Provenance constraints on the Xishanyao Formation, southern Yili Basin, northwest China: evidence from petrology, geochemistry, and detrital zircon U–Pb geochronology

Abstract

We conducted petrographic, geochemical, and new U–Pb laser ablation inductively coupled mass spectrometry analyses of detrital zircons in the sandstone samples from the important Mengqiguer sandstone-type uranium deposit located in the Yili basin of the Xishanyao Formation. This formation (Shuixigou Group) is a major uranium-bearing target stratum in the basin. The main purpose of our investigations was to determine the provenance of the host sand units that has remained unclear to date. Our petrographic results suggested that the host sandstone is texturally and chemically immature, indicating superior physicochemical conditions for later uranium mineralisation. The major and trace element data of the detrital sandstone samples point towards the upper continental crust, and the chondrite-normalised rare earth element (REE) plots show enriched light REE and relatively flat heavy-REE distribution, with a negative Eu anomaly. The characteristics of the REEs and the trace elements point to felsic rocks as the provenance of the target strata with a continental arc tectonic setting. The detrital zircons indicate an age span of ∼235–∼2327 Ma, with major age populations of ∼300–∼500 Ma. The increasing amount of zircon grains from the Late Devonian to the Early Carboniferous coinciding with the age of volcanic magmatic activities of the Wusun and Nalati mountains indicates that the rocks formed under the Tianshan collisional orogeny and the subsequent extensional environment.

Sedimentological Evidence for Pre‐Early Permian Continental Subduction in the Dabie Orogen, Central‐East China

“…Our conclusions are supported by other geochronological data from the scattered medium‐high grade Permian metamorphic bedrock, and limited paleomagnetic and provenance data, including: (a) c. 260–300 Ma 40 Ar/ 39 Ar ages from the Dabie‐Sulu orogen which are interpreted to record tectonothermal events associated with early continental collision and subduction (c. 265 Ma muscovite 40 Ar/ 39 Ar ages from low‐grade schists in the Sulu orogen, J.‐B. Zhou et al., 2008; c. 261–279 Ma muscovite 40 Ar/ 39 Ar ages from the Xinyang–Beihuaiyang unit on the northern margin of the Dabie orogen, Hacker et al., 2000; Ratschbacher et al., 2003, 2006; c. 300 Ma illite K‐Ar and illite‐whole rock Rb‐Sr isochron ages from low greenschist facies (epizonal) slates, Zhu et al., 1994); (b) Early‐Middle Permian (c. 258–297 Ma) garnet Lu‐Hf, apatite and zircon U‐Pb dates from (U)HP eclogite‐facies rocks in the Dabie orogen (Brouwer et al., 2011; H. Cheng & Cao, 2015; H. Cheng et al., 2009, 2016, 2018; Shi et al., 2022; K. Sun et al., 2022) that may record prograde metamorphism associated with continental subduction; (c) a Permian (c. 250–270 Ma) medium‐pressure, amphibolite‐facies metamorphic belt that supposedly extended for over 500 km in the Qinling‐Tongbai‐Hong'an‐Dabie orogen and interpreted to be related to Permian initial continental collision between the SCB‐NCC (L. Chen et al., 2014, 2020); (d) detrital metamorphic zircon of Permian age (280 Ma, n = 12) in the Lower Cretaceous of the Jiaolai Basin to the north of the Sulu Orogen (L. X. Zhang et al., 2021); (e) comparable regional medium‐to high‐pressure metamorphism in the eastern continuation of the Dabie‐Sulu orogen in South Korea (the Ogcheon metamorphic belt), which initiated as early as the Early Permian (281–291 Ma) and peaked in the Triassic (c. 225 to 255 Ma) (Cheong et al., 2003; D.‐L. Cho et al., 2008; M. Cho & Kim, 2005); (f) paleomagnetic results that show that the easternmost NCC and SCB were juxtaposed during the Middle Permian (c. 270 Ma) (X. Zhao & Coe, 1987); (g) various disparate lines of evidence that indicate initial continental subduction could have initiated in the Early Permian including c. 258–300 Ma geochronological ages recording metamorphism and rapid cooling, the Permian sedimentary facies distribution in the SCB, and Permian thrusting events on the southeastern NCC (Li, 1998).…”

“…Sun et al, 2022) that may record prograde metamorphism associated with continental subduction; (c) a Permian (c. 250-270 Ma) medium-pressure, amphibolite-facies metamorphic belt that supposedly extended for over 500 km in the Qinling-Tongbai-Hong'an-Dabie orogen and interpreted to be related to Permian initial continental collision between the SCB-NCC (L. Chen et al, 2014Chen et al, , 2020; (d) detrital metamorphic zircon of Permian age (280 Ma, n = 12) in the Lower Cretaceous of the Jiaolai Basin to the north of the Sulu Orogen (L. X. Zhang et al, 2021); (e) comparable regional medium-to high-pressure metamorphism in the eastern continuation of the Dabie-Sulu orogen in South Korea (the Ogcheon metamorphic belt), which initiated as early as the Early Permian (281-291 Ma) and peaked in the Triassic (c. 225 to 255 Ma) (Cheong et al, 2003;D.-L. Cho et al, 2008;M. Cho & Kim, 2005); (f) paleomagnetic results that show that the easternmost NCC and SCB were juxtaposed during the Middle Permian (c. 270 Ma) (X.…”

Relationship between Chamosite Alteration and Fe-Plugging in Sandstone Pores during Acid In Situ Leaching of Uranium

“…The early-middle Jurassic Shuixigou sedimentary group is the main uranium depositbearing horizon in Yili Basin, Xinjiang Province, NW China, and is dominated by alluvial fan-braided sandy conglomerate, sandstone, siltstone, shale, and coal measures (Figure 1; [16,20,21]). The studied uranium mineralization in this area mainly occurs as roll-front or tabular shape in interstratified oxidation zones of sandstone aquifers [22,23].…”

Timing of Paleozoic Metamorphism in the Jiaobei Terrane, East China: Evidence from Apatite U-Pb Age and Trace Element Composition

“…However, detrital zircon of the Early Permian age (280 Ma) with metamorphic genetic characteristics was found in the Linsishan Formation in the Jiaolai Basin, indicating the Jiaobei Terrane may have experienced the metamorphism during the Early Permian at ca. 280 Ma [102]. The stratum of the Linsishan Formation consists of conglomerate and microconglomerate, which have the properties of nearby depositions, implying the source of metamorphic zircon is Jiaobei Terrane [103,104].…”