Next Article in Journal
Volcano–Sedimentary Processes on an Ancient Oceanic Seafloor: Insights from the Gimigliano Metaophiolite Succession (Calabria, Southern Italy)
Previous Article in Journal
Advances in the Development of Hydrometallurgical Processes in Acidic and Alkaline Environments for the Extraction of Copper from Tailings Deposit
Previous Article in Special Issue
Identification and Geological Significance of Late Cambrian OIB-Type Volcanic Rocks in the Nailenggeledaban Area, Northern Yili Block
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Minerals
Volume 15
Issue 6
10.3390/min15060551
minerals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Petrogenesis and Tectonic Implications of the Early–Middle Ordovician Granodiorites in the Yaogou Area of the North Qilian Orogenic Belt

by
Dechao Li
1,2,
Yang Yang
1,2,*,
Yao Xiao
1,2,
Pengde Liu
3,
Xijun Liu
1,2,3,
Gang Chen
1,
Xiao Liu
1,2,
Rongguo Hu
1,2,
Hao Tian
1 and
Yande Liu
1
1
Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, College of Earth Sciences, Guilin University of Technology, Guilin 541004, China
2
Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resource, Guilin University of Technology, Guilin 541004, China
3
National Key Laboratory of Ecological Security and Resource Utilization in Arid Areas, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(6), 551; https://doi.org/10.3390/min15060551
Submission received: 13 April 2025 / Revised: 12 May 2025 / Accepted: 13 May 2025 / Published: 22 May 2025
(This article belongs to the Special Issue Geochronology and Geochemistry of Alkaline Rocks)
Browse Figures
Versions Notes

Abstract

:
A diverse range of granitoids in the North Qilian Orogenic Belt (NQOB) offers valuable insights into the region’s tectonomagmatic evolution. In this study, we undertook a geochronological, mineralogical, geochemical, and zircon Hf isotopic analysis of granodiorites from the Yaogou area of the NQOB. Zircon U-Pb dating reveals that the Yaogou granodiorites formed during the Early–Middle Ordovician (473–460 Ma). The Yaogou granodiorites have high SiO2 (63.3–71.1 wt.%), high Al2O3 (13.9–15.8 wt.%) contents, and low Zr (96–244 ppm), Nb (2.9–18 ppm), as well as low Ga/Al ratios (10,000 × Ga/Al ratios of 1.7–2.9) and FeOT/MgO ratios (1.9–3.2), and are characterized by elevated concentrations of light rare earth elements and large-ion lithophile elements such as Rb, Th, and U, coupled with significant depletion in heavy rare earth elements and high-field-strength elements including Nb, Ta, and Ti. Additionally, the presence of negative europium anomalies further reflects geochemical signatures typical of I-type granitic rocks. The zircon grains from these rocks display negative εHf(t) values (−14.6 to −10.7), with two-stage Hf model ages (TDM2) from 2129 to 1907 Ma. These characteristics suggest that the magmatic source of the Yaogou granodiorites likely originated from the partial melting of Paleoproterozoic basement-derived crustal materials within a tectonic environment associated with subduction in the North Qilian Ocean. Integrating regional geological data, we suggest that during the Early Paleozoic, the North Qilian Oceanic slab underwent double subduction: initially southward, followed by a northward shift. Due to the deep northward subduction of the Qaidam continental crust and oceanic crust along the southern margin of the Qilian Orogenic Belt, the southward subduction of the North Qilian ocean was obstructed, triggering a reversal in subduction polarity. This reversal likely decelerated the southward subduction and initiated northward subduction, ultimately leading to the formation of the Yaogou granodiorites. These findings enhance our understanding of the complex tectonic processes that shaped the North Qilian Orogenic Belt during the Early Paleozoic, emphasizing the role of subduction dynamics and continental interactions in the region’s geological evolution.

1. Introduction

Double subduction, referring here to the convergent configuration with oppositely directed subduction zones within a single tectonic system, represents a complex geodynamic process that significantly influences plate interactions, crustal evolution, and arc magmatism [1,2]. The dynamics of double-subduction systems have profound implications for mantle convection and plate motion reorganization [3]. The onset of double subduction can lead to significant changes in plate velocities and configurations, thereby controlling the reorganization of plate motions [4,5]. Additionally, subduction systems can induce episodic back-arc spreading, influencing the formation and evolution of back-arc basins [6,7,8,9]. Advancements in geophysical exploration techniques and geochronological methods have enhanced our understanding of double subduction. For instance, integrated studies combining seismic tomography and U–Pb geochronology have revealed remnants of double-subduction zones, exemplified by the Paleozoic system in the Great Xing’an Range [10]. Thus, these methodologies have propelled the study of double subduction to the forefront of plate tectonic research, offering a unique perspective on material cycling and energy exchange during plate convergence.
The Qilian orogen, situated in the northeastern Tibetan Plateau, is characterized by a significant presence of granitoid formations [11,12,13,14,15,16]. These granitoids are believed to have formed as a result of the subduction of the Proto-Tethys Ocean, followed by the accretion of arc crust and the proto-margin of the North China Craton [13,17]. The NQOB, a pivotal tectonic unit within the Qilian orogen, encapsulates a comprehensive Wilson cycle. This cycle encompasses the breakup of the Rodinia supercontinent, the subduction and eventual closure of the North Qilian Ocean, and the subsequent collision between the Qilian and Alxa blocks [16]. The Early Paleozoic granitoids in the Qilian orogen are also associated with the subduction processes of the North Qilian Ocean [11,12,13,14,15,16]. Ongoing debates surround the tectonic evolution, petrogenesis, and precise timing of the granitoid formations, particularly concerning the subduction polarity of the North Qilian Ocean during the Early Paleozoic. Several studies have proposed a comprehensive trench-arc-basin system model, suggesting unidirectional subduction (southward: Gehrels et al. [18]; northward: Chen et al. [19]). In contrast, an alternative subduction model has been proposed by some scholars, including double subduction [11,20], and multiple subduction-accretion events [21]. Determining the direction of subduction within the North Qilian Ocean plays a crucial role in deciphering the tectonic development of the North Qilian orogenic belt.
In this study, we present zircon U–Pb ages and Hf isotopic data, mineral chemistry, and whole-rock geochemical analyses of the Yaogou granodiorites in the NQOB. These data will provide insights into the lithogenesis of the granodiorites and help constrain the deep dynamic processes and tectonic evolution of the NQOB, thereby offering new scientific evidence to resolve controversies surrounding the subduction polarity and tectonic evolution of the NQOB during the early Paleozoic.

2. Geological Setting

The Qilian orogen, situated on the northeastern margin of the Tibetan Plateau, extends approximately 1200 km in an NWW direction [22]. It is bounded by the northeastern North China Craton, southeastern Yangtze Craton, and northwestern Tarim Craton (Figure 1A). As a pivotal segment of the Central China Orogenic System, this orogen preserves critical records of Paleozoic oceanic subduction and closure [13,23,24]. Tectonically, the Qilian orogen is subdivided into four units from north to south: the Alxa Block, North Qilian accretionary belt (high-pressure metamorphic belt), Central Qilian Block, and North Qaidam UHP metamorphic belt [24].
The North Qilian orogenic belt, a WNW-trending component of the Qilian orogen, lies between the Alxa Block to the north and the Central Qilian Block to the south, bounded and tectonically displaced by the Altyn Tagh Fault to the northwest [13]. The North Qinlian accretionary belt represents a classic example of an oceanic suture zone. It comprises several distinct geological units, including a southern ophiolite assemblage derived from oceanic crust, a central zone characterized by arc-related volcanic rocks, a northern segment containing back-arc basin ophiolitic remnants, and a basement composed of ancient Precambrian crystalline rocks [23,25,26]. Granitoid intrusions were widespread in the NQOB, primarily concentrated in its northern and southern belts (Figure 1B), with most emplaced during 481–453 Ma e.g., [11,12,14,27,28]. These intrusions have been linked to the Early Paleozoic subduction of the North Qilian Ocean [11,12], while magmatic activity after 445 Ma is interpreted as post-collisional, following the ocean’s closure [13,29,30].
The study area, situated in the northern periphery of the North Qilian orogenic belt (Figure 1B), encompasses a sequence of strata ranging from the Ordovician to the Jurassic, with representative samples collected from the Yaogou area. The Ordovician strata are primarily composed of basaltic to basaltic-andesitic volcanic rocks, into which a granitoid pluton—extending northwestward for approximately 2.5 km—has been emplaced. Overlying the Ordovician units, the Silurian succession includes metamorphosed polymictic conglomerates, metasandstones, and andesitic volcanic rocks. The Devonian and Jurassic successions are mainly sedimentary in composition. At both the eastern and western ends of the granitoid body, these older rocks are unconformably overlain by Neogene strata (Figure 2). Predominantly composed of granites, granodiorites and diorite, the pluton exhibits local lithologic variations. It appears grayish-white with a medium-grained, massive texture. The main mineral components include plagioclase (35–45 vol%), quartz (20–30 vol%), and hornblende (10–25 vol%), accompanied by accessory minerals such as apatite, zircon and magnetite (Figure 3).

3. Analytical Methods

All analytical procedures were conducted at the Guangxi Key Laboratory for the Exploration of Concealed Metallic Ore Deposits, located at Guilin University of Technology in Guangxi Province, China. Zircon U–Pb isotopic measurements were carried out using a GeolasPro 193 nm ArF excimer laser ablation system (COMPexPro 102, Coherent Inc., Santa Clara, CA, USA), which was interfaced with an Agilent 7700x quadrupole ICP–MS instrument. ICPMSDataCal software (V9.5) was used for offline data selection, integration of background and analyte signals, time drift corrections, and quantitative calibration of the data [31,32]. Concordia diagrams and weighted mean ages were obtained using Isoplot v. 4.15 [33]. In situ, Lu–Hf isotope data were obtained using a Neptune Plus multiple-collector (MC)–ICP–MS (Thermo-Fisher Scientific, Dreieich, Hesse state, Germany) coupled to a Geolas HD ArF excimer LA system (Coherent; Göttingen, Germany).
Major and trace element compositions of whole-rock samples were determined using a ZSX Primus II X-ray fluorescence spectrometer and an Agilent 7500cx inductively coupled plasma mass spectrometer (ICP-MS), respectively. Plagioclase mineral analyses were conducted via electron probe microanalysis (EPMA) on a JEOL JXA–8230 instrument outfitted with four wavelength-dispersive spectrometers (WDS). Analytical conditions included an accelerating voltage of 15 kV, a beam current of 20 nA, and a focused electron beam with a diameter of 1 μm. Measurement times were set at 10 s for element peaks and 5 s for background positions on both flanks. The acquired X-ray intensities were adjusted using the ZAF correction method, which accounts for atomic number effects, absorption, and fluorescence.

4. Results

4.1. Zircon U–Pb Dating and Lu–Hf Isotopes

The zircon grains extracted from the Yaogou granodiorite exhibit broadly uniform characteristics. These grains appear dark gray and display well-defined prismatic shapes—either elongated or stubby—ranging from 60 to 190 μm in length, with typical length-to-width ratios around 3:1. Cathodoluminescence imagery reveals distinct oscillatory zoning within the crystals. The dating results are listed in supplementary Tables S1 and S2. Geochemical analysis of zircons from sample 23ML-400 indicates thorium contents between 376 and 1087 ppm, and uranium levels spanning 459 to 1862 ppm, resulting in a mean Th/U ratio of approximately 0.84. Twenty-seven zircon measurements yielded concordant 206Pb/238U isotopic data, producing a weighted mean age of 462 ± 2.6 Ma (MSWD = 0.24) (Figure 4A). Similarly, analyses were conducted on zircons from samples 23ML-501 and 23ML-506, which also exhibited a high average Th/U ratio of 0.53. The results yielded concordant and consistent 206Pb/238U ages, with weighted mean values of 473 ± 3.9 Ma (MSWD = 0.24) and 471 ± 2.4 Ma (MSWD = 0.19) (Figure 4C,E), respectively. The analyzed zircon grains exhibit steep and heavy REE-enriched trace element patterns with pronounced negative Eu and positive Ce anomalies (Figure 4B,D,F), indicating a magmatic origin [34]. These three weighted mean ages (473–460 Ma) are consistent with the analytical errors and represent the crystallization age of the Yaogou granodiorites.
A total of twenty-four, seventeen and fifteen zircon grains from samples 23ML-400, 23ML-501 and 23ML-506, respectively, were analyzed for Lu–Hf isotopes following U-Pb dating and plotted in Figure 5 and the results are listed in supplementary Table S3. Zircons from sample 23ML-400 yielded εHf(t) values of −13.6 to −10.7 and two-stage model ages (TDM2) of 1913–2071 Ma. Sample 23ML-501 zircons exhibited εHf(t) values between −14.5 and −10.7 and TDM2 of 1907–2109 Ma. Meanwhile, zircons from sample 23ML-506 yielded εHf(t) values of −14.6 to −11.1 and TDM2 of 1933–2129 Ma.

4.2. Whole-Rock Geochemistry

All major element compositions were normalized on an anhydrous basis and the results are listed in supplementary Table S4. The studied samples have high SiO2 (63.3–71.1 wt.%) and relatively high Al2O3 (13.9–15.8 wt.%), TiO2 (0.48–0.72 wt.%), and MgO (1.58–3.43 wt.%) contents, with high Mg# values of 40–52. They consist primarily of medium-K calc-alkaline and peraluminous granodiorites (Figure 6), and are enriched in light rare earth elements (REEs), exhibiting relatively high (La/Yb)N ratios of 4.4–13.8 with negative Eu anomalies (Eu/Eu* = 0.56–0.93; Figure 7A). Additionally, the samples show enrichment in large-ion lithophile elements (LILEs), such as Rb, Th, and Pb, while exhibiting a depletion in high-field-strength elements (HFSEs) like Nb, Ta, and Ti (Figure 7B).

4.3. Mineral Chemistry

Feldspar, including both plagioclase and K-feldspar, is the predominant mineral found in the Yaogou granodiorites. The grains of these minerals typically range in length from 200 to 4000 μm and in width from 80 to 1500 μm. The major element compositions of plagioclase and K-feldspar in sample 23ML-400 are An1.4–50Ab47–98Or0.2–27 and An0–0.6Ab3–19Or81–97, with average values of An25Ab70Or5 and An0.2Ab10Or90, respectively (Table S5). The plagioclase is characterized by a higher Ab content than An and Or, with the sequence Ab > Or > An, and these feldspars range from sodic plagioclase to andesine (Figure 8).

5. Discussion

5.1. Petrogenetic Classification

The geochemistry of A-, I-, and S-type granites is generally well-known [41,42]. Granites are generally non-M-type due to the involvement of crustal material, crustal contamination during magma ascent, fractional crystallization limits in mantle-derived magma, and low volatile contents in mantle magma. The Yaogou granodiorites exhibit relatively high K2O contents (1.6–2.4 wt.%; except for one sample at 0.28 wt.%), and are geochemically distinct from M-type granites, which typically have K2O contents below 1 wt.%. Furthermore, Chappell and White [41] proposed that A/CNK = 1.1 is the boundary between S-type granites and I- and A-type granites, but it is difficult to distinguish S-type from highly fractionated I- and A-type granites due to their similar geochemical features (e.g., A/CNK values). A relationship between the contents of P2O5 and SiO2 can be utilized to identify the granite type. Apatite tends to reach saturation in granitic magmas that are metaluminous to weakly peraluminous or peralkaline, while it exhibits high solubility in strongly peraluminous magmas [43]. The observed negative correlation between the P2O5 and SiO2 contents (Table S4) suggests that the Yaogou granodiorites do not exhibit characteristics of S-type granites. The analyzed samples of granite are devoid of Al-rich minerals, such as garnet, cordierite, andalusite, and sillimanite, with the exception of biotite. Consequently, these granites can be classified as either I-type or A-type [41].
The Yaogou granodiorites have relatively low Zr (96–244 ppm), Nb (2.9–18 ppm), total REE (ΣREE = 85–224 ppm) and Zr + Nb + Y + Ce (148–378 ppm) values, as well as low Ga/Al ratios (10,000 × Ga/Al ratios of 1.7–2.9) and FeOT/MgO ratios (1.9–3.2), most samples far away from the A-type granites (Figure 9). It is commonly thought that A-type granites represent relatively anhydrous and high-temperature magmas [44,45]. The zircon saturation thermometer (TZr) was used to obtain minimum crystallization temperatures for the magmas when Zr was undersaturated [46]. The calculated TZr values for the Yaogou granodiorites are 745–814 °C, with a weighted mean of 792 °C [46,47,48]. These values are lower than those of A-type granites (the average TZr value of A-type granites is 839 °C) [47,49], but are consistent with those of I-type granites (average TZr values for unfractionated and fractionated I-type granites are 781 °C and 764 °C, respectively) [47,49]. Thus, we suggest that the Yaogou granodiorites are similar to typical I–type granites.

5.2. Petrogenesis

5.2.1. Nature of the Source

The zircon ages of the granodiorites (473–460 Ma) suggest their formation occurred during the Early–Middle Ordovician. Their comparable trace element patterns and zircon Lu-Hf isotopic compositions, along with the island arc-like features—characterized by enrichment in LILEs and REEs, and depletion in HFSEs—point to a shared origin. I-type granites, initially explained by the partial melting of older metaigneous rocks [41], are now understood to form through three primary processes. The first involves the fractional crystallization of mantle-derived magmas, with or without assimilation of crustal material [50]. The second process corresponds to the mixing of crustal and mantle-derived melts [51]. The third mechanism involves the partial melting of crustal components at either deep or shallow crustal levels [52].
Certain trace element ratios (such as Th/Nb, Th/La, La/Nb, and Nb/Ta) remain stable during the differentiation of magma, making them useful indicators of the nature of the source from which the granites originated [53]. The trace element ratios of the studied granodiorites (Th/Nb = 1.11–1.50; Th/La = 0.17–0.45; La/Nb = 2.6–9.1; Nb/Ta = 11.5–14.7) are higher than those of the primitive mantle (Th/Nb = 0.18; Th/La = 0.13; La/Nb = 0.94; Nb/Ta = 16.00), yet they closely align with the average values observed in the crust (Th/Nb = 0.44; Th/La = 0.20; La/Nb = 2.2; Nb/Ta = 11–12) [54,55]. Feldspar, a dominant mineral in granites, is influenced by both the magma’s chemistry and temperature. In the Yaogou granodiorites, the plagioclase’s An values range from 1 to 17 mol.%, exhibiting considerable variation. This variability reflects complex processes within the magma chamber rather than the introduction of hot mafic magma, as the latter would typically result in plagioclase with higher Fe, Mg, and An content [56].
Isotopic analysis reveals that the granodiorites display consistently and significantly low εHf(t) values (ranging from −14.6 to −10.7), accompanied by old two-stage Hf model ages (TDM2 = 2129–1907 Ma). In addition, the volume of the contemporaneous mafic magmas in this region is too small to account for the fractional crystallization of mantle-derived magmas. This observation suggests that the granodiorites were primarily derived from partial melting of ancient continental crust, rather than through fractional crystallization of mantle-derived magmas or mixing of crustal and mantle-derived melts. The light REE-enriched patterns of the Yaogou granodiorites (Figure 7) reflect REE fractionation during partial melting, with the heavy REEs being retained in residual amphibole or garnet in the source [57]. In addition, when compared with experimental melts of various source rocks [58], although a few samples plot near or within the field of graywacke-derived melts, the majority exhibit geochemical affinities with experimental melts derived from amphibolite (Figure 10). This suggests that the Yaogou granodiorites were primarily derived from the partial melting of the amphibolitic lower crust, with possible minor contributions or geochemical overprints from metasedimentary components. Therefore, we suggested that the Yaogou granodiorites likely formed owing to partial melting of ancient continental crust, with amphibolites being the main source of lithology.

5.2.2. Magmatic Evolution

Primary magmatic relationships can be inferred from an F (Fe + Mg + Mn)–An (anorthite)–Or (orthoclase) pseudo-ternary diagram, with a comparison to the compositions of experimental cotectic liquids providing further insights [59,60]. A comparison with experimental melts of intermediate (i.e., andesitic) composition reveals that the Yaogou granodiorites form geochemical trends that can be compared with cotectic liquids (Figure 11). These samples form rectilinear and cotectic trends and plot in the low-temperature undersaturated region, indicating that the magmatic evolution was controlled by an increasing degree of melting or a decrease (i.e., crystallization) in magma temperature rather than by crustal assimilation or magma mixing.
According to the An–Ab–Or ternary diagram (Figure 8), the crystallization temperature for plagioclase was below 750 °C, while for alkali feldspar it was under 900 °C. This suggests that the magmatic evolution involved slow cooling. The negative correlation between TiO2 and SiO2 is indicative of the crystallization of mafic minerals (likely biotite; Table S4). The decreasing P2O5 contents with increasing SiO2 indicate that apatite fractionation occurred (Table S4). The decreasing Al2O3 contents with increasing SiO2 suggest plagioclase fractionation, which is consistent with the presence of negative Eu and Sr anomalies (Table S4). Moreover, Fe–Ti oxide and/or biotite fractionation occurred, based on the negative Ti anomalies (Figure 7B).

5.3. Implications for Tectonic Evolution

The Early–Middle Ordovician Yaogou granodiorites are calc-alkaline, enriched in LILEs (e.g., Rb, Th, and U), and depleted in HFSEs (e.g., Nb, Ta, and Ti) and heavy REEs, which are typically attributed to subduction-related arc magmatism at convergent plate boundaries. In the tectonic setting discriminative diagrams (Figure 12), all the samples plot in the volcanic arc and post-collisional granite fields. Moreover, zircon trace element contents (e.g., Hf, Th, U, Yb, and Nb) can also be used to determine the tectonic setting of their host magma [61]. The zircons from the Yaogou granodiorites exhibit relatively elevated Hf/Th ratios and fall within the arc-related (orogenic) domain on a Th/Nb versus Hf/Th plot (Figure 13A). Additionally, on the log10(Nb/Yb) versus log10(U/Yb) diagram (Figure 13B), most zircons display relatively high U/Yb ratios, positioning them within the continental arc field [61,62]. Thus, we suggest that the Yaogou granodiorites originated in a tectonic environment associated with subduction.
The evolution of the NQOB is debated, with one model linking its formation to the closure of a short-lived Paleo-Tethyan Ocean segment, while another suggests it resulted from the eventual closure of a long-standing ocean basin south of the North China Block ([65] and reference therein). A key distinction between these models lies in their interpretations of the subduction direction of the North Qilian Ocean, which is fundamental to the Early–Middle Ordovician subduction model of the North Qilian Orogenic Belt and serves as a crucial framework for understanding regional tectonic evolution, paleo-oceanic basin closure, and continental amalgamation [13]. Structurally, the widespread subduction accretionary complexes (e.g., Baiquanmen–Qingshuigou accretionary complexes) within the orogen, comprising seamount fragments, ophiolitic mélanges, turbidites and high-pressure metamorphic rocks (blueschists, eclogites), document the dynamic process of bidirectional subduction-collision through their imbricate thrust architecture [66,67]. Petrologically, geochemical polarity is evident in magmatic rocks: Southern arc-type andesites (Lenglongling; 460 Ma) and quartz diorites (Niuxinshan; 476 Ma) exhibit enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE), indicative of southward subduction-related fluid metasomatism [12,68]. In contrast, northern Yaogou granodiorites (473–460 Ma) and Baiyin volcanic rocks (475–445 Ma) display oceanic crustal signatures, including elevated Nb/Ta ratios and flat REE patterns, consistent with partial melting triggered by northward subduction ([11,29] and this study). This spatiotemporal differentiation of magmatism provides robust petrogenetic constraints for the double-subduction model [11,12,20].
Drawing from regional geological evidence, we propose a dual-subduction model for the North Qilian Ocean during the early Paleozoic (Figure 14). In the Early to Middle Ordovician, the southward subduction and subsequent dehydration of the descending slab induced partial melting of the North Qilian oceanic crust, giving rise to the Niuxinshan granite (476 Ma). The closure of the South Qilian Ocean then initiated the northward subduction of the North Qaidam block beneath the Qilian terrane, reversing the subduction polarity of the North Qilian Ocean. As this process advanced, the North Qilian arc collided with the Alxa terrane, facilitating the emplacement of the Yaogou granodiorite (473–460 Ma) along the northern margin of the NQOB. This model effectively explains the temporal and spatial distinction between the Niuxinshan granite (476 Ma, linked to southward subduction) and the Yaogou intrusions (473–460 Ma, associated with northward subduction), offering crucial insights into the evolution of the NQOB.

6. Conclusions

(1)
New geochronological data for the Yaogou granodiorites were emplaced around 473–460 Ma.
(2)
The Yaogou granodiorites originated through the partial melting of ancient continental crust within a subduction-related magmatism.
(3)
Our findings support a northward subduction model of the North Qilian Ocean beneath the Alxa Block.
(4)
The Yaogou granodiorites formation is likely the result of a reversal in subduction polarity, driven by the inability of the North Qilian oceanic crust to subduct southward.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/min15060551/s1, Table S1. Zircon U–Pb age data for the Yaogou granodiorites in the North Qilian orogenic belt; Table S2. Zircon trace element data (ppm) for the Yaogou granodiorites in the North Qilian orogenic belt; Table S3. Hafnium isotope data for zircons from the Yaogou granodiorites in the North Qilian orogenic belt; Table S4. Major (wt.%) and trace (ppm) element data for the Yaogou granodiorites in the North Qilian orogenic belt; Table S5. Electron probe microanalysis (EPMA) of plagioclase for the Yaogou granodiorites in the North Qilian orogenic belt.

Author Contributions

D.L.: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Writing—original draft. Y.Y.: Supervision, Data curation, Investigation, Project administration, Writing—review and editing. Y.X.: Writing—review and editing. P.L.: Data curation, Investigation. X.L. (Xijun Liu): Data curation, Investigation. G.C.: Data curation, Investigation. X.L. (Xiao Liu): Investigation, Data curation. R.H.: Investigation, Data curation. H.T.: Data curation. Y.L.: Investigation. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported financially by funds from the Deep Earth probe and Mineral Resources Exploration-National Science and Technology Major Project: 2024ZD1001503, the Natural Science Foundation of Guangxi Province for Young Scholars (No. GuikeAD23026175) and the Scientific research startup funds of Guilin University of Technology (GUTQDJJ 2024081). This research is a contribution to “Xinjiang Tianchi Distinguished Expert” by Xi-Jun Liu.

Data Availability Statement

The data in this paper are reliable and have not been published elsewhere.

Acknowledgments

We would like to express our sincere gratitude to the editor for processing the manuscript.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Soesoo, A.; Bons, P.D.; Gray, D.R.; Foster, D.A. Divergent double subduction: Tectonic and petrologic consequences. Geology 1998, 25, 755–758. [Google Scholar] [CrossRef]
  2. Santosh, M. Assembling North China Craton within the Columbia supercontinent: The role of double–sided subduction. Precambrian Res. 2010, 178, 149–167. [Google Scholar] [CrossRef]
  3. Holt, A.F.; Royden, L.H.; Becker, T.W. The Dynamics of Double Slab Subduction. Geophys. J. Int. 2017, 209, 250–265. [Google Scholar] [CrossRef]
  4. Ritabrata, D.; Nibir, M. Role of double–subduction dynamics in the topographic evolution of the Sunda Plate. Geophys. J. Int. 2022, 230, 696–713. [Google Scholar]
  5. Li, L.S.; Capitanio, F.A.; Cawood, P.A.; Wu, B.J.; Zhai, M.G.; Wang, X.L. Double subduction controls on long–lived continental tectonics and subcontinental mantle temperatures. Geology 2024, 52, 5. [Google Scholar] [CrossRef]
  6. Barker, P.F.; Hill, I.A. Asymmetric spreading in back–arc basins. Nature 1980, 285, 652–654. [Google Scholar] [CrossRef]
  7. Gaina, C. Ridge Jumps and Mantle Exhumation in Back–Arc Basins. Geosciences 2021, 11, 475. [Google Scholar] [CrossRef]
  8. Ficini, E.; Cuffaro, M.; Doglioni, C.; Gerya, T. Variable plate kinematics promotes changes in back–arc deformation regime along the north–eastern Eurasia plate boundary. Sci. Rep. 2024, 14, 7220. [Google Scholar] [CrossRef]
  9. Xiao, Y.; Liu, X.; Xiao, W.; Gong, X.H.; Wu, H.; Song, Y.; Zhang, Z.; Liu, P. Hot subduction in the southern Paleo–Asian Ocean: Insights from clinopyroxene chemistry and Sr–Nd–Hf–Pb isotopes of Carboniferous volcanics in West Junggar. Geosci. Front. 2024, 15, 101716. [Google Scholar] [CrossRef]
  10. Tan, X.M.; Gao, R.; Zhou, J.B.; Wilde, S.A.; Hou, H.S.; Wang, H.Y.; Qi, R.; Li, W.H. Fossil divergent double–subduction zone in the Great Xing’an Range, NE China: Evidence from a deep seismic reflection profile. GSA Bull. 2023, 135, 2961–2970. [Google Scholar] [CrossRef]
  11. Wu, C.l.; Yao, S.Z.; Yang, J.S.; Zeng, L.S.; Chen, S.Y.; Li, H.B.; Qi, X.X.; Joseph, L.W.; Frank, K.M. Double subduction of the Early Paleozoic North Qilian oceanic plate: Evidence from granites in the central segment of North Qilian, NW China. Geol. China 2006, 33, 1197–1208, (In Chinese with English abstract). [Google Scholar]
  12. Wu, C.L.; Xu, X.Y.; Gao, Q.M.; Li, X.M.; Lei, M.; Gao, Y.H.; Frost, R.B.; Wooden, J.L. Early Palaezoic grranitoid magmatism and tectonic evolution in North Qilian, NW China. Acta Petrol. Sin. 2010, 26, 1027–1044. [Google Scholar]
  13. Song, S.G.; Niu, Y.L.; Su, L.; Xia, X.H. Tectonics of the North Qilian orogen, NW China. Gondwana Res. 2013, 23, 1378–1401. [Google Scholar] [CrossRef]
  14. Yang, F.; Xue, F.; Santosh, M.; Qian, Z.; Zhang, C.; Tu, J. Petrogenesis and tectonic evolution of the Palaeozoic to Mesozoic Niuxinshan granitoids in the North Qilian orogen, NW China. Geol. J. 2021, 56, 3207–3224. [Google Scholar] [CrossRef]
  15. Qin, Z.W.; Wu, Y.B.; Siebel, W.; Wang, H.; Fu, J.M.; Lu, Y.Y.; Shan, L.; Yu, Y.S. Source nature and magma evolution of I–type granites from the North Qinling orogen, China, revealed by zircon morphology and grain–scale variations in Hf[sbnd]O isotope composition. Lithos 2022, 428–429, 106819. [Google Scholar] [CrossRef]
  16. Xue, F.; Yang, F.; Ren, W.; Santosh, M.; Qian, Z.; Huang, Y.; Tan, Z. Petrogenesis of the Early Paleozoic Dioritic–Granitic Magmatism in the Eastern North Qilian Orogen, NW China: Implications for Tethyan Tectonic Evolution. Lithosphere 2024, 2024, 1. [Google Scholar] [CrossRef]
  17. Zhao, S.; Hai, L.; Liu, B.; Dong, H.; Mei, C.; Xu, Q.; Mu, C.; Wei, X. Late Ordovician High Ba–Sr Intrusion in the Eastern North Qilian Orogen: Implications for Crust-Mantle Interaction and Proto–Tethys Ocean Evolution. Minerals 2023, 13, 744. [Google Scholar] [CrossRef]
  18. Gehrels, G.; Kapp, P.; DeCelles, P.; Pullen, A.; Blakey, R.; Weislogel, A.; Ding, L.; Guynn, J.; Martin, A.; McQuarrie, N.; et al. Detrital zircon geochronology of pre–Tertiary strata in the Tibetan-Himalayan orogen. Tectonics 2011, 30, TC5016. [Google Scholar] [CrossRef]
  19. Chen, Y.; Song, S.; Niu, Y.; Wei, C. Melting of continental crust during subduction initiation: A case study from the Chaidanuo peraluminous granite in the North Qilian suture zone. Geochim. Et Cosmochim. Acta 2014, 132, 311–336. [Google Scholar] [CrossRef]
  20. Wang, N.; Wu, C.L.; Lei, M.; Chen, H.J. Petrogenesis and tectonic implications of the Early Paleozoic granites in the western segment of the North Qilian orogenic belt, China. Lithos 2018, 312–313, 89–107. [Google Scholar] [CrossRef]
  21. Fu, C.L.; Yan, Z.; Aitchison, J.C.; Xiao, W.J.; Buckman, S.; Wang, B.Z.; Li, W.F.; Li, Y.S.; Ren, H.D. Multiple subduction processes of the Proto–Tethyan Ocean: Implication from Cambrian intrusions along the North Qilian suture zone. Gondwana Res. 2020, 87, 207–223. [Google Scholar] [CrossRef]
  22. Li, C.Y.; Liu, Y.W.; Zhu, B.C.; Feng, Y.M.; Wu, H.Q. Structural evolutions of Qinling and Qilian Shan. Sci. Pap. Geol. Int. Exch. 1978, 174–185, (In Chinese with English abstract). [Google Scholar]
  23. Tseng, C.Y.; Yang, H.J.; Yang, H.Y.; Liu, D.Y.; Wu, C.L.; Cheng, C.K.; Chen, C.H.; Ker, C.M. Continuity of the North Qilian and North Qinling orogenic belts, Central Orogenic System of China: Evidence from newly discovered Paleozoic adakitic rocks. Gondwana Res. 2009, 16, 285–293. [Google Scholar] [CrossRef]
  24. Song, S.G.; Niu, Y.L.; Su, L.; Zhang, C.; Zhang, L.F. Continental orogenesis from ocean subduction, continent collision/subduction, to orogen collapse, and orogen recycling: The example of the North Qaidam UHPM belt, NW China. Earth–Sci. Rev. 2014, 129, 59–84. [Google Scholar] [CrossRef]
  25. Xia, X.H.; Song, S.G.; Niu, Y.L. Tholeiite-Boninite terrane in the North Qilian suture zone: Implications for subduction initiation and back–arc basin development. Chem. Geol. 2012, 328, 259–277. [Google Scholar] [CrossRef]
  26. Cheng, H.; Lu, T.Y.; Cao, D.D. Coupled Lu–Hf and Sm–Nd geochronology constrains blueschist-facies metamorphism and closure timing of the Qilian Ocean in the North Qilian orogen. Gondwana Res. 2016, 34, 99–108. [Google Scholar] [CrossRef]
  27. Mao, J.W.; Zhang, Z.C.; Yang, J.M.; Zuo, G.C.; Zhang, Z.H.; Ye, D.J.; Wang, Z.L.; Ren, F.S.; Zhang, Y.J.; Peng, C. The Metallogenic Series and Prospecting Assessment of Copper, Gold, Iron and Tungsten Polymetallic Ore Deposits in the West Sector of the Northern Qilian Mountains; Geological Publishing House: Beijing, China, 2003; pp. 157–242, (In Chinese with English abstract). [Google Scholar]
  28. Zhao, X.M.; Zhang, Z.H.; Liu, M.; Li, Y.S.; Guo, S.F. Zircon U–Pb geochronology, geochemistry and petrogenesis of the granites from the Xiaoliugou deposit in the western of the North Qilian. Acta Petrol. Sin. 2014, 30, 16–34, (In Chinese with English abstract). [Google Scholar]
  29. Wang, C.Y.; Zhang, Q.; Qian, Q.; Zhou, M.F. Geochemistry of the Early Paleozoic Baiyin Volcanic Rocks (NW China): Implications for the Tectonic Evolution of the North Qilian Orogenic Belt. J. Geol. 2005, 113, 83–94. [Google Scholar] [CrossRef]
  30. Xu, Y.J.; Du, Y.S.; Cawood, P.A.; Guo, H.; Huang, H.; An, Z.H. Detrital zircon record of continental collision: Assembly of the Qilian Orogen, China. Sediment. Geol. 2010, 230, 35–45. [Google Scholar] [CrossRef]
  31. Liu, Y.; Hu, Z.; Gao, S.; Günther, D.; Xu, J.; Gao, C.; Chen, H. In situ analysis of major and trace elements of anhydrous minerals by LA–ICP–MS without applying an internal standard. Chem. Geol. 2008, 257, 34–43. [Google Scholar] [CrossRef]
  32. Liu, Y.; Gao, S.; Hu, Z.; Gao, C.; Zong, K.; Wang, D. Continental and Oceanic Crust Recycling–induced Melt–Peridotite Interactions in the Trans–North China Orogen: U–Pb Dating, Hf Isotopes and Trace Elements in Zircons from Mantle Xenoliths. J. Petrol. 2009, 51, 537–571. [Google Scholar] [CrossRef]
  33. Ludwig, K.R. User’s Manual for Isoplot 3.00: A Geochronological Toolkit for Microsoft Excel; Kenneth R. Ludwig: Chicaga, IL, USA, 2003. [Google Scholar]
  34. Hoskin, P.W.O.; Schaltegger, U. The Composition of Zircon and Igneous and Metamorphic Petrogen esis. Rev. Mineral. Geochem. 2003, 53, 27–62. [Google Scholar] [CrossRef]
  35. Sun, S.s.; McDonough, W.F. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. Geol. Soc. Lond. Spec. Publ. 1989, 42, 313–345. [Google Scholar] [CrossRef]
  36. Middlemost, E.A.K. Naming materials in the magma/igneous rock system. Earth–Sci. Rev. 1994, 37, 215–224. [Google Scholar] [CrossRef]
  37. Peccerillo, A.; Taylor, S.R. Geochemistry of eocene calc–alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contrib. Mineral. Petrol. 1976, 58, 63–81. [Google Scholar] [CrossRef]
  38. Frost, C.D.; Frost, B.R. On Ferroan (A–type) Granitoids: Their Compositional Variability and Modes of Origin. J. Petrol. 2010, 52, 39–53. [Google Scholar] [CrossRef]
  39. Maniar, P.D.; Piccoli, P.M. Tectonic discrimination of granitoids. Geol. Soc. Am. Bull. 1989, 101, 635–643. [Google Scholar] [CrossRef]
  40. Smith, J.V. Feldspar Minerals; Springer: Berlin/Heidelberg, Germany, 1974. [Google Scholar]
  41. Chappell, B.W.; White, A.J.R. Two Contrasting Granite Types. Pac. Geol. 1974, 8, 173–174. [Google Scholar]
  42. Whalen, J.B.; Currie, K.L.; Chappell, B.W. A–type granites: Geochemical characteristics, discrimination and petrogenesis. Contrib. Mineral. Petrol. 1987, 95, 407–419. [Google Scholar] [CrossRef]
  43. Wolf, M.B.; London, D. Apatite dissolution into peraluminous haplogranitic melts: An experimental study of solubilities and mechanisms. Geochim. Et Cosmochim. Acta 1994, 58, 4127–4145. [Google Scholar] [CrossRef]
  44. Collins, W.J.; Beams, S.D.; White, A.J.R.; Chappell, B.W. Nature and origin of A–type granites with particular reference to southeastern Australia. Contrib. Mineral. Petrol. 1982, 80, 189–200. [Google Scholar] [CrossRef]
  45. Clemens, J.D.; Holloway, J.R.; White, A.J.R. Origin of an A–type granite; experimental constraints. Am. Mineral. 1986, 71, 317–324. [Google Scholar]
  46. Miller, C.F.; McDowell, S.M.; Mapes, R.W. Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance. Geology 2003, 31, 529–532. [Google Scholar] [CrossRef]
  47. Watson, E.B.; Harrison, T.M. Zircon saturation revisited: Temperature and composition effects in a variety of crustal magma types. Earth Planet. Sci. Lett. 1983, 64, 295–304. [Google Scholar] [CrossRef]
  48. Watson, E.; Wark, D.; Thomas, J. Crystallization thermometers for zircon and rutile. Contrib. Mineral. Petrol. 2006, 151, 413–433. [Google Scholar] [CrossRef]
  49. King, P.L.; White, A.J.R.; Chappell, B.W.; Allen, C.M. Characterization and Origin of Aluminous A–type Granites from the Lachlan Fold Belt, Southeastern Australia. J. Petrol. 1997, 38, 371–391. [Google Scholar] [CrossRef]
  50. Chiaradia, M. Adakite–like magmas from fractional crystallization and melting–assimilation of mafic lower crust (Eocene Macuchi arc, Western Cordillera, Ecuador). Chem. Geol. 2009, 265, 468–487. [Google Scholar] [CrossRef]
  51. Xie, H.J.; Wang, Y.W.; Li, D.D.; Zhou, G.C.; Zhang, Z.C. Late Triassic Magma Mixing and Fractional Crystallization in the Qingchengzi Orefield, Eastern Liaoning Province: Regional Petrogenetic and Metallogenic Implications. J. Earth Sci. 2021, 32, 144–157. [Google Scholar] [CrossRef]
  52. Gao, P.; Zheng, Y.F.; Zhao, Z.F. Experimental melts from crustal rocks: A lithochemical constraint on granite petrogenesis. Lithos 2016, 266–267, 133–157. [Google Scholar] [CrossRef]
  53. Shellnutt, J.G.; Wang, C.Y.; Zhou, M.F.; Yang, Y.H. Zircon Lu–Hf isotopic compositions of metaluminous and peralkaline A-type granitic plutons of the Emeishan large igneous province (SW China): Constraints on the mantle source. J. Asian Earth Sci. 2009, 35, 45–55. [Google Scholar] [CrossRef]
  54. Weaver, B.L. The origin of ocean island basalt end–member compositions: Trace element and isotopic constraints. Earth Planet. Sci. Lett. 1991, 104, 381–397. [Google Scholar] [CrossRef]
  55. Green, T.H. Significance of Nb/Ta as an indicator of geochemical processes in the crust-mantle system. Chem. Geol. 1995, 120, 347–359. [Google Scholar] [CrossRef]
  56. Guo, K.; Zhai, S.K.; Wang, X.Y.; Yu, Z.H.; Lai, Z.Q.; Chen, S.; Song, Z.J.; Ma, Y.; Chen, Z.X.; Li, X.H.; et al. The dynamics of the southern Okinawa Trough magmatic system: New insights from the microanalysis of the An contents, trace element concentrations and Sr isotopic compositions of plagioclase hosted in basalts and silicic rocks. Chem. Geol. 2018, 497, 146–161. [Google Scholar] [CrossRef]
  57. Martin, H.; Smithies, R.H.; Rapp, R.; Moyen, J.F.; Champion, D. An overview of adakite, tonalite–trondhjemite–granodiorite (TTG), and sanukitoid: Relationships and some implications for crustal evolution. Lithos 2005, 79, 1–24. [Google Scholar] [CrossRef]
  58. Patiño Douce, A.E. What do experiments tell us about the relative contributions of crust and mantle to the origin of granitic magmas? Geol. Soc. Lond. Spec. Publ. 1999, 168, 55–75. [Google Scholar] [CrossRef]
  59. Castro, A. Tonalite-granodiorite suites as cotectic systems: A review of experimental studies with applications to granitoid petrogenesis. Earth-Sci. Rev. 2013, 124, 68–95. [Google Scholar] [CrossRef]
  60. Castro, A. The off-crust origin of granite batholiths. Geosci. Front. 2014, 5, 63–75. [Google Scholar] [CrossRef]
  61. Yang, J.H.; Cawood, P.; Du, Y.S.; Hu, H.; Huang, H.W.; Tao, P. Large Igneous Province and magmatic arc sourced Permian-Triassic volcanogenic sediments in China. Sediment. Geol. 2012, 261–262, 120–131. [Google Scholar] [CrossRef]
  62. Grimes, C.B.; Wooden, J.L.; Cheadle, M.J.; John, B.E. “Fingerprinting” tectono-magmatic provenance using trace elements in igneous zircon. Contrib. Mineral. Petrol. 2015, 170, 46. [Google Scholar] [CrossRef]
  63. Song, Y.; Liu, X.J.; Xiao, W.J.; Gong, X.H.; Liu, X.; Xiao, Y.; Zhang, Z.G.; Liu, P.D. Tectonic evolution of circum-Rodinia subduction: Evidence from Neoproterozoic A-type granitic magmatism in the Central Tianshan Block, northwest China. Precambrian Res. 2023, 387, 106976. [Google Scholar] [CrossRef]
  64. Pearce, J.A.; Harris, N.B.W.; Tindle, A.G. Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks. J. Petrol. 1984, 25, 956–983. [Google Scholar] [CrossRef]
  65. Wu, C.L.; Gao, Y.H.; Frost, B.R.; Robinson, P.T.; Wooden, J.L.; Wu, S.P.; Chen, Q.L.; Lei, M. An early Palaeozoic double–subduction model for the North Qilian oceanic plate: Evidence from zircon SHRIMP dating of granites. Int. Geol. Rev. 2011, 53, 157–181. [Google Scholar] [CrossRef]
  66. Pei, X.Z.; WU, H.Q.; Zuo, G.C. Deformation features and tectonic evolution of Early-Paleozoic subductive complex belt in the north Qilian Mountains, China. J. Xi’an Eng. Univ. 1999, 21, 9–12, (In Chinese with English abstract). [Google Scholar]
  67. Xiao, W.J.; Windley, B.F.; Yong, Y.; Yan, Z.; Yuan, C.; Liu, C.Z.; Li, J.L. Early Paleozoic to Devonian multiple–accretionary model for the Qilian Shan, NW China. J. Asian Earth Sci. 2009, 35, 323–333. [Google Scholar] [CrossRef]
  68. Zhang, L.Q.; Zhang, H.F.; Zhang, S.S.; Xiong, Z.L.; Luo, B.J.; Yang, H.; Pan, F.B.; Zhou, X.C.; Xu, W.C.; Guo, L. Lithospheric delamination in post-collisional setting: Evidence from intrusive magmatism from the North Qilian orogen to southern margin of the Alxa block, NW China. Lithos 2017, 288–289, 20–34. [Google Scholar] [CrossRef]
Minerals 15 00551 g001
Figure 1. (A) Simplified map of China; (B) Simplified geological map of the central segment of North Qilian orogenic belt (modified after [13]).
Figure 1. (A) Simplified map of China; (B) Simplified geological map of the central segment of North Qilian orogenic belt (modified after [13]).
Minerals 15 00551 g001
Minerals 15 00551 g002
Figure 2. Simplified geological map of the Yaogou area.
Figure 2. Simplified geological map of the Yaogou area.
Minerals 15 00551 g002
Minerals 15 00551 g003
Figure 3. Representative Field and Microscopic Photographs of the Yaogou area in the NQOB. (A,D,G) Granodiorite; (B,E,H) were taken under plane-polarized light; (C,F,I) were taken under crosspolarized light. Pl = Plagioclase; Qz = Quartz; Hbl = Hornblende.
Figure 3. Representative Field and Microscopic Photographs of the Yaogou area in the NQOB. (A,D,G) Granodiorite; (B,E,H) were taken under plane-polarized light; (C,F,I) were taken under crosspolarized light. Pl = Plagioclase; Qz = Quartz; Hbl = Hornblende.
Minerals 15 00551 g003
Minerals 15 00551 g004
Figure 4. Zircon U–Pb Concordia diagrams and representative CL images of zircons (A,C,E), together with weighted mean ages and chondrite-normalized REE patterns of zircons (B,D,F) from the Yaogou granodiorite. Normalizing values were taken from Sun and McDonough [35].
Figure 4. Zircon U–Pb Concordia diagrams and representative CL images of zircons (A,C,E), together with weighted mean ages and chondrite-normalized REE patterns of zircons (B,D,F) from the Yaogou granodiorite. Normalizing values were taken from Sun and McDonough [35].
Minerals 15 00551 g004
Minerals 15 00551 g005
Figure 5. Zircon ages versus εHf(t) values for the Yaogou granodiorites. CHUR = chondritic uniform reservoir.
Figure 5. Zircon ages versus εHf(t) values for the Yaogou granodiorites. CHUR = chondritic uniform reservoir.
Minerals 15 00551 g005
Minerals 15 00551 g006
Figure 6. (A) Total alkalis versus silica diagram [36], (B) K2O versus SiO2 diagram [37], (C) (Na2O + K2O − CaO) versus SiO2 diagram [38], and (D) A/CNK versus A/NK diagram, where A/CNK = Al2O3/(K2O + Na2O + CaO) and A/NK = Al2O3/(K2O + Na2O) (molar ratios; [39]) for the Yaogou granodiorite.
Figure 6. (A) Total alkalis versus silica diagram [36], (B) K2O versus SiO2 diagram [37], (C) (Na2O + K2O − CaO) versus SiO2 diagram [38], and (D) A/CNK versus A/NK diagram, where A/CNK = Al2O3/(K2O + Na2O + CaO) and A/NK = Al2O3/(K2O + Na2O) (molar ratios; [39]) for the Yaogou granodiorite.
Minerals 15 00551 g006
Minerals 15 00551 g007
Figure 7. (A) Chondrite-normalized REE and (B) primitive mantle-normalized trace element patterns for the Yaogou granodiorite. Normalizing values were taken from Sun and McDonough [35].
Figure 7. (A) Chondrite-normalized REE and (B) primitive mantle-normalized trace element patterns for the Yaogou granodiorite. Normalizing values were taken from Sun and McDonough [35].
Minerals 15 00551 g007
Minerals 15 00551 g008
Figure 8. An–Ab–Or compositions of feldspar phenocrysts from Yaogou granodiorites [40].
Figure 8. An–Ab–Or compositions of feldspar phenocrysts from Yaogou granodiorites [40].
Minerals 15 00551 g008
Minerals 15 00551 g009
Figure 9. (A,B) Nb, Zr vs. 10,000 Ga/Al, (C,D) FeOT/MgO, 10,000 Ga/Al vs. (Zr + Nb + Ce + Y), discrimination diagrams to show the genetic characteristics of the Yaogou granodiorites [42]. A-type: A-type granite; I, S and M-type: I-, S- and M-type granite; FG: Fractionated I-type granite; OGT: Unfractionated M-, I-, and S-type granite.
Figure 9. (A,B) Nb, Zr vs. 10,000 Ga/Al, (C,D) FeOT/MgO, 10,000 Ga/Al vs. (Zr + Nb + Ce + Y), discrimination diagrams to show the genetic characteristics of the Yaogou granodiorites [42]. A-type: A-type granite; I, S and M-type: I-, S- and M-type granite; FG: Fractionated I-type granite; OGT: Unfractionated M-, I-, and S-type granite.
Minerals 15 00551 g009
Minerals 15 00551 g010
Figure 10. (A) CaO/Al2O3 versus CaO + Al2O3, (B) (Na2O + K2O)/CaO versus Na2O + K2O + CaO [58] diagrams for the Yaogou granodiorites.
Figure 10. (A) CaO/Al2O3 versus CaO + Al2O3, (B) (Na2O + K2O)/CaO versus Na2O + K2O + CaO [58] diagrams for the Yaogou granodiorites.
Minerals 15 00551 g010
Minerals 15 00551 g011
Figure 11. Pseudo-ternary projection onto the plane F (Fe + Mg + Mn)–An (anorthite)–Or (orthoclase) [59,60].
Figure 11. Pseudo-ternary projection onto the plane F (Fe + Mg + Mn)–An (anorthite)–Or (orthoclase) [59,60].
Minerals 15 00551 g011
Minerals 15 00551 g012
Figure 12. Tectonic classification diagrams for the Yaogou granodiorites include the following: (A) Ta versus Yb; (B) Rb versus (Y+Nb) [63].
Figure 12. Tectonic classification diagrams for the Yaogou granodiorites include the following: (A) Ta versus Yb; (B) Rb versus (Y+Nb) [63].
Minerals 15 00551 g012
Minerals 15 00551 g013
Figure 13. Zircon trace element discrimination plots are presented in two forms: (A) Th/Nb versus Hf/Th [61], and (B) density distribution diagrams derived from geochemical indicators of tectonomagmatic environments. The shaded regions on these plots represent overlapping two-dimensional kernel density distributions, which correspond to compiled datasets of zircons from mid-ocean ridge (MOR-type), plume-influenced regions such as Iceland and Hawaii (ocean island [OI]-type), and continental arc (Cont. arc-type) sources [62,64].
Figure 13. Zircon trace element discrimination plots are presented in two forms: (A) Th/Nb versus Hf/Th [61], and (B) density distribution diagrams derived from geochemical indicators of tectonomagmatic environments. The shaded regions on these plots represent overlapping two-dimensional kernel density distributions, which correspond to compiled datasets of zircons from mid-ocean ridge (MOR-type), plume-influenced regions such as Iceland and Hawaii (ocean island [OI]-type), and continental arc (Cont. arc-type) sources [62,64].
Minerals 15 00551 g013
Minerals 15 00551 g014
Figure 14. Schematic double-subduction model for the North Qilian oceanic plate during the Early Paleozoic: (A) Southward subduction of the North Qilian oceanic plate beneath the southern margin of the NQOB, leading to the emplacement of the Niuxinshan granites. (B) Following the closure of the South Qilian Ocean, the northward subduction of the North Qaidam block beneath the Qilian terrane reversed the subduction polarity of the North Qilian oceanic plate, resulting in the formation of the Yaogou granodiorites.
Figure 14. Schematic double-subduction model for the North Qilian oceanic plate during the Early Paleozoic: (A) Southward subduction of the North Qilian oceanic plate beneath the southern margin of the NQOB, leading to the emplacement of the Niuxinshan granites. (B) Following the closure of the South Qilian Ocean, the northward subduction of the North Qaidam block beneath the Qilian terrane reversed the subduction polarity of the North Qilian oceanic plate, resulting in the formation of the Yaogou granodiorites.
Minerals 15 00551 g014
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Li, D.; Yang, Y.; Xiao, Y.; Liu, P.; Liu, X.; Chen, G.; Liu, X.; Hu, R.; Tian, H.; Liu, Y. Petrogenesis and Tectonic Implications of the Early–Middle Ordovician Granodiorites in the Yaogou Area of the North Qilian Orogenic Belt. Minerals 2025, 15, 551. https://doi.org/10.3390/min15060551

AMA Style

Li D, Yang Y, Xiao Y, Liu P, Liu X, Chen G, Liu X, Hu R, Tian H, Liu Y. Petrogenesis and Tectonic Implications of the Early–Middle Ordovician Granodiorites in the Yaogou Area of the North Qilian Orogenic Belt. Minerals. 2025; 15(6):551. https://doi.org/10.3390/min15060551

Chicago/Turabian Style

Li, Dechao, Yang Yang, Yao Xiao, Pengde Liu, Xijun Liu, Gang Chen, Xiao Liu, Rongguo Hu, Hao Tian, and Yande Liu. 2025. "Petrogenesis and Tectonic Implications of the Early–Middle Ordovician Granodiorites in the Yaogou Area of the North Qilian Orogenic Belt" Minerals 15, no. 6: 551. https://doi.org/10.3390/min15060551

APA Style

Li, D., Yang, Y., Xiao, Y., Liu, P., Liu, X., Chen, G., Liu, X., Hu, R., Tian, H., & Liu, Y. (2025). Petrogenesis and Tectonic Implications of the Early–Middle Ordovician Granodiorites in the Yaogou Area of the North Qilian Orogenic Belt. Minerals, 15(6), 551. https://doi.org/10.3390/min15060551

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop