Layered pegmatites, southern Wind River mountains, Fremont County, Wyoming

Proctor, Paul Dean; El-Etr, Hasan A.

doi:10.2113/gsecongeo.63.6.595

Cited by 3 publications

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“…A contiguous area northwest of tne Anderson Ridge quadrangle was mapped by Hodge (1963). A special study of the pegmatites of the Anderson Ridge quadrangle was made by El-Etr (1963) and by Proctor and El-Etr (1968). Condie (1967a) made a geochemical study of the graywackes of• the area.…”

Section: Investigationsmentioning

confidence: 99%

“…1). They have been studied principally by Proctor and El-Etr ( 1968) . They are concordant and discordant and of various sizes and shapes.…”

Section: Louis Lake Batholithmentioning

confidence: 99%

“…FIGURE lB.-Anderson pegmatite (NW14 sec. 7, T. 28 N., R. 101 W.), showi•ng plan view and cross sections of the concordant pegmatite and its mineralogical characteristics.From Proctor and El-Etr (1968)…”

mentioning

confidence: 99%

“…28, T. 29 N., R. 101 W. A, albite; Q, quartz; M, muscovite; P, perthit•e; Gr Gra, graphic granite; Mi, microcline. FromProctor and El-Etr (1968).…”

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confidence: 99%

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Geology of the South Pass area, Fremont County, Wyoming

Bayley¹,

Proctor²,

Condie³

1973

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The South Pass are•a includes five 7%-minute quadrangles near the south end o;f the Wind R!i\ner Rang.e in Fremont County, Wyo. Laramide uplift and erosion exposed the Precambrian rocks along the cvest of the vange for over 100 miles. Abourt half of the South Pass area is underlain by Precambrian granitic and gneissic rocks that are about 2.7 billion years old. The other half is underlain by a large pendant of Precambrian metasedimentary • and metavolcanic rocks that al'e older than the granite. Inasmuch as the oldest metamorphic rocks are on the northwest and the southeast side of the pendrant, the original structural f•eature may have been a northeast-trending synclinorium. Gold and iron deposits are included in the pendant. The older rocks of the pendant probably correspond in age to the pregrani•te rocks (2.5 b.y.) of the Superior province of Ganada, Minnesota, and northern Michigan.The Precambrian rocks of the South Pass area are overlapped on the east by gently dipping Paleozoic rocks, and on the south and west by nearly flat-lying Tertiary rocks. Approximately half of the area is covered by a Tertiary pediment, which desc•ends east, through canyons in the Paleozoic rocks, to the Wind River Basin and south and west into the Green River Basin.The metasedimentary rocks of the pendant are underlain by gnei.ss, in which inclusions of greenstone and metagabbro amphibolite are abundant, and probably by some serpentinite. These lithologies suggest an ophiolite basement.The pendant contains three formations: the basal Goldman Meadows Formation, composed of quartzite, schist, and iron-formation; the intermediate Round top Mountain Greenstone, compos.ed mostly of ellipsoidal basaltic lavas; and the overlying Miners Delight Formation, composed . mostly of metagraywacke, but including some meta-andesite, conglomerate, and graphitic schist. These layered rocks were intt•uded by igneous rocks in the following order: metagabbro dikes, metadiorite dikes, metaleucodacite dikes and tonalite s•tocks, metagabbro dikes, a granodiorite batholith and satellitic grani•tic stocks, and gabbroic dikes.The intrusion of the batholith and satellite stocks caused refolding of the western part of the pendant. Differentiates of the batholith-pegmatites and aplites-were emplaced after the second folding.Major faulting occurred before and after the batholith was emplaced. The• ea.rly faults are on either side of the Roundtop Moun.tain Greenstone. They are apparently nor-

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Section: Investigationsmentioning

confidence: 99%

“…1). They have been studied principally by Proctor and El-Etr ( 1968) . They are concordant and discordant and of various sizes and shapes.…”

Section: Louis Lake Batholithmentioning

confidence: 99%

mentioning

confidence: 99%

“…28, T. 29 N., R. 101 W. A, albite; Q, quartz; M, muscovite; P, perthit•e; Gr Gra, graphic granite; Mi, microcline. FromProctor and El-Etr (1968).…”

mentioning

confidence: 99%

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Geology of the South Pass area, Fremont County, Wyoming

Bayley¹,

Proctor²,

Condie³

1973

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The pegmatitic rocks of El-Hudi and Um Hibal areas, Southeastern Desert, Egypt: genesis and petrological characteristics

et al. 2013

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In an effort to understand the genesis of the pegmatitic rocks of El-Hudi and Um Hibal areas, detailed field, petrographic, and geochemical investigations were conducted. These investigations revealed evidence of two distinct modes of emplacement of these rocks. El-Hudi pegmatites are emplaced concordantly in a belt of folded gneisses and migmatites that mostly fit well with a metasedimentary protolith, which are later cataclased or even mylonitized. El-Hudi pegmatites can be classified into (1) plagioclase or sodic and (2) k-feldspar or potassic pegmatites. Their mineral assemblage, the variable forms of albite bodies in perthitized k-feldspars, and the myrmekite and graphic intergrowths are conclusive evidence indicating metasomatic and later stages of replacement. Geochemically, the peraluminous character of these pegmatites, compressional setting, partial melting parentage, and S-type affinity confirm their metasedimentary source and support a linkage with their host gneisses. The following stages explained the most accepted scenario for the development of these pegmatites "partial melting from metasedimentary protoliths, minimal fractionation and differentiation, injection into foliation, fractures and/or tectonic planes of the host gneisses, and invading the gneiss and migmatite hosts reflecting metasomatic exchanges, segregated earlier or contemporaneous with the genesis of garnet-bearing granites." In Um Hibal pegmatites, their vein-and miarolitic-type emplacements with the characteristic chilled margin of the later, the recorded hydrothermal nature of the well-preserved silica gels, and the well-crystallized accessory zircons revealed their magmatogenic origin. The similar behavior in depletion or enrichment of the rare earth element contents of Um Hibal pegmatites and their host granites indicate that they are genetically related. They have a mild to peralkaline affinity, emplaced in an extensional regime and shallow depth environment, of within plate and A 1 -type granite characters. However, the pegmatites seem to be fractionally crystallized from the residual melt of the host granites.

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Archean Greenstone Belts

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Layered pegmatites, southern Wind River mountains, Fremont County, Wyoming

Cited by 3 publications

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Geology of the South Pass area, Fremont County, Wyoming

Geology of the South Pass area, Fremont County, Wyoming

The pegmatitic rocks of El-Hudi and Um Hibal areas, Southeastern Desert, Egypt: genesis and petrological characteristics

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