Hydrothermale Alterationsprozesse in Zirkonen

Kurz, Sabine

Isotopengeologische und geochemische Implikationen

dc.contributor.author	Kurz, Sabine	de
dc.date.accessioned	2001-11-01T15:25:43Z	de
dc.date.accessioned	2013-01-18T11:25:39Z	de
dc.date.available	2013-01-30T23:51:05Z	de
dc.date.issued	2001-11-01	de
dc.identifier.uri	http://hdl.handle.net/11858/00-1735-0000-0006-B356-E	de
dc.format.mimetype	application/pdf	de
dc.language.iso	ger	de
dc.rights.uri	http://webdoc.sub.gwdg.de/diss/copyrdiss.htm	de
dc.title	Hydrothermale Alterationsprozesse in Zirkonen	de
dc.title.alternative	Isotopengeologische und geochemische Implikationen	de
dc.type	doctoralThesis
dc.contributor.referee	Hansen, Bent T. Prof. Dr.	de
dc.date.examination	2000-04-18	de
dc.subject.dnb	550 Geowissenschaften	de
dc.description.abstracteng	The U/Pb isotopic system of zircons is a powerful tool to date rocks. Nevertheless interpretation of discordant U/Pb ages is again and again subject of discussions. We focussed our study on the mobilisation of U and Pb under the hydrothemal influence of Ca-dominated basement brines. Electron microprobe studies on discordant zircon fractions from different localities in Sweden, the German Fichtelgebirge and Erzgebirge show considerable influence of percolating Ca-rich fluids. Incorporation of Ca is restricted to disordered metamict zones with high U-content and accompanied by enrichment of Na, Al and Fe. Zones with low U-content remained nearly unaffected by the fluids. Accompanying U/Pb-analyses show that the varying share of zircon substance susceptible to alteration is responsible for strong diffences in degree of discordances. To determine the degree of influence of these reactive fluids on the U/Pb-systematics of zircons we carried out a sereis of hydrothermal eyperiments using NaCl-CaCl2-solutions. Experiments lead to considerable changes in the 207Pb/235U and 206Pb/238U ratios of the treated zircon fraction. Due to varying changes in the experimetnal conditions we were able to create artificial discordias. Leaching is not only restricted to Pb. U an! d the light and heavy rare earth elements are also mobilised during hydrothermal alteration. Furthermore studies on zircons of the Fichtelgebirge show U enrichment within hydrothermally altered areas which lead to geologically meaningless U/Pb-ages. This phenomenon is probably in close connexion with widespread U-ore-mineralisations formed during the intrusion of young variscan granites.	de
dc.contributor.coReferee	Hoefs, Jochen Prof. Dr.	de
dc.subject.topic	Mathematics and Computer Science	de
dc.subject.ger	Zirkonmineralien	de
dc.subject.ger	Hydrothermale Metamorphose	de
dc.subject.ger	Isotopenaustausch	de
dc.subject.bk	38.32	de
dc.subject.bk	38.03	de
dc.subject.bk	38.30	de
dc.identifier.urn	urn:nbn:de:gbv:7-webdoc-912-6	de
dc.identifier.purl	webdoc-912	de
dc.affiliation.institute	Fakultät für Geowissenschaften und Geographie	de
dc.subject.gokfull	VHC 400: Radioaktive Minerale	de
dc.subject.gokfull	VGF 200: Phasengleichgewichte und Umbildungen {Mineralogie}	de
dc.subject.gokfull	VJJ 120: Geochemie der Instabilen Isotopen	de
dc.subject.gokfull	VBO 000: Isotopengeologie	de
dc.identifier.ppn	320924955

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Fakultät für Geowissenschaften und Geographie (inkl. GAUSS) [342]

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