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Topic: Diatreme


  
 [No title]
The volume of the diatreme fill is about the same as that of the thinly bedded tephra ring and distal ash deposits.
This rootzone is irregular in shape and overlies the magmatic feeder dyke of the volcano.
Their reasons are very complex intrusion processes in the diatreme or in the sedimentary infilling of the maars.
www.mafi.hu /microsites/2IMC_Homepage/2IMC_Homepage_Files/Scientific_Symposia_2IMC.htm   (3409 words)

  
 PALEOMAGNETIC AND GEOCHRONOLOGIC DATA BEARING ON THE DEFORMATION AND TIMING OF THE CRIPPLE CREEK DIATREME COMPLEX AND ...   (Site not responding. Last check: 2007-10-15)
There is no correlation between degree of north-side down tilting of the diatreme complex and age relations, (i.e.
Block rotations are identified in the Cresson and Altman pits and are consistent with major sinistral and dextral faults that bisect the district.
We interpret the total available collection of paleomagnetic data to indicate that the diatreme and host rocks in the immediate vicinity were deformed by a slight yet distinguishable amount of north-side down tilting since the early Oligocene.
gsa.confex.com /gsa/2002AM/finalprogram/abstract_44533.htm   (407 words)

  
 Mount Rawdon, Southeast Queensland, Australia; a diatreme-hosted gold-silver deposit -- Brooker and Jaireth 90 (6): ...
The diatreme is filled by polymict, moderately to poorly sorted, matrix-supported fragmental units dominated- by clasts of variably altered dacite porphyry, basement metasediments, and granodiorite clasts.
The diatreme is intruded by a central dacitic plug and numerous smaller dacite plugs and dikes.
Premineralization alteration within the diatreme is associated with intrusions and consists of phyllic and propylitic assemblages generated by dacite porphyries, crosscut by trachyandesites with propylitic alteration and trachytes with weak illite-smectite alteration.
econgeol.geoscienceworld.org /cgi/content/abstract/90/6/1799   (345 words)

  
 The Martabe Gold Deposit, North Sumatra
Multiple diatreme facies superimposed each other at Purnama are thought to be coetaneous with early dacitic intrusive activity to the north.
As the geology of Purnama becomes better understood the fragmental units are recognised as intrusive diatreme that has been injected along bedding planes within the sandstone, siltstone sequence and not volcaniclastic density flows as originally thought.
It is interpreted that the emplacement of the later diatreme breccia was responsible for this fracturing and brecciation in competent (silicified) rocks around the diatreme margins and the diatreme itself became an impermeable hangingwall barrier due to the pervasive clay alteration.
www.smedg.org.au /Tiger/Purnama.htm   (3111 words)

  
 Mineral Resources - Minfact 90   (Site not responding. Last check: 2007-10-15)
The diatreme at Dundas was formed as a complex structure of rocks.
Thus the diatreme was a mixture or breccia, that was mixed with the basalt.
And the diatreme at Dundas was recognised early as a major source of blue metal.
minerals.nsw.gov.au /prodServices/minfacts/minfact_90   (943 words)

  
 Morphology of Kimberlite
Crater facies kimberlite is difficult to distinguish from diatreme facies kimberlite.
Kimberlite diatremes are 1-2 kilometer deep, generally carrot-shaped bodies which are circular to elliptical at surface and taper with depth.
Crystallisation in diatreme occurs at low temperatures based on the lack of thermal effects seen in intruded limestones.
www.eos.ubc.ca /research/diamonds/kopylova/intro/morphology.html   (645 words)

  
 scBN - Diatreme Resources Ltd   (Site not responding. Last check: 2007-10-15)
Diatreme Resources Limited was incorporated as Minstrike Mining Pty Ltd on 10 August 1993 and changed its name to Strike Exploration Pty Limited on 25 May 1994.
Diatreme is proposing to raise capital under a prospectus in 2003.
Diatreme's principal focus is on gold but it also has one diamond project and one base metal project.
www.scbn.com.au /article.php?story=2004042110084567   (323 words)

  
 Zircon a sparkling hope for Diatreme
Diatreme Resources Ltd is hoping interest in the global zircon market will translate to interest in its shares once it lists on the Australian Stock Exchange later this year.
Diatreme chief executive Tony Fawdon, in a briefing to media and analysts, said he believed the approximately 7,000 square kilometres held by his company in the Eucla Basin had the potential to match or better the quality of the Iluka heavy minerals find.
Diatreme is currently seeking to raise up to $5 million in an initial public offer and is yet to commence drilling in the Eucla Basin however the company is very optimistic.
news.ninemsn.com.au /article.aspx?id=51056   (609 words)

  
 Open File Report 98-06   (Site not responding. Last check: 2007-10-15)
Bark, twig and stem samples from trembling aspen trees over the Mountain Lake Diatreme proved to be viable sampling media in their ability to up take elements indicative of ultramafic and kimberlitic sources and their analysis provided a distinctive biogeochemical signature that may be used elsewhere in Alberta.
The geochemical variance between the second sampling transect and the Mountain Lake Diatreme transect indicate that the positive geochemical pattern obtained over the diatreme is not related to the physiographic environment and that biogeochemical sampling can detect an ultramafic signature from associated soil and bedrock.
The soil layer over the diatreme is enriched with varying combinations of soluble and immobile elements, which influence the surficial expression or vegetation characteristics, and may be of importance for defining kimberlitic surficial expressions in northern Alberta.
www.ags.gov.ab.ca /publications/ABSTRACTS/OFR_1998_06.shtml   (442 words)

  
 GEOS2150 Hornsby Quarry   (Site not responding. Last check: 2007-10-15)
The purpose of this stop is to become familiar with diatreme structures.
The Hornsby Diatreme is the largest and best exposed example of the 100 or so diatremes found in the Sydney Basin (Crawford et al., 1980).
Both diatreme and country rock are exposed in the walls.
www.newcastle.edu.au /discipline/geology/fieldwrk/geos2150/southcoast/hornsby.htm   (214 words)

  
 Kimberlite Emplacement Models
Diatreme facies/hypabyssal facies transitions are generally 2 km deep while craters are generally 1 km wide - thus producing a ratio of 1:2.
The main difference is the internal structure seen maar diatremes, which is generally absent in the kimberlite diatreme.
The relationship between the diatreme and feeder dike is unclear in the maar-diatreme example.
www.eos.ubc.ca /research/diamonds/kopylova/intro/emplacement.html   (1238 words)

  
  Mineral Property on MiningLife   (Site not responding. Last check: 2007-10-15)
The Clermont Gold Project is situated south and west of the town of Clermont in central Queensland.
Diatreme intends to explore for a stratabound bulk tonnage target containing at least one million ounces gold.
The principal prospect of interest for Diatreme in the project area is the Clermont South Gold Prospect, which is located 1 km south of the township of Clermont.
www.mininglife.com /operations/operationdetail.asp?Property=Clermont   (71 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
The extent of the Area E diatreme breccia, one of at least 5 separate diamond bearing areas on the GQ Property, has been significantly expanded by the discovery of numerous boulders and sub-outcrop at least 300 meters to the northwest of the latest sampling and trenching.
The diatreme breccia appears to be oriented more or less parallel to the enclosing Archean volcanic rocks that strike north-westerly and dip 30 degrees to the northeast.
The sample size, while insufficient for the purpose of determining the grade of the Area E diatreme breccia is expected to aid the company in determining the upward continuity of the diamond size distribution.
www.band-ore.com /Press99/Press01-7.htm   (555 words)

  
 Upcoming Floats
Diatreme is listed on the Stock Exchange of Newcastle (NSX) and has approximately 1,320 shareholders holding a total of approximately 52,000,000 fully paid ordinary shares.
Diatreme's single diamond project is at Warialda in northern New South Wales.
Diatreme's major base metal project, the Bellfield Project, is situated in Proterozoic rocks to the southwest of Georgetown in north Queensland.
www.floatnews.com.au /affiliates/floatfactscompanydetails.asp?intCompanyID=1774&affiliateID=62   (357 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
The hole remained in the diatreme until a pink phase of a granite/kimberlite diatreme breccia, with "kimberlite" sills, was encountered at 420 meters.
Diamond drilling tests of several aeromagnetic anomalies, in the vicinity of the previously announced Kyle Lake diamondiferous body, resulted in the discovery of another diatreme body believed to be akin to the Kyle Lake diatreme.
This diatreme body is geophysically estimated to be approximately 125 to 150 meters in diameter and has now been drill tested to a depth of 383 meters Samples of this new discovery will be submitted for diamond analysis once the core has been sent from the field.
www.kwg-resources.com /news/comm/majordiamond.html   (498 words)

  
 UWRF Geology - Dr. Bill Cordua   (Site not responding. Last check: 2007-10-15)
Diatremes are formed by the powerful explosive eruption of gas-rich magma from deep in the earth.
The Six Pak diatreme consists of rock called lamproite, which resembles, but is geochemically distinct from, kimberlite.
However, diatremes generally occur in groups, so where there is one, there should be others.
www.uwrf.edu /%7Ewc01/SixPak.html   (482 words)

  
 Open File Report 98-01   (Site not responding. Last check: 2007-10-15)
While the overall geochemical signature is indicative of an ultramafic source, apical and oxidation halo geochemical responses yield elevated concentrations of Co, CrO3, Cu and Ni with the presence of high Ba, Ga, Hf, PO4, Rb, Ta, Ti and light rare earth elements suggestive of a kimberlite or lamproite body.
Since the Mountain Lake Diatreme is near surface and forms a topographic high, the morphology of the enzyme leach-based geochemical signature is expected to yield an oxidation halo profile only.
Since altered ultrabasic volcanic rocks were observed at a depth of 1.8 m and represent the parent material to the soil, the geochemical abnormality at RE-ML97-015 may express the soil development profile that forms on top of kimberlitic and lamproitic bodies.
www.ags.gov.ab.ca /publications/ABSTRACTS/OFR_1998_01.shtml   (442 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
It is shown, that the colouring of garnets depends on the presence of high amounts of ferrous iron components, presence of chromium and manganese oxides.
The grossular-almandine-pyrope and andradite-almandine-pyrope types prevail among investigated garnets from diatreme rocks and xenoliths.
It is underlined that garnets from Nizhevskaya 674 diatreme are the most interest ing ones as indicators of diamond-bearing rocks.
www.igs.ac.by /lithosphere/1996.no5/l5-96e7.html   (176 words)

  
 UNIVERSITY OF GENEVA - DEPT OF MINERALOGY - ORE DEPOSITS
In the center of the Colquijirca district, a 4 km2, Miocene, mainly dacitic, diatreme-dome complex intrudes a >300-m-thick sequence of folded carbonate rocks, continental Eocene limestones, marls and detritic sediments (Pocobamba Formation) to the north, and marine, Triassic-Jurassic, nearly pure limestones and dolostones (Pucará Group) to the south (Figs.
In the northern flank of the diatreme vent, alteration selvages from the massive enargite-quartz-alunite ores overprint weakly argillized/propylitized dacitic domes and phreatomagmatic breccias related to the Au-(Ag) mineralization.
To the east of the diatreme vent, the argillic associations related to the Au(Ag) ores are cut by narrow sphalerite-galena-pyrite veins.
www.unige.ch /sciences/terre/mineral/publications/onlinepub/sga2002/sga2002.html   (1933 words)

  
 Western Copper Holdings Limited: Drilling Extends Chile Colorado Zone At Penasquito Silver Property   (Site not responding. Last check: 2007-10-15)
Nine holes drilled north of Chile Colorado in and adjacent to the Azul diatreme breccia have identified thick zones of moderate to low grade silver along the breccia margin.
Nine holes (WC-27, 29, 30, 31, 32, 33, 34, 36 and 38) were drilled to evaluate the extent and grades of mineralization in the Azul diatreme breccia and its contact with the Caracol sandstones.
Holes WC-30 and WC-34 tested the eastern contact of the diatreme breccia and both holes contain significant widths of mineralization along the diatreme breccia margin characterized by low to moderate silver, low gold and elevated copper values.
www2.ccnmatthews.com /scripts/ccn-release.pl?/2002/10/21/1021016n.html   (1154 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
Nevertheless, in order to better understand the nature of these features, their formation, the relationship between them and other structures such like scoria cones and tuff-rings, and their relevance to the formation of other geological structures such like kimberlite-diatremes, further geological and geophysical studies are required (Lorenz, 1986).
Although all the above studies were of valuable contributions to understanding the nature of the maar diatreme volcanoes, it is necessary to get more detailed answers to some pertinent questions related to their genesis, their morphology and their physics.
That is the reason, instead of selecting out one model for a given maar diatreme volcano, a range of possible models are defined beside a particular one, i.e., a model is presented with its probability intervals.
www.uni-mainz.de /FB/Geo/Geologie/Geophysik/Prj/eifel.html   (564 words)

  
 Porter GeoConsultancy - Ore Deposit Description   (Site not responding. Last check: 2007-10-15)
It is hosted within a late Triassic diatreme that cuts meta-sediments of the Carboniferous Curtis Island Group, and the Palaeozoic Briggs Creek Granodiorite.
The diatreme is filled with polymict, poorly sorted, matrix supported fragmentals dominated by clasts of variably altered dacite porphyry, meta-sediments and granodiorite.
The diatreme is in turn cut by a central dacite plug and numerous dykes.
www.portergeo.com.au /database/mineinfo.asp?mineid=mn234   (420 words)

  
 New Page 0
The Neys diatreme is considered by the author to represent the release of high level accumulation of volatiles in a crystallizing alkalic magma, entirely different from the other structures, which represent mantle-derived volatiles.
The volatiles of the Dead Horse structure were related to carbonatite intrusion, and in the case of the Slate Islands, perhaps, diabasic or gabbroic intrusion.
Most of the alkalic rock-carbonatite intrusive events are Late Precambrian in age, however, a middle Paleozoic age for the Slate Islands lamprohyre dike with carbonatite affinities suggests that alkalic magmatism, north of Lake Superior, along this trend, spanned at least 700 Ma.
users.renegadeisp.com /~rwahl/Prairie%20Lake%20Regional%20Structural%20Setting.htm   (593 words)

  
 Midway Gold Corporation - Corporate   (Site not responding. Last check: 2007-10-15)
The entire complex is 1 by 2 km in size and is covered by 15 to 60 m (50 to 200 feet) of alluvial gravel.
Four zones of gold have been encountered: 1) The Pond Breccia- two hydrothermal breccia pipe developed along the edge of the Spring Valley diatreme, 2) The Porphyry Zone- which hosts gold in altered rhyolite feldspar porphyry, 3) the Wabash Sill zone- which hosts gold in a stockwork altered rhyolite porphyry dike and sill(s) zone.
Most drilling has tested the Pond zone where mineralization is centered on a series of breccia pipes interpreted to be diatreme.
www.midwaygold.com /SpringValley.htm   (510 words)

  
 ASWRF Anglo Swiss Resources Inc,Stock Trading Message Board News - View Message   (Site not responding. Last check: 2007-10-15)
The sampled diatreme, (referred to now as "McAllister") may be spatially related to a major north-west to south-east structural break in the earth's crust.
This break may have provided deep-seated access for the diatreme to reach the surface, or may be coincident and unrelated.
An additional diatreme was recognised from the helicopter some 4 kilometers north-west of the McAllister Diatreme, suggesting that multiple diatremes (a "cluster") may be present within a structurally favourable zone.
www.equitygroups.com /otcbb/aswrf/messages/482.html   (796 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
The monocline is actually afault at depth, and there is a diatreme about a mile south of the river.
Mule Ear Diatreme is a small volume alkalic igneous body that has come up from depth along t his fault.
This is a view taken from the diatreme looking north along the Comb Wash Monocline to the snow-capped Abajo Mountains in the background.
ruby.colorado.edu /~smyth/Personal/Rivers/SanJuan/SanJuan.htm   (210 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
Trenching has established the presence of a xenolith rich diatreme breccia across a continuous outcrop exposure of 75 metres in proximity to samples collected by independent diamond consultant, Dr. Ed Walker.
Scattered outcrop and angular frost heaved boulder material indicate the ‘Area E’ diatreme breccia has a minimum strike length of 300 metres and horizontal widths in excess of 75 metres.
Based on the favourable diamond results received to date and the dimensions of the ‘Area E’ diatreme breccia, the Company has decided to proceed with the extraction and processing of a 10 tonne mini-bulk sample.
www.band-ore.com /Press99/Press01-6.htm   (369 words)

  
 SHORE GOLD DRILLS RIGHT DOWN THE THROAT OF THE STAR KIMBERLITE   (Site not responding. Last check: 2007-10-15)
As far as can be ascertained it has been drilled into a feeder zone of the pipe as evidenced by diatreme lithologies and abundant large, mantle derived xenoliths, pyrope and ecologitic garnets.
The core displays uniform diatreme textures throughout the lower portions of the hole.
As a result Shore is going to drill additional holes close by to define the dimensions of the feeder zone and to collect a larger sample for diamond extraction studies.
www.minesite.com /archives/news_archive/2001/Jan-2001/STAR-16.HTM   (503 words)

  
 Diatreme   (Site not responding. Last check: 2007-10-15)
A diatreme is what happens after hot matter explodes out of a volcano which leaves an empty feeder channel, that feeder channel becomes filled with Breccia and that is a Diatreme.
A diatreme is a small but violent volcanic explosion that arrives at the surface at mach 2.
A diatreme (also known as a phreatomagmatic breccia) is the column (or conduit or pipe) above which a maar-type (hydro) volcano developed.
hv.greenspun.com /bboard/q-and-a-fetch-msg.tcl?msg_id=004fNV   (186 words)

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