SHRIMP U–Pb Zircon geochronology of the Altai No. 3 Pegmatite, NW China, and its implications for the origin and tectonic setting of the pegmatite

Wang, Tao; Tong, Ying; Jahn, Bor‐ming; Zou, Tianren; Wang, Yanbin; Hong, Deshun; Han, Bao‐Fu

doi:10.1016/j.oregeorev.2006.10.001

Cited by 117 publications

(66 citation statements)

References 22 publications

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“…Zhu et al (2006) reported apatite and muscovite Rb-Sr isochron ages of 218.4 AE 5.8 Ma and an initial 87 Sr/ 86 Sr ratio of 0.708. On the other hand, SHRIMP UePb zircon dating by Wang, T., et al (2007b), yielded weighted mean ages of 220 AE 9 Ma, 213 AE 6 Ma and 198 AE 7 Ma, with the last two ages probably representing stages of hydrothermal alteration. The UePb age data indicate that the 220 Ma is the age of emplacement.…”

Section: Keketuohaimentioning

confidence: 99%

A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China

Pirajno

Seltmann

Yang

2011

Geoscience Frontiers

197

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KEYWORDSMineral system; Porphyry and epithermal deposits; Volcanogenic massive sulphides and skarn systems; Northern Xinjiang of NW ChinaAbstract In this paper we present a review of mineral systems in northern Xinjiang, NW China, focussing on the Tianshan, West and East Junggar and Altay orogenic belts, all of which are part of the greater Central Asian Orogenic Belt (CAOB). The CAOB is a complex collage of ancient microcontinents, island arcs, oceanic plateaux and oceanic plates, which were amalgamated and accreted in Early Palaeozoic to Early Permian times. The establishment of the CAOB collage was followed by strike-slip movements and affected by intraplate magmatism, linked to mantle plume activity, best exemplified by the 250 Ma Siberian Traps and the 280 Ma Tarim event. In northern Xinjiang, there are numerous and economically important mineral systems. In this contribution we describe a selection of representative mineral deposits, including subduction-related porphyry and epithermal deposits, volcanogenic massive sulphides and skarn systems. Shear zone-hosted Au lodes may have first formed as intrusion-related and subsequently re-worked during strike-slip deformation. Intraplate magmatism led to the emplacement of concentrically zoned (Alaskan-style) maficeultramafic intrusions, many of which host orthomagmatic sulphide deposits. A huge belt of pegmatites in the Altay orogen, locally hosts world-class rare metal deposits. Roll-front,

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Section: Keketuohaimentioning

confidence: 99%

A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China

Pirajno

Seltmann

Yang

2011

Geoscience Frontiers

197

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“…Important Paleozoic plutons are marked by their names and zircon ages. Data sources: a Wang et al (1998);b Windley et al (2002); c Yuan et al (2007); d Wang et al (2006); e Wang et al (2007); f Yang et al (2008);g Sun et al (2009a); h Lou (1997) et al (1996); Han et al (1997);x Li et al (2004); and others are our unpublished data (Shan et al 2005;Long et al 2008), and middle-Ordovician to Silurian amphibolite-and greenschist-facies metasediments and metavolcanic rocks in the southwest. Some high-grade metamorphic rocks are thought to be Neoproterozoic in age (e.g., Windley et al 2002;Li et al 2003;Xiao et al 2004), and these rocks were considered to constitute the nuclei of the Altai microcontinent (Hu et al 2000;Li et al 2003;Xiao et al 2004;Wang et al 2009).…”

Section: Geological Settingmentioning

confidence: 99%

Recognition of early Carboniferous alkaline granite in the southern Altai orogen: post-orogenic processes constrained by U–Pb zircon ages, Nd isotopes, and geochemical data

Tong

Wang

Siebel

et al. 2011

Int J Earth Sci (Geol Rundsch)

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The Altai orogen forms the southern part of the Central Asian Orogenic Belt (CAOB), the world's largest accretionary orogen. However, its tectonic evolution, particularly during the late Paleozoic, is still not well understood. U-Pb zircon analyses for the Bulgen alkaline granite yield crystallization ages of 358 ± 4 Ma (SHRIMP) and 354 ± 4 Ma (LA-ICP-MS). These ages are significantly younger than published emplacement ages for subduction/ collision-related syn-orogenic granitoids (460-375 Ma) in this region. The Bulgen granite has high SiO 2 , total alkalis, rare earth elements, HFSE (Th, Zr, Hf, Nb, and Ce), and low Ba, Sr with pronounced negative anomalies in Eu, Ba, Sr, P, and Ti, showing a clear A-type geochemical signature. The granite records high eNd(t) values of ?6.3 to ?6.4 and young model ages (T DM ) of ca. 600 Ma. The Bulgen alkaline granite is largely undeformed as opposed to the early-middle Paleozoic counterparts, which form elongated deformed bodies parallel to the prevailing tectonic fabric (NW direction). Available data suggest that magmatism in the southern Altai region evolved from early-middle Paleozoic I-type tholeiitic and calc-alkaline granitoids to late Paleozoic A-type alkaline granitoids. The high eNd(t) values of the Bulgen alkaline granite indicate a homogeneous juvenile mantle source, whereas the earlymiddle Paleozoic granitoids are characterized by lower and more variable eNd(t) values (-2.6 to ?4.2). These differences provide an important insight into the late Paleozoic orogenic processes of the Chinese Altai and indicate a significant change of the tectonic regime from a syn-orogenic regional compression setting to a post-orogenic extensional one. Major tectonic movements in this region ceased after the early Carboniferous.

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“…New Mexico, Australia, Canada, China and the Czech Republic) of economic rare-metal pegmatites that are found in high-grade metamorphic terranes comprising amphibolite to granulite facies metasedimentary rocks and migmatites (Jahns and Ewing, 1976;Marignac and Cuney, 1999;Sweetapple and Collins, 2002;Stilling et al, 2006;Wang et al, 2007;Küster et al, 2009;McKechnie et al, 2012;Melleton et al, 2012;Martins et al, 2013). It is possible that the composition of available protoliths for melting is more important for rare-metal pegmatites than large-volume melting and formation of a fertile parent granite that undergoes lengthy fractionation.…”

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Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: a case study from the Lewisian Gneiss Complex of north-west Scotland

Shaw

Goodenough

Horstwood³

et al. 2016

Applied Earth Science

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a b s t r a c tMany rare metals used today are derived from granitic pegmatites, but debate continues about the origin of these rocks. It is clear that some pegmatites represent the most highly fractionated products of a parental granite body, whilst others have formed by anatexis of local crust. However, the importance of these two processes in the formation of rare-metal pegmatites is not always evident.The Lewisian Gneiss Complex of NW Scotland comprises Archaean meta-igneous gneisses which were highly reworked during accretional and collisional events in the Palaeoproterozoic (Laxfordian orogeny). Crustal thickening and subsequent decompression led to melting and the formation of abundant granitic and pegmatitic sheets in many parts of the Lewisian Gneiss Complex. This paper presents new petrological, geochemical and age data for those pegmatites and shows that, whilst the majority are barren biotite-magnetite granitic pegmatites, a few muscovite-garnet (rare-metal) pegmatites are present. These are mainly intruded into a belt of Palaeoproterozoic metasedimentary and meta-igneous rocks known as the Harris Granulite Belt.The rare-metal pegmatites are distinct in their mineralogy, containing garnet and muscovite, with local tourmaline and a range of accessory minerals including columbite and tantalite. In contrast, the biotitemagnetite pegmatites have biotite and magnetite as their main mafic components. The rare-metal pegmatites are also distinguished by their bulk-rock and mineral chemistry, including a more peraluminous character and enrichments in Rb, Li, Cs, Be, Nb and Ta. New U-Pb ages (c. 1690-1710 Ma) suggest that these rare-metal pegmatites are within the age range of nearby biotite-magnetite pegmatites, indicating that similar genetic processes could have been responsible for their formation.The peraluminous nature of the rare-metal pegmatites strongly points towards a metasedimentary source. Notably, within the Lewisian Gneiss Complex, such pegmatites are only found in areas where a metasedimentary source is available. The evidence thus points towards all the Laxfordian pegmatites being formed by a process of crustal anatexis, with the formation of rare-metal pegmatites being largely controlled by source composition rather than solely by genetic process. This is in keeping with previous studies that have also challenged the widely accepted model that all rare-metal pegmatites are formed by fractionation from a parental granite, and raises questions about the origin of other mineralised pegmatites worldwide.

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SHRIMP U–Pb Zircon geochronology of the Altai No. 3 Pegmatite, NW China, and its implications for the origin and tectonic setting of the pegmatite

Cited by 117 publications

References 22 publications

A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China

A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China

Recognition of early Carboniferous alkaline granite in the southern Altai orogen: post-orogenic processes constrained by U–Pb zircon ages, Nd isotopes, and geochemical data

Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: a case study from the Lewisian Gneiss Complex of north-west Scotland

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