Mineralogy and origin of the titaniferous deposit at Pluma Hidalgo, Oaxaca, Mexico

Paulson, Edwin G.

doi:10.2113/gsecongeo.59.5.753

Cited by 18 publications

(6 citation statements)

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“…Pyroxenes, blue quartz (generally rutilated), clinozoisite, and muscovite are common accessory minerals. Thi.s anorthosite and its associated ores are remarkably similar• to those in Pluma Hidalgo (Paulson, 1964;T. P. Thayer, written commun., 1973).…”

Section: Roseland Virginiamentioning

confidence: 67%

Geology and resources of titanium

Force¹,

Blake²,

Morgan³

et al. 1976

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Section: Roseland Virginiamentioning

confidence: 67%

Geology and resources of titanium

Force¹,

Blake²,

Morgan³

et al. 1976

Professional Paper

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“…Se observan además, rutilo, ilmenita, y apatita diseminados. En algunas zonas las concentraciones de titanio llegan a ser importantes desde un punto de vista económico, formando yacimientos como el de Pluma Hidalgo, al norte de Pochutla (Paulson, 1969). En general, hay una variación en el índice de color de las rocas que es controlada por el contenido de cristales sub-a euédricos de clinopiroxenos, los cuales se presentan cloritizados y tremolitizados.…”

Section: The Mylonitic Rocks Of the Chacalapa Shear Zone Indicate Temunclassified

La falla Chacalapa en el sur de Oaxaca

Tolson

2005

BSGM

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ResumenA lo largo de la costa de Oaxaca, entre Puerto Ángel y Santiago Astata, afl oran rocas metamórfi cas del Complejo Xolapa intrusionadas por rocas ígneas de edad Paleógeno a Mioceno sin metamorfi smo regional. Ambas unidades se encuentran en contacto tectónico a lo largo de zonas de cizalla con rocas proterozoicas del Complejo Oaxaqueño al norte de Pochutla y con rocas sedimentarias mesozoicas discordantes que sobreyacen los gneises. La principal de estas zonas de cizalla en el área de estudio es la falla Chacalapa, expuesta al norte de Pochutla, que está constituida por ultramilonitas, milonitas, protomilonitas, pseudotaquilitas, fi lonitas y cataclasitas en orden cronológico de desarrollo. La cinemática de esta zona de cizalla vertical es predominantemente lateral-izquierda.Las rocas miloníticas de la falla Chacalapa registran temperaturas de recristalización dinámica de ~500ºC (deformación cristal-plástica de feldespatos) que disminuyen sistemáticamente hasta el régimen netamente quebradizo. Asociadas a la recristalización dinámica se desarrollaron texturas cristalográfi cas de cuarzo en las rocas miloníticas que, cuando son asimétricas, exhiben un sentido de cizalla izquierdo. Las rocas del régimen quebradizo también registran una cinemática izquierda, al igual que las fallas activas.La edad de las rocas miloníticas de la falla Chacalapa se ubica entre los 29±0.2 y los 23.7±1.2 Ma. El límite de edad superior lo constituye la edad del intrusivo Huatulco (U-Pb de circones, Herrmann et al. 1994) que se observa milonitizado en su margen septentrional y el límite de edad inferior corresponde a la edad K-Ar de hornblenda procedente de diques granodioríticos porfídicos que truncan la milonita.Palabras clave: Falla, México, Oaxaca, milonita, pseudotaquilita, Xolapa. Abstract Along the coast of Oaxaca between Puerto Angel and Santiago Astata a suite of rocks is exposed corresponding to the Xolapa metamorphic complex which is intruded by granitoid igneous rocks of

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“…The term alkalic anorthosite thus appears appropriate to describe the Roseland type anorthosite (Herz, 1969). Other alkalic anorthosites are found at Pluma Hidalgo in Oaxaca, Mexico (Paulson, 1964), and St. Urbain, Quebec (Mawdsley, 1927). At St. Urbain, Mawdsley (1927) and Dymek (1980) described the K20rich andesine anorthosite as comprising the bulk of the body but in the central part of the massif as crosscutting a labradorite anorthosite.…”

Section: Roseland Anorthositementioning

confidence: 99%

Geology and mineral deposits of the Roseland District of central Virginia

Herz¹,

Force²

1987

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The Roseland district of Nelson and Amherst Counties, Va., is centered on an intermontane basin along the southeastern margin of the Blue Ridge. The Grenville-age igneous rocks in this area are less altered than elsewhere in the Blue Ridge, and exposure is sufficient to map their relations. The district was formerly an important producer of titanium minerals and still contains over 5 percent of U.S. identified resources of those minerals. The valuable minerals, rutile and ilmenite, formed in two stages which largely correlate with anorthosite and ferrodiorite, respectively.The oldest rocks (apparently pre-Grenville) are garnet-graphitepyroxene-blue quartz granulites and quartz mangerites. Platytextured leucocratic charnockites are associated with these rocks but are probably a younger neosome.The Roseland Anorthosite (about 1,050 Ma) intrudes these older rocks as a largely concordant basal sheet. Crosscutting relations with country rock are abundant, however. The anorthosite consists of andesine-antiperthite megacrysts in a granulated oligoclase-potassium feldspar matrix. Its margins contain pyroxene and blue quartz megacrysts, probably as a result of high-temperature reaction between anorthosite melt and country rocks. The unusually alkalic nature of the anorthosite has led to unusual rutile mineralization in this contaminated marginal facies and its immediate country rocks, especially in swarms of anorthosite sills in mangeritic rocks forming the anorthosite roof along the eastern side of the body.The Shaeffer Hollow Granite (about 990 Ma) is a coarse leucocratic blue quartz granite, porphyritic with tabular feldspars. It cuts granulite but is present largely as roof pendants and screens in the younger ferrodioritic plutons, except in a wide deformation zone where it appears to be the dominant protolith of mylonitic rocks.The Roses Mill and Turkey Mountain ferrodiorite-charnockite plutons (about 970 Ma) together form a largely concordant upper intrusive sheet. Intrusive relations with older units, however, are abundant. These rocks have high ilmenite-apatite-(zircon) contents that reflect distinctively high values of Ti, P, Zr, Fe/Mg, and K/Si. Blue quartz is present only as abundant xenocrysts. Much of these plutons is isochemically altered to biotitic augen gneiss. Layered concordant impure nelsonite (ilmenite-apatite rock) is locally found along the bases of these plutons, and nelsonite forms discordant bodies in the immediately underlying country rock. These lithologies probably formed by liquid immiscibility. Nelsonites and ilmenite-rich ferrodiorite constitute the main ilmenite resources of the district.The anorthosite and ferrodiorite-charnockite plutons are apparently not comagmatic but probably cogenetic. The anorthosite formed in a deeper crustal environment than ferrodiorite and probably was emplaced as a diapir into the higher crustal level.In the northwestern side of the district are ferrodioritic charnockitic rocks of the Pedlar massif. They are about 1,040 m.y. old but are separated from all othe...

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Mineralogy and origin of the titaniferous deposit at Pluma Hidalgo, Oaxaca, Mexico

Cited by 18 publications

References 1 publication

Geology and resources of titanium

Geology and resources of titanium

La falla Chacalapa en el sur de Oaxaca

Geology and mineral deposits of the Roseland District of central Virginia

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