Baddeleyite is a key mineral in geochronology of mafic rocks as it crystallizes in silica-undersaturated systems that do not grow zircon. It has been shown that nanosecond ns- LA-ICP-MS U—Pb analysis requires matrix-matched calibration due to significantly stronger element downhole fractionation in baddeleyite compared to zircon. If the cause for previously observed reverse discordance is only downhole elemental fractionation, then raster analyses should remedy this even with ns-LA-ICP-MS. Our results show that elemental fractionation occurs in both fs- and ns-LA-ICP-MS and needs to be corrected for by application of baddeleyite as reference material. Although raster analyses are not affected by downhole fractionation, discordant ages result nevertheless. The underlying elemental fractionation process might be caused by ablation of material previously ablated and deposited along the raster path.
First U-Pb LA-ICP-MS zircon ages assessed from a volcano-sedimentary complex of
The high-grade metamorphic metasedimentary rocks that comprise the Wollaston Domain, northern Saskatchewan, are host to numerous REE-mineralized pegmatite bodies, including the Kulyk Lake monazite-apatite-Fe Ti -oxide occurrence. This occurrence, which is defined by a cm wide sinouous zone of granoblastic monazite, apatite, and titanomagnetite, is enclosed within aplitic monzonite and granitic pegmatite dikes. A combination of in situ LA-ICP-MS trace element mapping, trace-element quantification, and U-Pb dating were used to identify a significant volume of partial resorbed xenocyrstic monazite and zircon cores within the monazite-apatite-Fe Ti -oxide zone. The U-Pb age distribution of the inherited monazite and zircon populations matches that of the middle- to upper-Wollaston Group sedimentary succession. This study reveals the potential importance of metalliferous monazite-rich lithologies in the anatectic zone to these pegmatite-hosted REE occurrences and suggests that entrainment and magmatic segregation mechanisms may have helped to concentrate monazite, apatite, and Fe Ti -oxide prior to final emplacement of the aplite-pegmatite dikes. Similar processes may have occurred regionally and in other high-grade metamorphic terrains worldwide that are endowed with metalliferous metasedimentary protoliths. Zitat exportieren.
German Title: Spurenelementsignaturen in Rutil: Kalibrierung von Standards und Anwendungen auf akzessorische Bestandteile in metamorphen Gesteinen. This study focuses on the trace element composition of rutile, a frequent accessory mineral in various rock types mafic, pelitic and felsic protoliths; common at blueschist-, eclogite- and granulite-facies conditions and one of the most stable minerals in sedimentary environments.
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At the very end of the intro, they show a photo in a picture frame of two girls with bows on their chests. They are so cute. Anyone know who they are...like left to right?
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