1 edition of Some aspects of the geochemistry of kimberlite xenocrysts found in the catalog.
Some aspects of the geochemistry of kimberlite xenocrysts
|LC Classifications||QE 462 L418 1974 thesis|
|The Physical Object|
tually erupting as a kimberlite volcano, they often entrain pieces of unmelted mantle; thus, they are one of our pri-mary windows into Earth’s interior (Dawson ). These fragments of unmelted mantle are classified as xenoliths (rock fragments) and xenocrysts (single crystals or fragments thereof). Diamonds found in kimberlites are xenocrysts. Diamonds in Colorado! The State Line Kimberlite District, Colorado & Wyoming, USA While small compared to the great diamond-bearing kimberlite pipes of the African continent or more recent discoveries in northern Canada, Colorado is nonetheless endowed with a relatively substantial kimberlite district, many of which contain a history of exploration spanning a mere ~45 years, the.
Moore and Haynes () have reported biotite that occurs in large books in the Bala kimberlite, but I have observed none. The Bala kimberlite also contains large ( to cm maximum dimension) phenocrysts or xenocrysts of calcite. Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes, as well as igneous lite also occurs as horizontal sills. Kimberlite pipes are the most important source of mined diamonds today. The consensus on kimberlites is that they are formed deep within the ion occurs at depths between and kilometres (93 and mi), potentially.
Rare Earth Element Geochemistry of Kimberlite Aspects of the Geochemistry of Kimberlites from the Premier Mine, and other Selected South African Occurrences with Particular Reference to the Rare Earth Elements The Significance of the Inter-Element Relationships of some Minor and Trace Elements in South African Kimberlites Purchase Kimberlites I: Kimberlites and Related Rocks, Volume 11A - 1st Edition. Print Book & E-Book. ISBN ,
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A wide variety of magmas entrain, transport and erupt mantle material in the form of xenoliths and xenocrysts. The host magmas are often low viscosity. Petrol. 39 () 12 P.J. Lawless, Some aspects of the geochemistry of kimberlite xenocrysts, Thesis.
University of Cape Town (). 13 J.J. Gurney, Recent unpublished data (). Recommended articles Citing articles (0)Author: A.R. Newton, J.J.
Gurney. Some aspects of the geochemistry of Kimberlite xenocrysts [Microfiche] By Patrick Joseph Lawless. Publisher: Department of Geochemistry. Year: OAI identifier: oai: Provided by: Cape Town University OpenUCT. Download PDF: Author: Patrick Joseph Lawless. About this book Published by the American Geophysical Union as part of the Special Publications Series, Volume 1.
Since the first edition was published inthe Third International Kimberlite Conference was held in Clermont-Ferrand in Mg# vs.
a) Cr 2 O 3 and b) TiO 2 for garnet xenocrysts from the Sekameng kimberlite. Symbols as for Fig 3. Hops, J.J. Some aspects of the geochemistry. of high temperature peridotites. Since the first edition was published inthe Third International Kimberlite Conference was held in Clermont-Ferrand in Nevertheless, several of the problems addressed by papers in the first edition of this publication are still valid and remain unanswered today.
This is a book about the petrology of kimberlites. It is not about upper mantle xenoliths, diamonds, or prospecting for kimberlites. The object of the book is to provide a comprehensive survey and critique of the advances which have been made in kimberlite studies over the last twenty-five years.
Xenoliths consisting of two thirds pyrope (Py73Alm14GrPy15Alm18Gr31) and one third hercynite-bearing spinel with minor chromium, from Bellsbank and Jagersfontein kimberlites, South Africa, are compared with similar rocks, “alkremites”, from the Udachnaya pipe, U.S.S.R.
From published experimental data and textural relationships these formed as early dense cumulates in aluminous. There are two genetic types of spinel (magmatic spinel crystallizing directly from kimberlite magma and xenocrystic spinel derived from mantle xenoliths) in the No kimberlite pipe (Liaoning Province, North China Craton).
Their geochemistry is investigated to reveal processes of diamond capture and resorption during kimberlite magmatism to constrain the diamond potential. Kimberlite Peculiarity. When examining the data listed in Tables 1 and 2, one notes the peculiarity of the chemical composition of kimberlites from each region idea that the compositions of all known kimberlite bodies are unique was offered by Kryuchkov and Khar'kiv : "Each body of these rocks is a unique geologic object having no complete analog in nature in terms of its.
To gain better insight into the thermal state and composition of the lithospheric mantle beneath the Upper Muna kimberlite field (Siberian craton), a suite of clinopyroxene xenocrysts and Some diamonds have mineral inclusions that are thought to have originated from the transition zone or even the lower mantle, suggesting an almost unimaginably deep kimberlite source region.
An intriguing question is whether diamonds and kimberlites form as a result of the same fundamental process. Kimberlite is a type of igneous rock that is ultramafic and ultrapotassic.
Its mineral content usually includes olivine, phlogopite, pyroxene, and garnet, accompanied by a variety of trace minerals. Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes are the most important source of mined diamonds today.
a, Kimberlite hosts abundant rounded centimetre- to millimetre-scale mantle-derived xenocrysts of olivine (ol) and subordinate amounts of xenocrystic clinopyroxene (cpx), garnet (gar). Previously, this process was only inferred from some experimental studies (7, 9, 11, 14) and from resorption textures in xenoliths and xenocrysts entrained by kimberlite magmas (4, 6, 8, 10).
Our empirical observations, based on the compositions of xenocrystic and magmatic material from the same igneous rocks, unambiguously reveal that. Type I is characterized by two sub-types, specifically Type IA where xenocrysts or xenoliths of gem ruby of metamorphic (sometimes magmatic) origin are hosted by alkali basalts (Madagascar and others), and Type IB corresponding to xenocrysts of ruby in kimberlite (Democratic Republic of Congo).
Regional geology, mantle composition, and mean %Fo in olivine versus depth in individual sections corresponding to kimberlite fields across the Slave craton defined using garnet xenocrysts (modified after Griffin et al.).The xenocrysts can be classified according to the scheme described by Griffin et al.
and grouped into several broad categories in terms of their original host rock: depleted. Analyses are reported for garnet and pyroxene from 17 eclogites that contain diamond.
The garnets contain small but significant contents of Na, Ti and P and the pyroxenes contain traces of K. The diamond-bearing eclogites do not constitute a unique compositional group but show a range of mineral compositions consistent with a very high P-T environment.
Switzer, G. (), Composition of garnet xenocrysts from three kimberlite pipes in Arizona and New Mexico, in B. Mason (editor), Mineral Sciences Investigations,Smithsonian Contributions to Earth Sciences: ; USGS (), Mineral Resources Data System (MRDS): U.S.
Geological Survey, Reston, Virginia, loc. file ID # Spinel macrocrysts and xenocrysts in kimberlites (dark grey circles in Fig. 1) are derived from the breakup of upper-mantle peridotite, and are then transported to the surface by kimberlitic spinel macrocrysts and xenocrysts that are low in Fe 2+ /(Fe 2+ + Mg) tend to be low in both titanium (TiO 2 some macrocrysts with higher Fe 2+ /(Fe 2+ + Mg.
The outlined field is the mantle trend of Ramsay (), and the aluminous magnesian chromite (AMC), kimberlite trend 1, and kimberlite trend 2 are those of Mitchell (). The compositions of chromian spinel inclusions in diamond from Atri (Smith et al., ) are indicated by blue filled diamond symbols.The conditions under which kimberlite is generated in the mantle can be constrained from: experimental studies; geochemistry; and studies of xenoliths, xenocrysts, and their inclusions.
Some difficulties, discussed more fully below, are that kimberlite magmas are likely changed profoundly as they ascend, are erupted or emplaced, and are altered.mined are kimberlite pipes and dykes.
Kimberlite is defined as a volatile-rich, potassic, ultrabasic igneous rock that occurs as small volcanic pipes, dykes and sills. It has an inequigranular texture resulting from the presence of macrocrysts (phenocrysts and xenocrysts) set in a fine-grained matrix. The mineralogy comprises.