HYDRAULIC FRACTURING OF CRYSTALLINE ROCKS STIMULATES YIELD OF TWO TEST WELLS DRILLED IN NEW HAMPSHIRE     

Glenn W. Stewart 《Ground water》1974,12(1):46-47

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Extreme differentiation in the proterozoic Gjerstad-Morkeheia Complex of South Norway     

K. P. Milne  I. C. Starmer 《Contributions to Mineralogy and Petrology》1982,79(4):381-393

The Gjerstad-Morkeheia Complex contains a series of highly differentiated, iron and alkali enriched intrusions. The rocks range from basic to acid compositions and were variably mylonitised (under anhydrous conditions) before being metamorphosed (and hydrated) at upper amphibolite facies grade. They now form a series of ironenriched metagabbros, metadiorites and granodioritic gneisses, together with granitic and charnockitic augen gneisses. The augen formed by shearing of original megacrysts in the igneous rocks. A major mylonite zone formed at the same time.The rocks are enriched in Fe, Mn, K, Na, Ti, Zr, Ba, P, La, Ce and impoverished in Mg, V, Ni, Cr and are considered to result from extreme differentiation of an alkaline magma. They are interpreted in terms of a two-stage model, with the intrusion of several fractionated batches of magma, each of which differentiated in situ.The rocks show some affinities with other Proterozoic complexes, particularly some anorthosite-monzonite-charnockite suites (e.g. in SW Norway and in the Grenville Province) and differentiated alkaline suites (e.g. in the Gardar Province of South Greenland).The intrusions were anorogenic and emplaced in rocks which had been metamorphosed (between 1,600 and 1,500 Ma). Subsequent thrusting and mylonitisation was followed by crustal thinning and attempted rifting with widespread intrusion of basic rocks (around 1,200 Ma). The rifting was aborted by the onset of the Sveconorwegian (Grenvillian) orogeny and probably relates to similar basic intrusive activity elsewhere in the Proterozoic supercontinent which was ultimately, successfully broken up after the Grenville orogeny.  相似文献   

X-ray K-edge absorption spectra of Fe minerals and model compounds: Near-edge structure   总被引：1，自引：0，他引：1  

Glenn A. Waychunas  Michael J. Apted  Gordon E. Brown Jr. 《Physics and Chemistry of Minerals》1983,10(1):1-9

Synchrotron radiation has been used to collect high-resolution Fe K absorption near-edge spectra of a suite of Fe minerals and compounds having a range of Fe environments. These spectra, along with those of previous workers, indicate that the number, position, and intensity of near-edge features are characteristic of Fe valence and general site geometry. For example, the crest of the K-edge for Fe²⁺ in a six-coordinated site in the oxides studied is about 3 eV lower in energy than that for Fe³⁺ in a similar site. The K-edge crest for Fe³⁺ in a four-coordinated site is 1 to 2 eV lower than for Fe³⁺ in a regular site. The shape of the edge crest is sensitive to the details of first-neighbor bonding distances, tending to be broader in species with irregular Fe sites and varying in energy according to the average bond length. Comparison with Ca²⁺ and Zn²⁺ spectra from the literature is made and the applicability and utility of edge measurements discussed.  相似文献   

Late Holocene sea-level changes and isostatic crustal movements in Atlantic Canada     

W. Roland Gehrels  Glenn A. Milne  Jason R. Kirby  R. Timothy Patterson  D.F.Daniel F. Belknap 《Quaternary International》2004,120(1):79

It has long been recognised that sea levels along the shores of Atlantic Canada have been rising rapidly during the Holocene in response to isostatic crustal movements. New sea-level data for the Bay of Fundy coast of southern New Brunswick (Little Dipper Harbour) and the Atlantic coast of Nova Scotia (Chezzetcook Inlet) show that late Holocene average rates of sea-level rise in these areas have been 1.0 and 2.5 m per 1000 yr, respectively. Numerical model calculations suggest that the high rates of sea-level rise are due to crustal subsidence produced by the combined effects of Laurentide ice loading (forebulge collapse) and ocean loading of the Scotian shelf. Although ice loading is the dominant contributor to the regional sea-level pattern, ocean loading is also important, contributing up to 40% of the total crustal subsidence in some areas. Tide gauges record rates of sea-level rise during the 20^th century that are 0.7–1.9 mm/yr higher than late Holocene trends, with the highest residuals occurring in the Bay of Fundy.  相似文献   

Mineral/melt partitioning of trace elements during hydrous peridotite partial melting   总被引：6，自引：4，他引：2  

Glenn?A.?GaetaniEmail author  Adam?J.?R.?Kent  Timothy?L.?Grove  Ian?D.?Hutcheon  Edward?M.?Stolper 《Contributions to Mineralogy and Petrology》2003,145(4):391-405

This experimental study examines the mineral/melt partitioning of incompatible trace elements among high-Ca clinopyroxene, garnet, and hydrous silicate melt at upper mantle pressure and temperature conditions. Experiments were performed at pressures of 1.2 and 1.6 GPa and temperatures of 1,185 to 1,370 °C. Experimentally produced silicate melts contain up to 6.3 wt% dissolved H ₂O, and are saturated with an upper mantle peridotite mineral assemblage of olivine+orthopyroxene+clinopyroxene+spinel or garnet. Clinopyroxene/melt and garnet/melt partition coefficients were measured for Li, B, K, Sr, Y, Zr, Nb, and select rare earth elements by secondary ion mass spectrometry. A comparison of our experimental results for trivalent cations (REEs and Y) with the results from calculations carried out using the Wood-Blundy partitioning model indicates that H ₂O dissolved in the silicate melt has a discernible effect on trace element partitioning. Experiments carried out at 1.2 GPa, 1,315 °C and 1.6 GPa, 1,370 °C produced clinopyroxene containing 15.0 and 13.9 wt% CaO, respectively, coexisting with silicate melts containing ~1–2 wt% H ₂O. Partition coefficients measured in these experiments are consistent with the Wood-Blundy model. However, partition coefficients determined in an experiment carried out at 1.2 GPa and 1,185 °C, which produced clinopyroxene containing 19.3 wt% CaO coexisting with a high-H ₂O (6.26±0.10 wt%) silicate melt, are significantly smaller than predicted by the Wood-Blundy model. Accounting for the depolymerized structure of the H ₂O-rich melt eliminates the mismatch between experimental result and model prediction. Therefore, the increased Ca ²⁺ content of clinopyroxene at low-temperature, hydrous conditions does not enhance compatibility to the extent indicated by results from anhydrous experiments, and models used to predict mineral/melt partition coefficients during hydrous peridotite partial melting in the sub-arc mantle must take into account the effects of H ₂O on the structure of silicate melts.  相似文献   

Does scientific conjecture accurately describe restoration practice? Insight from an international river restoration survey     

Joseph M Wheaton  Stephen E Darby  David A Sear  Jim A Milne 《Area》2006,38(2):128-142

Few sources exist to draw generalizations about the incredibly diverse international river restoration community. Generalizations in the restoration literature tend to be grounded on individual experiences or logical conjecture. To fill this perceived gap, an international web-based survey was launched. Over 500 respondents from 37 different countries participated. The results, posted on the web, act as a database of perceptions and individual experiences, from which the restoration community can make their own interpretations. With three examples, we contrast scientific conjecture with the perceptions of the restoration community who participated in this survey.  相似文献   

Wine, regions and the geographic imperative: The Coonawarra example     

Glenn Banks  Scott Sharpe 《New Zealand geographer》2006,62(3):173-184

Abstract:   The growth of the global wine trade has focused attention on regional origin in the production, marketing and consumption of wine. This paper presents a case study of the regulatory processes around the development of one particular South Australian wine region: Coonawarra. The process of the delineation of the Coonawarra region illustrates the tensions between treating wine regions as biophysical entities, and the realities of the economic, political, legal and cultural forces that shape regions. The paper highlights how ambiguities in the physical and social criteria that frame regional definition legislation can lead to boundaries that form through a process of judicial accretion rather than relating directly to any of the criteria themselves.  相似文献   

20th Century sea-level change along the eastern US: Unravelling the contributions from steric changes, Greenland ice sheet mass balance and Late Pleistocene glacial loading     

Leanne Wake  Glenn Milne  Eric Leuliette 《Earth and Planetary Science Letters》2006,250(3-4):572-580

We have considered the influence of ocean temperature and salinity changes, mass changes of the Greenland ice sheet (GIS) and the isostatic response of the solid earth to the most recent glacial cycle on 20th century sea-level change along the US east coast with the intention of better understanding the observed signal as well as determining the potential of the tide gauge data for constraining the recent (past 50–100 yr) mass balance of the GIS and earth viscosity structure. Our results show that the signal due to steric changes is large and displays a complex spatial variation which can account for a significant portion of the observed signal. In contrast, that due to changes in the GIS is relatively small and insensitive to the specific geometry of the mass balance model adopted. As a consequence, the tide gauge data alone are not capable of providing useful constraints on either the magnitude or form of recent GIS mass balance. Our inference of mantle viscosity structure based on the tide gauge data was affected dramatically when the steric effect was accounted for: An earth model with an upper mantle viscosity of 8 × 10¹⁹ Pa s and a lower mantle viscosity of 5 × 10²² Pa s produced the best fit to the steric-corrected data; the optimal fit to the uncorrected data was obtained for upper and lower mantle viscosities of 5 × 10²⁰ Pa s and 10²² Pa s, respectively.  相似文献   

The influence of water on melting of mantle peridotite   总被引：47，自引：8，他引：39  

Glenn A. Gaetani  Timothy L. Grove 《Contributions to Mineralogy and Petrology》1998,131(4):323-346

This experimental study examines the effects of variable concentrations of dissolved H₂O on the compositions of silicate melts and their coexisting mineral assemblage of olivine + orthopyroxene ± clinopyroxene ± spinel ± garnet. Experiments were performed at pressures of 1.2 to 2.0 GPa and temperatures of 1100 to 1345 °C, with up to ∼12 wt% H₂O dissolved in the liquid. The effects of increasing the concentration of dissolved H₂O on the major element compositions of melts in equilibrium with a spinel lherzolite mineral assemblage are to decrease the concentrations of SiO₂, FeO, MgO, and CaO. The concentration of Al₂O₃ is unaffected. The lower SiO₂ contents of the hydrous melts result from an increase in the activity coefficient for SiO₂ with increasing dissolved H₂O. The lower concentrations of FeO and MgO result from the lower temperatures at which H₂O-bearing melts coexist with mantle minerals as compared to anhydrous melts. These compositional changes produce an elevated SiO₂/(MgO + FeO) ratio in hydrous peridotite partial melts, making them relatively SiO₂ rich when compared to anhydrous melts on a volatile-free basis. Hydrous peridotite melting reactions are affected primarily by the lowered mantle solidus. Temperature-induced compositional variations in coexisting pyroxenes lower the proportion of clinopyroxene entering the melt relative to orthopyroxene. Isobaric batch melting calculations indicate that fluid-undersaturated peridotite melting is characterized by significantly lower melt productivity than anhydrous peridotite melting, and that the peridotite melting process in subduction zones is strongly influenced by the composition of the H₂O-rich component introduced into the mantle wedge from the subducted slab. Received: 7 April 1997 / Accepted: 9 January 1998  相似文献   

Looking Down the Light Cone: Can Deep Redshift Surveys Alone Measure the Power Spectrum?     

Andrew A. de Lai  & Glenn D. Starkman 《Monthly notices of the Royal Astronomical Society》1998,299(4):977-984

We analyse the window functions for the spherical harmonic mode estimators of all-sky, volume-limited surveys, considering evolutionary effects along the past light-cone which include the deviation of the distance scale from a linear relationship with redshift, linear peculiar velocity corrections, and linear evolution of the density perturbations. The spherical harmonic basis functions are considered, because they correspond most closely to the symmetries of typical survey geometries and of the light-cone effects we consider. Our results show substantial broadening of the windows over that expected by ignoring light-cone effects, indicating the difficulty of measuring the power spectrum independently from cosmology. We suggest that because of light-cone effects, deep redshift surveys should be analysed either in conjunction with CMBR data which determines the cosmological parameters, or by using a Bayesian likelihood scheme in which varying cosmological parameters and a simple parametrization of the primordial power spectrum are assumed as the priors, so that observed data can be mapped from redshift to real space. The derived power spectrum can then be compared with underlying models of fluctuation generation and growth in structure formation to evaluate both these models and the cosmological priors.  相似文献