 | | Journal (article/letter/editorial) | | Tortola comprises the islands of Jost Van Dyke, Little Jost Van Dyke, Tobago, and Little Tobago. SSs"ff»n<«'T...southern promontory is comparatively flat. Jost Van Dyke is a topographical and geological replica of Tortola...Thomas, from which, with the exception of Jost Van Dyke and Great and Little Tobago, they are separated...essentially of diorites, granodiorites, and gabbros, the dyke rocks of pegmatites, felsites, hornblende1 Cleve...heathen " parts of the magma. Among the more unusual field characters presented by the plutonic rocks may be |  | | Journal (article/letter/editorial) | | areas in and adjacent to the Palmerville Fault northwest of Chillagoe. Regional geophysical studies include...and calcareous metasediments, quartzite and amphibolite. Less deformed metasediments and amphi- bolite...02:41 21 December 2014 Mountain Cr Congl Mbr Van Dyke lilh Mbr Quartzose flysch, shale Basalt Conglomerate...Gneiss, schist, quartzite, o_ [r.'..!i'".-.J amphibolite Xso Dip of bedding —|— Anticline -££- ...Quartz-intermediate greywacke MF Mulgrave Formation VM Van Dyke Litharenite Member (Mulgrave Formation) MC Mountain |  | | Journal (article/letter/editorial) | | leucosome; L, Litlefjord Granite; LP, Litlefjord Pegmatite; R, Repvåg Granite; H, Hårvika Granite; V, Revsneshamn...Revsneshamn Granite; VP, Revsneshamn Pegmatite; S, Siedgoaivi Granite; B, Bakfjord Granite 438 ± 2 Ma...the west. It is composed of greenschist- to amphibolite-facies metasedimentary rocks of inferred late...in Fig. 1 (modified after Gayer et al., 1985 and field mapping 2002, 2003). 1985; Ramsay et al., 1985a...tectonostratigraphic level of the KNC, Zwann and Van Roermund (1990) recognised a three-phase polymetamorphic |  | | Report (issue) | | unit label, that indicates the countries or territories within which a unit appears. This geologic map...map-unit label), their ages, and the countries or territories in which they can be found; table 2 lists a compilation...(Jurassic) Dominican Republic Jmg Mafic schist and amphibolite (Late to Middle Jurassic) Cuba; Dominican Republic...Jamaica; Puerto Rico Kmgb Gabbroic amphibolite and amphibolite (Cretaceous?) Dominican Republic Kmgd...Trois-Rivieres (Three Rivers) and in Nord-Ouest region (Northwest region), Aquitanian to Burdigalian detrital rocks |  | | Report (issue) | | Along the skyline, from left to right, are Jost Van Dyke and Great Thatch Islands of the British Virgin...–23. Photographs of— 1. Water Island Formation, northwest side of Ram Head . . . . . . . . . . . . . . ...in 1990 and 1995. Most of the time spent in the field, starting in 1985, was spent on St. John. The mapping...wife, Mary Louise, for her help as a volunteer field assistant under conditions that were not always...covers both St. Thomas and St. John and is based on field work done mostly in 1956 and 1957. Fragmentary earlier |  | | Journal (issue) | | 326 Rhodizite-Londonite from the Antsongombato Pegmatite, Central Madagascar Brendan M. Laurs, Federico...Carlsbad, California A. A. Levinson Calgary, Alberta, Canada Thomas M. Moses New York, New York SUBSCRIPTIONS...the submission of articles on all aspects of the field. Please see the Guidelines for Authors in the Summer...Gems, Los Angeles. Photo © GIA and Harold & Erica Van Pelt. Color separations for Gems & Gemology are by...a grateful subscriber! Sharon Wakefield, G.G. Northwest Gem Lab Boise, Idaho Reply: We thank Sharon for |  | | Journal (issue) | | aprivate collection. Photo 0 1985 Harold d Erica Van Pelt-Photographers, Los Angeles. Typesetting for...the submission of articles on all aspects of thc field. Please see the Suggestions for Authors for preparing...VALUABLE ARTICLE AWARD ALICE S. KELLER Editor T he field of gemology, like the people who comprise it, encompasses...as is-once again-the kindness of Harold and Erica Van Pelt for donating so much of their time and expertise...Most of this production has come from two major pegmatite regions: (1) the Araguai-Itinga and Araguai-Salinas |  | | Book (volume) | | English translation of a text-book by Cronstedt gave field-spar. In his text-book in English, Kirwan (1784)...its name from the locality Bytown (now Ottawa), Canada. Anorthite is compounded from the Greek negative...separately as barium felspars (p. 166). In some pegmatite microclines the rare alkalies may reach major... The clear yellow crystals from a miarolitic pegmatite are of gem quality and as a consequence have often...Orthoclase microperthite (moonstone) E. Spencer. pegmatite, Ambalangoda, Ceylon (Spencer, 1937). Anal |  | | Report (issue) | | Live Oak and Keystone veins _____ __________ _ Van Dyke deposit_ ________ _________ _______ _ Carlota...Section along a line striking N. 20° E. through Van Dyke shaft_________________________ 14. Index map of...to 1953 ______ __ _ 6. Copper production of the Van Dyke mine ____ _ 81 88 138 GEOLOGY AND ORE DEPOSITS...Budget, and McGaw faults, which strike north to northwest. The Globe Valley block is a graben inset between...area, and most of the larger ones trend north to northwest. The Castle Dome and Copper Cities horsts are |  | | Report (issue) | | __________________________________ . ____ . ___ _ Canada Nova Scotia _________ .. __________ . ___ . _..._ __ _ _ . __ ___ _ _____________ _ The Northwest Territories and the Yukon District __ British Columbia...the Gold Coast, are located in Warsaw. This gold-field, which is situated many miles inland, is at present...obtained as a by-product. Canada.- The principal gold-producing fields of Canada are located in Nova Scotia...The first important placer diggings, in the gold-field was carried on, along Forty Mile Creek, only a short |  | | Report (issue) | | __________________________________ . ____ . ___ _ Canada Nova Scotia _________ .. __________ . ___ . _..._ __ _ _ . __ ___ _ _____________ _ The Northwest Territories and the Yukon District __ British Columbia...the Gold Coast, are located in Warsaw. This gold-field, which is situated many miles inland, is at present...obtained as a by-product. Canada.- The principal gold-producing fields of Canada are located in Nova Scotia...The first important placer diggings, in the gold-field was carried on, along Forty Mile Creek, only a short |  | | Book (volume) | | Lithotectonic terrane map of Alaska and adjacent parts of Canada, 1 sheet, scale 1:2,500,000 (Norman J. Silberling...the volumes published by the Geological Survey of Canada vu . Foreword To those of you who are using...dedicate this volume to the generations of Alaska field geologists whose work, often under trying conditions...relations of the northern Cordillera are within Canada Excellent recent overviews of the western Cordillera...between the international boundaries with Russia and Canada. It spans the North American continent be¬ tween |  | | Journal (article/letter/editorial) | | have trends parallel to fractures: (1) Ortho-amphibolite dikes which may be pregranitization are the oldest...by warping with relative shortening along the northwest trend, resulting in two sets of tension fractures...tension and shear tests on various materials. Most field studies of fractures are confined to small areas...slope 482 3. Fracture trends associated with the northwest trend 493 4. Fracture trends on photographs in...most helpful through discussions and co-operative field work. Prof. R. M. Foose, Dr. D. U. Wise, and Dr |  | | Report (issue) | | deposits Deposits in, or in contact with, granite Pegmatite dikes Quartz veins Deposits in limestone and other...State East entrance I. E., E., Midway Oil Field, P. P. I. E., 1915 Alpine County. Gold-bearing...architectural tile showing andesite capping Slay pit northwest of Lincoln showing method of working. Dairy Farm...Federal Drift mine Glenn mine, Canada Hill district Monumental mine, Canada Hill district [View of hydraulic...and Brown hydraulic mine, Canada Hill district Pine Nut hydraulic mine, Canada Hill district Gravels in |  | | Book | | of the geomagnetic field; origin of the main field; models of the geomagnetic field Palaeomagnetism Magnetism...measurement of samples Sample collection in the field; astatic magnetometer; fluxgate magnetometer; spinner...of formation mean direction; analysis of poles Field tests for stability Consistency tests; reversals...Laboratory tests and cleaning techniques Alternating field demagnetization - magnetic cleaning; page 89 thermal... REVERSALS OF THE EARTH’s MAGNETIC FIELD 105 108 4.1 Field-reversal or self-reversal? Possible modes |  | | Report (issue) | | Climate and vegetation 16 work Acknowledgments Field 1 17 17 ~ GEOLOGIC FEATURES Previous investigations...__ Roblar leucogranite Other intrusive bodies Pegmatite and aplite dikes Economic significance __ ____...Fluorine minerals ._ Gem minerals Gem-bearing pegmatite deposits Distribution and general features Summaries...quartz crystal) and quartzite Inner zones of pegmatite deposits Massive quartz bodies (including veins)...rocks Meta volcanic rocks - Gabbroic rocks Pegmatite deposits Dumortierite-bearing rock Products and |  | | Report (issue) | | one mile northwest of Bound Brook, Somerset County. 7. Stony Brook mines; one mile northwest of Plainfield...demarcation between the two provinces. To the north and northwest the basin is bounded by higher ground at the edge...partial crescent with the concave side facing northwest. Toward this boundary and into the plane of the...recognizable paleontologic horizons still awaits further field and laboratory studies. TRIASSIC IGNEOUS ROCKS ...broadly curving crescent whose concavity faces northwest. The trace of the sheet disappears beneath Cretaceous |  | | Book (edition) | | rock or mineral that is casually picked up in the field. Recently, one researcher has said that the effort...occurrence of this metal, the valley was called "Canada de Hierro," or iron valley. Silver mines of great...sometimes called the Arizona mines, are situated northwest of the Cababi mines about 60 miles, and 40 miles...spangolite. Palmer (1909) describes arizonite from a pegmatite about 25 miles southeast of Hackberry, Mohave...southwestofWickenburg, and one and one-half miles northwest of the Angel mine. Garnet-Mr. J.L. Hubbell of |  | | Report (volume) | | determmatwn of thonum, uramum, and potassium m the field [abs 1 Geol Soc Amenca Spec Paper 68, p 125, 1962...5742 Alktre, James H Wtllows-Beehtve Bend gas field, Cahforma, m Geologtc gmde to the gas and otl fields... no 9, p 3538, 1962 3178 Alldredge, Leroy R , Van Voorhis, Gerald Source of the great arctic magnetic...the mythmterpretation of Mount Multnomah [abs] Northwest Set, v 36, no l, p 21, 1962, Ore Bm, v 24, no...Alhson, Ira S Landforms, m Atlas of the Pacific Northwest-Resources and development Corvallis, Oregon State |  | | Report (issue) | | undouhtedly soon assume a mu.li lar-cr copper field and that it will Ion- rcmaiu a that this State...out he joined the rush to the famous new silver field of Nevada, and later joined the returning procession...excitements, and expanding into adjoining States and Territories. The furor and speculative excitement lasted...ores and some matte from adjoin iny; States and Territories, includiipj liritish Columbia. Ore...the Sacramento River, and this important mining field thus has the advantage of close proximity to a |  | | Book | | mineralization within a stratovolcano, El Queva, northwest Argentina: Economic Geology, v. 70, p. 1190–1201...Sillitoe, R.H., 2000, Geologic analogy: A vital field component of mineral exploration: Society of Economic...227–240. Sillitoe, R.H., and Burrows, D.R., 2002, New field evidence bearing on the origin of the El Laco magnetite...105, p. 1361–1368. Sillitoe, R.H., Tolman, J., and Van Kerkvoort, G., 2013, Geology of the Caspiche porphyry...countries around the world. When not working in the field or writing up his observations, Dick has committed | | | Book (edition) | | rock or mineral that is casually picked up in the field. Recently, one researcher has said that the effort...sometimes called the Arizona mines, are situated northwest of the Cababi mines about 60 miles, and 40 miles...spangolite. Palmer (1909) describes arizonite from a pegmatite about 25 miles southeast of Hackberry, Mohave...southwest of Wickenburg, and one and one-half miles northwest of the Angel mine. Garnet—Mr. J.L. Hubbell of...Hurlbut (1936) first describes bermanite from a\ pegmatite on the 7U7 Ranch, Yavapai County. 1938 The orebody |  | | Book (edition) | | Anthony, Sidney Williams, and Richard Bideaux. The field of mineralogy has undergone many changes since the...six other special lists of minerals, such as pegmatite minerals, contact-metamorphic minerals, and secondary...(1970) of blue, red, and white material in a pegmatite dike with andalusite from Grand Wash Cliffs, Red...labradorite, at Red Mountain, twenty-five miles northwest of Flagstaff. Red Mountain is an eroded cinder...Spring, in the foothills, probably as a vein pegmatite dike. This amethyst-bearing property is owned |  | | Report (chapter) | | multiply-deformed schist at lower greenschist to ?amphibolite grade (Murray 1994). However, the ages of these...lithospheric mantle interpreted from SKIPPY data by Van der Hilst et aL (1998); and c. 562 Ma Sm-Nd isochron...basalts in the west of King Island that underwent amphibolite-grade metamorphism at c. 1270 Ma (Holm et al...827 Ma, see Preiss 2000) coeval with the Gairdner Dyke Swarm to the west dated at c. 827 Ma by Wingate...1998) (Fig. 5a). In the Cape River Metamorphics, amphibolite-grade sandstones with c. 1145 Ma dominant detrital |  | | Book (edition) | | contained a large mass of coarse orthoclaserich pegmatite associated with the quartz monzonite porphyry...about 10 miles wide by 75 miles long, extending northwest and southeast from Cameron along the Little Colorado...of Deadman Tank, as bladed green crystals in amphibolite dikes with an asbestiform variety, developed...in granite in sericitized veins (Schwartz, pegmatite (Frondel, 1964). Cerbat Mountains, Kingman Feldspar...Near Willow Springs Ranch, Oracle Junction, in pegmatite with schorlite (Robert O’Haire, pers. comm., 1972) |
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