New Chronological Evidence for Indosinian Diagenetic Mineralization in Eastern Xinjiang, NW China

Abstract

There have been conflicting ideas about the Indosinian mineralization in E. Xinjiang, a subject that has attracted many geologists' attention over a long period. Isotopic dating shows that the Shiyingtan gold deposit located on the southern margin of the Turpan‐Hami basin has a quartz fluid inclusion Rb‐Sr isochron age of 237±9 Ma (95% conf.); the Shuangfengshan gold deposit on the southern margin of the Junggar orogenic belt has a quartz fluid inclusion Rb‐Sr isochron age of 226±21 Ma (95% conf.); the Weiya vanadium‐titanium magnetite in the E. Tianshan mountains has a mineral‐whole rock Sm‐Nd isochron age of 220 ±30 Ma (95% conf.); the Jinwozi and Jinwozi 210 gold deposits in the E. Tianshan mountains have quartz fluid inclusion Rb‐Sr isochron ages of 228±22 Ma (95% conf.) and 230±6 Ma (95% conf.), respectively; and the Xiaobaishitouquan scheelite deposit in the E. Tianshan mountains has a quartz fluid inclusion Rb‐Sr isochron age of 248±7 Ma (95% conf.). The metallogenetic ages mentioned above prove the existence of Indosinian mineralization in E. Xinjiang, and the metallogenetic event might have been related to Triassic intraplate magmatic evolution, intra‐continent subduction, strike‐slip shoving and ductile shearing in the studied area, representing another mineralization peak after the Late Paleozoic.

Early Indosinian Weiya Gabbro in Eastern Tianshan, China: Elemental and Sr‐Nd‐O Isotopic Geochemistry, and Its Tectonic Implications

“…Then, tectonics converted from compression to extension, resulting in extension of the eastem Tianshan area and subsequent emplacement of numerous mafk and ultramafic rocks and coeval granitoids (Gu et al ., 1996Han et al, 1997Hong et al, 2004;Zhou et al, 2004). 2003;Li et al, 2005;Zhang et a]., 2005) have addressed the manifestation of Indosinian (Triassic) magmatism and mineralization in the eastern Tianshan Mountains, but their relationship to regional tectonics remains to be evaluated. 2003;Li et al, 2005;Zhang et a]., 2005) have addressed the manifestation of Indosinian (Triassic) magmatism and mineralization in the eastern Tianshan Mountains, but their relationship to regional tectonics remains to be evaluated.…”

“…Some authors (Gu et al. Although it has been emphasized (Han et al, 1997;Jahn et al, 2000;Zhao et al, 2004;Zhou et al, 2004; Li et al, 2005;Xia et al, 2005;Zhang et al, 2005) that mantle-derived magmas played a direct or indirect role in the formation of granitoids and mineralization in the eastern Tianshan Mountains and Central Asian Orogenic Belt, little is known about the nature, origin and tectonic setting of these magmas. As a consequence, it remains to be understood whether the Indosinian tectonism was a continuation of the Hercynian post-collisional extension in eastem Tianshan or was affected substantially by other tectonic system.…”

“…Some authors (Gu et al. 2003;Li et al, 2005;Zhang et a]., 2005) have addressed the manifestation of Indosinian (Triassic) magmatism and mineralization in the eastern Tianshan Mountains, but their relationship to regional tectonics remains to be evaluated. As a consequence, it remains to be understood whether the Indosinian tectonism was a continuation of the Hercynian post-collisional extension in eastem Tianshan or was affected substantially by other tectonic system.…”

“…As a consequence, it remains to be understood whether the Indosinian tectonism was a continuation of the Hercynian post-collisional extension in eastem Tianshan or was affected substantially by other tectonic system. Although it has been emphasized (Han et al, 1997;Jahn et al, 2000;Zhao et al, 2004;Zhou et al, 2004; Li et al, 2005;Xia et al, 2005;Zhang et al, 2005) that mantle-derived magmas played a direct or indirect role in the formation of granitoids and mineralization in the eastern Tianshan Mountains and Central Asian Orogenic Belt, little is known about the nature, origin and tectonic setting of these magmas.…”