Carboniferous–Early Permian sedimentary rocks from the north‐eastern Erenhot, North China: Implications on the tectono‐sedimentary evolution of the south‐eastern Central Asian Orogenic Belt

2020 ◽  
Vol 55 (3) ◽  
pp. 2383-2401 ◽  
Author(s):  
Zejia Ji ◽  
Zhicheng Zhang ◽  
Jinfu Yang ◽  
Yan Chen ◽  
Jianzhou Tang
Keyword(s):  
North China ◽  
Sedimentary Rocks ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Early Permian ◽  
South Eastern ◽  
The North ◽  
Sedimentary Evolution ◽  
Central Asian ◽  
North Eastern

scholarly journals Evaluating the Use of the Molybdenite Re-Os Chronometer in Dating Gold Mineralization: Evidence from the Haigou Deposit, Northeastern China

2019 ◽  
Vol 114 (5) ◽  
pp. 897-915 ◽  
Author(s):  
Degao Zhai ◽  
Anthony E. Williams-Jones ◽  
Jiajun Liu ◽  
David Selby ◽  
Chao Li ◽  
...  
Keyword(s):  
North China ◽  
Gold Mineralization ◽  
Northeastern China ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Lode Gold ◽  
Quartz Veins ◽  
The North ◽  
Central Asian ◽  
Lode Gold Deposit

Abstract The Haigou lode gold deposit (>40 tons [t] at 3.4 g/t), which is located near the eastern boundary of the Central Asian orogenic belt and the North China craton, is one of the largest gold deposits in northeastern China. Native gold is intergrown with molybdenite and pyrite in auriferous quartz veins hosted by a monzogranite-monzonite stock and locally by Proterozoic gneiss, thereby offering an excellent opportunity to directly date the mineralizing event. Uranium-Pb age determinations for zircon yielded ages for the monzogranite and monzonite of 327.1 ± 1.1 and 329.5 ± 1.0 Ma, respectively. Numerous mafic to felsic dikes, which are crosscut by ore veins (pre-ore), parallel to these veins (possibly synore), or crosscut by them (post-ore), were carefully examined and dated. Their zircon 206Pb/238U ages are 318.3 ± 1.0, 310.9 ± 1.1, and 134.9 ± 0.4 Ma, respectively, thereby placing the timing of gold mineralization within the relatively large interval of 318.3 ± 1.0 to 134.9 ± 0.4 Ma. The age of mineralization was determined directly using the Re-Os method applied to molybdenite. A total of 19 molybdenite samples separated from auriferous quartz veins yielded widely differing Re-Os model ages of 467 to 155 Ma, and replicate analyses of individual samples also yielded widely differing ages. Significantly, the wide range is attributable entirely to the results obtained for some coarse-grained molybdenite samples and is interpreted to be due to Re and Os isotope decoupling, the considerable spatial Re heterogeneity, the analytical procedure (e.g., use of small sample aliquots), and the post-ore deformation. Nine of the samples, which are all fine grained, yielded a robust weighted mean model age of 310 ± 3 Ma and an isochron age of 309 ± 8 Ma. Thus, the molybdenite Re-Os ages are identical, within uncertainty, to those of the dikes that are parallel to the ore veins, indicating that these dikes were emplaced contemporaneously with the ore and that they and the Haigou gold mineralization are of late Paleozoic age (ca. 310 Ma). Finally, a sericite sample obtained from an auriferous vein returned a 40Ar/39Ar plateau age of 165.3 ± 1.2 Ma, which is much younger than the age of the mineralization constrained by Re-Os age determinations of molybdenite. This indicates that the 40Ar/39Ar isotope system was reset by post-ore thermal events. Our new geochronological data provide evidence for late Paleozoic gold mineralization in Haigou, which makes it the oldest known lode gold deposit in the easternmost Central Asian orogenic belt, a finding that has important implications for precious metal mineral exploration in the eastern part of the Solonker-Xar Moron-Changchun-Yanji suture zone between the Central Asian orogenic belt and the North China craton. This study also indicates that accurate and reproducible molybdenite Re-Os ages representing the true timing of ore deposition need an integrated combination of careful petrography, proper sampling procedures, sufficiently large analyzed aliquots, multiple analyses of individual samples, and multiple dating methods.

Late Devonian–early Permian accretionary orogenesis along the North Tianshan in the southern Central Asian Orogenic Belt

2014 ◽  
Vol 57 (5-8) ◽  
pp. 1023-1050 ◽  
Author(s):  
Chao Li ◽  
Wenjiao Xiao ◽  
Chunming Han ◽  
Kefa Zhou ◽  
Ji’en Zhang ◽  
...  
Keyword(s):  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Late Devonian ◽  
Early Permian ◽  
The North ◽  
Central Asian ◽  
Southern Central
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