Cogenetic origin of mafic microgranular enclaves in calc-alkaline granitoids: The Permian plutons in the northern North China Block

Zhang, Shuan‐Hong; Zhao, Yue

doi:10.1130/ges01407.1

Cited by 37 publications

(11 citation statements)

References 231 publications

(299 reference statements)

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“…In the past two decades, several studies have been carried out using Ti‐in‐zircon thermometry to estimate the magma temperature at the time of zircon crystallization (e.g., Claiborne et al, 2010; El‐Bialy & Ali, 2013; Wang et al, 2013; Watson et al, 2006; Zhang & Zhao, 2017, and references therein). This method has become popular and has been increasingly applied to the growing number of natural zircons.…”

Section: Resultsmentioning

confidence: 99%

Zircon trace element geochemistry and Ti‐in‐zircon thermometry of the Linté Pan‐African granitoids, Central Cameroon: Constraints on the genesis of host magma and tectonic implications

et al. 2021

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The Linté area belongs to the central part of the Adamawa‐Yadé Domain (AYD) within the Pan‐African Central African Fold Belt (CAFB) in Cameroon. This area is dominated by Neoproterozoic high‐K calc‐alkaline syenite and monzonite intruding Archean to Palaeoproterozoic gneisses. In this contribution, trace element compositions of zircon obtained using laser ablation inductively coupled plasma mass spectrometry are used to constrain the petrogenesis and tectonic setting of Linté area. The analysed zircon grains display restricted ranges of Hf contents with an average of 8,197 ppm in syenite, 8,220 ppm in alkali‐feldspar syenite, and 9,026 ppm in monzonite. They display high Th/U ratios (>0.5) typical of magmatic zircons. The monzonite zircons have a higher ∑REE content (483.42 ppm) than the syenite zircons (237.70 ppm). The chondrite‐normalized rare‐earth element (REE) diagram of Linté samples shows very similar patterns, characterized by a steeply rising slope due to important heavy rare‐earth element enrichment relative to light rare‐earth element, with distinctive positive Ce and negative Eu anomalies. The application of the Ti‐in‐zircon thermometer reveals a wide range of crystallization temperatures (574–1,137°C for syenites and 713–1,008°C for monzonite), implying a deep level of melting, likely within the lower continental crust of the CAFB. The integration of geochemical behaviours of some trace elements (U, Hf, Zr, Ce, Th, and Nb), together with discrimination diagrams, suggests the crystallization of a continental crust‐derived magma under variable oxidation states and emplacement in a magmatic‐arc setting. This finding represents and adds on to the N‐S geodynamic convergence model between the AYD and the northern border of the Congo Craton.

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Section: Resultsmentioning

confidence: 99%

Zircon trace element geochemistry and Ti‐in‐zircon thermometry of the Linté Pan‐African granitoids, Central Cameroon: Constraints on the genesis of host magma and tectonic implications

et al. 2021

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“…And, all MEs have relatively lower contents of MgO (1.51–2.63 wt%), and Mg # values (27.7–39.9), which is significantly lower than those of with high magnesian andesites high Mg # (Mg # >57; Patiño Douce, 1999). Furthermore, the lack of coeval mafic intrusive rocks and coeval basaltic rocks in the SGHR sharply reduced the possibility of incorporation of relatively evolved basaltic magmas during magma mingling (Ouyang et al, 2015; Zhang & Zhao, 2017).…”

Section: Discussionmentioning

confidence: 99%

“…MEs in the granitoids contain critical information concerning the magma source characteristics as well as the mantle-crust interaction processes in continental crust (Barbarin & Didier, 1992). However, three genetic hypotheses are dominating those MEs: (a) autoliths related to their host rocks (Zhang & Zhao, 2017); (b) globules of mafic melts have mingled or are partly mixed with felsic magma in the lower crust (Kumar, Pieru, Rino, & Hayasaka, 2017); (c) refractory or restitic components of source material (White et al, 1999). Notably, the zircon U-Pb isotope results show that the MEs and the host granitoids have formed in the same magmatism (Figure 4).…”

Section: Petrogenesis Of the Sjz Mesmentioning

confidence: 99%

“…However, the intermediate magmas are dominantly produced by crystal‐liquid fractionation, while crystal‐liquid segregation appears to be the dominant process in generating intermediate magmas, with mixing playing a secondary role (Lee & Bachmann, 2014). Furthermore, recent studies show that early crystallized cumulates (chilled margin) related to their host rock may have played an important role in the formation of MEs (Zhang & Zhao, 2017). However, the entire range of magma compositions can be generated by fractionation, but at different levels (Lee & Morton, 2015).…”

Section: Introductionmentioning

confidence: 99%

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The origin of microgranular enclaves in the Early Cretaceous Shuangjianzishan granites in southern Great Hinggan Range, NE China

Dai

Gao

et al. 2022

Geological Journal

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The microgranular enclaves (MEs) and their host granitoids contain vital information on the genesis and evolution of the magma, especially for those which have close relationship with mineralization, yet remains a hot debate on their origin. Here, we investigate the MEs and their host granitoids in the Shuangjianzishan (SJZ) deposits, southern Great Hinggan Range, NE China, using ziron U-Pb dating and Hf isotopes, along with a systematic analysis of whole-rock geochemical and Sr-Nd isotopic compositions. The SJZ MEs mainly consist of monzonites and quartz monzonites, and the SJZ granitoids comprise a suite of fine-grained syenogranites and coarse-grained monzogranites. The zircon U-Pb dating results suggest that the SJZ granitoids and the SJZ MEs were emplaced at approximately 143-141 Ma. Geochemical features and isotopic compositions of the SJZ granitoids indicate that they are mainly generated by partial melting of juvenile lower-crustal basaltic rocks. The fine-grained syenogranites and the coarsegrained monzogranites have a gradual contact relationship, similar crystallization age, Sr-, Nd-, and Hf-isotopic compositions, suggesting that they were derived from a similar silicic magma reservoir. According to the geochemical compositions and petrographic characteristics (aggregates of coarse-grained euhedral plagioclase crystals) of the SJZ granitoids, we infer that the monzogranites (SiO 2 = 69.24-74.95 wt%) are regarded as the residual cumulate and the fine-grained syenogranites (SiO 2 = 74.83-77.97 wt%) are high silica melts segregated from a crystal mush. The SJZ MEs are characterised by low SiO 2 (50.03-64.20 wt%) and MgO (1.08-2.63 wt%) contents, high P 2 O 5 contents and contain acicular apatite, which are consistent with the products of intermediate magma.Combining with the MEs have comparable crystallization age, mineral assemblage, whole-rock Sr-Nd and zircon Hf-isotopic compositions with their host granitoids, implying the MEs were autoliths related to their host monzogranites. Collectively, we infer that the SJZ MEs were generated by the rapid cooling and crystallization of the hot ascending intermediate magmas contacted with the cooler wall rocks, then those subsolid fine-grained crystal-rich margins were fragmented and injected into the progressive evolved mush chamber, leading to the extraction and upward percolation of high silicic melts from the compacting crystal-rich mush in the shallow crust.

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“…Although significant progress has been made, the origin of MMEs remains controversial. One model suggests that MMEs are early crystallized cumulates of the same magma system (autolith or cogenetic xenoliths) (Dodge and Kistler, 1990;Niu et al, 2013;Zhang and Zhao, 2017;Xu et al, 2021), whereas others propose that they are a by-product of magma mixing of mantle-derived and crustal melts (hybrids) (Barbarin and Didier, 1992;Barbarin, 2005;Barnes et al, 2021). Generally, most of the MMEs hosted within the granitoids, are intermediate in composition (dioritic to tonalitic, with some granodioritic), and are therefore thought to have been produced by the latter process (Jin, 1986;Barbarin, 2005).…”

Section: Introductionmentioning

confidence: 99%

Mesoscopic and Microscopic Magmatic Structures in the Quxu Batholith of the Gangdese Belt, Southern Tibet: Implications for Multiple Hybridization Processes

Zhao

Cao

et al. 2021

Front. Earth Sci.

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The Quxu batholith of the Gangdese magmatic belt, southern Tibet, comprises predominantly Early Eocene calc-alkaline granitoids that feature a variety of types of magmatic microgranular enclaves and dikes. Previous studies have demonstrated that magma mixing played a crucial role in the formation of the Quxu batholith. However, the specific processes responsible for this mixing/hybridization have not been identified. The magmatic microgranular enclaves and dikes preserve a record of this magma mixing, and are therefore an excellent source of information about the processes involved. In this study, mesoscopic and microscopic magmatic structures have been investigated, in combination with analyses of mineral textures and chemical compositions. Texturally, most of the enclaves are microporphyritic, with large crystals such as clinopyroxene, hornblende, and plagioclase in a groundmass of hornblende, plagioclase, and biotite. Two types of enclave swarms can be distinguished: polygenic and monogenic swarms. Composite dikes are observed, and represent an intermediate stage between undisturbed mafic dike and dike-like monogenic enclave swarms. Our results reveal three distinct stages of magma mixing in the Quxu batholith, occurring at depth, during ascent and emplacement, and after emplacement, respectively. At depth, thorough and/or partial mixing occurred between mantle-derived mafic and crust-derived felsic magmas to produce hybrid magma. The mafic magma was generated from the primitive mantle, whereas the felsic end-member was produced by partial melting of the preexisting juvenile crust. Many types of enclaves and host granitoids are thus cogenetic, because all are hybrid products produced by the mixing of the two contrasting magmas in different proportions. In the second stage, segregation and differentiation of the hybrid magma led to the formation of the host granitoids as well as various types of magmatic microgranular enclaves. At this stage, mingling and/or local mixing happened during ascent and emplacement. In the final stage, mafic or hybrid magma was injected into early fractures in the crystallizing and cooling pluton to form dikes. Some dikes remained undisturbed, whereas others experienced local mingling and mixing to form composite dikes and eventually disturbed dike-like monogenic enclave swarms. In summary, our study demonstrates the coupling between magmatic texture and composition in an open-system batholith and highlights the potential of magmatic structures for understanding the magma mixing process.

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Cogenetic origin of mafic microgranular enclaves in calc-alkaline granitoids: The Permian plutons in the northern North China Block

Cited by 37 publications

References 231 publications

Zircon trace element geochemistry and Ti‐in‐zircon thermometry of the Linté Pan‐African granitoids, Central Cameroon: Constraints on the genesis of host magma and tectonic implications

Zircon trace element geochemistry and Ti‐in‐zircon thermometry of the Linté Pan‐African granitoids, Central Cameroon: Constraints on the genesis of host magma and tectonic implications

The origin of microgranular enclaves in the Early Cretaceous Shuangjianzishan granites in southern Great Hinggan Range, NE China

Mesoscopic and Microscopic Magmatic Structures in the Quxu Batholith of the Gangdese Belt, Southern Tibet: Implications for Multiple Hybridization Processes

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