New chronological evidence for Yanshanian diagenetic mineralization in China’s Altay orogenic belt

Chen, Fuwen; Huaqin, LI; Denghong, Wang; Cai, Hong; Chen, Wen

doi:10.1007/bf02884652

Cited by 27 publications

(21 citation statements)

References 4 publications

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“…Late Paleozoic granites have also been reported systematically (Tong et al, 2006a(Tong et al, ,b, 2007(Tong et al, , 2012, suggesting vertical growth (2.1 to 1.5%) of the continental crust in the Chinese Altay (Tong, 2006). The Mesozoic magmatism from this region appears to contribute very little (Chen et al, 1999;D.H. Wang et al, 2003;Wang et al, 2000;Zhang et al, 1994), but increasing numbers of granite and granitic pegmatite have been reported in recent years (Chen, 2011;Ren et al, 2011;Wang et al, 2007Wang et al, , 2010.…”

Section: Introductionmentioning

confidence: 89%

“…3 pegmatite, characterized by the concentric ring structure of nine textural zones, it was initially thought to be the product of fractional crystallization with a long history over~100 Ma (Zou et al, 1986). Chen et al (1999) proposed that the fractional crystallization process lasted~30 Ma, based on their determination of Ar\Ar ages from K-rich minerals. However, these studies failed to distinguish the duration of the magmatichydrothermal transition stage from the evolution of magma.…”

Section: Time Scale Of Magmatic-hydrothermal Evolutionmentioning

confidence: 99%

“…The Chinese Altay was in a passive continental margin from the late Precambrian to the early Paleozoic, before orogenic movement began (Chen et al, 1999), at which point its tectonic setting changed to a continental magmatic arc (active continental margin) during the middle Cambrian to Ordovician (Windley et al, 2002), Middle Cambrian to late Devonian (Wang et al, 2006), and early Cambrian to late Carboniferous (Cai et al, 2011a,c). The corresponding subduction and accretion processes began at ca.…”

Section: Introductionmentioning

confidence: 97%

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Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

Zhang

Tang

et al. 2012

Lithos

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Section: Introductionmentioning

confidence: 89%

Section: Time Scale Of Magmatic-hydrothermal Evolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

Zhang

Tang

et al. 2012

Lithos

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“…It lies south of the Sayan Block of Siberia and is separated from the Kazakhstan-Junggar Block farther south by the Erqis Fault [3] . The belt is characterized by voluminous granitoids and volcanic rock-bearing accretionary complexes, many of which host world-class ore deposits [4][5][6][7][8][9][10][11][12][13][14][15] . Therefore, a detailed study of the geological evolution of the region is important for understanding the orogenic process of the Central Asian Orogenic Belt, determining the origin of the mineral deposits, and guiding future mineral exploration.…”

Section: Geological Backgroundmentioning

confidence: 99%

Early Paleozoic ridge subduction in the Chinese Altai: Insight from the abrupt change in zircon Hf isotopic compositions

Sun

Long

Cai

et al. 2009

Sci. China Ser. D-Earth Sci.

168

110

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Zircons were separated from granitoids, gneisses, and sedimentary rocks of the Chinese Altai. Those with igneous characteristics yielded U-Pb ages of 280-2800 Ma, recording a long history of magmatic activity in the region. Zircon Hf isotopic compositions show an abrupt change at ~420 Ma, indicating that prior to that time the magmas came from both ancient and juvenile sources, whereas younger magmas were derived mainly from juvenile material. This may imply that the lithosphere was significantly modified in composition by a rapid addition of melt from the mantle. We suggest that this dramatic change was due to the onset of ridge subduction, which can account not only for the formation of voluminous granitoids, mafic rocks with complex compositions, and the association of adakite + high-Mg andesite + boninite + Nb-enriched basalt, but also for the coeval high-T, low-P metamorphism.Paleozoic, ridge subduction, Hf isotope, granite, Altai Zircon is ideal for Hf isotopic study, because the crystal chemistry of zircon allows entrain of large amounts of Hf, but not Lu, thus the radiogenic daughter of 176 Hf from the decay of 176 Lu is extremely low in zircon, and the 176 Hf/ 177 Hf ratios of the zircon reflect those of the precursor magma [1] . Significant advances have been made on zircon Hf isotopic systematics, for example the Laboratory of Lithospheric Evolution in the Institute of Geology and Geophysics, Chinese Academy of Sciences has contributed greatly to the technological aspects of this work.For this study, samples were collected from granitoids, gneisses, and sedimentary rocks of different age in the Chinese Altai and analyzed in the above-mentioned Laboratory of Lithospheric Evolution. Our results show an abrupt change in zircon Hf isotopic compositions at ~420 Ma, which may be result of an important regional geological event. Based on an evaluation of the regional geology, geochemical data, and metamorphic development, we suggest that the observed change may mark the onset of ridge subduction. We plan to test this model with further research.

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“…However, the age results are highly inconsistent, ranging from 120 to 331.9 Ma (Zou et al ., ; Chen et al ., ; Zhu et al ., ; Wang et al ., ; Ren et al ., ), which makes the emplacement time uncertain. Among these ages, Rb–Sr isochron ages (331.9 ± 1.5 Ma, Zou et al ., ; 238 ± 2.5 Ma, Zhu & Zeng, ; 218.4 ± 5.8 Ma, Zhu et al ., ) are based on initial 87 Sr– 86 Sr ratios with extremely high errors, muscovite and microcline K–Ar ages (120–292 Ma, Zou et al ., ) are based on old techniques, and the microcline 40 Ar– 39 Ar age (148 ± 1 Ma, Chen et al ., ) has a large uncertainty caused by argon loss. These ages are probably unreliable and these dating methods are not appropriate for pegmatites.…”

Section: Introductionmentioning

confidence: 99%

Formation Age and Evolution Time Span of the Koktokay No. 3 Pegmatite, Altai, NW China: Evidence from U–Pb Zircon and ⁴⁰Ar–³⁹Ar Muscovite Ages

et al. 2015

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The Koktokay No. 3 pegmatite is the largest Li-Be-Nb-Ta-Cs pegmatitic rare-metal deposit of the Chinese Altai orogenic belt, and is famous for its concentric ring zonation pattern (nine internal zones). However, the formation age and evolution time span have been controversial. Here, we present the results of LA-ICP-MS zircon U-Pb dating and muscovite 40 Ar-39 Ar dating. Four groups of zircon U-Pb ages (∼210 Ma, ∼193-198 Ma, ∼186-187 Ma and ∼172 Ma) for Zones II, V, VI, VII, and VIII, and a weighed mean 206 Pb/ 238 U age of 965 ± 11 Ma for Zone IV are identified. Also, Zones II, IV, and VI have muscovite 40 Ar-39 Ar plateau ages of 179.7 ± 1.1 Ma, 182.1 ± 1.0 Ma, and 181.8 ± 1.1 Ma, respectively. Considering previous U-Pb age studies (Zones I, V, and VII), the ages of emplacement, Li mineralization peak, hydrothermal stage of the No. 3 pegmatite are in ranges of 193-198 Ma, 184-187 Ma and 172-175 Ma, with weighted mean 206 Pb-238 U ages of 194.8 ± 2.3 Ma, 186.6 ± 1.3 Ma and 173.1 ± 3.9 Ma, respectively. The No. 3 pegmatite formed in the early Jurassic. The results of xenocrysts suggest that there is another pegmatite forming event of around 210 Ma in the mining district and the old zircon U-Pb ages imply that Neoproterozoic crustal rocks pertain to sources of the No. 3 pegmatite.Including the previous muscovite 40 Ar-39 Ar age studies (Zones I and V), a cooling age range of 177-182 Ma is considered as the time of hydrothermal stage and end of formation. The evolution process of the No. 3 pegmatite lasted 16 Ma. Therein, the magmatic stage continued for 9-11 Myr and the magmatic-hydrothermal transition and hydrothermal stages were sustained at 5-7 Ma. These time spans are long because of huge scale, cupola shape, large formation depth, and complex internal zoning patterns and formation processes. Considering some pegmatite dikes in the Chinese Altai, there is an early Jurassic pegmatite forming event.

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New chronological evidence for Yanshanian diagenetic mineralization in China’s Altay orogenic belt

Cited by 27 publications

References 4 publications

Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

Early Paleozoic ridge subduction in the Chinese Altai: Insight from the abrupt change in zircon Hf isotopic compositions

Formation Age and Evolution Time Span of the Koktokay No. 3 Pegmatite, Altai, NW China: Evidence from U–Pb Zircon and ⁴⁰Ar–³⁹Ar Muscovite Ages

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New chronological evidence for Yanshanian diagenetic mineralization in China’s Altay orogenic belt

Cited by 27 publications

References 4 publications

Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

Early Paleozoic ridge subduction in the Chinese Altai: Insight from the abrupt change in zircon Hf isotopic compositions

Formation Age and Evolution Time Span of the Koktokay No. 3 Pegmatite, Altai, NW China: Evidence from U–Pb Zircon and 40Ar–39Ar Muscovite Ages

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Formation Age and Evolution Time Span of the Koktokay No. 3 Pegmatite, Altai, NW China: Evidence from U–Pb Zircon and ⁴⁰Ar–³⁹Ar Muscovite Ages