Coexisting Centimeter-Scale Si-Droplets and Micrometer-Scale Fe-Si-Intergrowth in c. 1785 Ma Xiong'er Igneous Province: Tracking Micro- to Macroscopic Immiscibility.
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| Title: | Coexisting Centimeter-Scale Si-Droplets and Micrometer-Scale Fe-Si-Intergrowth in c. 1785 Ma Xiong'er Igneous Province: Tracking Micro- to Macroscopic Immiscibility. |
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| Authors: | Qin, Zhaoyuan1,2 (AUTHOR), Peng, Peng1,2 (AUTHOR), Liu, Xu1,2 (AUTHOR), Wang, Chong1 (AUTHOR), Wang, Xinping3 (AUTHOR), Xu, Bisheng1,2 (AUTHOR), Li, Binghe1,2 (AUTHOR), Shang, Guangrui1,2 (AUTHOR), Dai, Ke1,2 (AUTHOR) |
| Source: | Journal of Petrology. Sep2025, Vol. 66 Issue 9, p1-55. 55p. |
| Subjects: | Immiscibility, Igneous rocks, Phase separation, Igneous provinces, Mineralogy, Microdroplets |
| Abstract: | Centimeter- to sub-centimeter-scale Si-rich liquid droplets (Si-droplets) and coexisting sub-millimeter-scale Fe-Ti-rich spots (Fe-Ti-spots) and micrometer-scale Fe-Si-intergrowth are identified in the c. 1785 Ma Xiong'er igneous province in the North China craton. Such textures occur in meter-thick volcanic layers of irregular shape in the lower section of the first of the two igneous cycles in the Xiaoliangling Group in Lvliang Mountains. The Si-droplets and Fe-Ti-spots (mainly titanite) are dispersed in the Fe-Si-intergrowth. The glass feature of the matrix, as well as the dendritic minerals in droplets indicate their preservation by magma quenching. Micrometer-scale minerals of chlorite (likely altered from pyroxene), ilmenite, magnetite, and apatite occur in both the droplets and intergrowth, which likely crystallized after the segregation of the melt. Post-magmatic precipitation of titanite and chloritization are common in the Fe-intergrowth and Fe-Ti-spots, but weak in the Si-droplets and Si-intergrowth. Bulk compositions of cores of Si-droplets show average SiO2 of 67.7 wt %, MgO of 0.6 wt %, FeOt (total iron) of 3.6 wt %, K2O of 4.3 wt %, and Na2O of 4.2 wt %. Their rims are also Si-rich (more varied) but with distinctly higher K2O (10.0–15.0 wt %) while lower Na2O contents (0.2–2.0 wt %) than the cores. The Fe-Ti-spots have average SiO2 of 36.9 wt %, TiO2 of 18.4 wt %, and FeOt of 10.8 wt %. The Fe-intergrowth has average SiO2 of 37.9 wt %, MgO of 7.4 wt %, and FeOt of 34.5 wt %; while the Si-intergrowth has average SiO2 of 70.9 wt %, MgO of 0.6 wt %, FeOt of 4.5 wt %, K2O of 9.3 wt %, and Na2O of 0.3 wt %. Similar mineral assemblage (pyroxene, Fe-Ti oxides, apatite) in different phases, as well as the chemical and thermal tests approve two conjugated immiscible pairs, i.e. Si-droplets versus Fe-Ti-spots, and Fe- versus Si-intergrowth. It is proposed that the segregation of melts from metastable Fe-Si-intergrowth differentiated along spinodal (unstable zone), formed the Si-droplets and Fe-Ti-spots within the solvus/binodal curve (metastable zone). The different K and Na contents in K-rich rim and K-Na-rich core of the Si-droplets was probably formed by uphill diffusion above liquidus, while titanite in the Fe-Ti-spots crystallized at undercooling conditions during decomposition. The micrometer-scale Fe-Ti oxides and apatite were crystallized during the quench of the texture. The regressed Fe- and Si-rich pairs at the initial immiscible decomposition have SiO2 of 37.3/67.3 wt %, TiO2 of 2.8/0.97 wt %, FeOt of 31.1/3.5 wt %, MgO of 6.36/0.7 wt %, and K2O of 0.2/7.2 wt %, respectively. The Si-droplets formed above liquidus and are seen coalesced and thus were able to merge into rhyolite. The immiscible segregation may explain the bimodal features of the high-Fe-Ti and high-Si rocks of the Xiong'er igneous province. This rare coexisting immiscible texture with varied scales—the microscopic intergrowth and meso- to macroscopic Fe-Ti-spots/Si-droplets—tracks processes of micro- to macroscopic immiscible segregation, which depicts the role of immiscible differentiation in the diversification of natural rock types. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Petrology is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 188960818 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Coexisting Centimeter-Scale Si-Droplets and Micrometer-Scale Fe-Si-Intergrowth in c. 1785 Ma Xiong'er Igneous Province: Tracking Micro- to Macroscopic Immiscibility. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Qin%2C+Zhaoyuan%22">Qin, Zhaoyuan</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Peng%2C+Peng%22">Peng, Peng</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Liu%2C+Xu%22">Liu, Xu</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Wang%2C+Chong%22">Wang, Chong</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Wang%2C+Xinping%22">Wang, Xinping</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Xu%2C+Bisheng%22">Xu, Bisheng</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Li%2C+Binghe%22">Li, Binghe</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Shang%2C+Guangrui%22">Shang, Guangrui</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Dai%2C+Ke%22">Dai, Ke</searchLink><relatesTo>1,2</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Petrology%22">Journal of Petrology</searchLink>. Sep2025, Vol. 66 Issue 9, p1-55. 55p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Immiscibility%22">Immiscibility</searchLink><br /><searchLink fieldCode="DE" term="%22Igneous+rocks%22">Igneous rocks</searchLink><br /><searchLink fieldCode="DE" term="%22Phase+separation%22">Phase separation</searchLink><br /><searchLink fieldCode="DE" term="%22Igneous+provinces%22">Igneous provinces</searchLink><br /><searchLink fieldCode="DE" term="%22Mineralogy%22">Mineralogy</searchLink><br /><searchLink fieldCode="DE" term="%22Microdroplets%22">Microdroplets</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Centimeter- to sub-centimeter-scale Si-rich liquid droplets (Si-droplets) and coexisting sub-millimeter-scale Fe-Ti-rich spots (Fe-Ti-spots) and micrometer-scale Fe-Si-intergrowth are identified in the c. 1785 Ma Xiong'er igneous province in the North China craton. Such textures occur in meter-thick volcanic layers of irregular shape in the lower section of the first of the two igneous cycles in the Xiaoliangling Group in Lvliang Mountains. The Si-droplets and Fe-Ti-spots (mainly titanite) are dispersed in the Fe-Si-intergrowth. The glass feature of the matrix, as well as the dendritic minerals in droplets indicate their preservation by magma quenching. Micrometer-scale minerals of chlorite (likely altered from pyroxene), ilmenite, magnetite, and apatite occur in both the droplets and intergrowth, which likely crystallized after the segregation of the melt. Post-magmatic precipitation of titanite and chloritization are common in the Fe-intergrowth and Fe-Ti-spots, but weak in the Si-droplets and Si-intergrowth. Bulk compositions of cores of Si-droplets show average SiO2 of 67.7 wt %, MgO of 0.6 wt %, FeOt (total iron) of 3.6 wt %, K2O of 4.3 wt %, and Na2O of 4.2 wt %. Their rims are also Si-rich (more varied) but with distinctly higher K2O (10.0–15.0 wt %) while lower Na2O contents (0.2–2.0 wt %) than the cores. The Fe-Ti-spots have average SiO2 of 36.9 wt %, TiO2 of 18.4 wt %, and FeOt of 10.8 wt %. The Fe-intergrowth has average SiO2 of 37.9 wt %, MgO of 7.4 wt %, and FeOt of 34.5 wt %; while the Si-intergrowth has average SiO2 of 70.9 wt %, MgO of 0.6 wt %, FeOt of 4.5 wt %, K2O of 9.3 wt %, and Na2O of 0.3 wt %. Similar mineral assemblage (pyroxene, Fe-Ti oxides, apatite) in different phases, as well as the chemical and thermal tests approve two conjugated immiscible pairs, i.e. Si-droplets versus Fe-Ti-spots, and Fe- versus Si-intergrowth. It is proposed that the segregation of melts from metastable Fe-Si-intergrowth differentiated along spinodal (unstable zone), formed the Si-droplets and Fe-Ti-spots within the solvus/binodal curve (metastable zone). The different K and Na contents in K-rich rim and K-Na-rich core of the Si-droplets was probably formed by uphill diffusion above liquidus, while titanite in the Fe-Ti-spots crystallized at undercooling conditions during decomposition. The micrometer-scale Fe-Ti oxides and apatite were crystallized during the quench of the texture. The regressed Fe- and Si-rich pairs at the initial immiscible decomposition have SiO2 of 37.3/67.3 wt %, TiO2 of 2.8/0.97 wt %, FeOt of 31.1/3.5 wt %, MgO of 6.36/0.7 wt %, and K2O of 0.2/7.2 wt %, respectively. The Si-droplets formed above liquidus and are seen coalesced and thus were able to merge into rhyolite. The immiscible segregation may explain the bimodal features of the high-Fe-Ti and high-Si rocks of the Xiong'er igneous province. This rare coexisting immiscible texture with varied scales—the microscopic intergrowth and meso- to macroscopic Fe-Ti-spots/Si-droplets—tracks processes of micro- to macroscopic immiscible segregation, which depicts the role of immiscible differentiation in the diversification of natural rock types. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Petrology is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1093/petrology/egaf069 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 55 StartPage: 1 Subjects: – SubjectFull: Immiscibility Type: general – SubjectFull: Igneous rocks Type: general – SubjectFull: Phase separation Type: general – SubjectFull: Igneous provinces Type: general – SubjectFull: Mineralogy Type: general – SubjectFull: Microdroplets Type: general Titles: – TitleFull: Coexisting Centimeter-Scale Si-Droplets and Micrometer-Scale Fe-Si-Intergrowth in c. 1785 Ma Xiong'er Igneous Province: Tracking Micro- to Macroscopic Immiscibility. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Qin, Zhaoyuan – PersonEntity: Name: NameFull: Peng, Peng – PersonEntity: Name: NameFull: Liu, Xu – PersonEntity: Name: NameFull: Wang, Chong – PersonEntity: Name: NameFull: Wang, Xinping – PersonEntity: Name: NameFull: Xu, Bisheng – PersonEntity: Name: NameFull: Li, Binghe – PersonEntity: Name: NameFull: Shang, Guangrui – PersonEntity: Name: NameFull: Dai, Ke IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 09 Text: Sep2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 00223530 Numbering: – Type: volume Value: 66 – Type: issue Value: 9 Titles: – TitleFull: Journal of Petrology Type: main |
| ResultId | 1 |
