observation period occurred in 2008. In addition, the cumulative mass balance
reached 13,709 mm w.e. in 2008. However, in 2009, the mass balance was positive at 63 mm w.e. The equilibrium-line altitude
changes with the fluctuation in the mass balance, and the effective mass balance gradient is 7.4 mm/m. In this paper,
the headwaters of the Urumqi River were analyzed using meteorological data from 1958 to 2009, including the average
seasonal temperature and precipitation. The results showed that the main factor associated with the mass balance variation
of Glacier No. 1 is the fluctuation in the summer air temperature, followed by changes in the precipitation. 相似文献
829.
Jamesina J. Simpson 《Surveys in Geophysics》2009,30(2):105-130
Advances in computing technologies in recent decades have provided a means of generating and performing highly sophisticated
computational simulations of electromagnetic phenomena. In particular, just after the turn of the twenty-first century, improvements
to computing infrastructures provided for the first time the opportunity to conduct advanced, high-resolution three-dimensional
full-vector Maxwell’s equations investigations of electromagnetic propagation throughout the global Earth-ionosphere spherical
volume. These models, based on the finite-difference time-domain (FDTD) method, are capable of including such details as
the Earth’s topography and bathymetry, as well as arbitrary horizontal/vertical geometrical and electrical inhomogeneities
and anisotropies of the ionosphere, lithosphere, and oceans. Studies at this level of detail simply are not achievable using
analytical methods. The goal of this paper is to provide an historical overview and future prospectus of global FDTD computational
research for both natural and man-made electromagnetic phenomena around the world. Current and future applications of global
FDTD models relating to lightning sources and radiation, Schumann resonances, hypothesized earthquake precursors, remote sensing,
and space weather are discussed.
相似文献
Jamesina J. SimpsonEmail: |
830.
Christoph Clauser 《Surveys in Geophysics》2009,30(3):163-191
The heat of the Earth derives from internal and external sources. A heat balance shows that most of the heat provided by external
sources is re-emitted by long-wavelength heat radiation and that the dominant internal sources are original heat and heat
generated by decay of unstable radioactive isotopes. Understanding of the thermal regime of the Earth requires appreciation
of properties and mechanisms for heat generation, storage, and transport. Both experimental and indirect methods are available
for inferring the corresponding rock properties. Heat conduction is the dominant transport process in the Earth’s crust, except
for settings where appreciable fluid flow provides a mechanism for heat advection. For most crustal and mantle rocks, heat
radiation becomes significant only at temperatures above 1200°C.
相似文献
Christoph ClauserEmail: |