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Two-stage hybrid origin of Lachlan S-type magmas: A re-appraisal using isotopic microanalysis of lithic inclusion minerals

文献类型：期刊论文

作者Li, Rui2,4; Collins, William J.3; Yang, Jin-Hui1,2,4; Blereau, Eleanore3; Wang, Hao1,2,4
刊名LITHOS
出版日期2021-11-15
卷号402页码:17
关键词S-type granite Enclave Xenolith Monazite and apatite Nd isotopes Zircon Hf-O isotopes Lachlan Orogen THERMOCALC
ISSN号0024-4937
DOI10.1016/j.lithos.2021.106378
英文摘要Microanalysis of accessory minerals was carried out to elucidate the controversial origin of the classical, similar to 430 Ma (Silurian) S-type granites and related lithic inclusions from the eastern Lachlan Orogen, southeastern Australia. Inclusions were separated into igneous-derived, mafic microgranular enclaves (MME) and metasedimentary inclusions. Apatite epsilon Nd(t), and monazite epsilon Nd(t) isotopic values for granite host and inclusions cover a similar range (similar to-4 to -13), but their epsilon Nd(t) peaks are distinct. Whereas similar unimodal peaks exist for both minerals in the granites, suggesting widespread equilibration during hybridisation of two magmatic components in the host S-type magma, skewed or bimodal peaks characterize the MME and metasedimentary inclusions, indicating their different petrogenetic histories. The isotopic data suggests two endmembers: a mature meta sedimentary source with epsilon Nd(t) of -12, represented by ubiquitous Ordovician quartzose turbidites, and a more radiogenic component represented by a -5 epsilon Nd(t) peak in the MME. Zircon epsilon(Hf) values from -3 to -10, and delta O-18 values from 7.5 parts per thousand to 10.5 parts per thousand, reflect variable incorporation (40-80%) of metasedimentary material with a mantle-like endmember. Temperature estimates for magmatic equilibration are 750-800 degrees C, though evidence exists for transient higher temperatures in some inclusions. Phase equilibria modelling using the average composition of the Ordovician turbidites as a potential source-rock suggests that melt compositions were uniform, silicic (75-76 wt% SiO2) and peraluminous (ASI = 1.13-1.22), for a wide range of temperatures and water contents. However, neither the modelled residual rock (restite) compositions, nor the analysed metasedimentary inclusions, lie along the Lachlan S-type compositional array. Rather, the compositional array projects to a mafic endmember defined by the MME, suggesting widespread, efficient hybridization with weakly peraluminous, andesitic magmas. Source mixing models (without significant mantle-derived magma input) are rejected on petrological and geological criteria. The andesitic MME-type magmas were hybridized in the lower crust, probably during mafic magma underplating, before incorporation into large, cool, midcrustal S-type magma reservoirs, and the observed MME represent the final mingled stage of that interaction during emplacement at shallow crustal levels. Using a modern example from the Andes, a model is presented of 2-stage hybridization, initially near the Moho, then in the midcrust as hot, hybrid andesitic magmas repeatedly infused a resident, giant, low-T, S-type magma body. Late-stage injection of the MME generated localized inclusion swarms, as at Cowra and Deddick, and promoted eruption of vast S-type ignimbrite sheets during a major magmatic flare-up in the Lachlan orogen.
WOS关键词U-PB ZIRCON ; FOLD BELT ; SOUTHEASTERN AUSTRALIA ; DEDDICK GRANODIORITE ; GRANITIC-ROCKS ; METASEDIMENTARY ENCLAVES ; MICROGRANITOID ENCLAVES ; METAMORPHIC COMPLEX ; CENTRAL VICTORIA ; MIXING MODEL
资助项目NSFC of China[41688103] ; Curtin University Fellowship
WOS研究方向Geochemistry & Geophysics ; Mineralogy
语种英语
WOS记录号WOS:000712919500003
出版者ELSEVIER
资助机构NSFC of China ; NSFC of China ; NSFC of China ; NSFC of China ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; NSFC of China ; NSFC of China ; NSFC of China ; NSFC of China ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; NSFC of China ; NSFC of China ; NSFC of China ; NSFC of China ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; NSFC of China ; NSFC of China ; NSFC of China ; NSFC of China ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship ; Curtin University Fellowship
源URL[http://ir.iggcas.ac.cn/handle/132A11/103801]  
专题地质与地球物理研究所_岩石圈演化国家重点实验室
通讯作者Collins, William J.
作者单位1.Chinese Acad Sci, Inst Earth Sci, Beijing 100029, Peoples R China
2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
3.Curtin Univ, Inst Geosci Res TIGeR, Dept Appl Geol, GPO Box U1987, Perth, WA 6845, Australia
4.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式
GB/T 7714		 Li, Rui,Collins, William J.,Yang, Jin-Hui,et al. Two-stage hybrid origin of Lachlan S-type magmas: A re-appraisal using isotopic microanalysis of lithic inclusion minerals[J]. LITHOS,2021,402:17.
APA Li, Rui,Collins, William J.,Yang, Jin-Hui,Blereau, Eleanore,&Wang, Hao.(2021).Two-stage hybrid origin of Lachlan S-type magmas: A re-appraisal using isotopic microanalysis of lithic inclusion minerals.LITHOS,402,17.
MLA Li, Rui,et al."Two-stage hybrid origin of Lachlan S-type magmas: A re-appraisal using isotopic microanalysis of lithic inclusion minerals".LITHOS 402(2021):17.

入库方式： OAI收割

来源：地质与地球物理研究所

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