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Topic: Amphibolite

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  Amphibolite - Wikipedia, the free encyclopedia
Amphibolite is a gouping of rocks composed mainly of amphibole (as hornblende) and plagioclase feldspars, with little or no quartz.
Amphibolite is the name given to a rock consisting mainly of amphibole (hornblende), the use of the term being restricted, however, to metamorphic rocks.
The amphibolites are typical metamorphic rocks and as such attain a large development in all regions of crystalline schists and gneisses such as the Alps, Ardennes, Harz, Scottish Highlands, and the Lakes district of North America.
en.wikipedia.org /wiki/Amphibolite   (1171 words)

 Amphibolite (1911 Encyclopaedia Britannica) - InfoSearchPoint.com   (Site not responding. Last check: 2007-10-22)
Reddish garnets are often conspicuous in the rocks of this group (garnet-amphibolites), and when in addition a green-coloured augite occurs the rocks are intimately allied to the hornblende-eclogites.
The amphibolites are typical rocks of the metamorphic group and as such attain a large development in all regions of crystalline schists and gneisses such as the Alps, Ardennes, Harz, Scottish Highlands, and the Lakes district of North America.
The sedimentary amphibolites or para-amphibolites, less common than those above described, are frequent in some districts, such as the northern Alps, southern highlands of Scotland, Green Mountains, U.S.A. Many of them have been ash-beds, and their conversion into hornblende-schists follows exactly similar stages to those exemplified by basic crystalline igneous rocks.
www.infosearchpoint.com /display/Amphibolite_(1911_Encyclopaedia_Britannica)   (1005 words)

Amphibolite and associated gneiss of the PCG are compared within the UB on either side of the LOS using a combination of field relations, petrography, and geochemistry.
Southern amphibolite typically contain hornblende and plagioclase with variable amounts of biotite and contain a variety of accessory minerals, including clinopyroxene, epidote, sphene, zircon, and opaques, and tend to be coarser grained than their northern counterparts.
Amphibolite from the southern limb are primarily alkalic, whereas those from the northern limb tend to be sub-alkalic to tholeiitic with some overlap.
gsa.confex.com /gsa/2004AM/finalprogram/abstract_79798.htm   (526 words)

 Pennsylvania Geological Survey: Open-File Reports – Kennett Square Report Text
Baltimore Gneiss (Ybg) – The Baltimore Gneiss in the Avondale and Hockessin-Yorklyn Anticlines consists primarily of primarily felsic gneiss, with lesser hornblende gneiss and amphibolite.
Amphibolite was observed as sub-meter scale interlayers with felsic gneiss and occupying entire outcrops.
Amphibolite is found both as relatively thin (outcrop-scale or less) layers within the pelitic gneiss and as relatively large bodies elongate parallel to strike of the dominant foliation.
www.dcnr.state.pa.us /topogeo/openfile/kstext.aspx   (1453 words)

 Amphibolite -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-22)
The parent rock of amphibolite are (The commonest type of solidified lava; a dense dark gray fine-grained igneous rock composed chiefly of calcium-rich plagioclase feldspar and pyroxene) basalts and other mafic (Rock formed by the solidification of molten magma) igneous rocks.
It forms by regional (Change in the structure of rock by natural agencies such as pressure or heat of introduction of new chemical substances) metamorphism along convergent (A sheet of metal or wood or glass or plastic) plate boundaries.
The transitional stages from (One of a family of granular intrusive rocks) gabbro or diabase to amphibolite are so common that they form a widespread and important group of rocks, which have been described under names like (Click link for more info and facts about greenstone) greenstone, greenstone-schist, flaser-gabbro, saussurite-gabbro, meta-diabase, and others.
www.absoluteastronomy.com /encyclopedia/a/am/amphibolite.htm   (1105 words)

 AMPHIBOLITE - LoveToKnow Article on AMPHIBOLITE   (Site not responding. Last check: 2007-10-22)
The felspar breaks up into a mosaic in which albite, epidote or zoisite, quartz and garnet may often be identified* Biotite and primary hornblende suffer comparatively little change; olivine disappears, and garnet, talc and tremolite or anthophyllite take its place.
The transitional stages from gabbro or diabase to amphibolite are so common that they form a widespread and important group of rocks, which have been described under the names greenstone, greenstone-schist, flaser-gabbro, saussurite-gabbro, meta-diabase, andc.
Others have been greywackes of varied composition with epidote, chlorite, felspar, quartz, iron oxides, andc., and may have been mixed with volcanic materials, or may be partly derived from the disintegration of basic rocks.
www.1911encyclopedia.org /A/AM/AMPHIBOLITE.htm   (2138 words)

 Olympus Microscopy Resource Center: Polarized Light Microscopy Gallery - Amphibolite
Amphibolite is a type of rock chiefly comprised of minerals from the amphibole group.
Slightly foliated, amphibolites generally form during the regional metamorphism of igneous rocks primarily composed of ferromagnesian minerals, though other types of the rocks are also known to occur.
Amphibolites that are of metamorphic origin are common in a number of areas and are as various as the minerals for which they are named.
www.olympusmicro.com /galleries/polarizedlight/pages/amphibolitesmall.html   (273 words)

 SIU Abstract   (Site not responding. Last check: 2007-10-22)
Amphibolite is a durable metamorphic rock acquired via long distance exchange from sources in the uplands of western Iberia, 150 to 500km away.
The primary sources of amphibolite used during the Copper Age were in the Alentejo region of Portugal, an area with concentrations of highly visible, earlier Neolithic and Copper Age burial monuments.
Thus, amphibolite tools can be said to have had a pivotal role in transforming both the natural landscape of forests and fields and the social landscape of power and prestige.
www.ripon.edu /faculty/lilliosk/papers/siuabs.htm   (221 words)

 Blue Ridge Eclogite   (Site not responding. Last check: 2007-10-22)
Amphibolitization is associated with the obvious fracture and a granitoid dike that was ten centimeters from the left of the sample.(c) Dated sample (BAK-98-100) of eclogite showing omphacite, garnet, hornblende, and slight development of plagioclase rims around garnet.
The Lick Ridge eclogite and associated amphibolites of the Ashe Metamorphic Suite (AMS) lack igneous minerals and textures, and thus the nature of their protolith cannot be determined from petrography.
One garnet amphibolite has low REE concentrations and a convex-upward REE pattern, which is similar to the pattern of Group I amphibolites and these may be basalts generated in a subduction setting.
geoweb.tamu.edu /Faculty/Miller/BREclogite/BREclogite.html   (2220 words)

 CVO Menu - America's Volcanic Past - Vermont
In the Green Mountains: schist, gneiss, metagraywacke, quartzite, calcite and dolomite marbles, and amphibolite, with schist and gneiss being predominant or important.
In the Green Mountains: schist, phyllite, quartzite, graywacke, conglomerate, greenstone, dolomite, limestone, gneiss, and amphibolite, with schist, phyllite, greenstone, gneiss, and amphibolite being predominant or important.
Slate, phyllite, limestone, quartzite, conglomerate, greenstone, schist, and amphibolite.
vulcan.wr.usgs.gov /LivingWith/VolcanicPast/Places/volcanic_past_vermont.html   (894 words)

 Peter J. Wyllie   (Site not responding. Last check: 2007-10-22)
The tonalites, trondhjemites and granites (TTGs) of the Archean grey gneisses are characterized by highly fractionated rare earth elements, and this appears to require that amphibole, or garnet or both were residual minerals during generation of the magmas.
The forward approach of melting possible source rocks under known conditions is complemented by the inverse approach of crystallizing the magmas to determine the liquidus mineralogy as a function of pressure, temperature, H2O content, and other variables.
If the tonalites and trondhjemites are primary magmas from amphibolite, then for the pressure and temperature of their generation, the near-liquidus minerals should match the residual minerals in partially melted rocks.
www.gps.caltech.edu /faculty/wyllie/wyllie.html   (1032 words)

 Amphibolite (Enciclopedia 1911 Britannica)   (Site not responding. Last check: 2007-10-22)
Amphibolite es el nombre dado a una roca que consiste principalmente en el anfíbol (hornablenda), el uso del término que es restricto, sin embargo, a las rocas metamórficas.
Los amphibolites son rocas metamórficas típicas y como tales logran un revelado grande en todas las regiones esquistos cristalinos y los gneis tales como de las montan@as, del Ardennes, del Harz, de las montañas escocesas, y del districto de los lagos de Norteamérica.
Las etapas transitorias de la roca ígnea o diabase al amphibolite son tan comunes que forman un extenso y grupo importante de las rocas, que se han descrito bajo nombres como greenstone, greenstone-esquisto, flaser-roca i'gnea, saussurite-roca i'gnea, meta-diabase-diabase, y otros.
www.yotor.net /wiki/es/am/Amphibolite%20%28Enciclopedia%201911%20Britannica%29.htm   (1104 words)

 Geology and Mineral Resources   (Site not responding. Last check: 2007-10-22)
She mapped the Belvidere Mountain Complex which includes, from top to base, serpentinized ultramafic, coarse-grained amphibolite and garnet amphibolite, fine- grained amphibolite, greenstone, and muscovite schist (muscovite schist with small to large rounded blocks of amphibolites and greenstones).
The coarse grained amphibolite, exposed at the summit and above the silos on the east flank of the mountain, is a dark gray, banded massive rock composed of amphibole (barroisite cores, barroisite rims, (Laird, 1977)), epidote and garnet with lesser amounts of albite, chlorite, sphene, sericite, biotite and calcite.
The contact of the greenstone with the coarse grained and fine grained amphibolites, the serpentinite, and the pelitic schist/muscovite schist are fault contacts marked by fault slivers and thin talc zones.
www.anr.state.vt.us /dec/geo/bmtn.htm   (1266 words)

 CT DEP: Geology of Gay City State Park
Amphibolite, a metamorphic rock that forms under intense heat, pressure, and by the action of hot fluids, is exposed as boulders near the pond.
Originally, amphibolite was probably either basalt or shaly limestone, before metamorphism.
The dark mineral present in amphibolite is amphibole, an elongate fl splintery mineral (Figure 3).
dep.state.ct.us /stateparks/geology/gaycitygeo.htm   (744 words)

 Final Report   (Site not responding. Last check: 2007-10-22)
During the Copper Age (3000-2000 BC) of the Portuguese lowlands, amphibolite was the preferred raw material for groundstone tools, despite the fact that the principal sources used were located 500km away.
The primary aims of this project were to develop a sourcing methodology for amphibolite and to determine whether there was unequal access to the amphibolite sources during the Copper Age.
Amphibolite tools were probably valued as heirlooms and not considered appropriate offerings for the deceased.
www.ripon.edu /faculty/LilliosK/finrep.htm   (246 words)

Quartz sieve textures in biotite are absent in the undeformed plagioclase amphibolite in all three outcrops.
That is, there is no evidence for the migration of felsic materials from the plagioclase amphibolite that would produce a greater concentration of mafic components as a residue in the plagioclase amphibolite immediately adjacent to the supposed expelled felsic components in the granitic masses.
lThe absence of orthopyroxene in the plagioclase amphibolite and local abundance of primary biotite suggest that the quartz sieve textures in the biotite are the result of replacement of biotite by quartz rather than the reaction of K-bearing fluids with orthopyroxene to produce biotite and left-over quartz.
www.csun.edu /~vcgeo005/three.htm   (2529 words)

 Rocks of NW Scotland - Rock Sample Images
This is an amphibolite, consisting of hornblende and plagioclase feldspar.
Such rocks are called amphibolites, and they are medium-grade metamorphic rocks formed usually from basic igneous rocks like basalt and gabbro.
This amphibolite formed by metamorphism of a gabbro (in one of the Scourie dykes).
www.earth.ox.ac.uk /~oesis/nws/nws-s99-7.html   (432 words)

 [No title]   (Site not responding. Last check: 2007-10-22)
Amphibolite is a metamorphic rock, whose nearest sources lie in the uplands of eastern Portugal.
I suggest that when the biography of amphibolite tools and the cultural landscape from which amphibolite tools derive are considered, another potentially more significant explanation emerges.
As such a link, amphibolite tools may have been maintained in the land of the living as visible and durable mnemonics of lineage histories and may have functioned as heirlooms.
www.ripon.edu /Faculty/LilliosK/papers/meadabs.htm   (258 words)

The massive amphibolite, which is concordant with the steep main foliation of its host, is intruded by a small metagabbroic body and numerous meta-appinite dikes.
The second metamorphism was a retrograde upper greenschist-lower amphibolite facies event, producing talc-tremolite-chlorite at the expense of cummingtonite-oligoclase in the amphibolite, and minor chlorite in the Chazumba Fm.
The body is interpreted to have crystallized from a crustally contaminated basaltic magma that underwent differentiation by crystal settling of bronzite to form a norite cumulate.
gsa.confex.com /gsa/2001CD/finalprogram/abstract_3130.htm   (397 words)

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