Myrmekite — one hundred years later     

Evan R. Phillips 《Lithos》1974,7(3):181-194

Myrmekite, first detected by Michel-Lévy in 1875 and named by Sederholm in 1899, is an intergrowth between vermicular quartz and (sodic) plagioclase situated next to potash feldspar. In felsic plutonic rocks it occurs as: rims bordering granular plagioclase, intergranular blebs set between adjacent microperthite crystals, lobes associated with muscovite in deformed alkali feldspar megacrysts or as bulbous growths at their margins, and rims on plagioclase inclusions held within orthocalse megacrysts. A literature review based largely on papers published in the past quarter century shows that hypotheses for myrmekite genesis fall mainly into five categories: simultaneous or direct crystallization, replacement of potash feldspar by plagioclase, replacement of plagioclase by potash feldspar, solid-state exsolution, and recrystallizing quartz involved with blastic plagioclase.  相似文献   

Identifying Synergy Between Remedial Strategies and Land Reuse     

Evan K. Nyer  Lawrence S. Graves 《Ground Water Monitoring & Remediation》1998,18(4):61-65

"Today the environmental professional teams with the developer to use remedial technologies and approaches that complement planned land use and, conversely, use land in a fashion that accommodates environmental site conditions."  相似文献   

Magmatic changes during the stabilisation of a cordilleran fold belt: the Late Carboniferous–Triassic igneous history of eastern New South Wales, Australia     

Graziella Caprarelli  Evan C. Leitch 《Lithos》1998,45(1-4):413-430

In a 60 Ma interval between the Late Carboniferous and the Late Permian, the magmatic arc associated with the cordilleran-type New England Fold Belt in northeast New South Wales shifted eastward and changed in trend from north–northwest to north. The eastern margin of the earlier (Devonian–Late Carboniferous) arc is marked by a sequence of calcalkaline lava flows, tuffs and coarse volcaniclastic sedimentary rocks preserved in the west of the Fold Belt. The younger arc (Late Permian–Triassic) is marked by I-type calcalkaline granitoids and comagmatic volcanic rocks emplaced mostly in the earlier forearc, but extending into the southern Sydney Basin, in the former backarc region. The growth of the younger arc was accompanied by widespread compressional deformation that stabilised the New England Fold Belt. During the transitional interval, two suites of S-type granitoids were emplaced, the Hillgrove Suite at about 305 Ma during an episode of compressive deformation and regional metamorphism, and the Bundarra Suite at about 280 Ma, during the later stages of an extensional episode. Isotopic and REE data indicate that both suites resulted from the partial melting of young silicic sedimentary rocks, probably part of the Carboniferous accretionary subduction complex, with heat supplied by the rise of asthenospheric material. Both mafic and silicic volcanic activity were widespread within and behind the Fold Belt from the onset of rifting (ca. 295 Ma) until the reestablishment of the arc. These volcanic rocks range in composition from MORB-like to calcalkaline and alkaline. The termination of the earlier arc, and the subsequent widespread and diverse igneous activity are considered to have resulted from the shallow breakoff of the downgoing plate, which allowed the rise of asthenosphere through a widening lithospheric gap. In this setting, division of the igneous rocks into pre-, syn-, and post-collisional groups is of limited value.  相似文献   

Two-Dimensional Advective Transport in Ground-Water Flow Parameter Estimation   总被引：4，自引：0，他引：4  

Evan R. Anderman  Mary C. Hill  Eileen P. Poeter 《Ground water》1996,34(6):1001-1009

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Plumes Dont Move     

Evan K. Nyer  Mary J. Gearhart 《Ground Water Monitoring & Remediation》1997,17(1):52-55

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DISCUSSION     

Evan C. Henry  Glen Hackett 《Ground Water Monitoring & Remediation》1988,8(2):151-151

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A Practical Approach to Shallow Petroleum Hydrocarbon Recovery     

Douglas Hayes  Evan C. Henry  Stephen M. Testa 《Ground Water Monitoring & Remediation》1989,9(1):180-185

A practical pumping system for the recovery of free petroleum hydrocarbon product from shallow aquifers has been developed. The system is patterned after suction-lift well point dewatering systems used in the construction industry. Pumping equipment consists of double-diaphragm suction-lift pumps manifolded to up to four recovery wells. Recovery wells are constructed with screens below the water table and sealed wellheads to enable vacuum-assisted flow of fluids to the wells. Pumps utilized are pneumatically driven, can be pumped dry without damage, induce a vacuum on the wells when pumping dry, and provide delivery of pumped fluids to fluid separation and storage facilities. The system is effective in both low- and high-permeability formations due to the wide range in available pumping rates afforded by the pumps.  相似文献   

Relating the Physical and Chemical Properties of Petroleum Hydrocarbons to Soil and Aquifer Remediation   总被引：1，自引：0，他引：1  

Evan K. Nyer  George J. Skladany 《Ground Water Monitoring & Remediation》1989,9(1):54-60

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Island arc elements and arc-related ophiolites   总被引：1，自引：0，他引：1  

Evan C. Leitch 《Tectonophysics》1984,106(3-4)

All major structural elements in island arc systems, fore-arc, magmatic arc, back-arc basins and remnant arcs, are potential ophiolite sources, and those features that allegedly characterise ophiolites of ocean-ridge origin, sheeted dyke complexes, mantling pelagic rocks, hydrothermal metamorphism and associated mineralization, can also arise within arc settings. Age relations are critical in the interpretation of arc-related ophiolites. Remnants of oceanic lithosphere, identified by a pre-arc initiation age, are restricted to fore-arc, magmatic arc and remnant arc elements, as are ophiolite masses generated at the inception of underthrusting. The latter, apparently common in ancient fore-arc terrains, form in nascent arc systems in which the rate of role back of the subduction hinge exceeds the rate of convergence. Spreading occurs above a foundering slab resulting in some arc-like compositional features. In simple arc systems later ophiolitic rocks have formed either in the active back-arc basin or the magmatic arc. Only those ophiolites that have resided within or very close behind magmatic arcs should show calcalkaline or arc tholeiite magmatic affinities, or be intruded or overlain by these rocks. Volcanic-derived sediment or pelagic material may mantle ophiolites from all arc settings, but pelagic rocks will generally dominate in stratigraphic sequences above remnant arcs and on back-arc basin floors except adjacent to the magmatic arc. Ophiolites generated at major ocean ridges are unlikely to be immediately overlain by sediment with a significant volcanic component whereas such detritus may lie directly on arc-inception, arc and back-arc ophiolites. Some arc-derived ophiolites are preserved in their original tectonic position, others can be identified from their internal features, their relationship to other tectonic elements, and the nature of associated rocks.  相似文献   

    

Benjamin J. Kadlec  David A. Yuen  Xili L. Yang  Evan F. Bollig  Yunsong Wang  Gordon Erlebacher  Maxwell Rudolph 《Visual Geosciences》2004,9(1):61

We report here our experiences from using easily acquired web-cam components for collaborative ventures in the Earth sciences. We have used a variety of hardware and different software. We demonstrate from various locations in the U.S.A. the feasibility of using web-cam in multitudinous activities, relevant for conducting research and knowledge dissemination. We summarize the quality of the connections from the various combinations of communicating parties. Today, web-cams can be utilized as an economical and viable means of point-to-point communication in the Earth science community. Greater bandwidth is sorely needed for activities such as multi-party conferencing on the present internet network. We propose that web-cam can be readily deployed as a web-service for facilitating collaborative research over the GRID infrastructure, using the middleware Narada-Brokering. Web-cam will play an important role in the emerging field of geoinformatics.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s10069-004-0018-1  相似文献