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  • Original Article
    Qiuyu WANG, Shouming CHEN, Hongrui ZHANG, Saisai LI
    Acta Geologica Sinica (English Edition), 2024, 98(3): 641-656. https://doi.org/10.1111/1755-6724.15182
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    High-silica granitoids record the formation and evolution of the continental crust. A new intrusive complex has been recognized among silicic volcanic rocks of the Weixi arc, Southwest China. The intrusions consist of granites, granitic porphyries, and granodiorites. Zircon U-Pb age data indicate that the Weixi granitoids formed at 248–240 Ma and were coeval with silicic volcanic rocks of the Weixi arc. The Weixi granitoids are enriched in Rb, Th, and U, depleted in Ba, Sr, Nb, Ta, and Ti, and have high light/heavy rare earth element ratios and slightly negative Eu anomalies. The Weixi granitoids have negative εNd(t) values (–9.8 to –7.8) and negative zircon εHf(t) values (–12.02 to –5.11). The geochemical and isotopic features suggest the Weixi granitoids were derived by partial melting of ancient crustal material. The Weixi granitoids and silicic volcanic rocks were derived from the same magma by crystal accumulation and melt extraction, respectively, and they record the formation of a continental arc in the central Sanjiang orogenic belt.

  • Original Article
    Qinlong TONG, Mingkuan QIN, Fawang YE
    Acta Geologica Sinica (English Edition), 2024, 98(3): 585-601. https://doi.org/10.1111/1755-6724.15181
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    The Bayingobi basin is located in the middle of Central Asia Orogenic Belt, at the intersection of Paleo-Asian Ocean and Tethys Ocean, as well as the junction of multiple tectonic plates. This unique tectonic setting underpins the basin's intricate history of tectonic activity. To unravel the multifaceted tectono-thermal evolution within the southwestern region of the basin and to elucidate the implications of sandstone-hosted uranium mineralization, granitic and clastic rock samples were collected from the Zongnai Mts. uplift and Yingejing depression, and apatite fission track (AFT) dating and thermal history simulation analysis were performed. AFT dating findings reveal that the apparent ages of all samples fall within the range of 244 Ma to 112 Ma. In particular, the bedrock of the Zongnai Mts. and Jurassic detrital apatite fission tracks have undergone complete annealing, capturing the uplift-cooling age. Meanwhile, the AFT ages of Cretaceous detrital rocks are either equivalent to or notably exceed the age of sedimentary strata, signifying the cooling age of the provenance. A comprehensive examination of AFT ages and palaeocurrent direction analyses suggests that the Cretaceous source in the Tamusu area predominantly originated from the central and southern sectors of the Zongnai Mts. uplift. However, at a certain juncture during the Late Early Cretaceous, the Cretaceous provenance expanded to include the northern part of the Zongnai Mts. uplift. Based on the results of thermal history simulations and previous studies, it is considered that the Tamusu area has undergone four distinct tectonic uplift events since the Late Paleozoic. The first is the Late Permian to Early Triassic (260–240 Ma), which is associated with the closure of the Paleo-Asian Ocean and the accretionary orogeny within the Alxa region. The second uplift event took place in the Early Jurassic (190–175 Ma) and corresponded to intraplate orogeny following the closure of the Paleo-Asian Ocean. The third uplift event is the Late Jurassic to Early Cretaceous (160–120 Ma), which is linked to the East Asia's position as the convergence center of multiple tectonic plates during this period. The fourth uplift event is linked to the Late Early Cretaceous (112–100 Ma), driven either by the westward subduction of the eastern Pacific plate or the mantle upwelling resulting from the Bangong–Nujiang oceanic lithosphere subduction and slab break-off. The primary stress orientation for the first three tectonic uplift phases approximated a nearly SN direction, while the fourth stage featured a principal stress direction of NW. The fourth tectonic uplift event of the Late Early Cretaceous and basaltic eruption thermal event during this period likely exerted a significant influence on the formation of the Tamusu sandstone-hosted uranium deposit.

  • Original Article
    Hua JIANG, Hua KONG, Biao LIU, Fucheng TAN, Yixue QIN, Jingang HUANG, Yu ZHU
    Acta Geologica Sinica (English Edition), 2024, 98(3): 717-735. https://doi.org/10.1111/1755-6724.15177
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    Garnet is a primary mineral in skarn deposits and plays a significant role in recording copious mineralization and metallogenic information. This study systematically investigates the geochemistry and geochronology of garnet and zircon in the Dafang Au-Pb-Zn-Ag deposit, which represents prominent gold mineralization in southern Hunan, China. Garnet samples with distinct zoning patterns and compositional variations were identified using various analytical techniques, including Backscattered Electron (BSE) imaging, Cathodoluminescence (CL) response, textural characterization, and analysis of rare-earth elements (REE), major contents, and trace element compositions. The garnet was dated U-Pb dating, which yielded a lower intercept age of 161.06 ± 1.93 Ma. This age is older than the underlying granodiorite porphyry, which has a concordia age of 155.13 ± 0.95 Ma determined by zircon U-Pb dating. These results suggest that the gold mineralization may be related to the concealed granite. Two groups of garnet changed from depleted Al garnet to enriched Al garnet, and the rare earth element (REE) patterns of these groups were converted from light REE (LREE)-enriched and heavy REE (HREE)-depleted with positive europium (Eu) anomalies to medium REE (MREE)-enriched from core to rim zoning. The different REE patterns of garnet in various zones may be attributed to changes in the fluid environment and late superposition alteration. The development of distal skarn in the southern Hunan could be a significant indicator for identifying gold mineralization.

  • Original Article
    Qingqing ZHANG, Wiesław KRZEMIŃSKI, Jan ŠEVČÍK, Vladimir BLAGODEROV, Agnieszka SOSZYŃSKA, Kornelia SKIBIŃSKA
    Acta Geologica Sinica (English Edition), 2024, 98(3): 541-547. https://doi.org/10.1111/1755-6724.15173
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    A new genus and species, Cretopleciofungivora simpsoni gen. et sp. nov., from the extinct family Pleciofungivoridae (Diptera: Bibionomorpha), is discovered in mid-Cretaceous Kachin amber. Previously, this family was known only from imprints in sedimentary rocks of the Jurassic and the Lower Cretaceous. Discovery of a representative of Pleciofungivoridae in Kachin amber confirms the presence of the family in the Upper Cretaceous. The new species has a unique structure of fore tarsus, with lobed and extended tarsal segments II to IV, a feature hitherto known only in a few species of extant Sciaroidea. Although not particularly rare, the new species is currently known only from female specimens. Possible reasons for this phenomenon, very unusual in Sciaroidea, are briefly discussed, including parthenogenesis as a potentially plausible hypothesis.

  • Original Article
    Honggang ZHANG, Yalei YIN, Rui PEI, Changfu ZHOU
    Acta Geologica Sinica (English Edition), 2024, 98(2): 303-310. https://doi.org/10.1111/1755-6724.15169
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    Three eusauropod teeth (SDUST-V1064, PMOL-AD00176, PMOL-ADt0005) are reported from the Lower Cretaceous Yixian Formation of Ningcheng, southeastern Inner Mongolia, China. Two of them (SDUST-V1064, PMOL-AD00176) are assigned to early-diverging titanosauriforms in having slightly mesiodistal expansion at the base of the tooth crown, a slenderness index value >2.0 and <4.0, and D-shaped cross section. Furthermore, SDUST-V1064 and PMOL-AD00176 are referred as an Euhelopus-like titanosauriform on the basis of having a sub-circular boss on the lingual surface and an asymmetrical crown-root margin which slants apically, respectively. CT scan data of SDUST-V1064 reveals new dental information of early-diverging titanosauriforms, for example, the enamel on the labial side thicker than that on the lingual side, an enamel/dentine ratio of 0.26 and a boss present on the lingual side of the dentine of the crown.

  • Original Article
    Xutong LI, Yumeng ZHANG, Xianghong LIN, Min ZHU, Wenjin ZHAO, Lizhou TANG, Xianren SHAN, Zhikun GAI
    Acta Geologica Sinica (English Edition), 2024, 98(3): 531-540. https://doi.org/10.1111/1755-6724.15168
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    New discovery of the early Silurian fossil fish Changxingaspis (Xiushuiaspidae, Galeaspida), Changxingaspis nianzhongi sp. nov. and C. gui, are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation in Zhejiang Province, respectively. C. nianzhongi mainly differs from C. gui in the shape of the median dorsal opening that is transverse elliptic with a width/length ratio of about 3.0, the long lateral transverse canals extending to the lateral margin of the headshield, and the second lateral transverse canal with dichotomous branchings. Discovery of C. nianzhongi from the Tataertag Formation and C. gui from the Kangshan Formation provide direct evidence on the specific level for the correlation between these two formations, which further supports the Silurian fish-bearing red beds in northwest Zhejiang belonging to the Silurian Lower Red Beds (LRBs) rather than the Upper Red Beds (URBs). Additionally, as the first record of the Changxingaspis in Tarim Basin, it extends the paleogeographical distribution of this genus from the South China Block to the Tarim Block, providing new evidence to support faunal exchanges between these two blocks and the hypothesis of a united Tarim–South China Block during the early Silurian.

  • Original Article
    Naveed Ur RAHMAN, Benzhong XIAN, Linhao FANG, Sirui CHEN, Peng CHEN, Zaheen ULLAH, Pengyu WANG
    Acta Geologica Sinica (English Edition), 2024, 98(3): 753-770. https://doi.org/10.1111/1755-6724.15167
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    The Carnian Pluvial Episode (CPE) fingerprints global environmental perturbations and biological extinction on land and oceans and is potentially linked to the Wrangellia Large Igneous Province (LIP). However, the correlation between terrestrial environmental changes and Wrangellia volcanism in the Ordos Basin during the CPE remains poorly understood. Records of negative carbon isotopic excursions (NCIEs), mercury (Hg), Hg/TOC, and Hg enrichment factor (HgEF) from oil shales in a large-scale terrestrial Ordos Basin in the Eastern Tethys were correlated with marine and other terrestrial successions. The three significant NCIEs in the study section were consistently correlated with those in the CPE successions of Europe, the UK, and South and North China. The U-Pb geochronology indicates a Ladinian–Carnian age for the Chang 7 Member. A comprehensive overview of the geochronology, NCIE correlation, and previous bio- and chronostratigraphic frameworks shows that the Ladinian–Carnian boundary is located in the lower part of Chang 7 in the Yishicun section. HgEF may be a more reliable proxy for tracing volcanic eruptions than the Hg/TOC ratio because the accumulation rates of TOC content largely vary in terrestrial and marine successions. The records of Hg, Hg/TOC, HgEF, and NCIEs in the Ordos Basin aligned with Carnian successions worldwide and were marked by similar anomalies, indicating a global response to the Wrangellia LIP during the CPE. Anoxia, a warm-humid climate, enhancement of detrital input, and NCIEs are synchronous with the CPE interval in the Ordos Basin, which suggests that the CPE combined with the regional Qinling Orogeny should dominate the enhanced rate of terrigenous input and paleoenvironmental evolution in the Ordos Basin.

  • Original Article
    Limin WU, Touping PENG, Weiming FAN, Guochun ZHAO, Jianfeng GAO, Xiaohan DONG, Shili PENG, Kang MIN, Tin Aung MYINT
    Acta Geologica Sinica (English Edition), 2024, 98(3): 569-584. https://doi.org/10.1111/1755-6724.15164
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    Since the Cenozoic, the Tibetan Plateau has experienced large-scale uplift and outgrowth due to the India–Asia collision. However, the mechanism and timing of these tectonic processes still remain debated. Here, using apatite fission track dating and inverse thermal modeling, we explore the mechanism of different phases of rapid cooling for different batholiths and intrusions in the southeastern Tibetan Plateau. In contrast to previous views, we find that the coeval granitic batholith exposed in the same tectonic zone experienced differential fast uplift in different sites, indicating that the present Tibetan Plateau was the result of differential uplift rather than the entire lithosphere uplift related to lithospheric collapse during Cenozoic times. In addition, we also suggest that the 5–2 Ma mantle-related magmatism should be regarded as the critical trigger for the widely coeval cooling event in the southeastern Tibetan Plateau, because it led to the increase in atmospheric CO2 level and a hotter upper crust than before, which are efficient for suddenly fast rock weathering and erosion. Finally, we propose that the current landform of the southeastern Tibetan Plateau was the combined influences of tectonic and climate.

  • Original Article
    Xin LI, Ge CHEN, Zhimin XU, Qi LIU, Tianci CHEN, Yajun SUN
    Acta Geologica Sinica (English Edition), 2024, 98(3): 771-785. https://doi.org/10.1111/1755-6724.15162
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    Saline aquifers are the most popular waste and CO2 injection and storage reservoirs worldwide. This project proposes that several optimal injection positions should be investigated as hydraulic pressure-focused positions, in order to relieve the high demands of pump performance. The comprehensive indices (Fi) representing the injectivity of different burial depths were obtained by using information entropy, based on the mercury injection experimental data of 13 rock samples. The results demonstrated that the burial depths of No. 4, No. 1 and No. 2 in the Liujiagou Formation were the most suitable positions for hydraulic focused injection, which means the upper 30 m thickness could be regarded as the hydraulic focused range in the saline aquifer with an average thickness of 400 m. In addition, some laboratory experiments and in situ tests were carried out for the purpose of certifying and analyzing results, including SEM, XRD, brittleness index and logging. The results suggested that the rock samples at the No. 4, No. 1 and No. 2 burial depth ranges have loose microstructure, weak cementation, as well as dual pores and fractures. The lithology is mainly quartz and feldspar, but the clay mineral content is high (10%–25%), which is positive for dissolution. The lithology is suitable for hydraulic fracturing to form extended cracks and micro-fissures during high-TDS (total dissolved solids) mine water injection, because of the high brittleness index. Finally, a theoretical and technical framework for high-TDS mine water injection was established, based on operating pilot engineering. Some theoretical defects and drawbacks learned from the field practices were summarized and solutions proposed. The research in this study could provide guidance and a paradigm for the inexpensive treatment of high-TDS mine water by injection and storage.

  • Original Article
    Luyao WANG, Kai LIU, Yan MA, Yaoyao ZHANG, Jue TONG, Wuhui JIA, Shouchuan ZHANG, Junliang SUN
    Acta Geologica Sinica (English Edition), 2024, 98(3): 801-818. https://doi.org/10.1111/1755-6724.15161
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    Geothermal resources are increasingly gaining attention as a competitive, clean energy source to address the energy crisis and mitigate climate change. The Wugongshan area, situated in the southeast coast geothermal belt of China, is a typical geothermal anomaly and contains abundant medium- and low-temperature geothermal resources. This study employed hydrogeochemical and isotopic techniques to explore the cyclic evolution of geothermal water in the western Wugongshan region, encompassing the recharge origin, water–rock interaction mechanisms, and residence time. The results show that the geothermal water in the western region of Wugongshan is weakly alkaline, with low enthalpy and mineralization levels. The hydrochemistry of geothermal waters is dominated by Na-HCO3 and Na-SO4, while the hydrochemistry types of cold springs are all Na-HCO3. The hydrochemistry types of surface waters and rain waters are Na-HCO3 or Ca-HCO3. The δD and δ18O values reveal that the geothermal waters are recharged by atmospheric precipitation at an altitude between 550.0 and 1218.6 m. Molar ratios of major solutes and isotopic compositions of 87Sr/86Sr underscore the significant role of silicate weathering, dissolution, and cation exchange in controlling geothermal water chemistry. Additionally, geothermal waters experienced varying degrees of mixing with cold water during their ascent. The δ13C values suggest that the primary sources of carbon in the geothermal waters were biogenic and organic. The δ34S value suggests that the sulfates in geothermal water originate from sulfide minerals in the surrounding rock. Age dating using 3H and 14C isotopes suggests that geothermal waters have a residence time exceeding 1 kaBP and undergo a long-distance cycling process.

  • Original Article
    Gaoming DING, Genyuan JI, Guolong YAN, Yongzhong XU, Kunming WANG, Chun XIAO, Quanle WANG, Dongbao GUO
    Acta Geologica Sinica (English Edition), 2024, 98(3): 736-752. https://doi.org/10.1111/1755-6724.15160
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    Three-dimensional geochemical modeling of ore-forming elements is crucial for predicting deep mineralization. This approach provides key information for the quantitative prediction of deep mineral localization, three-dimensional fine interpolation, analysis of spatial distribution patterns, and extraction of quantitative mineral-seeking markers. The Yechangping molybdenum (Mo) deposit is a significant and extensive porphyry-skarn deposit in the East Qinling–Dabie Mo polymetallic metallogenic belt at the southern margin of the North China Block. Abundant borehole data on ore-forming elements underpin deep geochemical predictions. The methodology includes the following steps: (1) Three-dimensional geological modeling of the deposit was established. (2) Correlation, cluster, and factor analyses post delineation of mineralization stages and determination of mineral generation sequence to identify (Cu, Pb, Zn, Ag) and (Mo, W, mfe) assemblages. (3) A three-dimensional geochemical block model was constructed for Mo, W, mfe, Cu, Zn, Pb, and Ag using the ordinary kriging method, and the variational function was developed. (4) Spatial distribution and enrichment characteristics analysis of ore-forming elements are performed to extract geological information, employing the variogram and w(Cu + Pb + Zn + Ag)/w(Mo + W) as predictive indicators. (5) Identifying the western, northwestern, and southwestern areas of the mine with limited mineralization potential, contrasted by the northeastern and southeastern areas favorable for mineral exploration.

  • Original Article
    Xiang QIN, Xuanhua CHEN, Zhaogang SHAO, Yiping ZHANG, Yongchao WANG, Bing LI, He SU, Ye WANG, Kui LIU, Lele HAN
    Acta Geologica Sinica (English Edition), 2024, 98(3): 548-568. https://doi.org/10.1111/1755-6724.15157
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    The Tianshan range, a Paleozoic orogenic belt in Central Asia, has undergone multiple phases of tectonic activities characterized by the N–S compression after the early Mesozoic, including the far-field effects of the Cenozoic Indian–Asian collision. However, there are limited reports on the tectonic deformation and initiation of Triassic intracontinental deformation in the Tianshan range. Understanding this structural context is crucial for interpreting the early intracontinental deformation history of the Eurasian continent during the early Mesozoic. Growth strata and syn-tectonic sediments provide a rich source of information on tectonic activities and have been extensively used in the studies of orogenic belts. Based on detail fieldwork conducted in this study, the middle–late Triassic Kelamayi Formation of the northern Kuqa Depression in the southern Tianshan fold-thrust belt has been identified as the typical syn-tectonic growth strata. The youngest detrital zircon component in two lithic sandstone samples from the bottom and top of the Kelamayi growth strata yielded U-Pb ages of 223.4 ± 3.1 and 215.5 ± 2.9 Ma, respectively, indicating that the maximum depositional age of the bottom and top of the Kelamayi growth strata is 226–220 and 218–212 Ma. The geochronological distribution of detrital samples from the Early–Middle Triassic and Late Triassic revealed abrupt changes, suggesting a new source supply resulting from tectonic activation in the Tianshan range. The coupling relationship between the syn-tectonic sedimentation of the Kelamayi Formation and the South Tianshan fold-thrust system provides robust evidence that the Triassic intracontinental deformation of the South Tianshan range began at approximately 226–220 Ma (during the Late Triassic) and ended at approximately 218–212 Ma. These findings provide crucial constraints for understanding the intraplate deformation in the Tianshan range during the Triassic.

  • Original Article
    Qifeng XIE, Yunpeng DONG, Yuanfeng CAI, Mingguo ZHAI, Aifang XIAO, Hong ZHANG
    Acta Geologica Sinica (English Edition), 2024, 98(3): 630-640. https://doi.org/10.1111/1755-6724.15156
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    The magma sources, origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain. New results reveal that, miarolites from the Qishan and Kuiqi intrusions yield crystallization ages of ∼101 and ∼98 Ma, and they have a high formation temperature (∼910°C) and low oxygen fugacity value, indicating crystallization condition at low pressure in the upper crust with temperature of 678°C. The Qishan and Kuiqi miarolites are characterized by enrichment in SiO2 and high-K alkali, depletion in Ca and Mg, and belong to the high-K weak peraluminous rock series. The samples are enriched in HFSEs (i.e., Ta, Zr and Hf) and LILEs (i.e., Ba, P and Sr), depleted in Ba and Sr with the negative anomaly of Eu. In the primitive mantle normalized trace element spider diagram, the samples show a right-inclined ‘seagull-type’ pattern, combined the ratios of (La/Yb)N, 10000 × Al/Ga, Rb/Nb and Nb/Ta etc., they were proved to be alkaline A-type granite. Combined the characterize of the trace elements, they were derived from clay-rich source accompanied pelite melting, and subjected to K-feldspar crystallization fractional. The values of εHf(t) and tDM2 are distributed in the range of –2.8 to 3.3 with ∼1.2 Ga, and –6.0 to 4.0 with ∼1.2 Ga, revealing that they were generated from the Mesoproterozoic Cathaysia basement rocks. The comprehensive research reveals the Kuiqi and Qishan intrusions derived from crust-mantle mixing and partial melting of the crust, respectively, resulting from lithospheric extension generated by the Paleo-Pacific Plate subducted into the European–Asian Plate.

  • Original Article
    Junping LIU, Ming LI, Feng TANG, Jiangtai ZHAO, Sicun SONG, Ying ZHOU, Xiaohan SONG, Liudong REN
    Acta Geologica Sinica (English Edition), 2024, 98(2): 311-323. https://doi.org/10.1111/1755-6724.15153
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    The Jiangchuan Biota from the Jiucheng Member (Mb.) of the Dengying Formation (Fm.), discovered in Jiangchuan, eastern Yunnan, China, is marked by copious macrofossils at the apex of the Ediacaran strata. This fauna features benthic algae with varied holdfasts and other fossils of indeterminate taxonomic affinity and is compositionally unique compared to the Shibantan and Gaojiashan biotas of the Dengying Fm. and the Miaohe and Wenghui biotas of the Doushantuo Fm., elsewhere in China. One novel benthic saccular macroalgal fossil, named here Houjiashania yuxiensis gen. and sp. nov., from the Jiangchuan Biota is based on fossils that are sausage-shaped, elongate, tubular, ranging from 0.3 to 4 cm in length, and up to 0.8 cm in diameter. One terminus is blunt and rounded to an obtuse angle, the other is bent with a spread-out surface resembling a holdfast, suggesting a three-dimensional thallus. Thin, stipe-shaped outgrowths, likely vestiges of sessile saccular life forms, are prevalent in macroalgal fossils of analogous size and shape, as well as present brown algae Scytosiphonaceae, such as Colpomenia and Dactylosiphon. The new findings augment the diversity of benthic algae, such as those known from the Early Neoproterozoic Longfengshan Biota in North China. The benthic algal macrofossils in the Jiucheng Mb. add to knowledge of Late Ediacaran metaphyte diversification and offer more clues about the evolutionary positioning of primitive macroalgae. The co-occurrence of numerous planktonic and benthic multicellular algae and planktonic microbes might have facilitated ecologically the more extensive later Cambrian explosion evidenced by the Chengjiang Biota in Yunnan.

  • Original Article
    Min WANG, Fanbiao KONG, Xianglun KONG, Haitao CHEN, Jiawei WANG, Xiaodong MIAO, Guangju JIA, Mei HAN, Shujian XU
    Acta Geologica Sinica (English Edition), 2024, 98(2): 491-504. https://doi.org/10.1111/1755-6724.15152
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    Investigation of rarely studied gravel layers found in the loess in Shandong Province, eastern China, reveals the fabric characteristics of two gravel layers (G1, G2) and the sedimentary characteristics of loess at the typical and well-preserved Heiyu section (HY), where, to determine the paleoclimatic changes during Marine Isotope Stage 3a. Optically stimulated luminescence dates of the HY formation range from 0.26 ± 0.02 ka to 39.00 ± 2.00 ka. In addition, the ages of G1 and G2 were estimated using the Bayesian model to be 39.60–40.50 and 29.00–29.50 ka. G1 and G2 are mainly composed of fine and medium gravel, both of which were subangular to subrounded limestone, with gravel directions to NE and E. The average flow velocity, average depth, and flood peak flow of G1 are 1.10 m/s, 0.49 m, and 37.04 m3/s, respectively, calculated using the flow energy method, whereas those of G2 are 0.98 m/s, 0.38 m, and 18.38 m3/s, respectively. Analysis of climate proxy indices show that the sedimentary environment of the gravel and loess in HY might be a regional response to global change.