Zircon U-Pb dating is the most commonly used method for isotopic geochronology. However, it has been a difficult issue when relating zircon U-Pb ages to metamorphic conditions in complex metamorphic rocks. Much progress has been made in the past decade with respect to the genesis of zircon and its constraints on interpretation of U-Pb age. Three methods have been proposed to link zircon U-Pb age to metamorphic conditions: (i) internal structure; (ii) trace element feature; (iii) mineral inclusion composition. Magmatic zircon shows typical oscillatory zoning and/or sector zoning, whereas metamorphic zircon has internal structures such as no zoned, weakly zoned, cloudy zoned, sector zoned, planar zoned, and patched zoned ones. Zircons formed in different geological environments generally have characteristic internal structures. Magmatic zircons from different rock types have variable trace element abundances, with a general trend of increasing trace element abundances in zircons from ultramafic through mafic to granitic rocks. Zircons formed under different metamorphic conditions have different trace element characteristics that can be used to relate their formation to metamorphic conditions. It is an effective way to relate zircon growth to certain P-T conditions by studying the trace element partitioning between coexisting metamorphic zircon and garnet in high-grade metamorphic rocks containing both zircon and garnet. Primary mineral inclusions in zircon can also provide unambiguous constraints on its formation conditions. Therefore, interpretation of zircon U-Pb ages can be constrained by its internal structure, trace element composition, mineral inclusion and so on.

Genesis of zircon and its constraints on interpretation of U-Pb age

Paleozoic multiple accretionary and collisional tectonics of the Chinese Tianshan orogenic collage

https://www.geol.umd.edu/~rudnick/PDF/Gao_2003_EPSL.pdf

Re-Os evidence for replacement of ancient mantle lithosphere beneath the North China Craton

Phanerozoic tectonics of the South China Block: Key observations and controversies

http://shrimp.anu.edu.au/people/tri/Publications/2003RatschP1.pdf

Tectonics of the Qinling (Central China): tectonostratigraphy, geochronology, and deformation history

Large areal extent of ultrahigh-pressure metamorphism in the Sulu ultrahigh-pressure terrane of East China: new implications from coesite and omphacite inclusions in zircon of granitic gneiss

[1] The present-day topography of the Tian Shan range is considered to result from crustal shortening related to the ongoing India-Asia collision that started in the early Tertiary. In this study we report evidence for several episodes of localized tectonic activity which occurred prior to that major orogenic event. Apatite fission track analysis and (U-Th)/He dating on apatite and zircon indicate that inherited Paleozoic structures were reactivated in the late Paleozoic-early Mesozoic during a Cimmerian orogenic episode and also in the Late Cretaceous-Paleogene (around 65–60 Ma). These reactivations could have resulted from the accretion of the Kohistan-Dras arc or lithospheric extension in the Siberia-Mongolia zone. Activity resumed in the late Mesozoic prior to the major Tertiary orogenic phase. Finally, the ongoing deformation, which again reactivates inherited tectonic structures, tends to propagate inside the endoreic basins that were preserved in the range, leading to their progressive closure. This study demonstrates the importance of inherited structures in localizing the first increments of the deformation before it propagates into yet undeformed areas.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2010TC002712

Mesozoic and Cenozoic tectonic history of the central Chinese Tian Shan; reactivated tectonic structures and active deformation

Phanerozoic tectonics of south China block: New insights from the polyphase deformation in the Yunkai massif

The Tian Shan Mountains constitute central Asia's longest and highest mountain range Understanding their Cenozoic uplift history thus bears on mountain building processes in general, and on how deformation has occurred under the influence of the India-Asia collision in particular In order to help decipher the uplift history of the Tian Shan, we collected 970 samples for magnetostratigraphic analysis along a 4571-m-thick section at the Jingou River (Xinjiang Province, China) Stepwise alternating field and thermal demagnetization isolate a linear magnetization component that is interpreted as primary From this component, a magnetostratigraphic column composed of 67 polarity chrons are correlated with the reference geomagnetic polarity timescale between ∼1 Ma and ∼236 Ma, with some uncertainty below ∼21 Ma This correlation places precise temporal control on the Neogene stratigraphy of the southern Junggar Basin and provides evidence for two significant stepwise increases in sediment accumulation rate at ∼16–15 Ma and ∼11–10 Ma Rock magnetic parameters also undergo important changes at ∼16–15 Ma and ∼11–10 Ma that correlate with changes in sedimentary depositional environments Together with previous work, we conclude that growth history of the modern Tian Shan Mountains includes two pulses of uplift and erosion at ∼16–15 Ma and ∼11–10 Ma Middle to upper Tertiary rocks around the Tian Shan record very young (<∼5 Ma) counterclockwise paleomagnetic rotations, on the order of 15° to 20°, which are interpreted as because of strain partitioning with a component of sinistral shear that localized rotations in the piedmont

Neogene uplift of the Tian Shan Mountains observed in the magnetic record of the Jingou River section (northwest China)

http://www.igg.cas.cn/xwzx/yjcg/201301/W020130110309596219991.pdf

Qingchen Wang

Papers

Large areal extent of ultrahigh-pressure metamorphism in the Sulu ultrahigh-pressure terrane of East China: new implications from coesite and omphacite inclusions in zircon of granitic gneiss

Mesozoic and Cenozoic tectonic history of the central Chinese Tian Shan; reactivated tectonic structures and active deformation

Phanerozoic tectonics of south China block: New insights from the polyphase deformation in the Yunkai massif

Neogene uplift of the Tian Shan Mountains observed in the magnetic record of the Jingou River section (northwest China)

Phanerozoic tectonothermal events of the Xuefengshan Belt, central South China: Implications from UPb age and LuHf determinations of granites